VFA Delivery System

Abstract

Devices, systems and methods deliver implantable medical devices for atrioventricular (VfA) cardiac treatment. The VfA device can be implanted in the right atrium (RA), where electrodes extend from the right atrium into the left ventricular myocardium. A flexible lead or other probe can be advanced to a potential implantation site and used to identify the precise location of an implanted medical device, such as an electrode, a small lead, a lead, or an intracardiac device. Some methods may include locating a potential implantation site in the Koch triangle in the right atrium of the patient's heart; attaching a retaining sheath to the right atrial endocardium of the potential implantation site; and implanting the medical device via a guidewire at the potential implantation site. An implantable medical device may include an intracardiac housing and a small lead that can be delivered by these methods.

Description

[0001] The present technology generally relates to devices, systems, and methods for delivering implantable medical devices.

[0002] The cardiac conduction system includes the sinoatrial (SA) node, the atrioventricular (AV) node, the His bundle, bundle branches, and Purkinje fibers. The heartbeat is initiated in the SA node, which can be described as the natural "pacemaker" of the heart. The electrical impulses generated by the SA node cause the atrial myocardium to contract. The electrical impulses or electrical pulses or signals are conducted to the ventricles via the AV node, which inherently delays conduction to allow the atria to stop contracting before the ventricles begin to contract, thereby providing appropriate AV synchronization. The electrical impulses are conducted from the AV node to the ventricular myocardium through the His bundle, bundle branches, and Purkinje fibers.

[0003] Patients with conduction system abnormalities (such as AV node poor conduction or poor SA node function) may receive an implantable medical device (IMD), such as a pacemaker, to restore a more normal heart rhythm and AV synchrony. Some types of IMDs, such as pacemakers, implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) devices, provide therapeutic electrical stimulation to the patient's heart through electrodes on one or more implantable endocardial, epicardial, or coronary venous leads located in or near the heart. Therapeutic electrical stimulation can be delivered to the heart in the form of pulses or shocks for pacing, cardioversion, or defibrillation. In some cases, the IMD can sense the intrinsic depolarization of the heart and control the delivery of therapeutic stimulation to the heart based on the sensing.

[0004] Delivering therapeutic electrical stimulation to the heart can help address cardiac conditions, such as ventricular dyssynchrony, which may occur in a patient. Ventricular dyssynchrony can be described as a lack of synchronization in the timing of contractions in the right and left ventricles of the heart or as a difference in the timing of contractions. Significant differences in contraction timing can reduce cardiac efficiency. CRT delivered to the heart by an IMD can enhance cardiac output by resynchronizing the electromechanical activity of the heart's ventricles. CRT may include "three-chamber pacing" when pacing the right atrium, right ventricle, and left ventricle.

[0005] In addition to cardiac pacing, such as from an ICD, arrhythmias can also be treated by delivering shock therapy for cardioversion or defibrillation, which can sense the patient's heart rhythm and classify the rhythm according to an arrhythmia detection scheme to detect the onset of tachycardia or fibrillation. Detected arrhythmias can include ventricular tachycardia (VT), rapid ventricular tachycardia (FVT), ventricular fibrillation (VF), atrial tachycardia (AT), and atrial fibrillation (AT). Anti-tachycardia pacing (ATP) can be used to treat ventricular tachycardia (VT) to essentially terminate many monomorphic rapid rhythms.

[0006] Available dual chamber medical devices include a transvenous atrial lead with electrodes that can be placed in the right atrium and a transvenous ventricular lead with electrodes that can be placed in the right ventricle via the right atrium. The dual chamber medical device itself is usually implanted in a subcutaneous pocket, and the transvenous lead is threaded into the subcutaneous pocket. The dual chamber medical device can sense atrial and ventricular electrical signals and can provide atrial pacing and ventricular pacing as needed to promote normal heart rhythm and AV synchronization. Some dual chamber medical devices can treat atrial and ventricular arrhythmias.

[0007] Intracardiac medical devices such as leadless pacemakers have been introduced or proposed to be implanted completely within the patient's heart, thereby eliminating the need for transvenous leads. Leadless pacemakers can include one or more electrodes on their housing to deliver therapeutic electrical signals and / or sense intrinsic depolarization of the heart. Intracardiac medical devices can provide cardiac therapeutic functions, such as sensing and pacing, within a single chamber of the patient's heart. Single-chamber intracardiac devices can also treat atrial or ventricular arrhythmias or fibrillation. Some leadless pacemakers are not intracardiac and can be located outside the heart, and in some instances, can be anchored to the heart wall via a fixation mechanism.

[0008] In some patients, a single-chamber device may adequately meet the patient's needs. However, a single-chamber device capable of only single-chamber sensing and treatment may not fully address cardiac conduction disease or abnormalities, such as AV dyssynchrony or tachycardia, in all patients. In some cases, dual-chamber sensing and / or pacing capabilities, in addition to ICD functionality, may be used to restore a more normal heart rhythm. Summary of the invention

[0009] The technology of the present disclosure generally relates to devices, systems and methods for delivering implantable medical devices for atrioventricular (VfA) cardiac therapy, such as single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing or tachycardia-related therapy. The VfA device can be implanted in the right atrium (RA), wherein the electrode extends from the right atrium to the left ventricular myocardium. Specifically, the present disclosure provides a technology for delivering and implanting a medical device in the Koch triangle in the right atrium. Various devices can be used to identify the general location of the Koch triangle, which can be described as a potential implantation site. A flexible lead or other probe can be advanced to the potential implantation site and used to identify the precise location of an implanted medical device (such as an electrode, a small lead, a lead or an intracardiac device). In some embodiments, the VfA device may include a tissue puncture electrode or a left ventricular electrode. Advantageously, in one or more embodiments, the technology of the present disclosure can be used to accurately deliver one or more VfA devices to an implantation site for VfA cardiac therapy. In particular, the techniques of the present disclosure may be used to implant devices to provide synchronized pacing to asynchronous patients, as well as to provide dual-chamber pacing to bradycardic patients with moderate heart failure.

[0010] In one aspect, the present disclosure provides a method for delivering a medical device. The method includes locating a potential implantation site in the Koch triangle in the right atrium of a patient's heart. The method also includes attaching a retaining sheath to the right atrial endocardium of the potential implantation site. The method includes implanting the medical device over a guidewire at the potential implantation site.

[0011] In another aspect, the present disclosure provides a medical device delivery system. The system includes a retainer sheath having a retainer assembly attachable to a right atrial endocardium in a Koch's triangle in a right atrium of a patient's heart. The system also includes a steerable assembly configured to steer the retainer sheath. The system includes a flexible needle at least partially disposed in an inner cavity of the retainer sheath. The system further includes a guidewire at least partially disposed in the inner cavity of the retainer sheath.

[0012] On the other hand, the present disclosure provides an implantable medical device comprising an endocardial shell and a small lead coupled to the endocardial shell. The device also includes a plurality of electrodes coupled to the endocardial shell, the small lead, or both. The plurality of electrodes include a left ventricular electrode that can be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fiber body to deliver cardiac therapy to the left ventricle in the base and / or septal region of the left ventricular myocardium of the patient's heart or sense the electrical activity of the left ventricle. The plurality of electrodes also include a right atrial electrode that can be positioned in the right atrium to deliver cardiac therapy to the right atrium of the patient's heart or sense the electrical activity of the right atrium. The system includes a therapy delivery circuit that is operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart, and a sensing circuit that is operably coupled to the plurality of electrodes to sense the electrical activity of the patient's heart. The system further includes a controller having a processing circuit system that is operably coupled to the therapy delivery circuit and the sensing circuit. The controller is configured to monitor electrical activity of the right atrium using the right atrial electrode, monitor electrical activity of the left ventricle using the left ventricular electrode, or both. The controller is further configured to deliver cardiac therapy using at least one of the plurality of electrodes based on the monitored electrical activity.

[0013] The details of one or more aspects of the disclosure are set forth below in the drawings and the specification. Other features, subjects, and advantages of the technology described in the disclosure will be apparent from the specification and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is used with, for example Figures 16 to 20Conceptual diagram of an illustrative cardiac treatment system for use with an illustrative method of the invention, the cardiac treatment system including an intracardiac medical device implanted in a patient's heart and a separate medical device positioned outside the patient's heart.

[0015] Figures 2 to 4 is used with, for example Figures 16 to 20 Conceptual diagram of an illustrative cardiac treatment system including a medical device including leads having electrodes implanted in a patient's heart for use in conjunction with an illustrative method.

[0016] Figure 5 yes Figure 1 A magnified conceptual illustration of an intracardiac medical device and the anatomy of a patient's heart.

[0017] Figure 6 is a conceptual diagram of a mapping of a patient's heart in a standard 17-segment view of the left ventricle, showing the use of, for example, Figures 1 to 4 and Fig. 22 Illustrative systems and devices for use with various electrode implantation locations.

[0018] Figure 7 is used with, for example Figures 1 to 4 and Fig. 22 A perspective view of an intracardiac medical device having a distal fixation and electrode assembly including distal housing-based electrodes implemented as ring electrodes for use with illustrative systems and devices of the present invention.

[0019] Figure 8 is encapsulated in e.g. Figures 1 to 4 and Fig. 22 A block diagram of illustrative circuitry within the housing of a medical device to provide the functions and treatments described herein.

[0020] Fig. 9 is used with, for example Figures 1 to 4 and Fig. 22 A perspective view of another illustrative intracardiac medical device for use with the illustrative systems and devices of FIG.

[0021] Fig.10 is used with, for example Figures 1 to 4 and Fig. 22 A flow chart of an illustrative method of using an atrial motion detector to detect atrial activity for use with an illustrative system and apparatus.

[0022] Fig.11 is used with, for example Figures 1 to 4 and Fig. 22 A flow chart of an illustrative method of using an illustrative system and apparatus together with detecting heart sounds to represent physiological response information.

[0023] Fig.12 is used with, for example Figures 1 to 4 and Fig. 22 A flow chart of an illustrative system and apparatus for use with an illustrative method of detecting bioimpedance to represent physiological response information.

[0024] Fig.13 is used with, for example Figures 1 to 4 and Fig. 22 A diagram of an illustrative system including an electrode device, a display device, and a computing device for use with the illustrative system and apparatus.

[0025] Figures 14 to 15 is used with, for example Figures 1 to 4 and Fig. 22 A diagram of an illustrative external electrode device for measuring torso surface potentials used in conjunction with an illustrative system and apparatus.

[0026] Fig.16 is used with, for example Figures 1 to 4 , 13 to 15 and 22 are conceptual diagrams of illustrative methods for delivering VfA medical devices in conjunction with the illustrative systems and devices.

[0027] Fig.17 It is used in e.g. Fig.16 Conceptual diagram of an illustrative approach to locating potential implantation sites within the Koch triangle used in the methods.

[0028] Fig.18 It is used in e.g. Fig.16 Conceptual diagram of an illustrative method of attaching a retainer sheath to the right atrial endocardium in a potential implantation site for use in the method of.

[0029] Fig.19 It is used for example Fig.16 A conceptual diagram of an illustrative method for determining whether a potential implantation site is acceptable in a method of.

[0030] Fig. 20 It is used for example Fig.16 A conceptual diagram of an illustrative method for preparing a potential implantation site for a medical device in a method of.

[0031] Fig.21 is used with, for example Figures 16 to 20 methods and / or Figures 1 to 4 , 13 to 15 and 22 are diagrams of medical device delivery systems for use with illustrative systems and devices.

[0032] Fig. 22 It is available for example Figures 16 to 20 Methods and / or use Fig.21 Diagram of a medical device delivery system for implanting an implantable medical device.

[0033] Fig.23 yes Fig.21 An illustration of an example of a medical device delivery system.

[0034] Fig.24 Comes as a kit Fig.23 Illustration of components of a medical device delivery system.

[0035] Fig.25 Is used with leads Fig.23 Illustration of a medical device delivery system.

[0036] Figures 26A to 26B is an X-ray image of a catheter in the coronary sinus (CS) and a guidewire in the central cardiac vein. Fig.26A Lateral images at 90 degrees lateral and 25 degrees cephalad are shown. The valve plane is shown by the catheter curve in the CS. Fig.26B A dorsal-ventral (DV) view of the heart is shown, showing a near vertical view of the valve plane. The angle is 0 degrees lateral and 25 degrees cephalad.

[0037] Figures 27A to 27B is an X-ray image showing the orientation of the flexible catheter (eg, steerable sheath) and needle for the first penetration. Fig.27A A side view is shown. Fig.27B DV view is shown. The needle is not sufficiently apical in the lateral view and is not aligned with the aorta in the DV view. The flexible catheter and / or helix is ​​located in the CS ostium shown crossed by the midcardiac vein (MCV) sheath and the CS sheath.

[0038] Figures 28A to 28B is an X-ray image showing the second implantation location and the needle with the dilator on top. In addition, a 0.014" guidewire is extended into the left ventricle (LV). Fig.28A It is a side view. Fig.28B It is DV view.

[0039] Figures 29A to 29B is an X-ray image showing the final position of a lead placed over a guidewire passed from the right atrium (RA) to the LV. The electrodes are shown on the lead. Fig.29A It is a side view. Fig.29B It is DV view.

[0040] Figures 30A to 30B is an image showing the second passage of the needle and guidewire into the tissue, showing the flexible catheter, MCV guide catheter and CS catheter. The MCV and CS sheaths cross very close to the CS port. Fig. 30A It is a side view. Fig. 30B It is DV view.

[0041] Fig.31is an image of the spiral showing the location of the first needle and guidewire channel. The entry point for this attempted procedure was inside the CS but still near the tricuspid valve.

[0042] Figures 32A to 32B is an image of the leads leading to the LV chamber. The lead is routed from the very low CS ostium near the tricuspid annulus to the posterior papillary muscle in the LV. Fig.32A It is a side view. Fig.32B It is DV view.

[0043] Figures 33A to 33B are X-ray images of the catheter in CS and the guidewire in MCB. Fig.33A Lateral images at 90 degrees lateral and 25 degrees cephalad are shown. The valve plane is shown by the curve of the catheter aligned with the aortic valve in CS. Fig.33B A DV view of the heart is shown, showing a near vertical view of the valve plane. The angle is 0 degrees lateral and 25 degrees caudal. The aortic valve is located in the middle of the LV.

[0044] Figures 34A to 34B is an X-ray image of contrast agent injected into the LV. Fig.34A It is a side view. Fig.34B It is DV view.

[0045] Figures 35A to 35B is an X-ray image showing the orientation of the flexible catheter and needle for the first penetration. Fig.35A This is a lateral view. The needle is slightly apical to the plane of the valve. Fig.35B is a DV view. The needle is directed toward the aorta, while the tip of the flexible catheter is directed away from the CS.

[0046] Figures 36A to 36B is an X-ray image showing the first implantation location and the needle with the dilator extending into the LV. Fig.36A It is a side view. Fig.36B It is DV view.

[0047] Figures 37A to 37B is an X-ray image showing the final position of the lead as it passes from the RA to the LV. The side view shows the lead at the helix, while the DV view shows the tip of the lead in the LV cavity. The route of the lead in the side view is shown by the guidewire. Fig.37A It is a side view. Fig.37B It is DV view.

[0048] Figures 38A to 38B is an X-ray image of the second implantation of the lead, showing the position of the flexible catheter and helix prior to needle insertion. Fig.38A It is a side view. Fig.38B It is DV view.

[0049] Figures 39A to 39Bis an X-ray image showing the needle and dilator extended into the LV. Fig.39A It is a side view. Fig.39B It is DV view.

[0050] Figures 40A to 40B is an X-ray image showing a bipolar lead over a guidewire extending into the LV. Fig.40A This is a lateral view. The lead is routed slightly apically with the guidewire in the LV. Fig.40B This is a DV view. The lead is routed toward the aorta.

[0051] Figures 41A to 41B is an image showing the second passage of the needle and guidewire into the tissue, showing the flexible catheter and CS catheter. The entrance to the MCV is not shown. Fig.41A It is a side view. Fig.41B It is DV view.

[0052] Figures 42A to 42B is an image showing the lead entry site near the mouth in CS. The site is just on the substrate, such as Fig.42B Another entry site appears in the image about 1 cm "below" the lead entry site shown. This other entry site may be the first or initial penetration site, after which the tool is removed, followed by a second attempt. Fig.42A It is a side view. Fig.42B It is DV view.

[0053] Figures 43A to 43B is an image showing the tip of the lead in the left chamber. The valve is the mitral valve, and Fig.43A and Fig.43B In the figure, the tip of the lead can be seen protruding from beneath the posterior papillary muscle. This appears to be more toward the wall of the LV than the mid-chamber. Fig.43A It is a side view. Fig.43B It is DV view.

[0054] Figures 44A to 44B is an image showing a lead passing through the septum. The pass is relatively perpendicular to the tissue. While this can vary, the goal here is to have a perpendicular path to the LV chamber. Fig.44A It is a side view. Fig.44B It is DV view. DETAILED DESCRIPTION

[0055] The technology of the present disclosure generally relates to devices, systems and methods for delivering implantable medical devices for atrioventricular (VfA) cardiac therapy, such as single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related treatment. In some embodiments, the various techniques described herein may also be applied to His bundle pacing applications. Although reference is made herein to implantable medical devices, such as pacemakers or ICDs, the methods and processes may be used with any medical device, system or method involving a patient's heart. Various other applications will be apparent to those skilled in the art who benefit from the present disclosure.

[0056] It may be beneficial to provide an implantable medical device without a transvenous lead (e.g., a leadless device). It may also be beneficial to provide an implantable medical device that can be used for various cardiac therapies, such as single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), atrioventricular synchronous pacing, asynchronous pacing, triggered pacing, cardiac resynchronization pacing, or tachycardia-related therapy. In addition, it may be beneficial to provide a technique for delivering a medical device to the Koch triangle in the right atrium in an accurate and precise manner to facilitate pacing the endocardium and / or the His bundle conduction system.

[0057] The present disclosure provides an implantable medical device comprising a tissue puncturing electrode and optionally a right atrial electrode and / or a right atrial motion detector. The implantable medical device may be a VfA device implanted from the right atrium into the left ventricular myocardium. The implantable medical device may be used in adaptive cardiac therapy, for example, adapting pacing delays based on at least a measured heart rate. Physiological response measurements may be performed, and the VfA device may be configured to deliver cardiac therapy based on the physiological response information. Specifically, the VfA device may be configured to adapt pacing therapy based on different heart rates, for example, by determining and delivering pacing therapy with an optimal atrioventricular (AV) pacing delay. Advantageously, in one or more embodiments, the techniques of the present disclosure may be used to calibrate or deliver pacing therapy without using the electrical activity of the right ventricle of the patient's heart being monitored.

[0058] The tissue puncture electrode can be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fiber body into the basal region and / or septal region of the left ventricular myocardium of the patient's heart. In a leadless implantable medical device, the tissue puncture electrode can extend leadlessly from the distal region of the housing of the device, and the right atrial electrode can be leadlessly coupled to the housing (e.g., a portion of the exterior of the housing or positioned on the exterior of the housing). The right atrial motion detector can be within the implantable medical device. In a leaded implantable medical device, one or more of the electrodes can be coupled to the housing using an implantable lead. When the device is implanted, the electrodes can be used to sense electrical activity in one or more atria and / or ventricles of the patient's heart. The motion detector can be used to sense mechanical activity in one or more atria and / or ventricles of the patient's heart. Specifically, the activity of the right atrium and left ventricle can be monitored, and optionally, the activity of the right ventricle can be monitored. The electrodes can be used to deliver cardiac therapy, such as single chamber pacing for atrial fibrillation, atrioventricular synchronous pacing for bradycardia, asynchronous pacing, triggered pacing, cardiac resynchronization pacing for ventricular asynchrony, anti-tachycardia pacing, or shock therapy. Shock therapy can be initiated by the implantable medical device. A separate medical device such as an extravascular ICD that can also be implanted can communicate operably with the implantable medical device and can deliver a shock in response to a trigger such as a signaling pulse (e.g., a trigger, signaling, or distinguishing electrical pulse) provided by the device.

[0059] The present disclosure also provides a technique for delivering and implanting a medical device in the Koch triangle of the right atrium. Various devices can be used to identify the general location of the Koch triangle, which can be described as a potential implantation site. A flexible lead or other probe can be advanced to the potential implantation site and used to identify the precise location of an implanted medical device (such as an electrode, a small lead, a lead, or an intracardiac device). Specifically, the technology of the present disclosure can be used to implant a device to provide synchronized pacing to an asynchronous patient, and to provide dual-chamber pacing to a bradycardic patient with moderate heart failure.

[0060] Figures 1 to 4 It is shown that one can use, for example Figures 16 to 20 Examples of various cardiac treatment systems for delivering medical devices to implant sites using the methods shown. Although the present disclosure describes leadless and leaded implantable medical devices, reference is first made to Figure 1, which shows a conceptual diagram of a cardiac treatment system 2 including an intracardiac medical device 10, which can be configured for single-chamber or dual-chamber treatment and implanted in a patient's heart 8. In some embodiments, the device 10 can be configured for single-chamber pacing and can, for example, switch between single-chamber pacing and multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing). As used herein, "intracardiac" refers to a device that is configured to be completely implanted within a patient's heart (for example) to provide cardiac treatment. The device 10 is shown to be implanted in a target implantation area 4 of the right atrium (RA) of the patient's heart 8. The device 10 may include one or more fixation members 20 that anchor the distal end of the device to the atrial endocardium in the target implantation area 4. The target implantation area 4 can be located between the bundle of His 5 (or bundle of His) and the coronary sinus 3, and can be adjacent to the tricuspid valve 6. Device 10 may be described as an atrioventricular (VfA) device that can sense or provide therapy to one or both ventricles (e.g., the right ventricle, the left ventricle, or both ventricles, depending on the context) while typically being disposed in the right atrium. Specifically, device 10 may include a tissue-penetrating electrode that may be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fibrous body into the basal and / or septal region of the left ventricular myocardium of the patient's heart.

[0061] The device 10 can be described as a leadless implantable medical device. As used herein, "leadless" refers to a device that does not have leads extending out of the patient's heart 8. In other words, a leadless device can have leads that do not extend from the outside of the patient's heart to the inside of the patient's heart. Some leadless devices can be introduced intravenously, but once implanted, the device does not or may not include any transvenous leads and can be configured to provide cardiac therapy without the use of any transvenous leads. In addition, the leadless VfA device, in particular, does not use leads to be operably connected to electrodes in the ventricles when the housing of the device is located in the atrium. In addition, the leadless electrodes can be coupled to the housing of the medical device without the use of leads between the electrodes and the housing.

[0062] The device 10 may include a dart electrode assembly 12 that defines or has a straight axis extending from a distal region of the device 10. The dart electrode assembly 12 may be placed or at least configured to be placed through the atrial myocardium and the central fiber body and into the ventricular myocardium 14 or along the ventricular septum without completely penetrating the ventricular endocardial or epicardial surface. The dart electrode assembly 12 may carry or include an electrode at the distal region of the shaft so that the electrode may be positioned within the ventricular myocardium for sensing ventricular signals and delivering ventricular pulses (e.g., depolarizing the left ventricle to initiate contraction of the left ventricle). In some instances, the electrode at the distal region of the shaft is a cathode electrode that is provided for centering of a bipolar electrode pair for pacing and sensing. While the illustrated implantation region 4 may enable one or more electrodes of the dart electrode assembly 12 to be positioned within the ventricular myocardium, it will be appreciated that devices having aspects disclosed herein may be implanted in other locations for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing), single-chamber pacing with multi-chamber sensing, single-chamber pacing and / or sensing, or other clinical treatments and applications, as appropriate.

[0063] It should be understood that although the device 10 is described herein as including a single dart electrode assembly, the device 10 may include more than one dart electrode assembly that is placed or configured to be placed through the atrial myocardium and central fiber body and into the ventricular myocardium 14, or along the ventricular septum without completely penetrating the ventricular endocardial or epicardial surface. In addition, each dart electrode assembly may carry or include more than one single electrode at the distal region of the shaft or along other regions (e.g., the proximal or central region).

[0064] The cardiac treatment system 2 may also include a separate medical device 50 (in Figure 1 ), which can be located outside the patient's heart 8 (e.g., subcutaneously) and can be operably coupled to the patient's heart 8 to deliver cardiac therapy thereto. In one instance, the separate medical device 50 can be an extravascular ICD. In some embodiments, the extravascular ICD can include a defibrillation lead including or carrying a defibrillation electrode. The therapy vector can exist between the defibrillation electrode on the defibrillation lead and the housing electrode of the ICD. In addition, one or more electrodes of the ICD can also be used to sense electrical signals related to the patient's heart 8. The ICD can be configured to deliver electrical shock therapy including one or more defibrillation or cardioversion shocks. For example, if an arrhythmia is sensed, the ICD can send pulses via electrical leads to shock the heart and restore its normal rhythm. In some instances, the ICD can deliver electrical shock therapy without placing electrical leads in the heart or attaching wires directly to the heart (subcutaneous ICD). An example of an extravascular subcutaneous ICD that may be used with the system 2 described herein may be described in U.S. Patent No. 9,278,229 (Reinke et al.), issued on March 8, 2016.

[0065] In the case of shock therapy (e.g., a defibrillation shock provided by a defibrillation electrode of a defibrillation lead), a separate medical device 50 (e.g., an extravascular ICD) can include a control circuit that uses a therapy delivery circuit to generate a defibrillation shock having any of a variety of waveform characteristics, including leading edge voltage, tilt, delivered energy, pulse phase, etc. The therapy delivery circuit can, for example, generate a monophasic, biphasic, or multiphasic waveform. In addition, the therapy delivery circuit can generate a defibrillation waveform with different amounts of energy. For example, the therapy delivery circuit can generate a defibrillation waveform that delivers a total of about 60 to 80 joules (J) of energy for subcutaneous defibrillation.

[0066] The individual medical device 50 may further include a sensing circuit. The sensing circuit may be configured to obtain an electrical signal sensed via one or more combinations of electrodes, and process the obtained signal. The components of the sensing circuit may include analog components, digital components, or a combination thereof. The sensing circuit may, for example, include one or more sensing amplifiers, filters, rectifiers, threshold detectors, analog-to-digital converters (ADCs), etc. The sensing circuit may convert the sensed signal into a digital form, and provide the digital signal to the control circuit for processing and / or analysis. For example, the sensing circuit may amplify the signal from the sensing electrode, and may convert the amplified signal into a multi-bit digital signal by the ADC, and then provide the digital signal to the control circuit. In one or more embodiments, the sensing circuit may also compare the processed signal with a threshold value to detect the presence of atrial or ventricular depolarization (e.g., P wave or R wave), and indicate the presence of atrial depolarization (e.g., P wave) or ventricular depolarization (e.g., R wave) to the control circuit.

[0067] The device 10 and the separate medical device 50 can cooperate to provide cardiac therapy to the patient's heart 8. For example, the device 10 and the separate medical device 50 can be used to detect tachycardia, monitor tachycardia and / or provide tachycardia-related therapy. For example, the device 10 can wirelessly communicate with the separate medical device 50 to trigger an electric shock therapy using the separate medical device 50. As used herein, "wirelessly" refers to an operational coupling or connection between the device 10 and the separate medical device 50 without the use of metallic conductors. In one example, wireless communication can use a distinguishing signaling or triggering electrical pulse provided by the device 10, which is conducted through the patient's tissue and can be detected by the separate medical device 50. In another example, wireless communication can use a communication interface (e.g., an antenna) of the device 10 to provide electromagnetic radiation, which propagates through the patient's tissue and can be detected, for example, using a communication interface (e.g., an antenna) of the separate medical device 50.

[0068] Reference Figure 2, the leaded medical device 408 includes one or a single implantable lead 410 having a tissue piercing electrode assembly 12 coupled to a distal region of the lead and implanted within the patient's heart 8. The housing 420 of the leaded medical device 408 can be implanted and positioned outside the patient's heart 8 and is configured to calibrate pacing therapy and / or deliver pacing therapy, for example, based at least on a measured heart rate. The lead 410 may include a right atrial electrode, and the device 408 may be operated as a device with dual-channel capabilities (e.g., pacing and / or sensing in the right atrium and left ventricle). In some embodiments, the lead 410 may not include a right atrial electrode. In other words, the leaded medical device 408 may be a single-channel device that can be used for asynchronous, triggered, or other types of single-channel pacing. When the tissue piercing electrode assembly 12 is implanted, for example, in conjunction with a device related to Figure 1 In the same or similar manner as described, leaded medical device 408 using lead 410 can sense activity or deliver pacing to the left ventricle (LV).

[0069] refer to Figure 3 , a leaded medical device 418 similar to Figure 2 The leaded medical device 408 is a device 418 having two implantable leads 410, 412. Specifically, the implantable lead 412 may include an electrode (e.g., a right atrium electrode) coupled to a distal region of the lead 412 and may be implanted in a different location than the lead 410. In some embodiments, the lead 412 is implanted in a different region of the right atrium. In some embodiments, each lead 410, 412 may constitute one channel of the dual channel device 418. For example, when implanting a tissue piercing electrode of the tissue piercing electrode assembly 12, for example, in order to Figure 1 In the same or similar manner as described, lead 410 can sense activity or deliver pacing to the left ventricle (LV), and lead 412 can sense activity or deliver pacing to the right atrium (RA).

[0070] Reference Figure 4 , a leaded medical device 428 similar to Figure 3 414. In some embodiments, the lead 414 is implanted in the region of the right ventricle. In some embodiments, each lead 410, 412, 414 can constitute a channel of the multi-channel device 428. For example, when the tissue piercing electrode assembly 12 is implanted, for example, in a manner similar to that of the electrode assembly 12, the electrode assembly 12 can be implanted in a manner similar to that of the electrode assembly 12. Figure 1In the same or similar manner described, lead 410 can sense activity or deliver pacing to the left ventricle (LV), lead 412 can sense activity from the delivery of pacing to the right atrium (RA), and lead 414 can sense activity or deliver pacing to the right ventricle (RV).

[0071] In some embodiments, for example, a separate medical device such as an electrode device (e.g., an ECG strip) can be used to calibrate or optimize the pacing delay (e.g., RV-LV pacing delay, or more generally, VV pacing delay) between the RV electrode on lead 414 for pacing the RV and the LV electrode on lead 410 for pacing the LV. Various methods can be used to calibrate or optimize the VV delay. In some embodiments, the medical device 428 can be used to test pacing with multiple different VV delays. For example, the RV can be paced approximately 80, 60, 40, and 20 milliseconds (ms) before the LV, and the LV can be paced approximately 80, 60, 40, and 20 ms before the RV, as well as simultaneous RV-LV pacing (e.g., a VV pacing delay of approximately 0 ms). The medical device 428 can then be configured to, for example, automatically select a VV pacing delay that, when used for pacing, corresponds to the minimum electrical dyssynchrony measured using the electrode device. Test pacing at different VV pacing delays may be performed using a specific AV delay (such as a nominal AV delay set by medical device 428) or a predetermined optimal AV delay based on patient characteristics.

[0072] Figure 5 yes Figure 1 1 and an enlarged conceptual diagram of an intracardiac medical device 10 and the anatomy of a patient's heart 8. Specifically, the device 10 is configured to pace therapy and / or deliver pacing therapy, for example, based at least on a measured heart rate. The intracardiac device 10 may include a housing 30. The housing 30 may define a hermetically sealed lumen in which the internal components of the device 10 reside, such as sensing circuitry, therapy delivery circuitry, control circuitry, memory, telemetry circuitry, other optional sensors, and a power source, such as in combination with a heart rate sensor. Figure 8 Generally described. The housing 30 can be formed of a conductive material including titanium or a titanium alloy, stainless steel, MP35N (non-magnetic nickel-cobalt-chromium-molybdenum alloy), a platinum alloy, or other biocompatible metals or metal alloys. In other examples, the housing 30 can be formed of a non-conductive material including ceramic, glass, sapphire, silicone, polyurethane, epoxy resin, acetyl copolymer plastic, polyetheretherketone (PEEK), liquid crystal polymer, or other biocompatible polymers.

[0073] In at least one embodiment, the housing 30 can be described as extending in a generally cylindrical shape between a distal region 32 and a proximal region 34 to facilitate catheter delivery. In other embodiments, the housing 30 can be prismatic or any other shape to perform the functions and uses described herein. The housing 30, for example at the proximal region 34, can include a delivery tool interface member 26 for engaging with a delivery tool during implantation of the device 10.

[0074] All or a portion of the housing 30 may be used as an electrode during cardiac therapy, for example, in sensing and / or pacing. In the illustrated example, the housing-based electrode 24 is shown surrounding a proximal portion of the housing 30 (e.g., closer to the proximal region 34 than the distal region 32). When the housing 30 is formed of a conductive material, such as a titanium alloy or other examples listed above, portions of the housing 30 may be electrically insulated by a non-conductive material, such as a coating of parylene, polyurethane, silicone, epoxy, or other biocompatible polymer, leaving one or more discrete areas of the conductive material exposed to define the proximal housing-based electrode 24. When the housing 30 is formed of a non-conductive material such as a ceramic, glass, or polymer material, a conductive coating or layer such as titanium, platinum, stainless steel, or alloys thereof may be applied to one or more discrete areas of the housing 30 to form the proximal housing-based electrode 24. In other examples, the proximal housing-based electrode 24 may be a component mounted or assembled to the housing 30, such as a ring electrode. When the housing 30 is a non-conductive material, the proximal housing-based electrodes 24 may be electrically coupled to the internal circuitry of the device 10 , for example, via the conductive housing 30 or electrical conductors.

[0075] In the illustrated example, the proximal housing-based electrode 24 is closer to the housing proximal region 34 relative to the housing distal region 32, and is therefore referred to as a "proximal housing-based electrode" 24. However, in other examples, the housing-based electrode 24 can be located at other locations along the housing 30, for example, farther away from the illustrated location.

[0076] At the distal region 32, the device 10 may include a distal fixation and electrode assembly 36, which may include one or more fixation members 20 of equal or unequal length and one or more dart electrode assemblies 12. In one example, a single dart electrode assembly 12 includes a shaft 40 extending distally away from the housing distal region 32 and one or more electrode assemblies, such as a tip electrode 42, at or near a free distal region of the shaft 40. The tip electrode 42 may have a conical or hemispherical distal tip with a relatively narrow tip diameter (e.g., less than about 1 millimeter (mm)) for piercing and passing through tissue layers without using a sharp tip or a needle tip with a sharp or beveled edge.

[0077] The shaft 40 of the dart electrode assembly 12 can be a generally straight member and can be rigid. In other embodiments, the shaft 40 can be described as relatively stiff, but still having limited flexibility in the lateral direction. In addition, the shaft 40 can be non-rigid to allow some lateral flexure to occur with heart movement. However, in a relaxed state, when not subjected to any external forces, the shaft 40 can remain in a straight position as shown to space the tip electrode 42 from the housing distal region 32 by at least the height 47 of the shaft 40. In other words, the dart electrode assembly 12 can be described as elastic.

[0078] The dart electrode assembly 12 may be configured to pierce one or more tissue layers to position the tip electrode 42 within a desired tissue layer (e.g., ventricular myocardium). In this way, the height 47 or length of the shaft 40 may correspond to the expected pacing site depth, and the shaft 40 may have a relatively high compressive strength along its longitudinal axis to resist bending in the lateral or radial direction when pressed against the implantation area 4. If a second dart electrode assembly 12 is employed, its length may not be equal to the expected pacing site depth and may be configured to act as an indifferent electrode for delivering pacing energy to the tissue. For example, by applying a longitudinal thrust to the proximal region 34 of the housing 30, a longitudinal axial force may be applied to the tip electrode 42 to advance the dart electrode assembly 12 into tissue within the target implantation area. When subjected to a lateral force or a radial force, the shaft 40 may be described as being longitudinally non-compressible and / or elastically deformable in the lateral or radial direction to allow, for example, temporary bending as the tissue moves, but the shaft may return to its generally straight position when the lateral force is reduced. When the shaft 40 is not subjected to any external forces or is subjected only to forces along its longitudinal center axis, the shaft 40 may maintain a straight linear position, as shown.

[0079] One or more fixation members 20 may be described as one or more "tines" having a normal curved position. The tines may be located in a distally extending position within the delivery tool. Upon release from the delivery tool, the distal tips of the tines may penetrate the cardiac tissue to a limited depth before elastically bending proximally back to the normal curved position (shown). In addition, the fixation member 20 may include, for example, one or more aspects described in U.S. Pat. No. 9,675,579 (Grubac et al.), issued on June 13, 2017, and U.S. Pat. No. 9,119,959 (Rys et al.), issued on September 1, 2015.

[0080] In some examples, the distal fixation and electrode assembly 36 includes a distal housing-based electrode 22. In the case of using the device 10 as a pacemaker for multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) and sensing, the tip electrode 42 can be used as a cathode electrode paired with the proximal housing-based electrode 24 used as a return anode electrode. Alternatively, the distal housing-based electrode 22 can be used as a return anode electrode paired with the tip electrode 42 for sensing ventricular signals and delivering ventricular pacing pulses. In other examples, the distal housing-based electrode 22 can be a cathode electrode for sensing atrial signals and delivering pacing pulses to the atrial myocardium in the target implant area 4. When the distal housing-based electrode 22 is used as an atrial cathode electrode, the proximal housing-based electrode 24 can be used as a return anode paired with the tip electrode 42 for ventricular pacing and sensing, and can be used as a return anode paired with the distal housing-based electrode 22 for atrial pacing and sensing.

[0081] As shown in this figure, in some pacing applications, the target implantation area 4 is along the atrial endocardium 18, typically inferior to the AV node 15 and the bundle of His 5. The dart electrode assembly 12 can at least partially define a height 47 or length of the shaft 40 to pass through the atrial endocardium 18 in the target implantation area 4 and through the central fiber body 16 into the ventricular myocardium 14 without passing through the ventricular endocardial surface 17. When the height 47 or length of the dart electrode assembly 12 is fully advanced into the target implantation area 4, the tip electrode 42 can rest within the ventricular myocardium 14, and the distal housing-based electrode 22 can be positioned in close contact or close proximity to the atrial endocardium 18. In various examples, the dart electrode assembly 12 can have a total combined height 47 or length of the tip electrode 42 and the shaft 40 from about 3 mm to about 8 mm. The diameter of the shaft 40 can be less than about 2 mm, and can be about 1 mm or less, or even about 0.6 mm or less.

[0082] The device 10 may include an acoustic or motion detector 11 within the housing 30. The acoustic or motion detector 11 may be operably coupled to one or more control circuits 80 ( Figure 8 )、Sensing circuit 86( Figure 8 ) or therapy delivery circuit 84 ( Figure 8 In some embodiments, the acoustic or motion detector 11 may be coupled to Figures 10 to 12The acoustic or motion detector 11 can be used in conjunction with the method 600, 650 or 800 shown. The acoustic or motion detector 11 can be used to monitor mechanical activity, such as atrial mechanical activity (e.g., atrial contraction) and / or ventricular mechanical activity (e.g., ventricular contraction). In some embodiments, the acoustic or motion detector 11 can be used to detect right atrial mechanical activity. Non-limiting examples of the acoustic or motion detector 11 include an accelerometer or a microphone. In some embodiments, the mechanical activity detected by the acoustic or motion detector 11 can be used to supplement or replace the electrical activity detected by one or more of the electrodes of the device 10. For example, the acoustic or motion detector 11 can be used with the proximal housing-based electrode 24 or as a substitute for the proximal housing-based electrode.

[0083] The acoustic or motion detector 11 may also be used for rate responsiveness detection or to provide a rate responsiveness IMD. Various techniques related to rate responsiveness may be described in U.S. Pat. No. 5,154,170 (Bennett et al.), entitled "Optimization for rate responsive cardiac pacemaker," issued Oct. 13, 1992, and U.S. Pat. No. 5,562,711 (Yerich et al.), entitled "Method and apparatus for rate-responsive cardiac pacing," issued Oct. 8, 1996.

[0084] In various embodiments, an acoustic or motion detector 11 (or motion sensor) can be used as a HS sensor and can be implemented as a microphone or a 1-axis, 2-axis, or 3-axis accelerometer. In one embodiment, the acoustic sensor is implemented as a piezoelectric crystal mounted within the implantable medical device housing and responsive to mechanical motion associated with heart sounds. The piezoelectric crystal can be a dedicated HS sensor or can be used for multiple functions. In the illustrative embodiment shown, the acoustic sensor is implemented as a piezoelectric crystal that is also used to generate a patient alarm signal in the form of a perceptible vibration of the IMD housing. When an alarm condition is detected, the control circuit 80 can cause the patient alarm control circuit system to generate an alarm signal by activating the piezoelectric crystal.

[0085] The control circuitry may be used to control whether the piezoelectric crystal is used in a "listening mode" to sense HS signals via the HS sensing circuitry, or in an "output mode" to generate a patient alarm. During patient alarm generation, the HS sensing circuitry may be temporarily decoupled from the HS sensor by the control circuitry.

[0086] Examples of other embodiments of acoustic sensors that may be suitable for implementation using the techniques of the present disclosure may be generally described in U.S. Pat. No. 4,546,777 (Groch et al.), U.S. Pat. No. 6,869,404 (Schulhauser et al.), U.S. Pat. No. 5,554,177 (Kieval et al.), and U.S. Pat. No. 7,035,684 (Lee et al.).

[0087] Various types of acoustic sensors may be used. The acoustic sensor may be any implantable or external sensor that responds to one or more of the heart sounds generated as previously described, thereby producing an analog electrical signal that is related in time and amplitude to the heart sounds. The analog signal may then be processed by the HS sensing module, which may include digital conversion to obtain HS parameters, such as amplitude or relative time intervals derived by the HS sensing module or control circuit 80. The acoustic sensor and HS sensing module may be incorporated into an IMD capable of delivering CRT or another cardiac therapy being optimized, or may be implemented in a separate device having wired or wireless communication with the IMD or in an external programmer or computer used during a pacing parameter optimization procedure as described herein.

[0088] Figure 6 300 (e.g., a top view) of a patient's heart, showing a left ventricle 320 and a right ventricle 322 in a standard 17-segment view. The map 300 includes a plurality of regions 326 corresponding to different regions of a human heart. As shown, the regions 326 are numerically labeled 1-17 (e.g., corresponding to a standard 17-segment model of a human heart, corresponding to 17 segments of a left ventricle of a human heart, etc.). The regions 326 of the map 300 may include a basal anterior region 1, a basal anterior septal region 2, a basal inferior septal region 3, a basal inferior region 4, a basal inferior lateral region 5, a basal anterolateral region 6, a mid-anterior region 7, an anterior septal middle region 8, an inferior septal middle region 9, a lower middle region 10, a lower lateral middle region 11, an anterolateral middle region 12, an apical anterior region 13, an apical septal region 14, an apical inferior region 15, an apical region 16, and an apex region 17. Also shown are the infraseptal and anteroseptal regions of the right ventricle 322, as well as the right bundle branch (RBB) and left bundle branch (LBB).

[0089] In some embodiments, any tissue piercing electrode of the present disclosure can be implanted in the basal and / or septal region of the left ventricular myocardium of the patient's heart. Specifically, the tissue piercing electrode can be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fiber body.

[0090] Once implanted, the tissue-penetrating electrodes can be positioned at the target implantation area 4 ( Figures 1 to 5), such as the basal and / or septal regions of the left ventricular myocardium. Referring to FIG300, the basal region includes one or more of the basal anterior region 1, the basal anterior septal region 2, the basal inferior septal region 3, the basal inferior region 4, the mid-anterior region 7, the anterior septal middle region 8, the inferior septal middle region 9, and the inferior middle region 10. Referring to FIG300, the septal region includes one or more of the basal anterior septal region 2, the basal anterior septal region 3, the anterior septal middle region 8, the inferior septal middle region 9, and the apical septal region 14.

[0091] In some embodiments, when implanted, the tissue puncture electrode can be positioned in the basal septal region of the left ventricular myocardium. The basal septal region can include one or more of the basal anterior septal region 2, the basal inferior septal region 3, the anterior septal mid region 8, and the inferior septal mid region 9.

[0092] In some embodiments, when implanted, the tissue puncture electrode can be positioned in the superior inferior / posterior basal septum region of the left ventricular myocardium. The superior inferior / posterior basal septum region of the left ventricular myocardium may include a portion of one or more of the basal inferior septum region 3 and the inferior septal middle region 9 (e.g., only the basal inferior septum region, only the inferior septal middle region, or both the basal inferior septum region and the inferior septal middle region). For example, the superior inferior / posterior basal septum region may include an area 324 generally shown as a dashed line boundary. As shown, the dashed line boundary represents an approximation of where the superior inferior / posterior basal septum region is located, which may take a slightly different shape or size depending on the specific application.

[0093] Figure 7 3D perspective view of a device 10 capable of calibrating pacing therapy and / or delivering pacing therapy, for example, based at least on a measured heart rate. As shown, a distal fixation and electrode assembly 36 includes a distal housing-based electrode 22 implemented as a ring electrode. When the fixation member tines 20a, 20b, and 20c of the fixation member 20 engage the atrial tissue, the distal housing-based electrode 22 can be positioned in close contact with the atrial tissue or operably close to the atrial tissue. The elastically deformable tines 20a, 20b, and 20c can be extended distally during delivery of the device 10 to the implantation site. For example, when the device 10 is pushed out of the delivery tool, the tines 20a, 20b, and 20c can pierce the atrial endocardial surface, and when no longer constrained in the delivery tool, the tines bend back to their normal bent positions (as shown). When the tines 20a, 20b, and 20c bend back to their normal positions, the fixation member 20 can pull the distal fixation member and electrode assembly 36 toward the atrial endocardial surface. When the distal fixation member and electrode assembly 36 are pulled toward the atrial endocardium, the tip electrode 42 can be advanced through the atrial myocardium and the central fiber body and into the ventricular myocardium. The distal housing-based electrode 22 can then be positioned against the atrial endocardial surface.

[0094] The distal housing-based electrode 22 may include a ring formed of a conductive material, such as titanium, platinum, iridium, or alloys thereof. The distal housing-based electrode 22 may be a single continuous ring electrode. In other examples, portions of the ring may be coated with an electrically insulating coating, such as polyparaxylene, polyurethane, silicone, epoxy, or other insulating coating, to reduce the conductive surface area of ​​the ring electrode. For example, one or more segments of the ring may be coated to separate two or more conductive exposed surface areas of the distal housing-based electrode 22. Reducing the conductive surface area of ​​the distal housing-based electrode 22, such as by covering portions of the conductive ring with an insulating coating, may increase the electrical impedance of the distal housing-based electrode 22, and thereby reduce the current delivered during a pacing pulse that captures myocardium (e.g., atrial myocardial tissue). Lower current consumption may save a power source for the device 10, such as one or more rechargeable or non-rechargeable batteries.

[0095] As described above, the distal housing-based electrode 22 can be configured as an atrial cathode electrode for delivering pacing pulses to atrial tissue at the implant site in combination with the proximal housing-based electrode 24 as a return anode. The electrodes 22 and 24 can be used to sense atrial P waves for controlling atrial pacing pulses (delivered in the absence of the sensed P waves) and for controlling atrial synchronized ventricular pacing pulses delivered using the tip electrode 42 as a cathode and the proximal housing-based electrode 24 as a return anode. In other examples, the distal housing-based electrode 22 can be used as a return anode in conjunction with the cathode tip electrode 42 for ventricular pacing and sensing.

[0096] Figure 8 is a block diagram of a circuit system, which may be encapsulated in a housing 30 ( Figure 7 ) to provide for use of the device 10 according to one example or any other medical device described herein (e.g., Figure 2 Device 408, Figure 3 Device 418, Figure 4 Device 428 or Fig. 9 The device 710) has a housing that can be used to calibrate pacing therapy and / or deliver pacing therapy based on at least the measured heart rate. Figures 1 to 4) may include some or all of the same components, which may be configured in a similar manner. The electronic circuit system encapsulated in the housing 30 may include software, firmware, and hardware that collaboratively monitor atrial and ventricular electrocardiographic signals, determine when cardiac therapy is needed, and / or deliver electrical pulses to the patient's heart according to programmed treatment modes and pulse control parameters. The electronic circuit system may include a control circuit 80 (e.g., including a processing circuit system), a memory 82, a treatment delivery circuit 84, a sensing circuit 86, and / or a telemetry circuit 88. In some instances, the device 10 includes one or more sensors 90 for generating signals related to a patient's physiological function, state, or condition, such as a patient activity sensor, for determining whether pacing therapy is needed and / or controlling the pacing rate. For example, a sensor 90 may include an inertial measurement unit (e.g., an accelerometer) to measure motion.

[0097] The power supply 98 can provide power to the circuit system of the device 10 including each of the components 80, 82, 84, 86, 88, 90 as needed. The power supply 98 can include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. A person of ordinary skill in the art can understand the connection between the power supply 98 and each component 80, 82, 84, 86, 88, 90 through the general block diagram shown (not shown). For example, the power supply 98 can be coupled to one or more charging circuits included in the therapy delivery circuit 84 to provide power for charging the holding capacitor included in the therapy delivery circuit 84, and the holding capacitor is discharged at the appropriate time under the control of the control circuit 80, so as to deliver pacing pulses according to a dual-chamber pacing mode such as DDI (R). The power supply 98 can also be coupled to components of the sensing circuit 86 (e.g., sensing amplifiers, analog-to-digital converters, switching circuit systems, etc.), sensors 90, telemetry circuits 88, and memory 82 to provide power to various circuits.

[0098] The functional blocks shown represent the functions included in the device 10 and may include any discrete and / or integrated electronic circuit components that implement analog and / or digital circuits capable of producing the functions of the medical device 10 herein. The various components may include processing circuit systems (such as application specific integrated circuits (ASICs) that execute one or more software or firmware programs, electronic circuits, processors (shared, dedicated, or groups), and memory), combinational logic circuits, state machines, or other suitable components or combinations of components that provide the described functions. The specific form of software, hardware, and / or firmware used to implement the functions disclosed herein will be determined primarily by the specific system architecture employed in the medical device and the specific detection and treatment delivery methods employed by the medical device.

[0099] The memory 82 may include any volatile, nonvolatile, magnetic, or electrically non-transitory computer-readable storage medium, such as a random access memory (RAM), a read-only memory (ROM), a nonvolatile RAM (NVRAM), an electrically erasable programmable ROM (EEPROM), a flash memory, or any other memory device. In addition, the memory 82 may include a non-transitory computer-readable medium storing instructions that, when executed by one or more processing circuits, cause the control circuit 80 and / or other processing circuit systems to calibrate pacing therapy and / or perform pacing therapy (e.g., single-chamber or multi-chamber pacing) or other cardiac therapy functions (e.g., sensing or delivering therapy) attributed to single-chamber, dual-chamber, or triple-chamber calibration of the device 10. The non-transitory computer-readable medium storing instructions may include any of the media listed above.

[0100] The control circuit 80 can communicate with the therapy delivery circuit 84 and the sensing circuit 86, for example, via a data bus, to sense cardiac electrical signals and control the delivery of cardiac electrical stimulation therapy in response to sensed cardiac events (e.g., P waves and R waves, or the absence of P waves and R waves). The tip electrode 42, the distal housing-based electrode 22, and the proximal housing-based electrode 24 can be electrically coupled to the therapy delivery circuit 84 to deliver electrical stimulation pulses to the patient's heart and the sensing circuit 86, and for sensing cardiac electrical signals.

[0101] The sensing circuit 86 may include an atrial (A) sensing channel 87 and a ventricular (V) sensing channel 89. The distal housing-based electrode 22 and the proximal housing-based electrode 24 may be coupled to the atrial sensing channel 87 to sense atrial signals, such as a P wave accompanying atrial myocardial depolarization. In instances including two or more optional distal housing-based electrodes, the sensing circuit 86 may include a switching circuit system for selectively coupling one or more of the available distal housing-based electrodes to the cardiac event detection circuit system included in the atrial sensing channel 87. The switching circuit system may include a switch array, a switch matrix, a multiplexer, or any other type of switching device suitable for selectively coupling components of the sensing circuit 86 to selected electrodes. The tip electrode 42 and the proximal housing-based electrode 24 may be coupled to the ventricular sensing channel 89 to sense ventricular signals, such as an R wave accompanying atrial myocardial depolarization.

[0102] Each of the atrial sensing channel 87 and the ventricular sensing channel 89 may include a cardiac event detection circuit system for detecting P waves and R waves, respectively, from cardiac electrical signals received by the corresponding sensing channel. The cardiac event detection circuit system included in each channel 87 and 89 may be configured to amplify, filter, digitize and rectify the cardiac electrical signals received from the selected electrodes to improve the signal quality for detecting cardiac electrical events. The cardiac event detection circuit system within each channel 87 and 89 may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. Cardiac event sensing thresholds, such as P wave sensing thresholds and R wave sensing thresholds, can be automatically adjusted by each corresponding sensing channel 87 and 89 under the control of the control circuit 80 (e.g., based on a timing interval and a sensing threshold determined by the control circuit 80), stored in the memory 82, and / or controlled by the hardware, firmware, and / or software of the control circuit 80 and / or the sensing circuit 86.

[0103] Upon detecting a cardiac electrical event based on a sensing threshold crossing, the sensing circuit 86 may generate a sensed event signal that is transmitted to the control circuit 80. For example, the atrial sensing channel 87 may generate a P-wave sensed event signal in response to a P-wave sensing threshold crossing. The ventricular sensing channel 89 may generate an R-wave sensed event signal in response to an R-wave sensing threshold crossing. The sensed event signal may be used by the control circuit 80 to set a pacing escape interval timer that controls a base time interval for scheduling cardiac pacing pulses. The sensed event signal may trigger or inhibit pacing pulses according to a particular programmed pacing mode. For example, a P-wave sensed event signal received from the atrial sensing channel 87 may cause the control circuit 80 to inhibit a scheduled atrial pacing pulse and schedule a ventricular pacing pulse at a programmed atrioventricular (AV) pacing interval. If an R-wave is sensed before the AV pacing interval expires, the ventricular pacing pulse may be inhibited. If the AV pacing interval expires before control circuit 80 receives an R-wave sense event signal from ventricular sensing channel 89, control circuit 80 may use therapy delivery circuit 84 to deliver a predetermined ventricular pacing pulse synchronized with the sensed P-wave.

[0104] In some instances, the device 10 can be configured to deliver various pacing therapies, including bradycardia pacing, cardiac resynchronization therapy, post-shock pacing, and / or tachycardia-related therapies, such as ATP, etc. For example, the device 10 can be configured to detect non-sinus tachycardia and deliver ATP. The control circuit 80 can determine cardiac event time intervals, such as the PP interval between consecutive P wave sensing event signals received from the atrial sensing channel 87, the RR interval between consecutive R wave sensing event signals received from the ventricular sensing channel 89, and the PR and / or RP intervals received between the P wave sensing event signals and the R wave sensing event signals. These intervals can be compared to the tachycardia detection interval to detect non-sinus tachycardia. Tachycardia can be detected in a given cardiac chamber based on a threshold number of tachycardia detection intervals detected.

[0105] The therapy delivery circuit 84 may include an atrial pacing circuit 83 and a ventricular pacing circuit 85. Each pacing circuit 83, 85 may include charging circuitry, one or more charge storage devices (e.g., one or more low voltage holding capacitors), an output capacitor, and / or switching circuitry that controls the delivery of pacing pulses to a pacing electrode vector coupled to the respective pacing circuit 83, 85 as the holding capacitor is charged and discharged across the output capacitor. The tip electrode 42 and the proximal housing-based electrode 24 may be coupled to the ventricular pacing circuit 85 as a bipolar cathode and anode pair to deliver ventricular pacing pulses, for example, upon expiration of an AV or VV pacing interval set by the control circuit 80, thereby providing atrial synchronized ventricular pacing and a substantially lower ventricular pacing rate.

[0106] The atrial pacing circuit 83 can be coupled to the distal housing-based electrode 22 and the proximal housing-based electrode 24 to deliver atrial pacing pulses. The control circuit 80 can set one or more atrial pacing intervals based on a programmed lower pacing rate, or set a temporary lower rate based on a pacing rate indicated by a rate-responsive sensor. If the atrial pacing interval expires before a P-wave sense event signal is received from the atrial sensing channel 87, the atrial pacing circuit can be controlled to deliver an atrial pacing pulse. The control circuit 80 starts an AV pacing interval in response to the delivered atrial pacing pulse to provide synchronized multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing).

[0107] Charging the holding capacitors of the atrial or ventricular pacing circuits 83, 85 to a programmed pacing voltage amplitude and discharging the capacitors to a programmed pacing pulse width may be performed by the therapy delivery circuit 84 in accordance with control signals received from the control circuit 80. For example, a pacing timing circuit included in the control circuit 80 may include a programmable digital counter set by a microprocessor of the control circuit 80 to control basic pacing time intervals associated with various single-chamber or multi-chamber pacing (e.g., dual-chamber or triple-chamber pacing) modes or anti-tachycardia pacing sequences. The microprocessor of the control circuit 80 may also set the amplitude, pulse width, polarity, or other characteristics of the cardiac pacing pulses based on programmed values ​​stored in the memory 82.

[0108] The device 10 may include other sensors 90 for sensing signals from the patient for use in determining the need for and / or controlling the electrical stimulation therapy delivered by the therapy delivery circuit 84. In some instances, the sensor indicating the need for increased cardiac output may include a patient activity sensor, such as an accelerometer. An increase in the patient's metabolic demand caused by increased activity indicated by the patient activity sensor may be determined by the control circuit 80 for use in determining a pacing rate indicated by the sensor. The control circuit 80 may be used to calibrate and / or deliver pacing therapy based on the patient activity sensor (e.g., a measured heart rate).

[0109] The control parameters used by the control circuit 80 for sensing cardiac events and controlling the delivery of pacing therapy can be programmed into the memory 82 via the telemetry circuit 88, which can also be described as a communication interface. The telemetry circuit 88 includes a transceiver and an antenna for communicating with an external device such as a programmer or a home monitor using radio frequency communications or other communication protocols. The control circuit 80 can use the telemetry circuit 88 to receive downlink telemetry from the external device and send uplink telemetry to the external device. In some cases, the telemetry circuit 88 can be used to send and receive communication signals to / from another medical device implanted in the patient.

[0110] Fig. 9 7 is a three-dimensional perspective view of another leadless intracardiac medical device 710 according to another example, which can be configured for calibrating pacing therapy and / or delivering pacing therapy for single-chamber or multi-chamber heart therapy (e.g., dual-chamber or triple-chamber heart therapy), for example, based at least on a measured heart rate. The device 710 may include a housing 730 having an outer sidewall 735 extending from a housing distal region 732 to a housing proximal region 734, the outer sidewall being shown as a cylindrical outer sidewall. The housing 730 may encapsulate an electronic circuit system configured to perform single-chamber or multi-chamber heart therapy, including atrial and ventricular cardiac electrical signal sensing and pacing of atrial and ventricular chambers. A delivery tool interface member 726 is shown on the housing proximal region 734.

[0111] The distal fixation and electrode assembly 736 can be coupled to the housing distal region 732. The distal fixation and electrode assembly 736 can include an electrically insulating distal member 772 coupled to the housing distal region 732. The tissue piercing electrode assembly 712 extends away from the housing distal region 732, and the plurality of non-tissue piercing electrodes 722 can be directly coupled to the insulating distal member 772. The tissue piercing electrode assembly 712 extends longitudinally away from the housing distal region 732 and can be coaxial with the longitudinal center axis 731 of the housing 730.

[0112] The distal tissue piercing electrode assembly 712 may include an electrically insulated shaft 740 and a tip electrode 742 (e.g., a tissue piercing electrode). In some instances, the tissue piercing electrode assembly 712 is an active fixation member that includes a helical shaft 740 and a distal cathode tip electrode 742. The helical shaft 740 may extend from a shaft distal region 743 to a shaft proximal region 741, which may be directly coupled to an insulating distal member 772. The helical shaft 740 may be coated with an electrically insulating material, such as polyparaxylene or other examples listed herein, to avoid sensing or stimulating cardiac tissue along the length of the shaft. The tip electrode 742 is located at the shaft distal region 743 and may be used as a cathode electrode for delivering ventricular pacing pulses and sensing ventricular electrical signals using a proximal housing-based electrode 724 as a return anode when the tip electrode 742 is advanced into the ventricular tissue. The proximal housing-based electrode 724 may be a ring electrode surrounding the housing 730 and may be defined by an uninsulated portion of the longitudinal sidewall 735. Other portions of the housing 730 that are not used as electrodes may be coated with an electrically insulating material, such as in the above combination. Figure 7 described.

[0113] The use of two or more tissue piercing electrodes (e.g., any type of piercing electrodes) penetrating the LV myocardium can provide for more localized pacing capture and can mitigate the impact of atrial tissue capture of ventricular pacing spikes. In some embodiments, the multiple tissue piercing electrodes may include two or more dart-type electrode assemblies (e.g., Figure 7 The plurality of tissue piercing electrodes may also be used for bipolar or multipolar pacing.

[0114] In some embodiments, one or more tissue piercing electrodes (e.g., any type of piercing electrode) that penetrate the LV myocardium can be a multipolar tissue piercing electrode. The multipolar tissue piercing electrode can include one or more electroactive components and an electro-detachable component that can enable bipolar or multipolar pacing using one or more tissue piercing electrodes.

[0115] A plurality of non-tissue piercing electrodes 722 may be disposed along the periphery of the insulating distal member 772 and located around the tissue piercing electrode assembly 712. The insulating distal member 772 may define a distal-facing surface 738 of the device 710 and a circumferential surface 739 located at the periphery of the device 710 adjacent to the longitudinal sidewall 735 of the housing. The non-tissue piercing electrodes 722 may be formed of a conductive material, such as titanium, platinum, iridium, or alloys thereof. In the illustrated embodiment, six non-tissue piercing electrodes 722 are radially spaced at equal distances along the outer periphery of the insulating distal member 772. However, two or more non-tissue piercing electrodes 722 may be provided.

[0116] The non-tissue piercing electrodes 722 can be discrete components, each of which is retained within a corresponding recess 774 in an insulating member 772 that is sized and shaped to mate with the non-tissue piercing electrodes 722. In other examples, the non-tissue piercing electrodes 722 can each be an uninsulated exposed portion of a unitary component mounted within or on an insulating distal member 772. Intermediate portions of the unitary component that do not serve as electrodes can be insulated by the insulating distal member 772 or, if exposed to the surrounding environment, can be coated with an electrically insulating coating such as parylene, polyurethane, silicone, epoxy, or other insulating coating.

[0117] When tissue piercing electrode assembly 712 is advanced into cardiac tissue, at least one non-tissue piercing electrode 722 may be positioned against, in close contact with, or operably positioned near the surface of cardiac tissue for transmitting pulses generated by the patient's heart and / or sensing cardiac electrical signals. For example, non-tissue piercing electrode 722 may be positioned in contact with right atrial endocardial tissue for pacing and sensing in the atrium as tissue piercing electrode assembly 712 is advanced into atrial tissue and through the central fiber body until distal tip electrode 742 is positioned in direct contact with ventricular tissue (e.g., ventricular myocardium) and / or a portion of the ventricular conduction system.

[0118] The non-tissue piercing electrode 722 may be coupled to the therapy delivery circuit 84 and the sensing circuit 86 enclosed by the housing 730 (see Figure 8), to be used collectively as a cathode electrode in combination with a housing-based proximal electrode 724 as a return anode for delivering atrial pacing pulses and for sensing atrial electrical signals, such as P waves. The switch circuitry included in the sensing circuit 86 can be activated under the control of the control circuit 80 to couple one or more non-tissue piercing electrodes to the atrial sensing channel 87. The distal non-tissue piercing electrodes 722 can be electrically isolated from each other so that each individual electrode 722 can be individually selected by the switch circuitry included in the therapy delivery circuit 84 to be used as an atrial cathode electrode, either individually or in combination of two or more of the electrodes 722. The switch circuitry included in the therapy delivery circuit 84 can be activated under the control of the control circuit 80 to couple one or more of the non-tissue piercing electrodes 722 to the atrial pacing circuit 83. Two or more of the non-tissue piercing electrodes 722 can be selected at one time to operate as multiple atrial cathode electrodes.

[0119] Certain non-tissue piercing electrodes 722 may be selected for atrial pacing and / or atrial sensing based on atrial capture threshold testing, electrode impedance, P-wave signal strength in the ECG signal, or other factors. For example, any combination of a single or two or more individual non-tissue piercing electrodes 722 may be selected to achieve reliable atrial pacing with minimal current consumption from the power supply 98, wherein the non-tissue piercing electrodes serve as cathode electrodes that provide an optimal combination of low pacing capture threshold amplitude and relatively high electrode impedance.

[0120] In some cases, when the tissue piercing electrode assembly 712 anchors the housing 730 at the implantation site, the distal-facing surface 738 may uniformly contact the atrial endocardial surface. In that case, all of the electrodes 722 may be selected together to form an atrial cathode. Alternatively, every other one of the electrodes 722 may be selected together to form a multiple atrial cathode with higher electrical impedance, which is still evenly distributed along the distal-facing surface 738. Alternatively, a subset of one or more electrodes 722 along one side of the insulating distal member 772 may be selected to provide pacing at a desired location where the lowest pacing capture threshold is achieved due to the relative position of the electrodes 722 to the atrial tissue being paced.

[0121] In other cases, the distal-facing surface 738 may be oriented at an angle relative to the adjacent endocardial surface, depending on the positioning and orientation of the tissue piercing electrode assembly 712 into the cardiac tissue. In this case, one or more of the non-tissue piercing electrodes 722 may be positioned to contact the adjacent endocardial tissue closer than other non-tissue piercing electrodes 722, which may be angled away from the endocardial surface. By providing multiple non-tissue piercing electrodes along the periphery of the insulating distal member 772, the angle of the tissue piercing electrode assembly 712 and the housing distal region 732 relative to the cardiac surface (e.g., the right atrial endocardial surface) may not need to be substantially parallel. Anatomical and positional differences may cause the distal-facing surface 738 to be angled or tilted relative to the endocardial surface, however, multiple non-tissue piercing electrodes 722 distributed along the periphery of the insulating distal member 772 increase the likelihood of good contact between one or more electrodes 722 and adjacent cardiac tissue to facilitate acceptable pacing thresholds and reliable cardiac event sensing using at least a subset of the multiple electrodes 722. Circumferential contact or fixation along the entire periphery of the insulating distal member 772 may not be required.

[0122] The non-tissue piercing electrodes 722 shown each include a first portion 722a extending along a distal-facing surface 738 and a second portion 722b extending along a circumferential surface 739. The first portion 722a and the second portion 722b can be continuous exposed surfaces such that the active electrode surface wraps around a peripheral edge 776 of the insulating distal member 772, the peripheral edge engaging the distal-facing surface 738 and the circumferential surface 739. The non-tissue piercing electrodes 722 can include one or more of the electrodes 722 along the distal-facing surface 738, one or more electrodes along the circumferential surface 739, one or more electrodes extending along both the distal-facing surface 738 and the circumferential surface 739, or any combination thereof. The exposed surface of each non-tissue piercing electrode 722 can be flush with the corresponding distal-facing surface 738 and / or circumferential surface. In other examples, each non-tissue piercing electrode 722 can have a convex surface protruding from the insulating distal member 772. However, any raised surface of electrode 722 may define a smooth or rounded non-tissue piercing surface.

[0123] The distal fixation and electrode assembly 736 can seal the distal region of the housing 730 and can provide a basis on which the electrode 722 is mounted. The electrode 722 can be referred to as a housing-based electrode. The electrode 722 can be carried by a shaft or other extension that extends the active electrode portion away from the housing 730, such as a distal tip electrode 742 located at the distal tip of a helical shaft 740 extending away from the housing 730. Other examples of non-tissue piercing electrodes coupled to the distal-facing surface and / or circumferential surface of the insulated distal member proposed herein include a distal housing-based ring electrode 22 ( Figure 7 ), around component 36 ( Figure 7 ) circumferentially extending distal housing-based ring electrodes, button electrodes, other housing-based electrodes, and other circumferential ring electrodes. Any non-tissue piercing electrodes directly coupled to the distal insulating member and peripherally coupled to the central tissue piercing electrode may be provided to function individually, collectively, or in any combination as cathode electrodes for delivering pacing pulses to adjacent cardiac tissue. When ring electrodes, such as the distal ring electrode 22 and / or circumferential ring electrodes are provided, portions of the ring electrodes may be electrically insulated by a coating to provide a plurality of distributed non-tissue piercing electrodes along the distal-facing surface and / or circumferential surface of the insulating distal member.

[0124] The non-tissue piercing electrodes 722 and other examples listed above are expected to provide more reliable and effective atrial pacing and sensing than tissue piercing electrodes provided along the distal fixation and electrode assembly 736. The atrial wall is relatively thin compared to the ventricular wall. The tissue piercing atrial cathode electrode may extend too deep into the atrial tissue, resulting in inadvertent, continuous or intermittent capture of ventricular tissue. The tissue piercing atrial cathode electrode can cause interference with sensed atrial signals due to the ventricular signals having a greater signal strength in the cardiac electrical signals received via the tissue piercing atrial cathode electrode, which is physically closer to the ventricular tissue. The tissue piercing electrode assembly 712 can be firmly anchored into the ventricular tissue to stabilize the implantation position of the device 710 and provide reasonable certainty that the tip electrode 742 is sensing and pacing in the ventricular tissue while the non-tissue piercing electrode 722 is reliably pacing and sensing in the atrium. When the device 710 is implanted in the target implant area 4, for example, as Figure 1 Within the ventricular septum shown, the tip electrode 742 can reach the left ventricular tissue to pace the left ventricle, while the non-tissue piercing electrode 722 paces and senses in the right atrium. The length of the tissue piercing electrode assembly 712 ranges from about 4 mm to about 8 mm from the distal-facing surface 738 to the left ventricular tissue. In some cases, the device 710 can achieve four-chamber pacing by delivering atrial pacing pulses from the atrial pacing circuit 83 via the non-tissue piercing electrode 722 in the target implant area 4 to achieve bi-atrial (right atrium and left atrium) capture, and by delivering ventricular pacing pulses from the ventricular pacing circuit 85 via the tip electrode 742 that enters the ventricular tissue from the target implant area 4 to achieve bi-ventricular (right ventricle and left ventricle) capture.

[0125] Fig.10 shows an example using Figure 5An illustrative method 600 for detecting atrial activity using an acoustic or motion detector 11 of a patient's heart may be used to represent physiological response information. Specifically, method 600 may include detecting atrial contraction based on analysis of a motion signal (e.g., provided by motion detector 11), which may be performed by an IMD implanted in a patient's heart. In some embodiments, the motion signal may be provided by an IMD implanted in a ventricle of the patient's heart, such as a right ventricle. Method 600 may include starting an atrial contraction detection delay period 630 when a ventricular activation event is identified. Method 600 may include starting an atrial contraction detection window 632 when the atrial contraction delay period expires. Method 600 may include analyzing the motion signal within the atrial contraction detection window.

[0126] The method 600 may include filtering the motion signal within the atrial contraction detection window, rectifying the filtered signal, and generating a derivative signal of the filtered and rectified motion signal 634 within the atrial contraction detection window. The method 600 may include determining whether the amplitude of the derivative signal within the atrial contraction detection window exceeds a threshold 636. In response to determining that the amplitude of the derivative signal within the atrial contraction detection window exceeds the threshold (yes of 636), the method 600 may proceed to detecting atrial contraction 638. Otherwise (no of 636), the method 600 may return to filtering, rectifying, and generating the derivative signal 634. Various techniques using a motion detector that provides a motion signal may be described in U.S. Pat. No. 9,399,140 (Cho et al.), issued on July 26, 2016, entitled "Atrial contraction detection by aventricular leadless pacing device for atrio-synchronous ventricular pacing."

[0127] If you will refer to Fig.11As described herein, heart sounds (HS) can be detected and used to represent physiological response information. As described herein, the amplitude and / or relative time interval of one or more of the S1 to S4 heart sounds can be used to optimize the patient's hemodynamic response to CRT or other cardiac treatments including cardiac pacing and / or neural stimulation to achieve hemodynamic benefits. The first heart sound S1 corresponds to the beginning of ventricular contraction. Ventricular contraction begins when the action potential is conducted through the atrioventricular node (AV node) and rapidly depolarizes the ventricular myocardium. This event is distinguished by the QRS complex on the ECG. When the ventricles contract, the pressure in the ventricles begins to rise, causing the mitral and tricuspid valves to suddenly close between the ventricles and atria when the ventricular pressure exceeds the atrial pressure. This valve closure can produce S1. S1 typically has a duration of about 150ms and a frequency of about 20 to 250Hz. The amplitude of S1 can provide an alternative measure of LV contractility. Therefore, an increase in the S1 amplitude is positively correlated with an improvement in LV contractility. Other measurements, such as the pre-ejection period measured from the onset of the QRS to S1, can also be used as an alternative index of myocardial contractility.

[0128] Separation of mitral and tricuspid valve closure due to ventricular dyssynchrony can be observed as separate M1 and T1 peaks in the S1 signal. The merging of M1 (mitral valve closure sound) and T1 (tricuspid valve closure sound) can be used as an indicator of improved ventricular synchrony.

[0129] Normally, after the QRS complex of the ECG and the closure of the mitral valve, left ventricular pressure (LVP) rises sharply and continues to rise during ventricular contraction until the aortic and pulmonary valves open, ejecting blood into the aorta and pulmonary arteries. During the ejection phase, ventricular contraction usually continues to cause blood pressure to rise in the ventricles, aorta, and pulmonary arteries. As contraction decreases, blood pressure decreases until the aortic and pulmonary valves close.

[0130] The second heart sound S2 can be generated by the closure of the aortic valve and the pulmonary valve near the end of ventricular contraction and the beginning of ventricular diastole. Therefore, S2 can be related to the diastolic pressure in the aorta and the pulmonary artery. S2 typically has a duration of about 120ms and a frequency of 25 to 350Hz. The time interval between S1 and S2, that is, the S1-S2 time interval can represent the contraction time interval (STI) corresponding to the ventricular isovolumetric contraction (pre-ejection) and ejection phases of the cardiac cycle. The S1-S2 time interval can provide an alternative measure of stroke volume. In addition, the ratio of the pre-ejection period (Q-S1) to the S1-S2 time can be used as an indicator of myocardial contractility.

[0131] The third heart sound, S3, is associated with early passive diastolic filling of the ventricles, while the fourth heart sound, S4, may be associated with late active filling of the ventricles due to atrial contraction. Typically, the third heart sound is difficult to hear using a stethoscope in an average patient, while the fourth heart sound is not typically heard in an average patient. The presence of the third and fourth heart sounds during an examination using a stethoscope may indicate a pathological condition. The S3 and S4 heart sounds may be used to optimize pacing parameters because they relate to the diastolic function of the heart. Typically, these sounds will be minimized or disappear when optimal pacing parameters are identified. Other aspects of the S1 to S4 heart sounds and their timing may be used for cardiac pacing parameter optimization, as is known to those of ordinary skill in the art.

[0132] Fig.11 800 is a flow chart of a method for optimizing pacing control parameters using heart sounds, according to one embodiment. The disclosed method may include one or more of the blocks shown in flow chart 800. Other examples of optimizing cardiac therapy using heart sounds are generally described in U.S. Patent No. 9,643,0134, entitled “System and method for pacing parameter optimization using heart sounds,” issued on May 9, 2017.

[0133] The pacing parameter optimization method may be initiated at block 802. The optimization process may be initiated in response to a user command received via an external programmer. A user may initiate the HS-based optimization procedure using an external programmer or a networked computer at the time of initial IMD implantation or during an in-office follow-up visit or during a remote patient monitoring session. Additionally or alternatively, the process illustrated in flowchart 800 may be an automated process that is initiated periodically or in response to sensing a need for therapy delivery or therapy adjustment based on sensed physiological signals (which may include sensed HS signals).

[0134] At box 804, a pacing control parameter to be optimized is selected. The control parameter can be a timing-related parameter, such as an AV interval or a VV interval. A pacing vector is another control parameter that can be selected for optimization at box 804. For example, when a multipolar lead such as a coronary sinus lead is used, multiple bipolar or unipolar pacing vectors can be selected for pacing in a given cardiac chamber. The pacing site associated with a particular pacing vector can have a significant impact on the hemodynamic benefit of the pacing therapy. Therefore, the pacing vector is one pacing control parameter that can be optimized using the methods described herein.

[0135] A pacing sequence is initiated at box 806 using the initial parameter settings for the test parameters selected at box 804. In one embodiment, the AV interval is optimized and ventricular pacing is delivered at the initial AV interval setting. It should be understood that the initial AV interval setting can be selected at box 806 by first measuring the intrinsic AV interval in a patient with complete AV conduction (i.e., no AV block). The initial AV interval can be a default pacing interval, a last programmed AV interval, or a minimum or maximum AV interval to be measured. Alternatively, if a VV interval is selected for optimization, the intrinsic interventricular conduction time can be measured first, and the paced VV interval can be iteratively adjusted starting with a VV interval that is longer, shorter, or approximately equal to the intrinsic VV conduction time.

[0136] An iterative process for adjusting the selected test parameter to at least two different settings is performed. The parameters can be adjusted to the different settings in any desired order, e.g., ascending, descending, random, etc. For example, during adjustment of the AV interval, the initial AV interval can be set to just longer than or approximately equal to the measured intrinsic AV conduction time and then iteratively reduced to a minimum AV interval test setting. During pacing using each pacing parameter setting, an HS signal is acquired at box 808. At box 812, the iterative process advances to the next test parameter setting until all test parameter settings have been applied as determined at box 810 and an HS signal has been recorded for each setting.

[0137] HS signals may be acquired for multiple cardiac cycles, thereby enabling an overall average or averaging of HS parameter measurements acquired from each cardiac cycle. It should be understood that amplification, filtering, rectification, noise removal techniques, or other signal processing steps may be used to improve the signal-to-noise ratio of the HS signal, and that these steps may be different for each heart sound acquired (which may include any or all types of heart sounds).

[0138] At block 814, at least one HS parameter measurement is determined from the recorded HS signals for each test parameter setting.The IMD processor or an external processor, such as included in a programmer, or a combination of both, may perform the HS signal analysis described herein.

[0139] In one embodiment, at box 814, S1 and S2 are recorded and HS parameters are measured using the S1 and S2 signals. For example, the amplitude of S1, the V-S2 interval (where the V event can be a V paced or sensed R wave), and the S1-S2 interval are measured. In addition, the presence of S3 and / or S4 can be noted, or these signals or measurements can be performed to determine related parameters. HS signal parameters are determined for at least two different test parameter settings, for example, at least two different AV intervals, two or more different VV intervals, or two or more different pacing vectors.

[0140] At box 818, a trend is determined for each HS parameter determined at box 810 as a function of the pacing parameter test settings. In one embodiment, a trend is determined for each of the V-S2 interval, the S1 amplitude, and the S1-S2 interval. Other embodiments may include determining the separation of the M1 and T1 sounds during the S1 signal. At box 820, an optimal pacing parameter setting may be automatically identified by the processor based on the trend of the HS parameter relative to the varying pacing control parameter. Additionally or alternatively, at box 822, the HS trend is reported and displayed on an external device such as a programmer or a remote networked computer.

[0141] If the pacing parameter being tested is, for example, a pacing site or pacing vector when a multipolar electrode is positioned along a cardiac chamber (such as a quadripolar lead along the LV), the pacing site or vector may be selected based on maximizing a HS-based surrogate for ventricular contractility. In one embodiment, the amplitude of S1 is used as a surrogate for ventricular contractility, and the pacing site or vector associated with the maximum S1 is identified at block 820 as the optimal pacing vector setting.

[0142] Determining the trend of each HS parameter at block 818 may include determining whether the V-S2 interval trend exhibits an abrupt slope change, such as from a substantially flat trend to a decreasing trend. The AV interval associated with the abrupt change in the V-S2 interval trend may be identified as the optimal AV interval setting. The optimal AV interval may be further identified based on other HS trends, such as, for example, the maximum S1 amplitude and / or the maximum S1-S2 interval.

[0143] In some embodiments, the automatically identified optimal pacing parameter settings may also be automatically programmed in the IMD at block 824. In other embodiments, a clinician or user reviews the reported HS data and the recommended pacing parameter settings and may accept the recommended settings or select another setting based on the HS data.

[0144] The HS sensing module or circuit system can be operably coupled to the control circuit 80 ( Figure 8 ), and is configured to receive analog signals from the HS sensor for sensing one or more of these heart sounds. For example, the HS sensing module may include one or more "channels" that are configured to specifically sense specific heart sounds based on the frequency, duration, and timing of the heart sounds. For example, the control circuit 80 may use the ECG / EGM sensing circuit system to set the HS sensing window used by the HS sensing module to sense heart sounds. The HS sensing module may include one or more sensing amplifiers, filters, rectifiers for optimizing the signal-to-noise ratio of the heart sound signal. Separate and unique amplification and filtering characteristics may be provided for sensing each of the S1 to S4 sounds, thereby improving signal quality as needed.

[0145] Bioimpedance or intracardiac impedance can be measured and used to represent physiological response information. For example, any IMD described herein can measure intracardiac impedance signals by injecting current and measuring the voltage between electrodes (e.g., selected electrodes) of an electrode vector configuration. For example, the IMD can measure impedance signals by injecting current (e.g., non-pacing threshold current) between a first electrode (e.g., RV electrode) and an electrode located in the RV near the tricuspid valve and measuring the voltage between the first electrode and the second electrode. Another vector that can be used is from the LV electrode to the RV electrode. It will be appreciated that other vector pair configurations can be used for stimulation and measurement. Impedance can be measured between any set of electrodes surrounding the tissue or cardiac chamber of interest. Therefore, current can be injected and voltage can be measured to calculate impedance on the same two electrodes (bipolar configuration), or current can be injected and voltage can be measured on two separate electrode pairs (e.g., one pair for current injection and one pair for voltage sensing), so it is a quadruple configuration. For a quadruple electrode configuration, the current injection and voltage sensing electrodes can be in a straight line (or closely parallel) with each other, and the voltage sensing electrode can be in the current sensing field. For example, if there is an injected current between the SVC coil electrode and the RV tip electrode, there may be a voltage sensed between the RV coil electrode and the RV ring electrode. In such embodiments, the VfA lead may be used for LV cardiac therapy or sensing. The impedance vector may be configured to include a specific anatomical region of interest, such as the atria or ventricles.

[0146] The illustrative methods and / or apparatus described herein can monitor one or more electrode vector configurations. In addition, multiple impedance vectors can be measured simultaneously and / or periodically relative to one another. In at least one embodiment, the illustrative methods and / or apparatus can use impedance waveforms to obtain selection data for optimizing CRT (e.g., finding applicable reference points, allowing measurements to be extracted from such waveforms, etc.).

[0147] As used herein, the term "impedance signal" is not limited to a raw impedance signal. It should be implied that the raw impedance signal may be processed, normalized, and / or filtered (e.g., to remove artifacts, noise, static electricity, electromagnetic interference (EMI), and / or extraneous signals) to provide an impedance signal. In addition, the term "impedance signal" may include various mathematical derivatives thereof, including the real and imaginary parts of the impedance signal, an impedance-based conductance signal (i.e., the inverse or reciprocal of the impedance), and the like. In other words, the term "impedance signal" may be understood to include a conductance signal, i.e., a signal that is the inverse of the impedance signal.

[0148] In one or more embodiments of the methods and / or devices described herein, various patient physiological parameters (e.g., intracardiac impedance, heart sounds, cardiac cycle intervals such as RR intervals, etc.) can be monitored to obtain selected data to optimize CRT (e.g., setting AV and / or VV delays, such as by using and / or measuring the first-order derivative of impedance dZ / dt to optimize cardiac contractility, selecting a pacing site, selecting a pacing vector, lead placement, or assessing pacing capture from an electrical and mechanical perspective (e.g., electrical capture may not mean mechanical capture, and heart sounds and impedance can help assess whether electrical stimulation has captured the heart by looking at mechanical information from heart sounds and impedance), selecting an effective electrode vector configuration for pacing, etc.). For example, an intracardiac impedance signal between two or more electrodes can be monitored to provide such optimization.

[0149] Fig.12 An example of a method 850 for obtaining selection data for one of the device parameter options (e.g., one of the selectable device parameters that can be used to optimize CRT, such as potential AV delay that can be an optimal parameter) is shown. Other examples of using heart sounds to optimize cardiac therapy are generally described in U.S. Patent No. 9,707,399, entitled "Cardiac resynchronization therapy optimization based on intracardiac impedance and heart sounds," issued on July 18, 2017.

[0150] As shown, pacing therapy is delivered using one of a plurality of device options (box 852) (e.g., a plurality of device parameter options may be selected, AV delay may be determined and / or calculated, such as a percentage of intrinsic AV delay, e.g., 40% of intrinsic AV delay, 50% of intrinsic AV delay, 60% of intrinsic AV delay, 70% of intrinsic AV delay, 80% of intrinsic AV delay, etc.). For the device parameter option for pacing (box 852), selected data is acquired at each of a plurality of electrode vector configurations (e.g., intracardiac impedance is monitored over a plurality of cardiac cycles and selected data is extracted using such impedance signals). As shown in decision box 854, if selected data has not yet been acquired from all desired electrode vector configurations, a loop of acquiring selected data (e.g., the loop shown in boxes 858, 860, 862, and 864) is repeated. If selected data has been acquired from all desired electrode vector configurations, therapy is delivered using another different device parameter option (box 856), and the loop is repeated. Fig.12Method 850 (e.g., for different device parameter options) until selection data has been acquired for all different device parameter options (e.g., selection data is collected at each of a plurality of electrode vector configurations for each of the different device parameter options).

[0151] As shown in a repeating loop of acquiring selected data for each desired electrode vector configuration (e.g., blocks 858, 860, 862, and 864), one of a plurality of electrode vector configurations is selected for acquiring selected data (block 858). Time reference points associated with at least a portion of a systolic portion of at least one cardiac cycle and / or time reference points associated with at least a portion of a diastolic portion of at least one cardiac cycle for the selected electrode vector configuration are acquired (block 860) (e.g., such as using heart sounds, analysis of impedance signal minima and maxima, application of algorithms based on physiological parameters such as RR intervals, etc.). For example, time reference points associated with a systolic and / or diastolic portion of a cardiac cycle may be acquired, time reference points associated with one or more defined segments within a systolic and / or diastolic portion of a cardiac cycle may be acquired, and / or time reference points within or associated with one or more points and / or portions of a systolic and / or diastolic portion of a cardiac cycle may be acquired. Further, for example, time reference points may be acquired that are associated only with the systolic or diastolic portion of the cardiac cycle, time reference points may be acquired that are associated only with one or more defined segments within the systolic or diastolic portion of the cardiac cycle, and / or time reference points may be acquired within or associated with one or more points and / or portions of only the systolic or only the diastolic portion of the cardiac cycle. In other words, reference points may be acquired that are associated with both the systolic and diastolic portions of the cardiac cycle or associated with only one of these portions of the cardiac cycle. Further, for example, such reference points may represent or indicate a measurement window and / or time period (e.g., interval, point, etc.) at or during which intracardiac impedance may be measured for analysis as described herein.

[0152] An intracardiac impedance signal is acquired at the selected electrode vector configuration in approximately the same time frame (e.g., approximately simultaneously with the acquired fiducial points) (block 862). Using the acquired fiducial points and the acquired intracardiac impedance signal, measurements from the impedance signal are extracted based on the temporal fiducial points (block 864) (e.g., an integral of the impedance signal in a measurement window defined between the fiducial points, a maximum slope of the impedance signal in a measurement window defined between the fiducial points, the time between the fiducial points, a maximum impedance at the fiducial points, etc.). One or more of these measurements may be comparable to expected values ​​for these measurements, thereby allowing a determination to be made as to whether the measurement may indicate that the device parameter option may be an effective device parameter for optimizing therapy (e.g., if the device parameter option may be an optimal parameter may be determined using a scoring algorithm based on whether a plurality of such measurements meet certain criteria or thresholds).

[0153] Each device parameter option (e.g., Fig.12 In one or more embodiments, the measurement data are obtained for multiple cardiac cycles. The cardiac cycle in which the measurement data are obtained can be any suitable cardiac cycle. In one or more embodiments, the cardiac cycle selected to obtain the measurement data is based on the respiratory cycle. In at least one embodiment, the measurement data is obtained during the cardiac cycle that occurs at the end of the respiratory cycle (e.g., near the end of exhalation).

[0154] Fig.13 An illustrative system 100 is shown that includes an electrode device 110, a display device 130, and a computing device 140. The electrode device 110 as shown includes a plurality of electrodes that are incorporated into or included in a band that wraps around the chest or torso of a patient 120. The electrode device 110 is operably coupled to the computing device 140 (e.g., via one or wired electrical connections, wirelessly, etc.) to provide electrical signals from each of the electrodes to the computing device 140 for analysis, evaluation, etc. An illustrative electrode device may be described in U.S. Patent No. 9,320,446, entitled “Bioelectric Sensor Device and Methods,” issued on April 26, 2016. In addition, reference will be made to Figures 14 to 15 Illustrative electrode apparatus 110 is described in greater detail.

[0155] Although not described herein, the illustrative system 100 may also include an imaging device. The imaging device may be any type of imaging device configured to image or provide an image of at least a portion of a patient in a non-invasive manner. For example, the imaging device may provide an image of the patient without using any components or parts located within the patient's body, except for non-invasive tools such as contrast media solutions. It should be understood that the illustrative systems, methods, and interfaces described herein may also use imaging devices to provide non-invasive assistance to a user (e.g., a physician) to calibrate and / or deliver VfA pacing therapy, thereby positioning and placing a device for delivering VfA cardiac pacing therapy, and / or positioning or selecting a pacing electrode or pacing vector close to the patient's heart for atrial ventricular pacing therapy in conjunction with an evaluation of atrial ventricular pacing therapy.

[0156] For example, the illustrative systems, methods, and interfaces can provide image-guided navigation that can be used to navigate leads including leadless devices, electrodes, leadless electrodes, wireless electrodes, catheters, etc. within a patient's body while also providing non-invasive cardiac therapy assessments, including determining whether atrial ventricular (VfA) pacing settings are optimal, or determining whether one or more selected parameters are optimal, such as selected position information (e.g., position information of an electrode to target a specific location in the left ventricle). Illustrative systems and methods for using imaging devices and / or electrode devices may be described in U.S. Patent Publication No. 2014 / 0371832, filed on June 12, 2013, entitled “Implantable Electrode Location Selection,” U.S. Patent Publication No. 2014 / 0371833, filed on June 12, 2013, entitled “Implantable Electrode Location Selection,” U.S. Patent Publication No. 2014 / 0323892, filed on March 27, 2014, entitled “Systems, Methods, and Interfaces for Identifying Effective Electrodes,” and U.S. Patent Publication No. 2014 / 0323882, filed on March 27, 2014, entitled “Systems, Methods, and Interfaces for Identifying Optical-Electrical Vectors.”

[0157] Illustrative imaging devices can be configured to capture x-ray images and / or any other alternative imaging modalities. For example, the imaging device can be configured to capture images or image data using isocentric fluoroscopy, biplane fluoroscopy, ultrasound, computed tomography (CT), multi-slice computed tomography (MSCT), magnetic resonance imaging (MRI), high frequency ultrasound (HIFU), optical coherence tomography (OCT), intravascular ultrasound (IVUS), two-dimensional (2D) ultrasound, three-dimensional (3D) ultrasound, four-dimensional (4D) ultrasound, intraoperative CT, intraoperative MRI, etc. In addition, it should be understood that the imaging device can be configured to capture multiple continuous images (e.g., continuously) to provide video frame data. In other words, multiple images acquired over time using the imaging device can provide video frames or motion picture data. In addition, images can also be obtained and displayed in two-dimensional, three-dimensional or four-dimensional ways. In a more advanced form, four-dimensional surface reproduction of the heart or other areas of the body can also be achieved by combining cardiac data or other soft tissue data from images captured by MRI, CT or echocardiography modalities or preoperative image data. Image datasets from hybrid modalities (such as positron emission tomography (PET) combined with CT, or single photon emission computed tomography (SPECT) combined with CT) can also provide functional image data superimposed on the anatomical data, for example, for navigating a therapeutic device approaching a target location within the heart or other region of interest (e.g., such as a location within the left ventricle, including selected locations within the high posterior base and / or septal region of the left ventricular cavity).

[0158] Systems and / or imaging devices that may be used in conjunction with the illustrative systems and methods described herein are disclosed in U.S. Patent Application Publication No. 2005 / 0008210 to Evron et al., published on January 13, 2005, U.S. Patent Application Publication No. 2006 / 0074285 to Zarkh et al., published on April 6, 2006, U.S. Patent Application Publication No. 2011 / 0112398 to Zarkh et al., published on May 12, 2011, U.S. Patent Application Publication No. 2013 / 0116739 to Brada et al., published on May 9, 2013, U.S. Patent No. 6,980,675 issued on December 27, 2005 to Evron et al., No. 7,286,866 issued to Okerlund et al. on October 23, 2007, No. 7,308,297 issued to Reddy et al. on December 11, 2011, No. 7,308,299 issued to Burrell et al. on December 11, 2011, No. 7,321,677 issued to Evron et al. on January 22, 2008, No. 7,346,381 issued to Okerlund et al. on March 18, 2008, No. 7,454,248 issued to Burrell et al. on November 18, 2008, and No. 7,464,249 issued to Vass et al. on January 22, 2008. U.S. Patent No. 7,499,743 issued on March 3, 2009, U.S. Patent No. 7,565,190 issued on July 21, 2009 to Okerlund et al., U.S. Patent No. 7,587,074 issued on September 8, 2009 to Zarkh et al., U.S. Patent No. 7,599,730 issued on October 6, 2009 to Hunter et al., U.S. Patent No. 7,613,500 issued on November 3, 2009 to Vass et al., U.S. Patent No. 7,742,629 issued on June 22, 2010 to Zarkh et al., U.S. Patent No. 7,587,074 issued on September 8, 2009 to Zarkh et al. No. 7,747,047 issued to Evron et al., No. 7,778,685 issued on August 17, 2010, No. 7,778,686 issued on August 17, 2010 to Vass et al., No. 7,813,785 issued on October 12, 2010 to Okerlund et al., No. 7,996,063 issued on August 9, 2011 to Vass et al., No. 8,060,185 issued on November 15, 2011 to Hunter et al., and No. 8,401,616 issued on March 19, 2013 to Verard et al.

[0159] The display device 130 and the computing device 140 can be configured to display and analyze data, such as electrical signals (e.g., electrocardiogram data), cardiac information representing one or more of mechanical heart function and electrical heart function (e.g., only mechanical heart function, only electrical heart function, or both mechanical heart function and electrical heart function), etc. The cardiac information may include, for example, electrical heterogeneity information or electrical dyssynchrony information, alternative electrical activation information or data, etc., which is generated using electrical signals acquired, monitored, or collected by the electrode device 110. In at least one embodiment, the computing device 140 can be a server, a personal computer, or a tablet computer. The computing device 140 can be configured to receive input from the input device 142 and send output to the display device 130. In addition, the computing device 140 may include a data storage device that can enable access to processing programs or routines and / or one or more other types of data, such as for use in calibrating and / or delivering pacing therapy based, for example, at least on heart rate, for driving a graphical user interface configured to non-invasively assist a user in locating placement of a pacing device, and / or for evaluating pacing therapy at that location (e.g., the location of an implantable electrode for pacing, the location of pacing therapy delivered by a particular pacing vector, etc.).

[0160] The computing device 140 may be operably coupled to the input device 142 and the display device 130, for example, to transmit data to / from each of the input device 142 and the display device 130. For example, the computing device 140 may be electrically coupled to each of the input device 142 and the display device 130 using, for example, an analog electrical connection, a digital electrical connection, a wireless connection, a bus-based connection, a network-based connection, an Internet-based connection, etc. As further described herein, a user may provide input to the input device 142 to manipulate or modify one or more graphical depictions displayed on the display device 130, and to view and / or select one or more pieces of information related to cardiac therapy.

[0161] Although the input device 142 is shown as a keyboard, it should be understood that the input device 142 can include any device capable of providing input to the computing device 140 to perform the functions, methods, and / or logic described herein. For example, the input device 142 can include a mouse, a trackball, a touch screen (e.g., a capacitive touch screen, a resistive touch screen, a multi-touch touch screen, etc.), etc. Similarly, the display device 130 can include any device capable of displaying information to a user, such as a graphical user interface 132, which includes cardiac information, text instructions, a graphical depiction of electrical activation information, a graphical depiction of human cardiac anatomy, an image or graphical depiction of a patient's heart, a graphical depiction of a leadless pacing device used to calibrate and / or deliver pacing therapy (e.g., based at least on a measured heart rate), a graphical depiction of a leadless pacing device positioned or placed to provide VfA pacing therapy, a graphical depiction of the location of one or more electrodes, a graphical depiction of a human torso, an image or graphical depiction of a patient's torso, a graphical depiction or actual image of implanted electrodes and / or leads, etc. In addition, the display device 130 can include a liquid crystal display, an organic light emitting diode screen, a touch screen, a cathode ray tube display, etc.

[0162] The processing programs or routines stored and / or executed by the computing device 140 may include programs or routines for computational mathematics, matrix mathematics, dispersion determination (e.g., standard deviation, variance, range, interquartile range, mean absolute difference, mean absolute deviation, etc.), filtering algorithms, maximum determination, minimum determination, threshold determination, moving window algorithms, decomposition algorithms, compression algorithms (e.g., data compression algorithms), calibration algorithms, image construction algorithms, signal processing algorithms (e.g., various filtering algorithms, Fourier transforms, fast Fourier transforms, etc.), normalization algorithms, comparison algorithms, vector mathematics, or any other processing required to implement one or more of the illustrative methods and / or processes described herein. The data stored and / or used by the computing device 140 may include, for example, electrical signal / waveform data from the electrode device 110, dispersion signals, windowed dispersion signals, portions of various signals, electrical activation times from the electrode device 110, graphics (e.g., graphical elements, icons, buttons, windows, dialogs, drop-down menus, graphic areas, graphic regions, 3D graphics, etc.), graphical user interfaces, results from one or more processing programs or routines used in accordance with the present disclosure (e.g., electrical signals, cardiac information, etc.), or any other data that may be necessary to perform one and / or more of the processes or methods described herein.

[0163] In one or more embodiments, the illustrative systems, methods, and interfaces may be implemented using one or more computer programs executed on a programmable computer such as a computer that includes, for example, processing capabilities, data storage (e.g., volatile or non-volatile memory and / or storage components), input devices, and output devices. The program code and / or logic described herein may be applied to input data to perform the functions described herein and generate desired output information. The output information may be applied as input to one or more other devices and / or methods as described herein or to be applied in a known manner.

[0164] One or more programs for implementing the systems, methods and / or interfaces described herein can be provided using any programmable language, such as high-level programs and / or object-oriented programming languages ​​suitable for communicating with a computer system. Any such program can be stored, for example, on any suitable device, such as a storage medium, which can be read by a general or special program running on a computer system (e.g., including a processing device), for configuring and operating the computer system when reading a suitable device for performing the process described herein. In other words, in at least one embodiment, an illustrative system, method and / or interface can be implemented using a computer-readable storage medium configured with a computer program, wherein the storage medium so configured causes the computer to operate in a specific and predefined manner to perform the functions described herein. In addition, in at least one embodiment, the illustrative system, method and / or interface can be described as being implemented by logic (e.g., object code) encoded in one or more non-transitory media, the non-transitory media including code for execution and when executed by a processor, operable to perform operations such as the methods, processes and / or functions described herein.

[0165] The computing device 140 may be, for example, any fixed or mobile computer system (e.g., a controller, a microcontroller, a personal computer, a minicomputer, a tablet computer, etc.), and may generally be described as including a processing circuit system. The exact configuration of the computing device 140 is not limiting, and substantially any device that can provide suitable computing power and control capabilities (e.g., graphics processing, etc.) may be used. As described herein, a digital file may be any medium (e.g., volatile or non-volatile memory, CD-ROM, punched card, magnetic recordable medium such as a disk or tape, etc.) containing digital bits (e.g., encoded in binary, ternary, etc.), which may be read and / or written by the computing device 140 described herein. Furthermore, as described herein, a file in a user-readable format may be any representation of data (e.g., ASCII text, binary numbers, hexadecimal numbers, decimal numbers, graphics, etc.) that may be presented on any medium (e.g., paper, a display, etc.) that is readable and / or understandable to a user.

[0166] In view of the above, it will be readily apparent that the functions described in one or more embodiments of the present disclosure may be implemented in any manner known to those skilled in the art. Therefore, computer languages, computer systems, or any other software / hardware to be used to implement the processes described herein should not limit the scope of the systems, processes, or programs described herein (e.g., the functions provided by such systems, processes, or programs).

[0167] The electrical activation time of the patient's heart can be used to assess the patient's cardiac condition and / or to calibrate, deliver, or assess atrial ventricular (VfA) cardiac therapy to be or being delivered to the patient. Figures 13 to 15 The illustrated electrode device 110 is used to monitor or determine surrogate electrical activation information or data of one or more regions of a patient's heart. The illustrative electrode device 110 may be configured to measure body surface electrical potentials of the patient 120 , and more specifically, to measure torso surface electrical potentials of the patient 120 .

[0168] like Fig.14 1, the illustrative electrode device 110 can include a group or array of electrodes 112, a belt 113, and an interface / amplifier circuit system 116. In at least one embodiment, a portion of the group of electrodes can be used, wherein the portion corresponds to a specific location on the patient's heart. The electrode 112 can be attached or coupled to the belt 113, and the belt 113 can be configured to wrap around the torso of the patient 120 so that the electrode 112 surrounds the patient's heart. As further shown, the electrode 112 can be positioned around the chest of the patient 120, including the posterior, lateral, posterior lateral, anterolateral, and anterior locations of the torso of the patient 120.

[0169] In addition, the electrodes 112 may be electrically connected to the interface / amplifier circuitry 116 via a wired connection 118. The interface / amplifier circuitry 116 may be configured to amplify signals from the electrodes 112 and provide the signals to the computing device 140. Other illustrative systems may use a wireless connection to transmit the signals sensed by the electrodes 112 to the interface / amplifier circuitry 116 and, in turn, to the computing device 140, e.g., as a data channel. For example, the interface / amplifier circuitry 116 may be electrically coupled to each of the computing device 140 and the display device 130 using, for example, an analog electrical connection, a digital electrical connection, a wireless connection, a bus-based connection, a network-based connection, an Internet-based connection, etc.

[0170] Despite Fig.14In some embodiments, the electrode device 110 includes a band 113, but in other embodiments, any of a variety of mechanisms (e.g., tape or adhesive) can be used to facilitate spacing and placement of the electrodes 112. In some embodiments, the band 113 can include an elastic band, a strap, or a cloth. In other embodiments, the electrodes 112 can be placed individually on the torso of the patient 120. In addition, in other embodiments, the electrodes 112 (e.g., arranged in an array) can be part of or located within a patch, a vest, and / or other means of securing the electrodes 112 to the torso of the patient 120.

[0171] The electrodes 112 can be configured to surround the heart of the patient 120 and record or monitor electrical signals associated with the depolarization and repolarization of the heart after the signals have propagated through the torso of the patient 120. Each of the electrodes 112 can be used in a unipolar configuration to sense the surface potential of the torso that reflects the cardiac signals. The interface / amplifier circuit system 116 can also be coupled to a return or indifferent electrode (not shown), which can be combined with each electrode 112 for unipolar sensing. In some instances, there can be about 12 to about 50 electrodes 112 distributed spatially around the torso of the patient. Other configurations can have more or fewer electrodes 112.

[0172] The computing device 140 may record and analyze the electrical activity (e.g., torso surface potential signals) sensed by the electrodes 112 and amplified / conditioned by the interface / amplifier circuitry 116. The computing device 140 may be configured to analyze the signals from the electrodes 112 to provide as anterior electrode signals and posterior electrode signals and surrogate cardiac electrical activation times, e.g., representing actual or local electrical activation times of one or more regions of the patient's heart, as will be further described herein. The computing device 140 may be configured to analyze the signals from the electrodes 112 to provide as anterior septal electrode signals and surrogate cardiac electrical activation times, e.g., representing actual or local electrical activation times of one or more anterior septal regions of the patient's heart, as will be further described herein, e.g., for calibrating, delivering, and / or evaluating VfA pacing therapy. In addition, the electrical signal measured at the left anterior surface location of the patient's torso can represent or replace the electrical signal of the left anterior left ventricular region of the patient's heart, the electrical signal measured at the left lateral surface location of the patient's torso can represent or replace the electrical signal of the left lateral left ventricular region of the patient's heart, the electrical signal measured at the left posterolateral surface location of the patient's torso can represent or replace the electrical signal of the posterolateral left ventricular region of the patient's heart, and the electrical signal measured at the posterior surface location of the patient's torso can represent or replace the electrical signal of the posterior left ventricular region of the patient's heart. In one or more embodiments, the measurement of activation time can be performed by measuring the time period between the start of cardiac depolarization (e.g., the start of a QRS complex) and an appropriate reference point (e.g., a peak, minimum, minimum slope, maximum slope, zero crossing, threshold crossing, etc.).

[0173] Additionally, the computing device 140 may be configured to provide a graphical user interface that depicts alternative electrical activation times obtained using the electrode device 110. The illustrative systems, methods, and / or interfaces may non-invasively use electrical information collected by the electrode device 110 to assess a patient's cardiac condition and / or to calibrate, deliver, or assess VfA pacing therapy to be or being delivered to the patient.

[0174] Fig.15 Another illustrative electrode device 110 is shown that includes a plurality of electrodes 112 configured to surround the heart of a patient 120 and record or monitor electrical signals associated with depolarization and repolarization of the heart after the signals have propagated through the torso of the patient 120. The electrode device 110 may include a vest 114 to which the plurality of electrodes 112 may be attached or to which the electrodes 112 may be coupled. In at least one embodiment, the plurality of electrodes 112 or an array of electrodes may be used to collect electrical information, for example, surrogate electrical activation times.

[0175] Similar to Fig.14 The electrode device 110, Fig.13 The electrode device 110 may include an interface / amplifier circuit system 116 electrically coupled to each of the electrodes 112 via a wired connection 118 and configured to send signals from the electrodes 112 to a computing device 140. As shown, the electrodes 112 may be distributed over the torso of the patient 120, including, for example, the anterior surface, the lateral surface, the posterior lateral surface, the anterior lateral surface, and the posterior surface of the torso of the patient 120.

[0176] The vest 114 can be formed of a fabric, wherein the electrodes 112 are attached to the fabric. The vest 114 can be configured to maintain the location and spacing of the electrodes 112 on the torso of the patient 120. In addition, the vest 114 can be marked to help determine the location of the electrodes 112 on the surface of the torso of the patient 120. In one or more embodiments, the vest 114 can include about 17 or more front electrodes that can be positioned near the front torso of the patient, and about 39 or more rear electrodes that can be positioned near the front torso of the patient. In some instances, there can be about 25 electrodes 112 to about 256 electrodes 112 distributed around the torso of the patient 120, although other configurations can have more or fewer electrodes 112.

[0177] As described herein, the electrode device 110 can be configured to measure electrical information (e.g., electrical signals) representing different regions of the patient's heart. For example, activation times of different regions of the patient's heart can be approximated by surface electrocardiogram (ECG) activation times measured using surface electrodes near surface regions corresponding to different regions of the patient's heart. In at least one instance, activation times of an anterior septal region of the patient's heart can be approximated by surface ECG activation times measured using surface electrodes near surface regions corresponding to the anterior septal region of the patient's heart. That is, a portion of the electrode set 112, rather than the entire set, can be used to generate activation times corresponding to a specific location of the patient's heart corresponding to that portion of the electrode set.

[0178] The illustrative systems, methods, and interfaces may be used to provide non-invasive assistance to a user in the assessment of a patient's cardiac health or status and / or in the assessment of cardiac therapy, such as atrioventricular (VfA) pacing therapy (e.g., a cardiac therapy currently delivered to a patient during or after implantation) using the electrode device 110. In addition, the illustrative systems, methods, and interfaces may be used to assist a user in configuring or calibrating a cardiac therapy, such as VfA pacing therapy, that is to be or is being delivered to a patient (e.g., based on a measured heart rate).

[0179] VfA pacing can be described as providing synchronized uniform activation of the ventricles. For example, patients with atrial-ventricular (AV) block or prolonged AV timing that can lead to heart failure (otherwise having a complete (e.g., normal) QRS) may benefit from VfA pacing therapy. In addition, for example, VfA pacing can provide beneficial activation for heart failure patients with intrinsic ventricular conduction disorders. In addition, appropriate placement of VfA pacing can provide optimal activation of the ventricles for such patients. In addition, left ventricular (LV) resynchronization in heart failure patients with left bundle branch block (LBBB) may find that VfA pacing enables easier access to the left ventricular endocardium without exposing leadless devices or leads to the endocardial blood pool. At the same time, in this instance, this can help engage a portion of the conduction system to potentially correct the LBBB and effectively resynchronize the patient.

[0180] Multiple external electrodes (e.g. Figures 13 to 15Electrode 112) is used to monitor electrical activity. Electrical activity can be monitored by multiple electrodes during VfA pacing therapy or in the absence of VfA pacing therapy. The monitored electrical activity can be used to evaluate VfA pacing therapy for patients. The electrical activity monitored using the described ECG band can be used to evaluate at least one pacing setting for VfA pacing therapy on the heart. As an example, the pacing setting can be any one parameter or a combination of parameters, including but not limited to electrode position, pacing polarity, pacing output, pacing pulse width, timing of VfA pacing delivered relative to the atrium (A), pacing rate, etc. In addition, as an example, the position of the leadless device or pacing lead can include a position in the left ventricle, in or adjacent to the high posterior base and / or septum (HPBS) region of the left ventricular cavity through the right atrium. In addition, pacing in or adjacent to the HPBS region can be selective (e.g., involving stimulation of a specific region of the HPBS only) or non-selective (e.g., combined pacing at the position of the HPBS and other atrial and / or ventricular septal regions).

[0181] In addition, the monitored electrical activity can be used to construct a surface isochronal map of ventricular activation during VfA pacing therapy or in the absence of VfA pacing therapy. The monitored electrical activity and / or ventricular activation map can be used to generate electrical heterogeneity information (EHI). The electrical heterogeneity information can include a measure of determining electrical heterogeneity. The measure of electrical heterogeneity can include a measure of the standard deviation of activation time (SDAT) of the electrodes on the left side of the patient's torso and / or a measure of the average left ventricular activation time (LVAT) of the electrodes on the left side of the patient's torso. The measure of LVAT can be determined from electrodes on the anterior and posterior surfaces closer to the left ventricle. The measure of electrical heterogeneity information can include a measure of the average right ventricular activation time (RVAT) of the electrodes on the right side of the patient's torso. The measure of RVAT can be determined from electrodes on the anterior and posterior surfaces closer to the right ventricle. The measure of electrical heterogeneity may include a measure of the mean total activation time (mTAT) obtained from multiple electrode signals from both sides of the patient's torso, or it may include other measures (e.g., standard deviation, interquartile range, difference between the most recent activation time and the earliest activation time) that reflect the range or dispersion of activation times on multiple electrodes located on the right side of the patient's torso, or the left side of the patient's torso, or a combination of the right and left sides of the patient's torso. The measure of electrical heterogeneity information may include a measure of the anterior septal activation time (ASAT) of an electrode on the torso proximal to the anterior septal portion of the heart.

[0182] Electrical heterogeneity information (EHI) may be generated during delivery of VfA pacing therapy at one or more VfA pacing settings. The electrical heterogeneity information may be generated using a measure of electrical heterogeneity. As an example, the measure of electrical heterogeneity may include one or more of SDAT, LVAT, RVAT, mTAT, and ASAT. In at least one embodiment, only ASAT may be determined and further used, and / or ASAT may be weighted more heavily than other values.

[0183] One or more pacing settings associated with VfA pacing therapy can be evaluated. The pacing settings can include multiple pacing parameters. If the patient's cardiac condition improves, if the VfA pacing therapy effectively captures the desired portion of the left ventricle (e.g., the high posterior basal and / or septal regions), and / or if the measure of electrical heterogeneity improves by a certain threshold compared to the baseline rhythm or therapy, then the multiple pacing parameters can be optimal. In at least one embodiment, it can be determined whether the pacing settings are optimal based on at least one measure of electrical heterogeneity generated by electrical activity during VfA pacing (and in some embodiments, during natural conduction, or in the absence of VfA pacing). The at least one metric can include one or more of SDAT, LVAT, RVAT, mTAT, and ASAT.

[0184] In addition, if the measure of electrical heterogeneity is greater than or less than a particular threshold, and / or if the location of the pacing therapy used to stimulate the left ventricle causes a particular stimulation pattern of muscle fibers in the heart, then the plurality of pacing parameters may be optimal. In addition, if the measure of electrical heterogeneity indicates correction of left bundle branch block (LBBB), and / or if the measure of electrical heterogeneity indicates full engagement of the Purkinje system, etc., then the plurality of pacing parameters may be optimal. As an example, a measure of electrical heterogeneity of ASAT less than or equal to a threshold (e.g., a threshold of 30 ms) and LVAT less than or equal to a threshold (e.g., a threshold of 30 ms) may indicate correction of LBBB, and thus, the pacing settings are optimal. As an example, a measure of electrical heterogeneity of RVAT less than or equal to a threshold (e.g., a threshold of 30 ms), an ASAT less than or equal to a threshold (e.g., a threshold of 30 ms), and LVAT less than or equal to a threshold (e.g., a threshold of 30 ms) may indicate full engagement of the Purkinje system, and thus, the pacing settings may be optimal.

[0185] The pacing settings may be determined to be optimal in response to VfA pacing therapy using pacing settings that are acceptable, beneficial, indicate full engagement of the patient's native cardiac conduction system, indicate correction of a ventricular conduction disorder (e.g., left bundle branch block), etc. The pacing settings may include pacing electrode position (including one or more of depth, angle, amount of rotation of a screw-based fixation mechanism, etc.), voltage, pulse width, intensity, pacing polarity, pacing vector, pacing waveform, time and / or pacing position at which pacing is delivered relative to intrinsic or paced atrial events or relative to intrinsic His bundle potentials, etc. The pacing vector may include any two or more pacing electrodes for delivering VfA pacing therapy, etc., such as a tip electrode to a can electrode, a tip electrode to a ring electrode, etc. The pacing position may refer to the position of any of one or more pacing electrodes positioned using a lead, a leadless device, and / or any device or apparatus configured to deliver VfA.

[0186] The pacing settings for the VfA pacing therapy may be adjusted. In at least one embodiment, in response to the pacing settings being not optimal, the pacing settings may be adjusted. In at least one embodiment, the pacing settings may be adjusted in response to the pacing settings being within an optimal range to determine whether the pacing settings may be at a position within the optimal range that is more beneficial, more useful, more functional, etc. for the VfA pacing therapy. The pacing settings may be adjusted to find an optimal measure of electrical heterogeneity.

[0187] In one or more embodiments, it can be determined whether pacing settings are optimal based on a particular measure of electrical heterogeneity using an ECG strip. In at least one instance, the pacing settings can be adjusted at intervals associated with changes in the measure of electrical heterogeneity until the measure of electrical heterogeneity is at or near the particular measure value. For example, adjusting the pacing settings can cause the measure of electrical heterogeneity to approach a particular threshold measure of electrical heterogeneity, and the rate at which the pacing settings are adjusted can be slowed as the measure approaches the particular threshold. In other words, the pacing settings can be adjusted more quickly as the measure of electrical heterogeneity moves away from the particular threshold measure, and the pacing settings can be adjusted more slowly as the measure of electrical heterogeneity gets closer to the particular threshold measure until the measure of electrical heterogeneity is at the particular threshold measure.

[0188] Various techniques for monitoring electrical activity from patient tissue using an electrode device having multiple external electrodes are disclosed in U.S. patent application serial number 15 / 934,517, filed on March 23, 2018, and entitled “Evaluation of Ventricle from Atrium Pacing Therapy,” which may be used with the devices, systems, and methods described herein.

[0189] Fig.16An illustrative method 500 for delivering a VfA medical device is shown. The method 500 may begin by locating a potential implantation site in the Koch triangle in the right atrium of a patient's heart 502. In response to locating the potential implantation site, the method 500 may include attaching a retaining sheath to the right atrial endocardium in the potential implantation site 504. The retaining sheath may include, for example, a helical retaining component that may be attached to the right atrial endocardium. The retaining sheath may provide a sturdy anchor for implanting the medical device after finding the optimal orientation using an electrical probe such as a flexible needle. The method 500 may further include implanting the medical device over a guidewire at the potential implantation site 510.

[0190] Method 500 may include determining whether the potential implant site is acceptable 506. If the potential implant site is acceptable 512, method 500 may include preparing the potential implant site for a medical device 508 in response to determining that the potential implant site is acceptable. In some embodiments, the medical device 510 may be implanted after preparing the potential implant site 508.

[0191] If the potential implantation site is unacceptable 512, the method 500 may include reorienting the retainer sheath 514, for example, to try to find the best orientation for implanting a medical device for cardiac treatment. For example, the retainer sheath may be reoriented by pushing, pulling, or twisting the sheath to create a new trajectory for the needle to leave the sheath.

[0192] The implanted device 510 may include one or more of an implanted right atrial electrode, a left ventricular electrode, and an intracardiac medical device. The intracardiac medical device may include one or more electronic components described with respect to the leadless medical device described above (see Figure 1 ). In some embodiments, the left ventricular electrode can be coupled to a small lead. The small lead can be coupled to an intracardiac medical device. The small lead and the intracardiac medical device can be implanted simultaneously. For example, the same guidewire can be used to guide the small lead and the intracardiac medical device. In some embodiments, the intracardiac housing can be attached to a container, which can be used to push the intracardiac housing toward the implantation site. For example, a side sheath can be used to couple the guidewire to the container. The guidewire can be used to guide a small lead, for example, in front of the intracardiac housing toward the implantation site.

[0193] The left ventricular electrode of the medical device can be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fibrous body to deliver cardiac therapy to the left ventricle in the base and / or septal region of the left ventricular myocardium of the patient's heart or to sense the electrical activity of the left ventricle. In some embodiments, the left ventricular electrode can be disposed on a flexible or semi-rigid lead or a small lead. In other embodiments, the left ventricular electrode can be the same as the tissue puncture electrode.

[0194] The right atrial electrode of the medical device can be positioned to deliver cardiac therapy to the right atrium of the patient's heart or to sense the electrical activity of the right atrium. For example, the right atrial electrode can contact the surface of the septal wall in the right atrium. The left ventricular electrode can extend into or through the septal wall toward the left ventricle or even into the left ventricle.

[0195] Fig.17 An illustrative method 502 for locating a potential implantation site in the Koch's triangle is shown. The method 502 may include introducing a first guidewire into the coronary sinus 520 of the patient's heart through the great cardiac vein (e.g., to the apex of the heart). The method 502 may also include introducing a second guidewire into the middle cardiac vein 522 of the patient's heart. In some embodiments, the intersection of the first guidewire and the second guidewire may provide an approximate proximity for locating the Koch's triangle. The method 500 may further include identifying a potential implantation site 524 based on the position of the first guidewire relative to the position of the second guidewire. Although a guidewire is described, other elongated components, such as a sheath or a lead, may also be used to pass through the coronary sinus of the patient's heart or through the middle cardiac vein.

[0196] Once the approximate proximity of the Koch triangle is identified, method 502 may include retroaortically placing a diagnostic catheter to a non-coronary sinus of the aortic valve of the patient's heart, or capturing an aortogram of a ventriculogram 526. In some embodiments, a craniocaudal angle may be identified that provides a most perpendicular or nearly perpendicular view of the valve plane in a DV view and a most parallel or nearly parallel view of the valve plane in a lateral view. Method 502 may also include identifying a target placement 528 of a left ventricular electrode based on or relative to a location of the diagnostic catheter or aortic valve identified in the aortogram or ventriculogram using the craniocaudal angle.

[0197] In some embodiments, the tip of the diagnostic catheter can be used as a target reference in parallel and perpendicular views of the valve plane. The target reference can be used to insert a pacing electrode of a medical device at a potential implantation site. For example, during implantation, the pacing electrode can be aimed approximately 1 to 2 cm below the tip of the diagnostic catheter.

[0198] In some embodiments, target placement relative to the aortic valve position can be identified based on capturing an aortogram or ventriculogram using parallel and perpendicular views of the valve plane. For example, an aortogram or LV ventriculogram can be captured from a DV view and a lateral view using the determined cranio-caudal angle.

[0199] Fig.18An illustrative method 504 for attaching a retainer sheath to the right atrium endocardium in a potential implantation site is shown. The method 504 may include introducing a steerable sheath, which may be described as a flex cath, into the right atrium of a patient's heart 540. Although a steerable sheath is described, any suitable steerable assembly may be used to guide the retainer sheath to the potential implantation site. The method 504 may include, for example, guiding the retainer sheath to the potential implantation site 542 while the retainer sheath is at least partially disposed in the steerable sheath. In some embodiments, once the steerable sheath is in the right atrium, the curve of the steerable sheath may be pulled so that the distal end of the steerable sheath is positioned near the ostium of the coronary sinus (CS). The distal portion (e.g., the last inch) may be directed more toward the apex in a side view and toward the aorta in a DV view. Both the side view and the DV view may be used to ensure the correct orientation of the retainer sheath.

[0200] The method 504 may also include rotating the retainer sheath relative to the steerable sheath 544, for example when the retainer sheath includes a helical retainer assembly. The retainer sheath may be coupled to the steerable sheath in a manner such that the retainer sheath is freely rotatable relative to the steerable sheath.

[0201] Prior to rotating the retainer sheath, the retainer sheath may be advanced distally from the steerable sheath to engage tissue of the right atrial endocardium. In some embodiments, a contrast agent may be used to facilitate engagement between the retainer sheath and the tissue.

[0202] Fig.19 An illustrative method 506 for determining whether a potential implantation site is acceptable is shown. The method 506 may include advancing a flexible needle and a dilator relative to a retaining sheath to engage tissue in the potential implantation site 560. Typically, the flexible needle and dilator may be at least partially disposed in the retaining sheath. In some embodiments, the flexible needle may be advanced to extend a few millimeters beyond the end of the dilator. In some embodiments, a torque tool is used on the proximal portion of the needle and the tool is locked so that the dilator is located at a point where the needle is approximately 2 to 3 mm from the end of the dilator. The dilator and flexible needle assembly may be advanced until the needle contacts the tissue.

[0203] The method 506 may include monitoring electrical activity 562 using a flexible needle. In some embodiments, an electrogram (EGM) may be recorded using the needle. The method 506 may also include delivering pacing pulses 564 at different depths between the right atrium and the left ventricle. In some embodiments, the flexible needle may be used to deliver the pacing pulses, and the electrical activity may be monitored using multiple external electrodes such as a 12-lead electrocardiogram (ECG).

[0204] The method 506 may also include determining 566 whether a pacing threshold is acceptable based on electrical activity measured using multiple external electrodes (e.g., using an ECG strip or vest) in response to delivering a pacing pulse. For example, the activation pattern may be checked using measurements of electrical activity taken with an ECG strip or vest. In some embodiments, the flexible needle and dilator may be advanced until the flexible needle reaches the LV cavity. The flexible needle may be pulled back until the flexible needle begins to pace the tissue. The pacing threshold may be recorded at this time. If the threshold is poor, the flexible needle may be pulled back. If present, the diagnostic catheter may be moved. The steerable sheath may be redirected toward a target placement of a left ventricular electrode (e.g., toward a diagnostic catheter). The method 506 may return to boxes 560, 562, 564, and 566. If the threshold is acceptable, the method 506 may end and a method of preparing a potential implantation site 508 for a medical device may begin.

[0205] Fig. 20 An illustrative method 508 for preparing a potential implantation site for use with a medical device is shown. The method 508 may include advancing a guidewire to a potential implantation site 580. In some embodiments, the guidewire may be further advanced into LV tissue and / or cavity. In some embodiments, the flexible needle and steerable sheath may be removed before, during, or after advancing the guidewire. The method 508 may include advancing a pacing lead through the guidewire to test a pacing threshold 582. The pacing lead may be used to test the pacing threshold. The method 508 may include removing a retaining sheath 584 before, during, or after advancing the pacing lead through the guidewire. In some embodiments, the retaining sheath may be removed after testing the pacing threshold. In some embodiments, all sheaths may be removed, leaving only the guidewire at the implantation site, before advancing the medical device for implantation over or along the guidewire.

[0206] In some embodiments, the retaining sheath can be removed before the pacing lead is attached to the guidewire. This can facilitate detaching the sheath from the lead after the lead is implanted.

[0207] In one embodiment, the medical device delivery method of the present disclosure may follow this general procedure using a diagnostic catheter:

[0208] 1. Place the guidewire deep into the CS and along the great cardiac vein to the apex. This guidewire can guide the location of the CS orifice and display the valve plane.

[0209] 2. Place another guide wire into the cardiac vein.

[0210] 3. The intersection of these two guidewires is the approximate location for attachment of the spiral sheath.

[0211] 4. Place the diagnostic catheter retroaortically into the noncoronary sinus of the aortic valve. The tip of this catheter is the target for the pacing electrode. The target should be 1 or 2 cm below the tip of the catheter.

[0212] 5. Place the flexible catheter in the atrium and pull the curve so the catheter tip is near the CS ostium and the last inch of the catheter points to the diagnostic tip in the LV endocardium. Use Lateral and DV to ensure the correct orientation of the sheath.

[0213] 6. Introduce the inner sheath with a spiral connected to the tip of the flexible catheter. Engage the spiral into the tissue near the tip of the flexible catheter. Use contrast medium if necessary.

[0214] 7. Push the flexible needle out of the dilator a few millimeters. Place the torque tool proximal to the needle and lock it at a point where the needle is approximately 2 to 3 mm from the end of the dilator.

[0215] 8. Advance the dilator / needle combination until the needle contacts the tissue. Record the EGM of the needle.

[0216] 9. Pacing was performed through the needle and 12-lead ECG was recorded on Pruka.

[0217] 10. Advance the dilator / needle a few millimeters at a time and record the pacing and intrinsic beats on a 12-lead ECG.

[0218] 11. When the dilator needle reaches the LV cavity, pull back the dilator / needle until it just begins to pace the tissue. Record the pacing threshold at this time.

[0219] 12. If the threshold is poor, pull back on the needle and guidewire, move the diagnostic catheter, realign the flexible catheter with the diagnostic catheter, and return to step 8.

[0220] 13. If thresholds are good, the guidewire is advanced deeper into the LV and the needle and sheath are removed.

[0221] 14. Place the pacing lead over the guidewire and extend it down to the LV.

[0222] 15. Test the pacing threshold.

[0223] 16. Unscrew the spiral sheath and remove all sheaths, leaving the guidewire in the LV.

[0224] 17. Add RV and LV leads and fittings.

[0225] In another embodiment, the medical device delivery method of the present disclosure may follow this general procedure using craniocaudal angles and aortograms and / or LV ventriculograms:

[0226] 1. Place a guidewire, sheath or lead deep into the CS along the great cardiac vein to the apex. The guidewire can guide the location of the CS orifice and display the valve plane.

[0227] 2. Place another guide wire into the cardiac vein.

[0228] 3. The intersection of these two guidewires is the approximate location for attachment of the spiral sheath.

[0229] 4. Find the craniocaudal angle that provides the most perpendicular view of the valve plane in the DV view and the most parallel view in the lateral view.

[0230] 5. Take an aortic angiogram and LV ventriculogram. Obtain these data from the DV view and lateral view, with the cranial / caudal angle determined in 4 above.

[0231] 6. Place the flexible catheter in the atrium and pull the curve so the catheter tip is near the CS ostium and the last inch of the catheter is pointing more toward the apex in lateral view and toward the aorta in DV view.

[0232] 7. Introduce the inner sheath with a spiral connected to the tip of the flexible catheter. Engage the spiral into the tissue near the tip of the flexible catheter using contrast medium as needed.

[0233] 8. Push the flexible needle out of the dilator a few millimeters. The easiest way to do this is to place the torque tool proximal to the needle and lock it at a point where the needle is about 2 to 3 mm from the end of the dilator.

[0234] 9. Advance the dilator / needle combination until the needle contacts the tissue. Record the EGM of the needle.

[0235] 10. Pacing was performed through the needle and 12-lead ECG was recorded on Pruka.

[0236] 11. Advance the dilator / needle a few millimeters at a time and record the pacing and intrinsic beats on a 12-lead ECG.

[0237] 12. When the dilator needle reaches the LV cavity, pull back the dilator / needle until it just begins to pace the tissue. Record the pacing threshold at this time.

[0238] 13. If the threshold is poor, pull back on the needle and guidewire, re-aim the flexible catheter (eg, more laterally or distally, etc.), and return to step 9.

[0239] 14. If thresholds are good, the guidewire is advanced deeper into the LV and the needle and sheath are removed.

[0240] 15. Place the pacing lead over the guidewire and extend it down to the LV.

[0241] 16. Test the pacing threshold.

[0242] 17. Unscrew the spiral sheath and remove all sheaths, leaving the guidewire in the LV.

[0243] 18. Add RV and LV leads and fittings.

[0244] Fig.21 A medical device delivery system 900 is shown which may include one or more of a steerable assembly 902, a retainer sheath 904 having a fixation assembly 906, a dilator 908, a flexible needle 910, and a guidewire 912. The fixation assembly 906 of the retainer sheath 904 may be attached to the right atrial endocardium in the Koch's triangle in the right atrium of the patient's heart. The flexible needle 910 may be free to translate in a longitudinal direction relative to the retainer sheath 904. The steerable assembly 902 may be configured to steer the retainer sheath 904.

[0245] When assembled for introduction into a patient's heart, flexible needle 910 can be at least partially disposed within the lumen of retainer sheath 904. Dilator 908 can be at least partially disposed within the lumen of retainer sheath 904, and flexible needle 910 can be at least partially disposed within the lumen of dilator 908. Guidewire 912 can be at least partially disposed within the lumen of retainer sheath 904 and / or flexible needle 910.

[0246] In some embodiments, fixation assembly 906 is a helical attachment assembly and retainer sheath 904 can freely rotate relative to steerable assembly 902. In some embodiments, steerable assembly 902 can be a steerable sheath. Retainer sheath 904 can be at least partially disposed within a lumen of the steerable sheath.

[0247] Various implantable medical devices may be configured for use in conjunction with the delivery system 900. In some embodiments, the medical device may be configured to extend over or along the guidewire 912 to be implanted in the right atrial endocardium in the Koch's triangle in the right atrium of the patient's heart. For example, the implantable medical device may include one or more of a right atrial electrode, a left ventricular electrode, an intracardiac pacing device, a small lead, and a lead. The left ventricular electrode may be implanted from the Koch's triangle of the right atrium through the right atrial endocardium and the central fiber body, and is configured to deliver cardiac therapy to the left ventricle in the base and / or septal region of the left ventricular myocardium of the patient's heart or sense the electrical activity of the left ventricle. The right atrial electrode may be configured to deliver cardiac therapy to the right atrium of the patient's heart or sense the electrical activity of the right atrium of the patient's heart.

[0248] Fig. 22 An implantable medical device 920 is shown that can be implanted using various methods described herein and / or using a medical device delivery system described herein. The device 920 can include one or more of an intracardiac housing 922 and a small lead 924. The device 920 can include a plurality of electrodes coupled to the intracardiac housing 922, the small lead 924, or both.

[0249] In some embodiments, the plurality of electrodes include a left ventricular electrode 926 that can be implanted from the Koch triangle of the right atrium through the right atrial endocardium and the central fiber body to deliver cardiac therapy to the left ventricle in the base and / or septal region of the left ventricular myocardium of the patient's heart or sense the electrical activity of the left ventricle. As shown, the left ventricular electrode 926 is coupled to the distal portion of the small lead 924. In some embodiments, the plurality of electrodes include a right atrial electrode 928 that can be positioned within the right atrium to deliver cardiac therapy to the right atrium of the patient's heart or sense the electrical activity of the right atrium. As shown, the right atrial electrode 928 is coupled to the distal portion of the endocardial housing 922.

[0250] The endocardial housing 922 can include various components similar to the leadless pacing devices described herein, which are not shown again here. Specifically, the endocardial housing can at least partially include a therapy delivery circuit operably coupled to the plurality of electrodes to deliver cardiac therapy to the patient's heart, a sensing circuit operably coupled to the plurality of electrodes to sense electrical activity of the patient's heart, and a controller having a processing circuit system operably coupled to the therapy delivery circuit and the sensing circuit. The controller can be configured to monitor electrical activity of the right atrium using the right atrial electrode, monitor electrical activity of the left ventricle using the left ventricular electrode, or both. The controller can also be configured to deliver cardiac therapy using at least one of the plurality of electrodes based on the monitored electrical activity.

[0251] Fig.23 Medical device delivery system 900 is shown. Fig.21 ) is an illustrative system 940. In the illustrated embodiment, a flexible needle, a dilator, and a spiral sheath having a spiral (e.g., a retainer sheath) are all at least partially disposed within a steerable sheath. The distal end of the steerable sheath can be held against tissue, and the spiral can be attached to cardiac tissue. The needle and dilator can penetrate the LV.

[0252] In some embodiments, the illustrative system 940 can be assembled by first fitting the spiral sheath within the steerable sheath. This can allow the spiral sheath to be rotated independently of the steerable sheath to secure the spiral to a desired location in the heart. Once the spiral sheath is secured to the tissue, the spiral sheath can provide a very stable platform to inject a needle or guidewire or lead into the heart.

[0253] Next, a dilator, which can be described as another coaxial sheath with a steerable sheath and a helical sheath, can contain a flexible needle. The dilator can be used to safely pull the needle down the helical sheath.

[0254] The needle can be loaded into the dilator, and the tip of the needle can be placed just near the outlet or distal end of the dilator. Once the spiral is attached to the tissue, the needle can extend a few millimeters beyond the end of the dilator.

[0255] Pacing pulses can then be applied to the needle and the response can be recorded on a 12-lead ECG on an electrophysiological recording system such as Pruka. The needle and dilator can be advanced a few millimeters at a time and a 12-lead ECG can be recorded with and without pacing. When the threshold increases significantly, this can indicate that the needle is in the LV cavity.

[0256] If the threshold or activation pattern is unacceptable, repositioning may be necessary. The needle and dilator may be withdrawn, and the steerable sheath may be simply “re-aim” by advancing, withdrawing, or rotating the steerable sheath. When the new direction is found, the needle may be reinserted into the LV, and thresholds and activation may be tested again.

[0257] If pacing thresholds and ventricular activation patterns are acceptable, a 0.014" guidewire can be extended into the LV through the flexible needle.

[0258] Fig.24 Various components of an illustrative system 940 are shown as a kit. The illustrative system 940 may include: a sheath with a helix that screws into Koch's triangle, a paceable "needle" or tunneling tool, and a guidewire that will remain in the tunnel to allow easy placement of a small lead. The small lead can be delivered over the guidewire as part of a leadless pacemaker system. Such a system can facilitate easy retrieval because the small lead will provide a convenient connection.

[0259] In some embodiments, the illustrative system 940 may more specifically include: a steerable sheath, a straight sheath with a soft distal portion and a rigid helix attached to the end (which may fit within the steerable sheath), a flexible hypotube with a sharp needle-like tip, a dilator with an inner diameter to accommodate the flexible hypotube, a 0.014" or 0.018" guidewire over which the lead may be delivered, and a bipolar LV lead. The inner diameter of the hypotube / needle may be sized to accept a 0.014" or 0.018" guidewire. The distal end of the hypotube / needle may be insulated, except for the last approximately 2 mm, which may facilitate pacing and sensing from the flexible needle.

[0260] Fig.25 An illustrative system 940 is shown for use with a lead. For example, the needle and dilator can be removed and replaced with a lead. As shown, the illustrative system 940 can be configured for use with a steerable sheath, a spiral sheath, a tripolar lead shown exiting the spiral sheath, and a guidewire exiting the tripolar lead.

[0261] Although the present disclosure is not limited thereto, an understanding of various aspects of the present disclosure will be gained through a discussion of the specific examples provided below. Various modifications of the examples as well as additional embodiments of the present disclosure will become apparent herein.

[0262] Examples

[0263] The concept of delivering a lead from the atrium to the left ventricle was tested in pigs. The experimental goal was to be able to pace the right atrium and left ventricle from a single device in the right atrium. In addition, the goal was to pace the ventricle with a short QRS in an attempt to provide "resynchronization" of the heart. One theory was that high pacing on the septal LV could engage the endocardial fibers, which are thought to have fast conduction, and the left bundle branch fibers, which are known to have fast conduction. Specifically, the concept tested was to deliver an over-the-wire pacing lead from the right atrium near the ostium of the coronary sinus (CS) to the basal left ventricular (LV) septum.

[0264] Example 1

[0265] We used a 94kg pig. The pig was placed in the supine position. A jugular venotomy was performed and a Sentran 20Fr sheath was placed in the jugular vein. A guidewire was placed in the coronary sinus and guided down the anterior interventricular vein and back up along the midcardiac vein. This outlined the septum. A lead was placed in the midcardiac vein. The point where the midcardiac vein lead and the CS lead intersect creates the target of Koch's triangle. The fluoroscope was moved to find an angle showing a view parallel to the plane of the valve and a view perpendicular to the plane of the valve. These two images were Figures 26A to 26B Shown in.

[0266] The modified flexible catheter is then inserted into the coronary sinus and the curve is pulled in an attempt to align the axis with the left ventricle. After bending, the intersection of the MCV and CS guidewires is used as the starting point for the tip of the flexible catheter. The angle is restored to 0 degrees for cranial imaging. Figures 27A to 27B The images shown can provide more precise aiming. The helix on the inner sheath is then attached to the adjacent tissue by rotating the sheath. Figures 28A to 28B shown.

[0267] The catheter is reoriented and another needle injection is attempted. The final needle position can be Figures 28A to 28B The needle angle in the DV image is closer to the aorta.

[0268] The needle and dilator are removed, and a guidewire is inserted over the guidewire into the LV. Figures 29A to 29B The leads are located with Figures 28A to 28B The needle and guidewire are in very similar positions.

[0269] The animal was then transferred to necropsy, and the heart was opened to observe the route of the catheter and leads. Figures 30A to 30B As shown, the CS catheter and the MCV catheter meet near the CS orifice (actually the orifice of the azygos vein). The flexible sheath, spiral sheath and guide wire enter the tissue near the tricuspid annulus or near the base of Koch's (TOK) triangle.

[0270] During the first attempt to insert the needle and dilator into the LV, it was determined that the trajectory was incorrect. However, during the procedure, the helix broke free from the sheath. The helix was found within the CS. Fig.31 The position in Figures 27A to 27B Comparison of the fluorescence images shown in indicates that by using the intersection of the MCV and CS sheath to indicate the CS ostium, one can estimate the distance to this structure by attempting to attach the helix.

[0271] The lead was found in the LV. The lead had exited the endocardium into the chamber near the posterior papillary muscle, and the tip was located behind the posterior papillary muscle. Figures 32A to 32B As shown, the tip is completely at the base near the mitral valve.

[0272] Example 2

[0273] The pig was placed in the supine position. A jugular venotomy was performed and a shortened 24Fr Micra-type introducer was placed into the jugular vein. An attempt was made to place the guidewire deep to the CS, but the great cardiac vein was not divided into any parts before being used for the apex. The guiding catheter was placed as distally as possible. The middle cardiac vein is a challenge to cannulate. The lead was placed into the middle cardiac vein. The point where the middle cardiac vein lead and the CS lead intersected creates the target of Koch's triangle. The fluoroscope was moved to find an angle that showed a view parallel to the plane of the valve and a view perpendicular to the plane of the valve. The optimal angle for the lateral and DV images was 25 degrees caudal. Both images were Figures 33A to 33B Shown in.

[0274] Ventriculography is performed from the lateral side and DV to understand the position of the LV endocardium. Figures 34A to 34B Shown in.

[0275] Using these images, a good definition of the cardiac anatomy and landmarks used for navigation is established. During the flexible catheter manipulation, the MCV lead was pulled out and not reimplanted. Navigation was performed without the MCV lead. In both views, the flexible catheter is pointed at the crossing of the MCV lead and the CS sheath. The spiral sheath will be attached to the heart near this point. The flexible catheter will then be bent and rotated so that it is pointing just over the apex of the aortic valve in the lateral view and over the aorta in the DV view. Figures 35A to 35B A first attempt in this direction is shown in .

[0276] exist Figures 35A to 35B In the DV view, the flexible catheter appears to be moving away from the CS toward the aorta, probably due to the deformation of the heart caused by the rigid flexible catheter. The needle and guidewire are extended into the LV. These images can be seen in Figures 36A to 36B Seen in.

[0277] A 0.014" guidewire is extended from the needle, the needle and dilator are removed, and a lead is extended over the guidewire into the LV. The lead is positioned as Figures 36A to 36B As shown, the helix is ​​not pointing toward the apex, but the guidewire is routed in the left ventricle. Figures 35A to 35B The needle and guidewire are in very similar positions in the helix. It was very difficult to push the lead into the ventricle. The lead got stuck on the right side where the helix was entangled in the tissue, probably because the tissue could not expand within the helix.

[0278] The lead was then removed and the helix separated from the tissue. A second lead implantation was attempted again without the MCV lead. As before, the flexible catheter was guided to the CS ostium (using a guess based on previous images) and then curved apically and toward the aorta. The helix engaged in the tissue, and the needle and dilator were guided out of the helix into the LV chamber. Pacing thresholds and a 12-lead ECG were recorded along the way.

[0279] The second implantation of the lead appears to occur in the expected position. In the lateral view, the lead is just slightly toward the apex of the CS, so the final position will be completely basal. In the DV view, the lead appears to cross directly under the aorta, which should result in a completely vertical crossing of the septum.

[0280] A 12-lead ECG was used and pacing thresholds were acquired while the needle was advanced across the septum. Lead thresholds were not acquired.

[0281] The animal is then transferred to necropsy, and the heart is opened to observe the route of the catheter and leads. Figures 41A to 43B As seen in Figure 3, the lead entry site in the CS is close to the ostium and very near the base. The MCV lead was dislodged before the flexible catheter lead was tunneled. However, based on the fluoroscopic images saved with the MCV lead in place, the lead tunnel was able to begin close to the CS ostium. It appears that the two tunnels began close to each other. However, the exit of the first tunnel in the LV could not be found, and no leads or guidewires were left in place. The flexible sheath, spiral sheath, and leads enter tissue near the tricuspid annulus or near the base of Koch's (TOK) triangle. It appears that the use of the CS and MCV structures provides the location for identification of the TOK.

[0282] The lead is found in the LV. The lead has exited the endocardium into the chamber near the posterior papillary muscle, and the tip is located behind the posterior papillary muscle. It is located at the base near the mitral valve. Figures 43A to 43B shown.

[0283] Thus, various embodiments of VFA delivery systems and methods are disclosed. The various aspects disclosed herein may be combined in combinations different from those specifically presented in the specification and drawings. It should also be understood that, depending on the example, certain actions or events of any process or method described herein may be performed in a different order, may be added, merged, or omitted entirely (e.g., all described actions or events may not be necessary to perform the technology). In addition, although certain aspects of the present disclosure are described as being performed by a single module or unit for purposes of clarity, the technology of the present disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0284] In one or more examples, the techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. A computer-readable medium may include a non-transitory computer-readable medium, which corresponds to a tangible medium, such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and can be accessed by a computer).

[0285] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, the term "processor" as used herein may refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Moreover, the techniques may be fully implemented in one or more circuits or logic components.

[0286] All references and publications cited herein are expressly incorporated by reference in their entirety for all purposes, unless any aspect of the incorporation is directly inconsistent with this disclosure.

[0287] Unless otherwise specified, all scientific and technical terms used herein have the meanings commonly used in the art. The definitions provided herein are to facilitate understanding of certain terms frequently used herein and are not meant to limit the scope of the present disclosure.

[0288] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims may be understood to be modified by the terms “exactly” or “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by one skilled in the art utilizing the teachings disclosed herein or, for example, within typical ranges of experimental error.

[0289] The recitation of numerical ranges by endpoints includes all values ​​contained in that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. As used herein, the term "at most" or "not greater than" a value (e.g., at most 50) includes that value (e.g., 50), and the term "not less than" a value (e.g., not less than 5) includes that value (e.g., 5).

[0290] The terms "coupled" or "connected" refer to components being directly connected to each other (in direct contact with each other) or indirectly connected (having one or more components between and connected to the two components). Both terms can be modified by "operably" and "operably", which can be used interchangeably to describe a coupling or connection configured to allow the components to interact to perform at least some functions (e.g., a first medical device can be operably coupled to another medical device to send information in the form of data or receive data from it).

[0291] Directional terms, such as "top", "bottom", "side" and "end", are used to describe the relative positions of components and are not meant to limit the orientation of the embodiments under consideration. For example, an embodiment described as having a "top" and a "bottom" also includes embodiments thereof rotated in various orientations, unless the context clearly indicates otherwise.

[0292] Reference to "one embodiment," "an embodiment," "certain embodiments," or "some embodiments," etc., means that a particular feature, configuration, composition, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of these phrases in various places do not necessarily refer to the same embodiment of the present disclosure. Furthermore, in one or more embodiments, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner.

[0293] As used in this specification and the appended claims, the singular forms "a," "an," and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense to include "and / or," unless the content clearly dictates otherwise.

[0294] As used herein, "having", "including", "comprising", etc. are used in their open-ended sense and generally mean "including but not limited to". It will be understood that "consisting essentially of", "consisting of", etc. are included in "comprising", etc.

[0295] The term "and / or" means one or all of the listed elements or a combination of at least two of the listed elements.

[0296] The phrases "at least one," "comprising at least one," and "one or more" preceding a list refer to any one of the items in the list and any combination of two or more items in the list.

Claims

1. A medical device delivery system, comprising: a retainer sheath comprising a fixation element attachable to the right atrial endocardium in Koch's triangle in the right atrium of the patient's heart; a steerable sheath defining a lumen and configured to steer the retainer sheath, wherein the retainer sheath is at least partially disposed within the lumen of the steerable sheath and the retainer sheath is freely rotatable relative to the steerable sheath; a flexible needle disposed at least partially within the lumen of the retainer sheath and configured to flex with the retainer sheath when disposed within the lumen of the retainer sheath and when the retainer sheath is steerable by the steerable sheath; a guidewire disposed at least partially within the lumen of the retainer sheath, an implantable medical device configured to extend over or along the guidewire, wherein the implantable medical device comprises a left ventricular electrode implantable from the Koch triangle of the right atrium through the right atrial endocardium and central fibrous body and configured to deliver cardiac therapy to the left ventricle in a basal region and / or septal region of the left ventricular myocardium of the patient's heart or to sense electrical activity of the left ventricle, and The fixation element of the retainer sheath is configured to anchor the retainer sheath to the right atrial endocardium at least during delivery of the flexible needle through the Koch triangle in the right atrium of the patient's heart.

2. The system of claim 1, wherein the fixation element comprises a helical attachment element.

3. The system of claim 1 or 2, wherein the guidewire is at least partially disposed within the lumen of the flexible needle.

4. The system of claim 1, further comprising a dilator disposed at least partially within the lumen of the retaining sheath, wherein the flexible needle is disposed at least partially within the lumen of the dilator.

5. The system of claim 1, wherein the flexible needle is free to translate longitudinally relative to the retaining sheath.

6. The system of claim 1, wherein the implantable medical device further comprises one or more of a leadless device, a small lead, and a lead.

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