Systems and methods for synchronizing circumferential intracardiac resynchronization and pacing

Abstract

Various systems and methods for cardiac resynchronization therapy are provided. In one example, an apparatus for a multi-electrode pacemaker lead includes a plurality of annular electrodes distributed along a length of the multi-electrode pacemaker lead, the multi-electrode pacemaker lead configured to be implanted within a myocardium of a wall of a ventricle of a heart, such that an outer surface defining a periphery of at least one of the plurality of ring electrodes is in direct contact with the myocardium.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is an international application claiming priority to U.S. Provisional Application No. 63 / 364,319, entitled “SYSTEMS AND METHOD FOR SYNCHRONOUS CIRCUMFERENTIAL INTRAMYOCARDIAL RESYNCHRONIZATION AND PACING” and filed on May 6, 2022. The entire contents of the above-referenced applications are hereby incorporated by reference for all purposes. Technical Field

[0003] The present specification generally relates to medical devices for cardiac resynchronization and methods of operating and implanting the same. Background Art

[0004] The contraction and relaxation of the heart muscle (also known as the myocardium) are caused by muscle depolarization and repolarization, which are triggered by electrical impulses. Cardiac resynchronization therapy (CRT) is intended to alleviate asynchronous cardiac contractions that may be caused by intrinsic conduction system diseases, myocardial scarring, or cardiac pacing therapy. Conventional CRT includes coordinated pacing of the right ventricle and the left ventricle. The CRT left ventricular pacing site is limited by the anatomical structure of the heart veins, which may not be consistent with the optimal pacing site. In addition to poor or unreliable electrode-myocardial contact, the pacing site is suboptimal because of abnormal, non-conductive or scarred myocardium near the pacing site. In addition, CRT relies on a small number of simultaneous pacing sites. These factors result in suboptimal clinical response rates as low as 60-70%.

[0005] Similarly, conventional single-site right ventricular (RV) pacing induces nonphysiological cardiac contraction patterns that induce cardiomyopathy. Recently, alternatives to single-site RV pacing include pacing directly or proximally to the His bundle or to the left bundle branch (LBB) of the congenital cardiac conduction system. However, His bundle pacing is associated with high pacing thresholds, and both are subject to lead dislodgement. In addition, His bundle and LBB pacing utilize an intact cardiac conduction system, so these methods may not be suitable for individuals with damaged or abnormal cardiac conduction systems. In addition, conventional pacing lead implantation methods may have the risk of chronic damage to the tricuspid valve. Summary of the invention

[0006] In one example, the above problem can be solved by a device for a multi-electrode pacemaker lead, the device comprising a plurality of ring electrodes distributed along the length of the multi-electrode pacemaker lead, the multi-electrode pacemaker lead being configured to be implanted into the myocardium of the wall of a ventricle of the heart such that an outer surface defining the periphery of at least one of the plurality of ring electrodes is in direct contact with the myocardium. In this way, the variability of the contact between the myocardium and the ring electrodes can be reduced, while the risk of electrode dislodgment is also reduced. In addition, the circumferential distribution of the plurality of electrodes simultaneously activates the myocardium to reduce asynchrony.

[0007] It should be understood that the above brief description is provided to introduce in simplified form a series of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that solve any disadvantages noted above or in any part of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure will be better understood from the following description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0009] Figure 1 An embodiment of a pacing system including a multi-electrode lead encircling a left ventricle of a heart is depicted;

[0010] Figure 2A and 2B shows a schematic cross-sectional view of a multi-electrode lead implanted in the wall of the left ventricle of a heart;

[0011] Figure 3 schematically illustrates simultaneous multi-site pacing from a multi-electrode lead implanted in the wall of the left ventricle of a heart;

[0012] Figure 4 Schematic showing placement of a multi-electrode lead within the ventricular septum close to the cardiac conduction system;

[0013] Figure 5 A first example of a bipolar pacing pair of a multi-electrode lead is schematically shown;

[0014] Figure 6 A second example of a bipolar pacing pair of a multi-electrode lead is schematically shown;

[0015] Figure 7 Depicts exemplary dimensions of an embodiment of a multi-electrode lead that may be implanted into the wall of the left ventricle of a heart;

[0016] Figure 8Depicts exemplary dimensions of another embodiment of a multi-electrode lead that may be implanted in a wall of a left ventricle of a heart;

[0017] Fig. 9 A flow chart showing an exemplary method for implanting a multi-electrode lead into the myocardium;

[0018] Fig.10 A flow chart showing an exemplary method for optimizing an intramyocardial multi-electrode circumferential pacing system; and

[0019] Fig.11 A flow chart is shown of an exemplary method for operating a pacing system including a multi-electrode lead encircling a left ventricle of a heart for providing cardiac resynchronization therapy. DETAILED DESCRIPTION

[0020] The following description relates to systems and methods for cardiac resynchronization therapy (CRT). In a normal heart, the contraction of the left ventricle is coordinated by the interaction of intrinsic cardiac conduction tissue and healthy myocardium, so that contraction occurs synchronously from the base to the apex throughout a given layer of the myocardial wall, and by similar amounts in order to effectively pump blood. This contraction pattern may be disrupted by dysfunction of the cardiac conduction system (e.g., left bundle branch block), by scars in the myocardium, or by electrical stimulation generated by cardiac pacing therapy at a single point. Therefore, cardiac asynchrony may occur, in which parts of the left ventricle may contract at different times. For example, cardiac asynchrony can be identified based on uncoordinated segmental left ventricular wall motion in imaging studies (such as echo, cardiac magnetic resonance imaging, etc.) and uncoordinated left ventricular electrical activation, such as by causing wide QRS complexes in an electrocardiogram. CRT aims to stimulate coordinated contraction of the left ventricle by providing electrical pulses to relieve unsynchronized cardiac contractions.

[0021] However, conventional pacemaker leads for CRT and defibrillator leads for implantable defibrillators have unpredictable and variable tissue-electrode contact areas, resulting in high or variable sensing and stimulation thresholds. In addition, conventional pacemaker leads may produce non-target pacing, such as phrenic nerve stimulation. In addition, conventional pacemaker leads may include variable anchoring based on an arbitrary "landing zone" because the lead needs to be implanted extremely far from the ventricular base. In addition, bipolar pacing configurations may rely on one intravascular electrode and one myocardial electrode, which may increase the current required for myocardial stimulation. As another example, conventional His bundle (also referred to herein as the "His bundle") and left bundle branch (LBB) pacing systems may have insufficient intramyocardial lead positioning tracks and therefore undergo repeated insertion and removal to select a site during implantation. In the event of inaccurate positioning, the pacing output may be increased to capture the conducting tissue, with deleterious consequences for the generator battery life. Additionally, the risk of damaging or interfering with tricuspid valve function is higher. Furthermore, conventional His bundle and LBB pacing systems may have unstable implant positions, which increases the incidence of lead dislodgement or perforation.

[0022] Therefore, according to the embodiments described herein, synchronized circumferential pacing (SCIRP) can be employed by a multi-electrode lead embedded in the myocardium. By utilizing intramyocardial positioning, the ring electrodes of the multi-electrode lead increase contact with the myocardial wall to reduce contact variability. The ring electrodes can also have a reduced risk of infection, although most such infections involve the generator pocket. In addition, intramyocardial deployment avoids non-target depolarization, such as undesired phrenic nerve stimulation. As another example, multiple ring electrodes can be implanted around the myocardium in an array, thereby achieving both multiple unipolar configurations and multiple bipolar configurations, both of which can be used to overcome areas with poor excitability or high pacing thresholds. It should be understood that the term "multiple" indicates more than one. Still further, the multi-electrode lead can be implanted near the cardiac conduction system in the ventricular septum to complete His bundle or LBB pacing, where the risk of dislodgement is reduced and the integrity and excursion of the tricuspid valve leaflets are not disturbed. Overall, positive patient outcomes may increase.

[0023] Figure 1 An embodiment of a pacing system including a multi-electrode lead embedded within the myocardial wall of the left ventricle of the heart is shown. Figure 2A and 2B Schematic cross-sectional views are shown that further depict the intramyocardial positioning of a multi-electrode lead and how the electrode density across the lead body can be varied to provide the desired pacing effect. Figure 4A higher concentration of electrodes in the ventricular septum conduction system can allow for His bundle or LBB pacing with reduced placement difficulty. The multi-electrode lead provides an array of ring electrodes around the myocardium to stimulate base-to-apex pacing throughout the left ventricle even in the presence of non-conductive scar tissue, as schematically shown in Figure 3 Further, the multi-electrode lead can be adapted for a variety of pacing configurations, including those shown in Figure 5 and 6 An exemplary bipolar pacing configuration in. Figure 7 and 8 Exemplary dimensions are shown for a multi-electrode lead that includes extremely narrow (eg, less than 1 mm) ring electrodes distributed along the length of the lead body and features that may facilitate implantation. Figure 7 and 8 For example, the Fig. 9 The multi-electrode lead is implanted into the myocardium surrounding the left ventricle and Fig.10 Once implanted, the multi-electrode lead can be optimized based on Fig.11 The method provides synchronized pacing around the periphery of the myocardium for CRT.

[0024] Turning now to the accompanying drawings, Figure 1 An example of a circumferential pacing system 100 is schematically depicted relative to a patient's heart 101. The heart 101 is shown as a simplified cartoon of the relative positioning of a left ventricle (LV), a right ventricle (RV), a left atrium (LA), and a right atrium (RA). The circumferential pacing system 100 includes a pulse generator 102 coupled to a multi-electrode lead 106. A body 108 of the multi-electrode lead 106 is shown as being fully implanted within the wall of the heart 101 and surrounding the left ventricle. As will be further described below, the body 108 refers to a portion of the multi-electrode lead 106 that is implanted into the myocardium and includes a plurality of annular electrodes 110, while a connecting portion 104 of the multi-electrode lead 106 connects the body 108 to the pulse generator 102. Specifically, the body 108 is implanted within the myocardium surrounding the left ventricle of the heart 101, as will be described below with respect to Figure 2A and 2B Detailed description, and connecting portion 104 includes an insulated conductor (e.g., a wire) that electrically couples the plurality of ring electrodes 110 to the pulse generator 102. Further, the pulse generator 102 is an implantable device such that the pulse generator 102 and the multi-electrode lead 106 can be completely positioned within the patient's body, completely positioned within the heart, or can be wirelessly connected to a remotely located generator system.

[0025] The body 108 of the multi-electrode lead 106 is configured to follow the curvature of the left ventricle of the heart 101 when implanted and can substantially encircle the left ventricle along a short axis trajectory of the heart. Figure 1 In the example of the present invention, the body 108 surrounds the entire circumference of the left ventricle, wherein the first end 107 is positioned adjacent to the second end 109. However, in other examples, the body 108 can be sized to surround a portion of the left ventricle, wherein the first end 107 is spaced apart from the second end 109 by a desired amount.

[0026] For example, the body 108 can be sized to surround the circumference of the left ventricle by approximately 180-360 degrees (e.g., 270 degrees or greater). Unlike pacing systems used in conventional CRT that can utilize leads terminating in electrodes extending to both the left ventricle and the right ventricle, the circumferential pacing system 100 provides multi-site synchronous pacing of the wall of the left ventricle and the interventricular septum (IVS) separating the left ventricle from the right ventricle. Due to the synchronous multi-site pacing around the circumference of the left ventricle, the multi-electrode lead 106 may also be referred to herein as a synchronized circumferential pacing (SCIRP) lead.

[0027] Although the examples described herein show a generally circular multi-electrode lead trajectory around the ventricle, the path that the multi-electrode lead traverses at least partially around the ventricle can be winding, including straight and non-straight portions and / or combinations thereof. For example, the path that the multi-electrode lead traverses at least partially around the ventricle can include multiple segments connected by multiple bends. In another example, the path that the multi-electrode lead traverses at least partially around the ventricle can include multiple curved segments, each curved segment having a potentially different radius of curvature. In still other examples, the path that the multi-electrode lead traverses at least partially around the ventricle can be maintained in a single plane, while other examples can include a three-dimensional path that cannot be maintained in a single plane.

[0028] The multi-electrode lead 106 includes a plurality of ring electrodes 110 distributed along the body 108. For example, the multi-electrode lead 106 may include six ring electrodes 110, as in the example shown. In other examples, the multi-electrode lead 106 may include more or less than six ring electrodes, such as a number of ring electrodes in the range of 2-16. As an example, the multi-electrode lead 106 may include at least two ring electrodes 110. As another example, the multi-electrode lead 106 may include at least four ring electrodes 110. For example, the ring electrodes 110 may be gold-coated, stainless steel, nickel-titanium alloy (e.g., Nitinol), nickel-cobalt alloy (e.g., MP35N), cobalt superalloy (e.g., 35N LT), silver, platinum and platinum-iridium and / or carbon conductive rings, and each ring electrode 110 provides a terminal of the circumferential pacing system 100 in contact with the myocardium.

[0029] Each of the plurality of annular electrodes 110 has a cylindrical shape, wherein the outer periphery (e.g., the outer peripheral surface) of the cylinder contacts the myocardium of the heart 101 when implanted in the body 108, and is completely surrounded by it. Each annular electrode 110 has a length in a dimension parallel to the central axis of the cylindrical shape. The length of each annular electrode 110 in the multi-electrode wire 106 can be uniform, or the annular electrodes 110 can have different lengths. The length of each annular electrode 110 can be less than 1 millimeter (mm). For example, the length can be 0.5mm or less. As another example, the length can be in the range of 0.1mm to 0.2mm. As yet another example, the length of at least one of the annular electrodes 110 can be 0.1mm or less. All the annular electrodes in the plurality of annular electrodes 110 of the multi-electrode wire 106 can have the same length. Alternatively, the length of the annular electrode 110 can be variable, so that different annular electrodes have different lengths, as will be described in detail below. Further, in some embodiments, the edges (e.g., the first edge of the length and the second edge of the length) of each ring electrode in the ring electrodes 110 can be coated with a polymer. For example, charge can be otherwise concentrated at the edges, and the polymer coating can alleviate this charge accumulation.

[0030] The ring electrodes 110 are distributed along the body 108 at a fixed or variable spacing, which may be 10-30 cm, from the first end 107 to the second end 109 around the circumference of the left ventricle of the heart 101. For example, along the multi-electrode lead 106, each of the ring electrodes 110 may be equidistant from the adjacent ring electrodes 110. Alternatively, the distance between adjacent ring electrodes 110 may vary based on the desired spacing of the ring electrodes within the heart 101 when implanted, as will be described below with respect to Figure 2A In some embodiments, the multi-electrode lead 106 may further include a tip electrode having a surface area comparable to any of the plurality of ring electrodes 110. In some embodiments, the variable inter-electrode spacing may be configured to produce intramyocardial unipolar pacing at one or more of the plurality of ring electrodes 110, or bipolar pacing between at least one cathode of the plurality of ring electrodes 110 and at least one anode of the plurality of ring electrodes 110.

[0031] In a bipolar pacing configuration, one or more of the ring electrodes 110 can be configured as a common intramyocardial return electrode (e.g., anode) for distance bipolar pairing with one or more of the other ring electrodes 110. The common intramyocardial return electrode can have a larger cylindrical length than the other ring electrodes 110 (e.g., cathode). The common intramyocardial return electrode can also have a larger surface area than the cathode ring electrode 110 to reduce bipolar power usage and / or reduce anode capture by reducing return path resistance. When there is a single larger bipolar return electrode, it can be positioned in the septum near the His bundle or left bundle to optimize and enhance its performance. For example, the larger length bipolar return electrode can be a distal electrode on the body 108. Alternatively, an additional or second larger length bipolar return electrode can be positioned in the posterior fundus.

[0032] As an example, the distance between each of the plurality of cathode ring electrodes 110 and the common intramyocardial return electrode can be in the range of 15 mm to 200 mm, which can provide power savings while still providing sufficient contact area for delivering electrical stimulation. As another example, the maximum spacing distance between each of the plurality of cathode ring electrodes 110 and the common intramyocardial return electrode can be equal to the minimum spacing distance multiplied by the number of ring electrodes included in the plurality of ring electrodes 110 minus one. As yet another example, the minimum spacing distance can be in the range of between 5 and 20 mm (e.g., approximately 14-15 mm). For example, the minimum spacing distance can be calibrated to provide effective His bundle or left bundle branch stimulation through an array of extremely narrow ring electrodes 110 rather than one larger electrode, because the extremely narrow ring electrodes 110 can have reduced power consumption compared to one larger electrode. Example sizes of the ring electrodes 110 will be described below with respect to Figure 7 and 8 Give a description.

[0033] The multiple ring electrodes 110 may include a surface treatment, such as a fractal surface treatment. The fractal surface treatment may lower the myocardial stimulation threshold and extend the battery life of the pulse generator (e.g., the battery life of the power supply 116). For example, including a fractal coating may enhance the electrical performance of the multiple ring electrodes 110, such as by reducing polarization losses associated with the capacitance of small surface area electrodes. Further, the fractal surface treatment may increase the electrochemical surface area of ​​each of the ring electrodes 110. Additionally or alternatively, the surface treatment may include a drug eluting ring surface, such as a steroid eluting ring surface (e.g., a glucocorticoid eluting surface). For example, the use of steroid elution may help suppress myocardial inflammation, to lower the pacing threshold, and to alleviate variable pacing and sensing thresholds.

[0034] The body 108 of the multi-electrode lead 106 comprises one or more tubular materials having a desired stiffness (or flexibility) and compressive strength to enable the multi-electrode lead 106 to flex with the mechanical movement of the heart 101 while maintaining its shape between heartbeats. For example, the tubular material can be a bio-inert or biocompatible polymer, a thermoplastic polymer, a polyester, a plastic, an elastomer, or a combination of such materials. As an example, the outer surface of the body 108 can comprise As another example, the outer surface of the body 108 can include a polyetheretherketone (PEEK) tube. The inner surface (e.g., the inner lumen) of the body 108 can include a thin polymer lining, such as a thin-walled polyamide tube or a polytetrafluoroethylene (PTFE) lining. The relative dimensions of the body 108 will be described below with respect to Figure 7 and 8 Give a description.

[0035] The body 108 can provide a substrate for the plurality of ring electrodes 110 and also house a transmission line (e.g., a wire) for each of the ring electrodes 110. For example, each of the ring electrodes 110 can be connected to the pulse generator 102 via an individual enamel-coated copper wire, and the body 108 can further provide insulation for the copper wire conductor. Thus, the plurality of ring electrodes 110 can experience individual impedance matching for each electrode channel at the pulse generator 102. For example, the enamel-coated copper wire can be 38 gauge (according to the American Wire Gauge system). The enamel-coated copper wire connected to each of the ring electrodes 110 can be coated by the body 108 and extend through at least a portion of the body 108 before exiting the body 108 at a wire outlet at the second end 109. The wire outlet can guide the enamel-coated copper wire into the connection portion 104 of the multi-electrode lead 106 to electrically couple (e.g., connect) the plurality of ring electrodes 110 to the pulse generator 102. The connecting portion 104 can include the same or similar material as the body 108 of the multi-electrode lead 106 (e.g., a tubular bioinert thermoplastic polymer or elastomer). Further, the connecting portion 104 can be removably coupled to the pulse generator 102 so that the connecting portion 104 and the multi-electrode lead 106 can remain implanted during situations in which the pulse generator 102 is removed from the body. For example, the pulse generator 102 can be temporarily removed to replace the power supply 116 of the pulse generator 102. In some embodiments, the connecting portion 104 can be seamlessly integrated with the body 108, and the body 108 can be distinguished from the connecting portion 104 based on its intramyocardial location and / or inclusion of the ring electrodes 110.

[0036] As will be further described herein, the multi-electrode lead 106 can be configured to be implanted through the coronary sinus vein. Thus, the first end 107, the second end 109, and the wire exit can be positioned proximate to the coronary sinus. However, it will be appreciated that the multi-electrode lead 106 can be implanted into the myocardium through other access points. Further, in some embodiments, the multi-electrode lead 106 can include a mechanically fragile rupture point 112 between where the multi-electrode lead 106 enters the myocardium and the blood space (e.g., proximate to the second end 109 of the body 108 positioned within the myocardium). The rupture point 112 can disconnect the body 108 of the multi-electrode lead 106 from the remainder of the circumferential pacing system 100 (including the connecting portion 104 and the pulse generator 102). Thus, in the event of a related infection, portions of the circumferential pacing system 100 positioned within the blood space (e.g., the connecting portion 104) can be withdrawn without withdrawing the implanted body 108 of the multi-electrode lead 106.

[0037] The multi-electrode wire 106 can be adapted for an "over-the-wire" configuration for implantation. For example, the inner surface of the multi-electrode wire 106 can include a guidewire lumen for positioning over the wire. During implantation, a guidewire having an outer diameter less than the inner diameter of the multi-electrode wire 106 can first be navigated to a target position in the heart 101 (e.g., through the coronary sinus). For example, the outer diameter of the guidewire can be 0.014 inches, while the inner diameter of the multi-electrode wire 106 can be 0.0165 inches. The target position can include the base of the pre-selected left ventricle or the base of the central chamber to the apex level. In some embodiments, the target position can be close to a late electrical activation site or a late mechanical activation site. In some embodiments, the target position can be close to the basal lateral left ventricle. The guidewire can be navigated by fluoroscopic, electroanatomical, and electrocardiographic depth navigation techniques. Once the guidewire is placed, the multi-electrode wire 106 can be advanced onto the guidewire, such as being pushed into place by a detachable catheter. As an example, lining the inner surface of the multi-electrode wire 106 with PTFE can reduce friction when the multi-electrode wire 106 is advanced over the guidewire. Additional structures of the multi-electrode wire 106 that may aid in implantation are described herein. Figure 7 and 8 Give a description.

[0038] The pulse generator 102 further includes a power supply 116 and a control unit 118. The power supply 116 may include a battery, such as a lithium iodide battery. In some instances, the battery may be a rechargeable battery. In other instances, the power supply 116 may not be rechargeable, and thus the pulse generator 102 may be replaced in response to a low power situation. The pulse generator 102 may be a multi-channel generator. For example, one or a group (e.g., a portion) of the plurality of ring electrodes 110 may be coupled to a selected channel by individual enamel-coated copper wires of each ring electrode. For example, a first group of ring electrodes in the plurality of ring electrodes 110 may be coupled to a first channel of the pulse generator 102, a second group of ring electrodes in the plurality of ring electrodes 110 may be coupled to a second channel of the pulse generator 102, a third group of ring electrodes in the plurality of ring electrodes 110 may be coupled to a third channel of the pulse generator 102, and the remaining fourth group of ring electrodes in the plurality of ring electrodes 110 may be coupled to a fourth channel of the pulse generator 102. As a non-limiting example, where there are 12 ring electrodes 110 and the pulse generator 102 has four channels, each of the four channels can be electrically coupled to 3 different ring electrodes. As another example, each of the ring electrodes 110 can be coupled to a different channel of the pulse generator 102. As yet another example, depending on the desired pacing configuration of the circumferential pacing system 100, only a subset of the ring electrodes can be electrically coupled to the pulse generator 102. Thus, the pulse generator 102 can have more or less than four individual pacing channels. For example, the pulse generator 102 can be a specially built generator for operating a multi-electrode lead 106. For example, the output of each channel can be individually tuned during implantation based on the minimum capture threshold of each ring electrode of the channel.

[0039] The control unit 118 may include a computing device, such as a microcontroller. The control unit 118 may monitor the electrical activity of the heart 101 and analyze the activity to detect abnormalities in the morphology and / or timing of electrical pulses in the heart 101. Based on the detected abnormalities, the pulse generator 102 may generate electrical pulses through the circuit system and deliver the electrical pulses through the enamel-coated copper wire through the connecting portion 104 to one or more of the plurality of ring electrodes 110. In some instances, the control unit 118 may adjust the current and / or voltage output by the pulse generator 102 for each channel. The control unit 118 may include a processor and a memory storing calibration and computer-readable instructions (e.g., software) corresponding to one or more methods, examples of which are described herein with respect to Fig.11Provided. For example, the processor can be configured to execute computer-readable instructions stored in the memory to implement one or more methods. In some instances, the control unit 118 can receive input from one or more sensors or sensing electrodes to monitor the mechanical and / or electrical activity of the heart 101. The sensors or sensing electrodes can be included in the pulse generator 102. Alternatively, the sensors or sensing electrodes can be located outside the pulse generator 102 and can communicate with the control unit 118.

[0040] When the multi-electrode lead 106 is implanted in the heart 101, the periphery of each of the ring electrodes 110 is completely surrounded by the myocardium and in direct contact with the myocardium. Therefore, the multiple ring electrodes 110 can deliver the electrical pulses generated by the pulse generator 102 directly to the surrounding myocardium, and the electrical pulses can further propagate through the myocardium to cause coordinated contraction through muscle depolarization and repolarization. In this way, the circumferential pacing system 100 can provide synchronized cardiac contraction.

[0041] In some embodiments, the circumferential pacing system 100 can be configured as a combined pacemaker and defibrillator (e.g., a CRT-D device). For example, the circumferential pacing system 100 can provide electrical pulses to the heart 101 to help the left and right ventricles contract synchronously and provide an electrical shock in response to the control unit 118 detecting an abnormal heart rhythm (e.g., ventricular fibrillation). Additionally or alternatively, in some embodiments, the circumferential pacing system 100 can be configured to operate in an atrioventricular pacing mode to allow and optimize atrioventricular pacing.

[0042] Now turn to Figure 2A and 2B , shows a schematic cross-sectional view of a multi-electrode lead 206 positioned in a heart 201. For example, the multi-electrode lead 206 may be Figure 1 The multi-electrode wire 106 is provided. Figure 2A A short-axis view 200 of a heart 201 is depicted, and Figure 2B A vertical long axis view 250 of the heart 201 is depicted. Specifically, the short axis view 200 depicts a cross section of the left ventricle 202, the right ventricle 216, and the coronary sinus 218, while the vertical long axis view 250 depicts a cross section of the left ventricle 202 and the coronary sinus 218.

[0043] Heart 201 includes myocardium 204, which is bounded on the outside by epicardium 203 and on the inside by endocardium 205. As can be seen in each of short-axis view 200 and perpendicular long-axis view 250, multi-electrode lead 206 is positioned entirely within myocardium 204. Figure 2AAs shown in the short-axis view 200 of FIG. 2 , the multi-electrode lead 206 encircles the left ventricle 202 and passes through the IVS 220 separating the left ventricle 202 and the right ventricle 216. Figure 2A The multi-electrode lead 206 is shown as having a circular shape, but it is understood that the multi-electrode lead 206 can have another generally curved shape that follows the curvature of the left ventricle 202 when implanted in the heart 201. Further, the curved shape can include a first end (or terminal end) that is first advanced into the myocardium 204 during implantation and a second end (or terminal end) at an exit site of the myocardium 204, such as Figure 1 As described in relation to the multi-electrode lead 106 in . In some instances, the myocardium can be accessed through a shared entry site and exit site, while in other instances, the entry site and exit site can be at different locations. For example, because the multi-electrode lead 206 can be implanted through the coronary sinus 218, the first end and the second end can be positioned proximate to the coronary sinus 218. Therefore, both the first end and the second end of the multi-electrode lead 206 can be positioned within or proximate to the coronary sinus 218 or the heart base. Alternatively, the entry and exit sites can be positioned at any arbitrary myocardial-blood interface in the wall of the left ventricle or the right ventricle. For example, the myocardium can be accessed from the right ventricular surface of the ventricular septum and exit to the posterior base of the left ventricle.

[0044] The multi-electrode lead 206 includes a plurality of ring electrodes 210, which may be Figure 1 The plurality of annular electrodes 110 can function as previously described. Figure 2A In the example of FIG. 1 , the multi-electrode wire 206 includes five ring electrodes 210 having a body 208 (e.g., Figure 1 The invention provides a variable inter-electrode spacing of the body 208 of the multi-electrode lead 206. The inter-electrode spacing is smaller at a first portion 212 of the multi-electrode lead 206 implanted in the anterior IVS 220, and is larger at a second portion 214 of the multi-electrode lead 206, the second portion being away from the anterior IVS 220, such as near the posterior fundus of the heart 201. For example, the inter-electrode spacing between adjacent ring electrodes 210 in the first portion 212 is a first spacing s1, and the second portion 214 is a larger second spacing s2 between adjacent ring electrodes 210. Positioning more concentrated ring electrodes at the IVS 220 can allow capture of the proximal His branch to utilize a functional conduction system (if present) or synchronized fundus activation (if not present). However, it will be appreciated that there can be other variations in the inter-electrode spacing, including uniform spacing along the body 208 of the multi-electrode lead 206.

[0045] The arrangement of the ring electrodes 210 along the body 208 provides an array of electrodes around the myocardium 204, and the ring electrodes 210 can be configured into a plurality of different unipolar or bipolar configurations to overcome areas of poor excitability or high pacing thresholds in the heart 201. For example, the plurality of ring electrodes 210 can be divided into pairs for bipolar pacing, wherein two immediately adjacent ring electrodes 210 form each bipolar pacing pair. As another example, one or more common return electrodes can provide an anode for multiple cathodes for a distanced bipolar configuration. Exemplary bipolar pacing pairs are shown in Figure 5 and 6 As another example, the ring electrodes 210 can be configured as multiple unipolar electrodes with the pulse generator as the anode. Anatomical sites in the heart 201 that may benefit from specific positioning of individual ring electrodes 210, a higher density of ring electrodes 210, and / or positioning of a common bipolar pacing return electrode include locations in the IVS 220 near the His bundle or left bundle branch or near the posterior fundus. Additionally, if only four ring electrodes 210 are available, it may be desirable to position one ring electrode in the IVS 220, one ring electrode in the posterior fundus, one ring electrode in the lateral fundus, and one ring electrode in the anterior fundus.

[0046] Figure 2B An exemplary basal position of the multi-electrode lead 206 is shown, although other basal to apical positions may be used. However, the basal position enables the multi-electrode lead 206 to be positioned near the branch bundles of His for increased stimulation of the intrinsic cardiac conduction system, as will be described below with respect to Figure 4 Detailed description.

[0047] Now turn to Figure 3 , shows a schematic vertical long axis view 300 of the left ventricle 202 of the heart 201. Figure 2A and 2B Components introduced in have the same numbering and will not be reintroduced. Figure 3 The vertical long axis view 300 schematically depicts the propagation of an electrical pulse 302 delivered by the plurality of annular electrodes 210 through an activation path in the myocardium 204. Figure 3 In the example of , the myocardium 204 includes a scar 304 that impedes the propagation of the electrical pulse 302. However, because the multi-electrode lead 206 utilizes all basal pacing sites simultaneously, the scar 304 interrupts only a portion of the activation path. Thus, even in the presence of the scar 304, the multi-electrode lead 206 effectively provides circumferential multipolar basal to apex pacing for the entire left ventricle 202. It will be appreciated that Figure 3 The density of ring electrodes 210 shown in FIG. 5 is exemplary, and the density of ring electrodes 210 and / or pacing channels may be varied as desired.

[0048] Because the pacing site (e.g., ring electrode 210) is positioned within the myocardium, the pacing site is not subject to dislodgement. Further, because the position of the ring electrode 210 is within the myocardium, the ring electrode 210 makes uniform circumferential contact with the myocardium 204, thereby eliminating the problem of variable contact that may occur with typical endocardial transvenous pacing electrodes or epicardial pacing electrodes, and eliminating the risk of dislodgement. For example, a fully intramyocardial ring electrode 210 can increase contact with the myocardium 204 compared to conventional endocardial or epicardial pacing electrodes. As used herein, "circumferential contact" refers to the outer surface defining the periphery of a given ring electrode being in direct contact with the surrounding myocardium.

[0049] As mentioned above, the multi-electrode lead 206 can be used for direct His bundle or left bundle branch (LBB) pacing (LBBP). Figure 4 , schematic view 400 shows the placement of the multi-electrode lead 206 within the IVS 220 relative to the cardiac conduction system (e.g., the interventricular septal conduction system). Dashed line 402 represents the separation between the atria and ventricles. When cardiac conduction is functional, the atrioventricular node (AVN) 404 receives a pacing signal originating from the sinoatrial node in the right atrium and transmits the pacing signal along the His bundle (HB) 406 and through the left bundle branch (LBB) 408 and the right bundle branch (RBB) 410 to cause coordinated (e.g., synchronous) contraction of the ventricles. However, cardiac conduction abnormalities caused by, for example, activation dispersion or refractory changes may result in cardiac asynchrony. For example, due to slow or absent conduction through the LBB 408, the LBBB may cause delayed contraction of the left ventricle, which may lead to poor ventricular remodeling and heart failure.

[0050] Thus, the multi-electrode lead 206 can be placed in the IVS 220 proximal to the LBB 408 and the HB 406 to stimulate the cardiac conduction system via LBB or HB pacing. Additionally or alternatively, the multi-electrode lead 206 can directly activate the IVS 220 to provide synchronized pacing. For example, such synchronized pacing can provide increased positive patient outcomes compared to right ventricular pacing. Further, the intramyocardial location within the IVS 220 and the basal location of the ring electrode 210 can reduce interference with tricuspid valve leaflet integrity and reduce excursions while also avoiding non-target depolarizations, such as undesired phrenic nerve stimulation.

[0051] Reference now Figure 5 , shows a schematic cross-sectional view of a multi-electrode lead 506 positioned in the heart 201. For example, the multi-electrode lead 506 may be Figure 1 The multi-electrode wire 106 is shown in Figure 5 The view in Figure 2AThe short-axis view 200 of the multi-electrode wire 206 in FIG. 2 is similar, and the position of the multi-electrode wire 506 in the heart 201 is described above with respect to the multi-electrode wire 206. Further, the multi-electrode wire 506 is similar to the short-axis view 200 of the multi-electrode wire 206 in FIG. Figure 2A and 2B The multi-electrode lead 206 of FIG. 506 functions similarly, with similar components being numbered similarly. Therefore, for the sake of brevity, the differences between the multi-electrode lead 506 and the multi-electrode lead 206 will be discussed herein.

[0052] In the Figure 5 In the example of the embodiment of the present invention, the multi-electrode lead 506 includes 9 ring electrodes 510, although in other examples a different number of ring electrodes 510 (e.g., 2-8 ring electrodes or more than 9 ring electrodes) may be included. In the present example, the ring electrodes 510 include a first ring electrode 510a, a second ring electrode 510b, a third ring electrode 510c, a fourth ring electrode 510d, a fifth ring electrode 510e, a sixth ring electrode 510f, a seventh ring electrode 510g, an eighth ring electrode 510h, and a ninth ring electrode 510i. The multi-electrode lead 506 operates in a first bipolar pacing configuration 500, wherein the second ring electrode 510b and the third ring electrode 510c include a first bipolar pair 522, and the sixth ring electrode 510f and the seventh ring electrode 510g include a second bipolar pair 524. In the first bipolar pair 522, the second ring electrode 510b includes a cathode, and the third ring electrode 510c includes an anode. During operation, the second ring electrode 510b can receive pulses from a connected pulse generator (e.g., Figure 1 The sixth annular electrode 510f comprises a cathode and the seventh annular electrode 510g comprises an anode, and thus, in response to the sixth annular electrode 510f receiving an electrical pulse from the pulse generator, current flows from the sixth annular electrode 510f to the seventh annular electrode 510g through the myocardium 204. However, in other examples, the anode and the cathode may be swapped, such that in the first bipolar pair 522, the second annular electrode 510b comprises an anode and the third annular electrode 510c comprises a cathode, and in the second bipolar pair 524, the sixth annular electrode 510f comprises an anode and the seventh annular electrode 510g comprises a cathode.

[0053] Additional ring electrodes 510 (e.g., first ring electrode 510a, fourth ring electrode 510d, fifth ring electrode 510e, eighth ring electrode 510h, and ninth ring electrode 510i) not included in first bipolar pair 522 and second bipolar pair 524 may not be operated (e.g., may not receive current from the pulse generator) while multi-electrode lead 506 is operated in first bipolar pacing configuration 500 in at least some embodiments. For example, when fewer connectors are available on the pulse generator than electrodes, a portion of the electrodes may be disabled to save battery life by programming the pulse generator or using an adapter to select which electrode is physically connected to the pulse generator. However, in other embodiments, all ring electrodes 510 may be operated.

[0054] Figure 6 Schematic cross-sectional view of multi-electrode lead 506 in second bipolar pacing configuration 600 is shown. Therefore, the components are numbered the same and will not be reintroduced, wherein Figure 5 The first bipolar pacing configuration 500 with Figure 6 The differences between the second bipolar pacing configuration 600 are described herein.

[0055] In the second bipolar pacing configuration 600, the third ring electrode 510c and the fourth ring electrode 510d comprise a first bipolar pair 622, and the eighth ring electrode 510h and the ninth ring electrode 510i comprise a second bipolar pair 624. In the first bipolar pair 622, the third ring electrode 510c comprises a cathode, and the fourth ring electrode 510d comprises an anode. During operation, the third ring electrode 510c can receive an electrical pulse from a pulse generator, and in response to the electrical pulse, current flows from the third ring electrode 510c through the myocardium 204 to the fourth ring electrode 510d. Similarly, in the second bipolar pair 624, the eighth ring electrode 510h comprises a cathode, and the ninth ring electrode 510i comprises an anode, and thus, in response to the eighth ring electrode 510h receiving an electrical pulse from the pulse generator, current flows from the eighth ring electrode 510h through the myocardium 204 to the ninth ring electrode 510i. However, in other embodiments, in the first bipolar pair 622, the third annular electrode 510c includes an anode and the fourth annular electrode 510d includes a cathode, and in the second bipolar pair 624, the eighth annular electrode 510h may include an anode and the ninth annular electrode 510i may include a cathode.

[0056] Thus, the multi-electrode lead 506 can be adapted to a variety of different bipolar and unipolar pacing configurations by operating specific ring electrodes 510 differently as desired, such as based on their positioning in the heart 201 and the desired pacing configuration. Specifically, in each of the first bipolar pacing configuration 500 and the second bipolar pacing configuration 600, providing bipolar pacing near the IVS and also near the posterior base of the left ventricle can provide effective His bundle and LBB pacing. In this way, the multi-electrode lead 506 provides a multi-purpose intramyocardial pacing device.

[0057] Steering Figure 7 , a rendering 700 of a first exemplary embodiment of a synchronized circumferential pacing (SCIRP) lead 706 is shown. The SCIRP lead 706 is Figure 1 Multi-electrode wire 106, Figure 2A-4 The multi-electrode wire 206 or Figure 5 and 6 An example of a multi-electrode lead 506 and can function as previously described. It is understood that Figure 7 The relative dimensions shown are exemplary and variations may be used without departing from the scope of the present disclosure.

[0058] The SCIRP lead 706 includes a body 708 having 12 ring electrodes 710 distributed along its length, the length extending from a first end 707 to a second end 709. However, it will be appreciated that the SCIRP lead 706 can have fewer ring electrodes 710, such as in the range of 4-6. The length of the body 708 can be approximately 300 millimeters (mm). For example, the length of the body 708 can be in the range of 250-350 mm, although other lengths are possible. The length of the body 708 can be sized to approximately surround the left ventricle of the heart.

[0059] In a first exemplary embodiment, each ring electrode 710 is 0.50 mm in length, with the inter-electrode spacing between adjacent ring electrodes 710 being uniform. For example, the inter-electrode spacing between adjacent ring electrodes may be in a range between 1 and 200 mm, although other spacings are possible. The inter-electrode spacing between adjacent electrodes may vary based on the length of the body 708, the number of ring electrodes 710 included in the SCIRP lead 706, and whether the spacing of the ring electrodes 710 is variable or uniform.

[0060] The SCIRP lead 706 includes a tapered nose cone 711 extending from the first annular electrode 710a to the first end 707. In the present example, the length of the tapered nose cone 711 is approximately one-tenth the length of the body 708. As a non-limiting example, the length of the tapered nose cone 711 can be approximately 20 mm. The tapered nose cone 711 is a region where the outer diameter of the body 708 tapers to reduce the diameter mismatch between the SCIRP lead 706 and the guidewire used during implantation, which may help simplify implantation of the SCIRP lead 706 in the myocardium. For example, the tapered nose cone 711 can be advanced within the myocardium from an access site in the coronary sinus by pushing and / or pulling. Due to the tapered nose cone 711, the first end 707 has a smaller outer diameter d1, while the second end 709 has a larger outer diameter d2. For example, the SCIRP lead 706 can have a uniform diameter (e.g., d2) from the first ring electrode 710a to the second end 709, and the diameter of the tapered nose cone 711 can taper from d2 to d1. As a non-limiting example, d1 can be 0.89 mm and d2 can be 1.30 mm. In other embodiments, the length of the SCIRP lead can be tapered so that the lead tapers gradually (e.g., continuously) or abruptly (e.g., in a stepwise manner) toward a minimum tip diameter from any point along its length (e.g., any point intermediate the first end 707 and the second end 709). In connection with this tapering, the plurality of ring electrodes 710 can have variable diameters and surface areas, with the diameters and surface areas being larger when the diameter of the SCIRP lead 706 is larger, and the diameters and surface areas gradually decreasing as the diameter of the SCIRP lead 706 decreases toward the minimum tip diameter at the first end 707. In some embodiments, the tapering can continue uniformly from the second end 709 to the first end 707. In such embodiments, the electrode diameter is matched based on its position in the tapering, being larger near the second end 709 and narrower away from the second end 709. Thus, at least a portion of the SCIRP lead 706 can have a decreasing diameter toward the first end 707, which is configured to be inserted into the myocardium prior to the second end 709 during implantation.

[0061] Although not shown in Figure 7In some embodiments, however, the SCIRP guidewire 706 may further include a mechanical loop (e.g., a ring) or other removable pulling mechanism positioned on a conical nose cone 711 adapted to receive a removable tether. For example, the tether may be removably attached to the mechanical loop so as to pull the conical nose cone 711 of the SCIRP guidewire 706 antegrade in a veno-venous or veno-cameral fashion during implantation. For example, the removable pulling mechanism may be a looped suture or fine wire including a removable screw or lock to allow the removable guide to be pulled along the trajectory of the guidewire during implantation. Thus, during implantation, the SCIRP guidewire 706 may be simultaneously pulled at the first end 707 and pushed at the second end 709 by the tethered mechanical loop. For example, after the SCIRP guidewire 706 reaches a desired location within the heart muscle, the tether may be removed from the mechanical loop of the conical nose cone 711.

[0062] In at least some embodiments, the tapered nose cone 711 can have a greater length than the rear portion of the SCIRP guidewire 706 between the final ring electrode 710b and the second end 709. Thus, the greater length of the tapered nose cone 711 can make the change in diameter more gradual for smoother insertion.

[0063] Figure 8 A rendering 800 of a second exemplary embodiment of a SCIRP guidewire 806 is shown. The SCIRP guidewire 806 is Figure 1 Multi-electrode wire 106, Figure 2A-4 The multi-electrode wire 206 or Figure 5 and 6 An example of a multi-electrode lead 506 and can function as previously described. It is understood that Figure 8 The relative dimensions shown are exemplary and variations may be used without departing from the scope of the present disclosure.

[0064] The SCIRP lead 806 includes a body 808 having twelve ring electrodes 810 distributed along its length, the length extending from a first end 807 to a second end 809. However, it is understood that the SCIRP lead 806 may have fewer ring electrodes 810, such as in the range of 4-6. The SCIRP lead 806 is similar to Figure 7 The SCIRP wire 706 of FIG. 8 is a SCIRP wire 806 of FIG. 806 , and therefore, the present specification will describe the difference between the SCIRP wire 806 and the SCIRP wire 706 . In the second exemplary embodiment, the length of each ring electrode 810 is 0.10 mm, wherein the inter-electrode spacing between adjacent ring electrodes 810 is uniform. Figure 7The length of the annular electrode 710 is smaller than that of the annular electrode 710, so the inter-electrode spacing between adjacent annular electrodes may be smaller than Figure 7 The distance between electrodes is larger.

[0065] The SCIRP lead 806 includes a conical nose cone 811 extending from a first ring electrode 810a to a first end 807. In this example, the conical nose cone 811 has a Figure 7 The conical nose cone 811 of the SCIRP guide wire 806 is the same size as the conical nose cone 711 of the SCIRP guide wire 806 and functions as previously described. For example, the conical nose cone 811 may also optionally include a mechanical ring for tethering during insertion. Further, the diameter of the body 808 of the SCIRP guide wire 806 from the first ring electrode 810a to the second end 809 is the same as the diameter of the body 808 of the SCIRP guide wire 806 from the first ring electrode 810a to the second end 809. Figure 7 The diameters of the bodies of the SCIRP wires 706 are the same.

[0066] Shown in Figure 7 A first exemplary embodiment of a SCIRP lead in and shown in Figure 8 The second exemplary embodiment of the SCIRP lead in both can be less than 1 mm in length (e.g., Figure 7 The middle is 0.50mm and Figure 8 The electrode-tissue impedance can be increased by using extremely narrow ring electrodes (0.1 mm in diameter) of the SCIRP lead. For example, the reduced surface area of ​​the extremely narrow ring electrodes of the SCIRP lead results in a smaller surface contact area, which further results in increased resistance. As an example, the ring electrodes of the SCIRP lead can each have a tissue contact impedance greater than 1 ohm. As another example, each of the electrodes of the SCIRP lead can have a tissue contact impedance greater than 20 ohms.

[0067] Compared to standard right ventricular or left ventricular intravenous endocardial electrodes, the intramyocardial electrodes described herein increase the load resistance by minimizing the low resistance blood path because the standard transvenous electrodes are exposed to blood and have variable contact with the myocardium. Smaller intramyocardial electrodes increase impedance, which is desirable for limiting current and increasing the voltage drop at the electrode interface with the myocardium. The reduced current consumption increases the life of the pulse generator. The intramyocardial electrodes also avoid the problem of wasteful parallel voltage drop from the electrode to the blood pool of the intravascular wire, and this avoidance reduces the current consumption of the myocardial capture for the intramyocardial electrodes.

[0068] Because of this increased electrode-tissue impedance, battery depletion may be reduced with SCIRP leads compared to conventional intravenous pacemaker leads that must be exposed to a blood pool. Figure 1 As explained, the SCIRP lead may be included in a pacing system that includes a pacing device having a power source (e.g., Figure 1The pulse generator of the power source 116) of the SCIRP lead can be used, and the lower battery depletion can result in less frequent recharging or replacement of the power source. Further, for a given battery energy budget, the intramyocardial electrode placement of the ring electrodes of the SCIRP lead allows the use of more channels, which can reduce battery life compared to operating fewer channels, but can enable the use of more channels compared to conventional intravenous pacemaker leads.

[0069] Next, Fig. 9 An example method 900 is shown for implanting a SCIRP lead (eg, multi-electrode lead 106) within the myocardium surrounding the left ventricle of a subject's heart.

[0070] At 902, method 900 includes advancing a guidewire into the myocardium via transvascular access. For example, the guidewire can pass through the myocardium through the subject's circulatory system and allow the lumen-containing SCIRP lead to be advanced into the myocardial location. Specifically, the guidewire can access the coronary sinus via the vena cava and exit the coronary sinus into the ventricular myocardium for transvenous access. However, in other examples, the guidewire can be advanced into the myocardium via transarterial access.

[0071] At 904, method 900 includes navigating a guidewire through the myocardium at a desired base-to-apex level to define a trajectory for SCIRP lead implantation. For example, the operator may navigate the guidewire via fluoroscope (e.g., biplane fluoroscope), intracardiac electrogram, and ultrasound. Fluoroscopes and ultrasound (e.g., cardiac ultrasound) may provide a visual indication of the guidewire within the heart, while the intracardiac electrogram may indicate the radial depth of the guidewire within the ventricular myocardium (e.g., the depth from the epicardial and endocardial borders of the myocardium). Prior to entering a cardiac chamber, the guidewire may traverse some or all of the trajectory for SCIRP lead implantation, where the guidewire may be advanced to achieve guidewire grasping or captured to apply countertraction or externalization, as will be described in detail below at 906. For example, the desired base-to-apex level may be a preselected base implantation level in order to position the SCIRP lead proximal to a cardiac conduction system structure, such as the bundle of His.

[0072] In some embodiments, method 900 includes techniques for achieving a strong guidewire "grasp" to facilitate advancement of the SCIRP wire over the guidewire. These techniques include advancing the guidewire deep into the myocardium, or navigating the guidewire deep into a heart chamber such as the right ventricle or left ventricle, where the guidewire is optionally captured, as optionally indicated at 906. For example, the guidewire can be captured by an antegrade transvenous snare catheter (e.g., with the same direction of guidewire advancement) or a retrograde arterial transaortic snare catheter (e.g., with a direction opposite to the direction of guidewire advancement around the ventricle). The snare catheter can include one or more loops that capture the distal end of the guidewire to optionally provide countertraction. Prior to capture, the guidewire can traverse some or all of the trajectory of SCIRP wire implantation.

[0073] At 908, method 900 includes advancing the SCIRP wire delivery system over the guidewire into the myocardium. The SCIRP wire delivery system can be advanced along a trajectory defined by the guidewire by sliding the SCIRP wire over the guidewire, wherein the leading distal end of the SCIRP wire includes a portion of the SCIRP wire with the smallest diameter to reduce a diameter mismatch between the guidewire and the SCIRP wire to facilitate implantation, as described above with respect to Figure 7 and 8 As described. For example, a catheter can be used to advance the second end of the SCIRP guidewire opposite the smallest diameter portion. For example, the smallest diameter portion can include a tapered nose cone, or the SCIRP guidewire can be tapered along its length with a continuous tapering or a step-wise tapering. For example, the diameter of the SCIRP guidewire can gradually increase from the distal end of the SCIRP guidewire to the largest diameter portion, which can be at the second end of the SCIRP guidewire and / or at an intermediate portion between the distal end and the second end of the SCIRP guidewire.

[0074] At 910, method 900 optionally includes capturing a pulling mechanism of the SCIRP lead delivery system by a retrograde guide. The pulling mechanism can be a mechanical loop, a loop, a hook, or another structure that can be captured by the retrograde guide. For example, the retrograde guide can be a looped suture or a fine wire including a removable screw or lock to allow traction on the pulling mechanism. Once the pulling mechanism is captured, if desired, the SCIRP lead can be pulled further antegrade by the retrograde guide along the trajectory defined by the guidewire.

[0075] At 912, method 900 includes pushing and / or pulling the SCIRP wire to advance the SCIRP wire within the myocardium along the track defined by the guidewire. For example, a fluoroscope can be used to visually monitor the position of the SCIRP wire along the track defined by the guidewire, and the SCIRP wire can be advanced until the SCIRP wire surrounds a desired portion of the periphery of the left ventricle.

[0076] At 914, method 900 includes evaluating the rotational circumferential position of the ring electrodes of the SCIRP lead. For example, once the SCIRP lead is around a desired portion of the periphery of the left ventricle, the rotational circumferential position of the ring electrodes can be fine-tuned to achieve a desired position that advantageously positions the predetermined ring electrodes relative to anatomical features. As an example, the predetermined ring electrodes on the SCIRP lead can have a desired rotational circumferential position around the left posterior bundle of the LBB or His bundle, near the left ventricular endocardial surface surrounding the left ventricular septal myocardium, so as to facilitate His bundle or LBB pacing. As an example, the rotational circumferential position of the predetermined ring electrodes relative to the LBB or His bundle can be determined by intracardiac electrogram sensing or pacing to check the left ventricular activation time, which can be measured by surface ECG or by other SCIRP electrodes. For example, the predetermined ring electrodes can be determined to be in the desired position in response to the left ventricular activation time being less than a non-zero predetermined threshold time. As another example, if the spacing of the ring electrodes along the body of the SCIRP lead is variable, the desired rotational circumferential positions may include positioning the higher concentration (eg, density) ring electrodes at the interventricular septum and the posterior base of the left ventricle.

[0077] At 916, method 900 includes determining whether the desired position has been reached. If the desired position has not been reached (e.g., the left ventricular activation time is greater than or equal to a predetermined threshold time), method 900 proceeds to 918 and includes pushing and / or pulling the SCIRP lead to adjust the rotational circumferential positioning of the SCIRP lead. Method 900 can then return to 914 to reassess the position. In some embodiments, the rotational circumferential positioning can be incrementally adjusted between assessment positions, while in other embodiments, the rotational circumferential position of the SCIRP lead can be adjusted while the positioning is being assessed (e.g., substantially at the same time). If adequate capture is not achieved by rotational positioning (such as in the presence of extensive basal scarring), method 900 can return to 904 and reposition the electrode in a more apical position away from the basal scar, as detected by electrograms or imaging.

[0078] Returning to 916, if the desired positioning has been reached, method 900 proceeds to 920 and includes withdrawing the SCIRP lead delivery system, including any catheter or guide (e.g., a pulling structure), thereby leaving the SCIRP lead in the appropriate position. Thus, the SCIRP lead can remain implanted in the myocardium surrounding the left ventricle, and the components used during the implantation process can be removed from the subject. Further, the ring electrodes of the SCIRP lead can be evaluated for pacing capture thresholds, which can be used to program a pulse generator electrically coupled to the ring electrodes. Method 900 can then end.

[0079] Fig.10 An example method 1000 is shown for setting electrodes of a SCIRP lead (e.g., multi-electrode lead 106) that has been implanted within the myocardium surrounding the left ventricle of a subject's heart. Electrode optimization according to method 1000 can help ensure that electrical pulses from the intramyocardial electrodes (e.g., ring electrodes 110) of the SCIRP lead stimulate the myocardium and / or the cardiac conduction system without consuming excessive energy in order to extend the battery life of the pulse generator.

[0080] At 1002, method 1000 includes determining a capture threshold for each electrode pair (eg, monopolar and bipolar pairs).

[0081] At 1004, method 1000 includes excluding electrodes having a capture threshold exceeding an upper threshold from further optimization. The upper threshold may be a predetermined non-zero capture threshold that distinguishes electrodes capable of producing propagated contractions in the heart from electrodes that cannot reliably produce a contractile response.

[0082] At 1006, method 1000 includes assessing conduction system capture based on R wave peak time. R wave peak time may refer to the paced to lateral lead R wave peak time. R wave peak time may be used to determine whether adequate threshold conduction system capture has been achieved.

[0083] At 1008, method 1000 includes determining whether the R-wave peak time is less than a threshold. The threshold may be a predetermined (eg, pre-specified) non-zero duration.

[0084] If the R-wave peak time is less than the threshold, method 1000 proceeds to 1010 and includes performing further testing during the baseline rhythm.

[0085] If the R-wave peak time is not less than the threshold (eg, the R-wave peak time is greater than or equal to the threshold), method 1000 proceeds to 1012 and includes performing further testing during conduction system pacing.

[0086] At 1014, method 1000 includes determining the most lately (eg, most delayed with respect to time) activated electrode by electrical or mechanical activation.

[0087] At 1016, method 1000 includes determining whether the most recent activation exceeds a delay threshold. For example, the delay threshold may be a predetermined non-zero duration different from the duration of the R-wave peak time threshold.

[0088] If the latest activation does not exceed the delay threshold, method 1000 proceeds to 1024 and includes ending the electrode optimization process. Method 1000 accordingly ends.

[0089] If the latest activation exceeds the delay threshold, method 1000 proceeds to 1018 and includes selecting an optimal threshold configuration for the electrode at the site of the latest activation.

[0090] At 1020, method 1000 includes performing further testing with the most delayed activated electrode added to the pacing configuration during the late activation assessment.

[0091] At 1022, method 1000 includes determining whether there are additional electrodes to test. If there are additional electrodes to test, method 1000 returns to 1014 to determine the electrode with the most delayed activation again by electrical or mechanical activation. If there are no additional electrodes to test, method 1000 proceeds to 1024 to end the electrode optimization process.

[0092] Fig.11 A flow chart of an example method 1100 for operating a pacing system including an intramyocardial multi-electrode lead encircling a left ventricle of a heart of a subject is shown. Figure 1-8 The method 1000 is described with reference to the system and components of the pacing system, but it should be understood that the method 1000 may be implemented with other systems and components without departing from the scope of the present disclosure. The method 1100 may be implemented with reference to the system and components of the pacing system. Figure 1 The method 1100 is executed by instructions in a non-volatile memory of a control unit 118 of the pulse generator 102. Although the method 1100 will be described with respect to cardiac resynchronization therapy (CRT), it will be appreciated that the method 1100 is applicable to other types of pacing.

[0093] At 1102, method 1100 includes generating electrical pulses by a pulse generator. Generating electrical pulses by the pulse generator may include determining a current and / or voltage for each channel of the pulse generator based on channel output tuning and the type of pacing to be provided (e.g., unipolar or bipolar pacing), as indicated at 1104. For example, during implantation, channel output tuning may be performed by an operator measuring a minimum capture threshold for each ring electrode and storing in memory so that the pulse generator is programmed to adjust the output current / voltage for each channel accordingly. As described above with respect to Figure 1 As discussed, channels may be connected to individual ring electrodes or groups of ring electrodes, depending on the number of available channels relative to the ring electrodes and / or the desired pacing configuration.

[0094] At 1106, method 1100 includes transmitting the generated electrical pulses from each channel of the pulse generator to corresponding ring electrodes of the multi-electrode lead within the myocardium. For example, the pulse generator may be implanted in a subject and the pulse generator may be connected to the myocardium via copper wires (e.g., body 108 and connection portion 104 of multi-electrode lead 106) encased in an insulating material. Figure 1 ) are electrically connected to the ring electrodes. Thus, the electrical pulses generated by each channel of the pulse generator can travel from the space outside the heart to the intramyocardial space within the heart. The pulse generator can transmit electrical pulses through a single channel or multiple channels.

[0095] At 1108, method 1100 includes applying electrical pulses directly to the myocardium of the left ventricular wall via a ring electrode in circumferential contact with the myocardium. In some examples, method 1100 may further include stimulating the cardiac conduction system by applying electrical pulses directly to the myocardium via the ring electrode, as optionally indicated at 1110. For example, as described above with respect to Figure 4 As explained, the intramyocardial multi-electrode wire can cross the ventricular septum at a basal position near the His bundle and LBB. As another example, the intramyocardial multi-electrode wire can be embedded in the myocardium of the left ventricular wall in whole or in part. As another example, the intramyocardial multi-electrode wire can be embedded in the His bundle branch. As another example, the intramyocardial multi-electrode wire can be positioned near the left posterior branch conduction system. Therefore, the electrical pulse can stimulate at least a portion of the cardiac conduction system (such as the ventricular septal conduction system), and / or directly activate the contractile tissue of the heart (for example, the contractile tissue in the ventricular septum). In one example, the electrical pulse can be directly applied to a portion of the cardiac conduction system containing the His bundle. In another example, the electrical pulse can be directly applied to a portion of the cardiac conduction system containing the left bundle branch conduction system. Then, method 1100 can return so that subsequent electrical pulses can be generated.

[0096] In this way, the SCIRP lead can be used for CRT with a higher success rate (e.g., lower non-responder rate). In addition, the SCIRP lead can be used for physiological (His bundle and LBB) pacemaker therapy, where lead dislodgement and tricuspid valve injury rates are lower compared to conventional CRT methods. By utilizing intramyocardial positioning of the pacemaker ring electrodes, the pacemaker ring electrodes have increased contact with the myocardial wall, and the extremely narrow length of each electrode can help reduce the pacemaker's battery usage to increase battery life. In addition, intramyocardial deployment avoids non-target depolarizations, such as undesired phrenic nerve stimulation. Overall, positive patient outcomes may be increased.

[0097] The technical effect of providing synchronized circumferential pacing to the entire left ventricle of the heart via an intramyocardial multi-electrode lead is that cardiac resynchronization with improved uniformity, reduced lead dropout, and reduced battery depletion can be achieved.

[0098] The present disclosure also provides support for a device for a multi-electrode pacemaker lead, the multi-electrode pacemaker lead comprising: a plurality of ring electrodes distributed along the length of the multi-electrode pacemaker lead, the multi-electrode pacemaker lead being configured to be implanted into the myocardium of the wall of the ventricle of the heart so that the outer surface defining the periphery of at least one of the plurality of ring electrodes is in direct contact with the myocardium. In a first example of the system, the shape of the multi-electrode pacemaker lead is configured to extend at least 180 degrees around the periphery of the ventricle of the left ventricle when implanted into the myocardium of the wall of the ventricle of the heart. In a second example of the system that optionally includes the first example, each of the plurality of ring electrodes comprises a cylindrical shape having a length in a dimension parallel to a central axis of the cylindrical shape, and wherein the length is 1 mm or less. In a third example of the system that optionally includes one or both of the first and second examples, the length of one or more of the plurality of ring electrodes is 0.1 mm or less. In a fourth example of the system optionally including one or more or each of the first to third examples, the multi-electrode pacemaker lead is configured for implantation in an over-the-wire configuration within the myocardium of the wall of the ventricle of the heart. In a fifth example of the system optionally including one or more or each of the first to fourth examples, the multi-electrode pacemaker lead comprises a variable inter-electrode spacing between the plurality of ring electrodes along the length of the multi-electrode pacemaker lead, and wherein the spacing distance between each of the plurality of ring electrodes along the length of the multi-electrode pacemaker lead ranges from 1 mm to 200 mm. In a sixth example of the system optionally including one or more or each of the first to fifth examples, the multi-electrode pacemaker lead is configured to be positioned within the myocardium of the left ventricle of the heart such that the variable inter-electrode spacing is smaller in a portion of at least one of the ventricular septum, or the left posterior fascicular conduction system, or the left ventricular basal side, or a late electrical activation site, or a late mechanical activation site in a region proximal to the His bundle. In a seventh example of the system that optionally includes one or more or each of the first to sixth examples, the plurality of ring electrodes comprises ring electrodes having different lengths, and wherein a multi-electrode pacemaker lead is implanted to position a predetermined one of the plurality of ring electrodes at a desired rotational position around the ventricle of the heart.In an eighth example of the system, optionally including one or more or each of the first to seventh examples, the variable inter-electrode spacing between the plurality of ring electrodes is configured to produce intramyocardial unipolar pacing at one or more of the plurality of ring electrodes, or bipolar pacing between at least one cathode of the plurality of ring electrodes and at least one anode of the plurality of ring electrodes, and wherein a maximum spacing distance between each of the plurality of ring electrodes along the length of the multi-electrode pacemaker lead is equal to a minimum spacing distance multiplied by the number of ring electrodes in the plurality of ring electrodes minus one. In a ninth example of the system, optionally including one or more or each of the first to eighth examples, the multi-electrode pacemaker lead comprises a tapered nose cone on a first end, or wherein at least a portion of the length of the multi-electrode pacemaker lead is tapered toward the first end, wherein the diameter decreases toward the end of the multi-electrode pacemaker lead, the end configured to be first inserted into the myocardium during implantation. In a tenth example of the system optionally including one or more or each of the first to ninth examples, the multi-electrode pacemaker lead comprises a detachable pulling mechanism for implantation, and wherein the detachable pulling mechanism is adapted to receive a retrograde tether configured to pull the multi-electrode pacemaker lead antegradely during implantation of the multi-electrode pacemaker lead into the myocardium of the wall of the ventricle of the heart. In an eleventh example of the system optionally including one or more or each of the first to tenth examples, the multi-electrode pacemaker lead comprises a break site configured to be positioned at a myocardial-blood-space interface when implanted into the myocardium of the wall of the ventricle of the heart.

[0099] The present disclosure also provides support for a method, the method comprising: generating electrical pulses by a pulse generator, transmitting the electrical pulses from the pulse generator to a plurality of ring electrodes of a pacing lead embedded in the myocardium of a heart through a single channel or a plurality of channels, and applying the electrical pulses directly to the myocardium through the plurality of ring electrodes, wherein at least one of the plurality of ring electrodes is in circumferential contact with the myocardium. In a first instance of the method, the pacing lead is fully or partially embedded in the myocardium near the left ventricular wall or ventricular septum of the conduction system of the heart, and wherein applying the electrical pulses directly to the myocardium through the plurality of ring electrodes comprises applying the electrical pulses directly to the myocardium of the left ventricular wall of the heart. In a second instance of the method, which optionally includes the first instance, the pacing lead surrounds the base of the left ventricle of the heart by at least 180 degrees, and wherein applying the electrical pulses directly to the myocardium through the plurality of ring electrodes comprises applying base-to-apex pacing throughout the left ventricle. In a third example of the method that optionally includes one or both of the first and second examples, generating the electrical pulses by the pulse generator includes tuning each of the electrical pulses based on a channel of the pulse generator, a channel output tuning stored in a memory, and a desired pacing type. In a fourth example of the method that optionally includes one or more or each of the first to third examples, the desired pacing type is unipolar pacing or bipolar pacing. In a fifth example of the method that optionally includes one or more or each of the first to fourth examples, a portion of the pacing lead is embedded in the myocardium of the ventricular septum of the heart, and the method further includes applying the electrical pulses directly to a portion of the cardiac conduction system of the heart, and wherein the portion of the cardiac conduction system includes the bundle of His, or wherein the portion of the cardiac conduction system includes a left bundle branch conduction system.

[0100] As used herein, an element or step described in singular form and preceded by the words "a" or "an" should be understood as not excluding a plurality of said elements or steps, unless such exclusion is explicitly stated. In addition, reference to "one embodiment" of the present invention is not intended to be interpreted as excluding the existence of other embodiments that also incorporate the described features. In addition, unless explicitly stated to the contrary, embodiments that "comprise (comprising)", "include (including)" or "have (having)" an element or multiple elements with a specific characteristic may include other such elements without the characteristic. The terms "including" and "wherein" are used as the plain language equivalents of the corresponding terms "including" and "wherein". In addition, the terms "first", "second" and "third" etc. are used only as labels, and are not intended to impose numerical requirements or specific positional order on their objects.

[0101] This written description uses examples to disclose the invention, including the best mode, and also to enable a person of ordinary skill in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The scope of the invention for which patent protection may be applied is defined by the claims, and may include other examples that occur to a person of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A device for a multi-electrode pacemaker lead, the device comprising: A plurality of ring electrodes are distributed along the length of the multi-electrode pacemaker lead, the multi-electrode pacemaker lead being configured to be implanted into the myocardium of a wall of a ventricle of the heart such that an outer surface defining the periphery of at least one of the plurality of ring electrodes is in direct contact with the myocardium.

2. The apparatus of claim 1 , wherein the multi-electrode pacemaker lead is shaped to extend at least 180 degrees around the ventricular periphery of the left ventricle when implanted within the myocardium of the wall of the ventricle of the heart.

3. The apparatus of claim 1 or 2, wherein each of the plurality of annular electrodes comprises a cylindrical shape having a length in a dimension parallel to a central axis of the cylindrical shape, and wherein the length is 1 mm or less.

4. The apparatus of claim 3, wherein the length of one or more of the plurality of ring electrodes is 0.1 mm or less.

5. The apparatus of any one of claims 1 to 4, wherein the multi-electrode pacemaker lead is configured for implantation into the myocardium of the wall of the ventricle of the heart in an on-wire configuration.

6. An apparatus according to any one of claims 1 to 5, wherein the multi-electrode pacemaker lead includes a variable inter-electrode spacing between the multiple ring electrodes along the length of the multi-electrode pacemaker lead, and wherein the spacing distance between each of the multiple ring electrodes along the length of the multi-electrode pacemaker lead ranges from 1 mm to 200 mm.

7. An apparatus according to claim 6, wherein the multi-electrode pacemaker lead is configured to be positioned within the myocardium of the left ventricle of the heart so that the variable inter-electrode spacing is smaller in a portion of at least one of the ventricular septum in a region near the His bundle, or the left posterior fascicular conduction system, or the basal side of the left ventricle, or a late electrical activation site, or a late mechanical activation site.

8. The apparatus of claim 6, wherein the plurality of ring electrodes comprises ring electrodes having different lengths, and wherein a multi-electrode pacemaker lead is implanted to position a predetermined one of the plurality of ring electrodes at a desired rotational position about the ventricle of the heart.

9. The apparatus of claim 6 , wherein the variable inter-electrode spacing between the plurality of ring electrodes is configured to produce intramyocardial unipolar pacing at one or more of the plurality of ring electrodes, or bipolar pacing between at least one cathode of the plurality of ring electrodes and at least one anode of the plurality of ring electrodes, and wherein a maximum spacing distance between each of the plurality of ring electrodes along the length of the multi-electrode pacemaker lead is equal to a minimum spacing distance multiplied by the number of ring electrodes of the plurality of ring electrodes minus one.

10. An apparatus according to any one of claims 1 to 9, wherein the multi-electrode pacemaker lead includes a tapered nose cone on a first end, or wherein at least a portion of the length of the multi-electrode pacemaker lead is tapered toward the first end, wherein the diameter decreases toward the end of the multi-electrode pacemaker lead, which end is configured to be inserted first into the myocardium during implantation.

11. The apparatus according to any one of claims 1 to 10, wherein the multi-electrode pacemaker lead comprises a detachable pulling mechanism for implantation, and wherein the detachable pulling mechanism is suitable for receiving a retrograde tether, the retrograde tether being configured to pull the multi-electrode pacemaker lead antegradely during implantation of the multi-electrode pacemaker lead into the myocardium of the wall of the ventricle of the heart.

12. The apparatus of any one of claims 1 to 11, wherein the multi-electrode pacemaker lead comprises a break site configured to be positioned at a myocardial-blood-space interface when implanted within the myocardium of the wall of the ventricle of the heart.

13. A method comprising: generating electrical pulses by means of a pulse generator; transmitting the electrical pulses from the pulse generator to a plurality of ring electrodes of a pacing lead embedded in the myocardium of the heart through a single channel or a plurality of channels; and The electrical pulses are applied directly to the myocardium through the plurality of annular electrodes, wherein at least one annular electrode of the plurality of annular electrodes is in circumferential contact with the myocardium.

14. A method according to claim 13, wherein the pacing lead is fully or partially embedded in the myocardium near the left ventricular wall or the ventricular septum of the conduction system of the heart, and wherein applying the electrical pulses directly to the myocardium through the multiple ring electrodes includes applying the electrical pulses directly to the myocardium of the left ventricular wall of the heart.

15. A method according to claim 13 or 14, wherein the pacing lead encircles the base of the left ventricle of the heart by at least 180 degrees, and wherein applying the electrical pulses directly to the myocardium through the multiple annular electrodes includes applying base-to-apex pacing throughout the entire left ventricle.

16. The method of any one of claims 13 to 15, wherein generating the electrical pulses by the pulse generator comprises tuning each of the electrical pulses based on a channel of the pulse generator, a channel output tuning stored in a memory, and a desired pacing type.

17. The method of claim 16, wherein the desired pacing type is unipolar pacing or bipolar pacing.

18. A method according to any one of claims 13 to 17, wherein a portion of the pacing lead is embedded in the myocardium of the ventricular septum of the heart, and the method further comprises applying the electrical pulse directly to a portion of the cardiac conduction system of the heart, and wherein the portion of the cardiac conduction system comprises the bundle of His, or wherein the portion of the cardiac conduction system comprises the left bundle branch conduction system.

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