ICE-optimized left atrial and left atrial appendage pacing

Abstract

The pacing system is configured to detect a patient's cardiac activity and to deliver pacing therapy to the patient's heart. The pacing system may comprise a first electrode configured to be positioned in a first cavity of the heart and to deliver a first pacing therapy to the first cavity, and a second electrode configured to be positioned in the left atrial appendage and to deliver a second pacing therapy to the left atrial appendage. The processing module of the pacing system may be configured to determine the timing of the delivery of the first pacing therapy based on a first timing index, and may be configured to determine the timing of the delivery of the second pacing therapy based on a determined pacing delay between the first and second pacing therapy. The determined pacing delay may be configured to maximize blood flow to and / or from the left atrial appendage.

Description

Technical Field

[0001] The present disclosure generally relates to implantable medical devices, and more specifically to implantable cardiac pacemakers.

Background Art

[0002] The left atrial appendage (LAA) is a small organ attached to the left atrium as a sac-like extension. In patients suffering from atrial fibrillation, the LAA may not contract properly with the left atrium, and as a result, blood may stagnate and accumulate inside it, which can cause the formation of undesirable thrombi in the LAA. Thrombi formed in the LAA may break away from this region and enter the bloodstream. Thrombi moving within the blood vessels can ultimately occlude smaller blood vessels, thereby contributing to stroke or myocardial infarction. Clinical studies have shown that the majority of thrombi in patients with atrial fibrillation are present in the LAA. There continues to be a need for improved medical devices and methods for controlling thrombus formation in the LAA of patients suffering from atrial fibrillation.

Summary of the Invention

[0003] The present disclosure provides alternatives for the design, materials, manufacturing methods, and use of medical devices. In the first example, a pacing system configured to detect a patient's cardiac activity and to deliver pacing therapy to the patient's heart may comprise a first electrode and a second electrode. The first electrode is configured to be positioned in a first cavity of the heart and to deliver a first pacing therapy to the first cavity. The second electrode is configured to be positioned adjacent to the left atrial appendage and to deliver a second pacing therapy to the left atrial appendage. The processing module of the pacing system may be configured to determine the timing of the delivery of at least a portion of the first pacing therapy by the first electrode, at least in part on a first timing fiducial. Furthermore, the processing module may be configured to determine the timing of the delivery of at least a portion of the second pacing therapy by the second electrode, at least in part on a determined pacing delay between the first and second pacing therapy. The determined pacing delay may be configured to maximize blood flow to and / or from the left atrial appendage.

[0004] In an alternative to or in addition to any of the above examples, the first electrode may be coupled to a first lead extending from a pacemaker, and the second electrode may be coupled to a second lead extending from the same pacemaker.

[0005] In an alternative or additional example, the second lead may comprise a punch needle, an adhesive growth pad, a second electrode, and a conductor extending proximal to the second electrode.

[0006] In an alternative or in addition to any of the above examples, the punch needle and the adhesive growth pad may be configured to penetrate the outer surface of the left atrial appendage and to be pressed against the outer surface.

[0007] In an alternative to or in addition to any of the above examples, the first electrode may be coupled to a first lead extending from a pacemaker, and the second electrode may be coupled to a leadless cardiac pacemaker.

[0008] In an alternative or in addition to any of the above examples, the pacemaker may communicate with the leadless cardiac pacemaker in another example. In addition to or instead of any of the above examples, in another example, the first timing indicator may include heart sounds.

[0009] In addition to or instead of any of the above examples, in another example, the first timing indicator may include the opening of a valve. In addition to or instead of any of the above examples, in another example, the first timing indicator may include a pressure drop.

[0010] In an alternative to or in addition to any of the above examples, the determined pacing delay may be configured to be customized when the pacing system is implanted.

[0011] In addition to or instead of any of the above examples, in another example, the first cavity may be the left atrium. In an alternative or in addition to any of the above examples, the second electrode may be configured to be located within the left atrial appendage.

[0012] In an alternative or in addition to any of the above examples, the second electrode may be configured to be located outside the left atrial appendage. In an alternative example, either in lieu of or in addition to any of the above examples, the determined pacing delay may be based on the first timing index.

[0013] In place of, or in addition to, any of the above examples, in another example, the determined pacing delay may be based on the first pacing treatment. In another example, a method for implanting a pacing system involves delivering a first electrode to a first chamber of the heart, delivering a second electrode to the left atrial appendage, positioning an echocardiographic system to measure blood flow to and / or from the left atrial appendage, supplying a first pacing treatment to the first chamber of the heart, supplying a second pacing treatment to the left atrial appendage, supplying the second pacing treatment at a time interval after the first pacing treatment, and supplying the first and second pacing treatments while monitoring blood flow to and / or from the left atrial appendage. The method may include measuring flow, repeatedly supplying the first pacing treatment to the first cavity and the second pacing treatment to the left atrial appendage, and measuring blood flow to and / or from the left atrial appendage while varying the time interval between the first and second pacing treatments in each iteration, selecting an operational time interval between the first and second pacing treatments that maximizes blood flow to and / or from the left atrial appendage, and supplying pacing treatment to the heart using the selected operational time interval.

[0014] In place of, or in addition to, any of the above examples, in another example, the first pacing treatment may be repeatedly supplied to the first chamber of the heart and the second pacing treatment to the left atrial appendage, and the blood flow to and / or from the left atrial appendage may be measured while varying the time interval between the first and second pacing treatments in each iteration, during the implantation of the first and second electrodes.

[0015] In an alternative to or in addition to any of the above examples, in another example, the operational time interval between the first pacing treatment and the second pacing treatment may be stored in a processing module that communicates with the first electrode and the second electrode.

[0016] In place of or in addition to any of the above examples, in another example, changing the time interval between the first pacing treatment and the second pacing treatment may include gradually increasing the time interval.

[0017] In place of, or in addition to, any of the above examples, in another example, the timing of the first pacing treatment may be based at least in part on the first timing indicator.

[0018] In an alternative to or in addition to any of the above examples, in another example, the operational time interval between the first pacing treatment and the second pacing treatment may be based at least in part on the first timing index.

[0019] In place of, or in addition to, any of the above examples, in another example, the first pacing treatment may be repeatedly supplied to the first chamber of the heart and the second pacing treatment to the left atrial appendage, and the blood flow to and / or from the left atrial appendage may be measured while varying the time interval between the first and second pacing treatments in each iteration, during configuration mode.

[0020] In addition to or instead of any of the above examples, in another example, the supply of pacing therapy to the heart using the selected operational time interval may be performed in response to a predetermined condition detected.

[0021] In an alternative or in addition to any of the above examples, the detected predetermined condition may be detected atrial fibrillation and / or detected pressure drop. In another example, a method for implanting a pacing system involves delivering a first electrode to a first cavity of the heart, delivering a second electrode to the left atrial appendage, advancing an echocardiographic system to a position adjacent to the left atrial appendage, cauterizing the area of ​​cardiac tissue between the first and second electrodes, supplying a first pacing treatment to the first cavity of the heart, supplying a second pacing treatment to the left atrial appendage, supplying the second pacing treatment after a time interval following the first pacing treatment, and supplying blood flow to the left atrial appendage and / or left atrial appendage while supplying the first and second pacing treatments. This may include measuring blood flow from the atrial appendage; repeatedly supplying the first pacing treatment to the first cavity and the second pacing treatment to the left atrial appendage, while varying the time interval between the first and second pacing treatments in each iteration, measuring blood flow to and / or from the left atrial appendage; selecting an operational time interval between the first and second pacing treatments that maximizes blood flow to and / or from the left atrial appendage; and supplying pacing treatment to the heart using the selected operational time interval.

[0022] In place of, or in addition to, any of the above examples, in another example, the supply of pacing to the heart using the operational time interval between the first pacing treatment and the second pacing treatment may be performed on each heartbeat.

[0023] In another example, a method of implanting a pacing system into the heart may include: a) detecting a first pacing metric; b) delivering a first electrode to the left atrial appendage after a delay following said pacing metric; c) advancing an echocardiographic system to a position adjacent to the left atrial appendage; d) delivering a first pacing therapy to the left atrial appendage; e) measuring blood flow into and / or out of the left atrial appendage after said first pacing therapy; f) repeatedly delivering said first pacing therapy to a first chamber of the heart while varying said delay to identify a default delay associated with a maximum flow rate; and g) configuring a pacing system including said first electrode using said default delay based on said first pacing metric. Alternatively, or in addition thereto, in another example, the method may further include selecting a second pacing metric and repeating steps a), b), d), e), f) and g) using said second pacing metric in place of said first pacing metric.

[0024] Instead of or in addition to any of the above examples, in another example, the method may further include ablating an area of heart tissue adjacent to the left atrial appendage. In any of the foregoing examples, "flow" or "blood flow" may be measured or parameterized as, for example, without limitation, flow velocity, peak velocity, average velocity, flow rate, ejection fraction, or other suitably related parameters. Further, in any of the foregoing examples, echocardiographic methods may include, for example, without limitation, intracardiac echocardiogram (ICE), transesophageal echocardiogram (TEE), transthoracic echocardiogram (TTE), and may be performed at the time of or after implantation of the pacing system and may be used to optimize pacing delay or other aspects of the device or method.

[0025] The summary of some of the above embodiments is not intended to describe each embodiment or every implementation of the present disclosure. The following drawings and detailed description illustrate these embodiments more specifically. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure can be more fully understood by considering the following detailed description of various embodiments in connection with the accompanying drawings. [Figure 1] FIG. 1 is a partial cross-sectional view of certain elements of the heart and some adjacent blood vessels. [Figure 2] FIG. 2 is a schematic diagram of an exemplary leadless cardiac pacemaker (LCP). [Figure 3] FIG. 3 is a schematic diagram of another medical device (MD). [Figure 4] FIG. 4 is a graphical representation of an exemplary electrocardiogram (ECG) showing the temporal relationship between the electrical signals of the heart and the mechanical manifestations of the heart's contractions. [Figure 5] FIG. 5 is a plan view of an exemplary medical device system. [Figure 6] FIG. 6 is a plan view of another exemplary medical system. [Figure 7] FIG. 7 is a plan view of yet another exemplary medical system. [Figure 8] FIG. 8 is a schematic cross-sectional view of the heart with an implanted medical device and an exemplary intracardiac echo system. [Figure 9A] FIG. 9A is a schematic graph of an exemplary device stimulation protocol. [Figure 9B] FIG. 9B is a schematic graph of the flow rate versus the pacing delay of a pacing system. [Figure 10] FIGS. 10A - 10C show schematic views of an exemplary alternative lead delivered to the left atrial appendage.

[0027] Aspects of the present disclosure are applicable to various modifications and alternative forms, and specific examples thereof are shown in the drawings as examples and will be described in detail. However, it should be understood that the aspects of the present disclosure are not intended to be limited to the specific embodiments described. Rather, it is intended to embrace all modifications, equivalents, and alternative forms within the spirit and scope of the present disclosure.

Best Mode for Carrying Out the Invention

[0028] The following description should be read with reference to the drawings, which are not necessarily to scale, and the same reference numeral indicates the same element across multiple drawings. The detailed description and drawings are illustrative of, but not limiting, the disclosure. Those skilled in the art will recognize that the various elements described and / or illustrated may be arranged in various combinations and configurations without departing from the scope of the disclosure. The detailed description and drawings illustrate examples of embodiments of the disclosure. However, for clarity and ease of understanding, not all features and / or elements are shown in each drawing, but unless otherwise specified, those features and / or elements can be understood to be present.

[0029] The terms defined below shall apply unless otherwise given in the claims or elsewhere in this specification. All numerical values ​​in this specification, whether expressly indicated or not, are deemed to be modified by the term “approximately.” In the context of numerical values, “approximately” generally refers to a range of numerical values ​​that a person skilled in the art would consider equivalent to the stated value (e.g., a range having the same function or result). In many cases, “approximately” may include numerical values ​​rounded to significant figures. Any other use of the term “approximately” (e.g., in contexts other than numerical values) is deemed to have the ordinary and customary meaning understood and consistent with the context of this specification, unless otherwise specified.

[0030] Numerical ranges specified by endpoints include all numbers within that range (including the endpoints) (for example, 1-5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). While several appropriate dimensions, ranges, and / or values ​​relating to various components, features, and / or specifications are disclosed, a person skilled in the art inspired by this disclosure will understand that desired dimensions, ranges, and / or values ​​may deviate from those expressly disclosed.

[0031] In this specification and the appended claims, the singular forms “a,” “an,” and “the” include the plural unless otherwise clearly indicated in the context. The term “or” in this specification and the appended claims generally includes “and / or” unless otherwise clearly indicated in the context. For ease of understanding, some features of this disclosure may be described in the singular form, but it should be noted that such features may be plural or repetitive in the disclosed embodiments. Unless otherwise specified, each example of such feature is included in and / or encompassed by the singular disclosure. For brevity and clarity, not all elements of this disclosure are shown in each figure and not all are discussed in detail below. However, unless otherwise specified, it should be understood that the following descriptions apply equally to any and / or all of the multiple components. Furthermore, for clarity, not all examples of some elements or features are shown in each figure.

[0032] The relative terms “proximal,” “distal,” “forward,” “backward,” and their variations and similar terms generally refer to the position, orientation, and / or movement of various elements relative to the user / operator / operating entity of the device, where “proximal” and “backward” indicate a position closer to the user or direction toward the user, and “distal” and “forward” indicate a position further away from the user or direction toward the user. In some cases, the terms “proximal” and “distal” may be arbitrarily assigned to facilitate understanding of this disclosure, and in such cases will be readily recognizable to those skilled in the art. Other relative terms such as “upstream,” “downstream,” “inflow,” and “outflow” refer to the direction of fluid flow within a lumen, such as a body cavity, blood vessel, or device.

[0033] Where the terms "one embodiment," "several embodiments," or "other embodiments" are used herein, it is indicated that the described embodiments may include certain features, structures, or characteristics, but it should be noted that not all embodiments necessarily include such specific features, structures, or characteristics. Furthermore, such expressions do not necessarily refer to the same embodiment. Also, where certain features, structures, or characteristics are described in relation to a particular embodiment, it is possible, within the knowledge of those skilled in the art, to implement such features, structures, or characteristics in relation to other embodiments, whether or not they are explicitly stated. That is, the various individual elements described below are intended to be combined or arranged with each other to form other embodiments or to complement and / or extend the described embodiments, as will be understood by those skilled in the art, even if no particular combination is explicitly shown.

[0034] For clarity, specific identification numbers (e.g., 1st, 2nd, 3rd, 4th, etc.) may be used throughout this specification to name and / or distinguish various described and / or claimed features. It should be understood that these identification numbers are not intended to be limiting, but merely illustrative. In some embodiments, changes and deviations from previously used identification numbers may be made for the sake of brevity and clarity. That is, a feature identified as the "1st" element may later be referred to as the "2nd" element, the "3rd" element, etc., or may be omitted entirely, or another feature may be referred to as the "1st" element. The meaning and / or designation in each case will be obvious to those skilled in the art.

[0035] A normal, healthy heart contracts by conducting intrinsically generated electrical signals throughout the heart muscle. These intrinsic signals cause the heart's muscle cells or tissue to contract in a coordinated manner. These contractions circulate blood throughout the body by pushing it out of and into the heart. Many patients have heart diseases that affect the efficient function of the heart. For example, in some hearts, diseased tissue develops that no longer generates intrinsic electrical signals or conducts them efficiently. In some cases, the diseased heart tissue conducts electrical signals at different rates, resulting in asynchronous and inefficient contractions of the heart. In other cases, the heart generates intrinsic signals at extremely low rates, resulting in a dangerously low heart rate. In yet another case, the heart generates electrical signals at abnormally high rates, even causing cardiac tachycardia or fibrillation. In some cases, such abnormalities progress to fibrillation, where the contractions of the patient's heart chambers become almost completely asynchronous, and the heart pumps little to no blood. An implantable medical device (e.g., a pacing device) may be configured to detect the occurrence of such cardiac abnormalities or arrhythmias and to deliver one or more types of electrical stimulation therapy to the patient's heart, which may help to terminate or alleviate these and other cardiac conditions.

[0036] Thrombosis in the left atrial appendage (LAA) during atrial fibrillation can be caused by blood stagnation and accumulation in the LAA. While the accumulated blood can still be drawn out of the left atrium by the left ventricle, this efficiency is reduced by the irregular contractions of the left atrium caused by atrial fibrillation. Therefore, instead of active assistance of blood flow by the contracting left atrium and left atrial appendage, left ventricular filling may depend primarily, or exclusively, on the suction effect produced by the left ventricle. However, left atrial appendage contractions may not be synchronized with the left ventricular cycle. For example, left atrial appendage contractions may be out of phase with the left ventricle by up to 180 degrees, which can create significant resistance to the desired blood flow. Furthermore, the shape of most left atrial appendages is complex and can vary greatly, with a narrow opening relative to the depth of the appendage and a large, irregular surface area. These and other factors, individually or in various combinations, can result in high flow resistance to blood outflow from the left atrial appendage.

[0037] In order to reduce the occurrence of thrombus formation in the left atrial appendage and prevent thrombi from entering the bloodstream from the left atrial appendage, it may be desirable to develop medical devices and / or systems that increase the contractility of the left atrial appendage and / or increase blood flow to and / or from the LAA, thereby reducing blood stagnation and thrombus formation within the LAA. Exemplary medical devices and / or systems that increase the contractility of the LAA and / or increase blood flow to and / or from the LAA are disclosed herein.

[0038] Figure 1 is a partial cross-sectional view of a specific element of the heart 10 and several adjacent blood vessels. The heart 10 may include the left ventricle 12, the right ventricle 14, the left atrium 16, and the right atrium 18. The aortic valve 22 is located between the left ventricle 12 and the aorta 20. The pulmonary valve or semilunar valve 26 is located between the right ventricle 14 and the pulmonary artery 24. The superior vena cava 28 and inferior vena cava 30 return blood from the body to the right atrium 18. The tricuspid valve 34 is located between the right atrium 18 and the right ventricle 14. The pulmonary vein 36 returns blood from the lungs to the left atrium 16. The mitral valve 32 is located between the left atrium 16 and the left ventricle 12. The left atrial appendage (LAA) 50 is attached to and in fluid communication with the left atrium 16.

[0039] Figures 2 and 3 show exemplary implantable medical devices, and Figure 4 shows exemplary ECG 300 and heart sound 302 signals, illustrating their respective details and temporal relationships. A more detailed explanation of Figures 2 to 4 is given below. As an introduction, Figure 2 shows a leadless cardiac pacemaker (LCP), which can be understood to include an anchor portion 116 that can be used to fix the LCP in or on the heart, such as by attachment to the heart wall. The LCP 100 includes electrodes 114, 114' that can be used to detect cardiac signals via an electrical sensing module 106, and these signals are processed by a processing module 110. In response to detected signals (or lack thereof), the pulse generation module 104 uses power from the battery 112 to output electrical pulses via the electrodes 114, 114' to pace the heart, thereby causing myocardial contraction. In some exemplary cases, the LCP100 may be implanted in, on, or adjacent to the LAA and may be used to guide blood flow from the LAA, thereby preventing excessive blood accumulation in the LAA and preventing thrombus formation. Figure 3 shows a pacemaker, which similarly includes an electrical sensing module 206, a processing module 210, and a pulse generation module 204, which may be used to detect the heart rhythm and output pacing pulses via electrodes on one or more leads 214. In some exemplary cases, these leads may be positioned in, on, or adjacent to the LAA and may be used to guide blood flow from the LAA, thereby preventing excessive blood accumulation in the LAA and preventing thrombus formation.

[0040] Figures 5–7 show exemplary medical device systems that may be configured to operate in accordance with the technology disclosed herein. Other exemplary medical device systems may include additional or different medical devices and / or configurations. For example, another medical device system suitable for operating in accordance with the technology disclosed herein may include an additional LCP implanted in the heart. Another exemplary medical device system may include multiple LCPs without other devices such as the MD200. In yet another example, the configuration or arrangement of medical devices, leads, and / or electrodes may differ from those shown in Figures 5–7. It should be recognized that a number of other medical device systems different from those shown in Figures 5–7 may operate in accordance with the technology disclosed herein. Thus, the examples shown in Figures 5–7 should not be considered limiting in any sense.

[0041] Figure 5 is a plan view of an exemplary MD200 configured to be implanted in the chest (or other location), with leads 212a and 212b implanted in or over the left atrium 16 and LAA 50. A second lead 212b may be positioned distal to the LAA 50, although this is not mandatory. Other implantation sites may also be used as desired. Furthermore, multiple leads may be attached to the left atrium 16 and / or multiple leads may be attached to the LAA 50. Additionally, it is conceivable that additional leads may be attached to other parts of the heart 10. In Figure 5, leads 212a and 212b are shown extending into the tissue of the heart 10 to position one or more electrodes 214a and 214b within the myocardium. For leads 212a and 212b, an epicardial approach is shown. Alternatively, instead of epicardial implantation, there is an approach using leads 212c and 212d, in which the leads are introduced into the right atrium 18 via the venous system, then pass through the atrial septal puncture site to the left atrium 16, and are fixed adjacent to or within the atrial wall of the LAA50. This system may be configured to stimulate both the left atrium 16 and the LAA50 to increase blood flow to and / or from the LAA50.

[0042] In the system shown in Figure 5, pacing pulses can be supplied in various ways. The pacing pulse may, if desired, be output between electrodes 214a and 214b, thereby creating an electric field over a relatively wide area between them. Alternatively, at least electrode 214b may be a composite electrode having a tip electrode and a ring electrode positioned a few millimeters proximal to the tip electrode, in which case the pacing pulse can be output between the tip electrode and the ring electrode. If electrode 214b is a composite electrode, electrode 214a may be used to detect whether a biosignal is propagating (retrograde) along the myocardium to the location of electrode 214a, and / or to determine the magnitude of pacing artifacts at the location of electrode 214a when outputting a pacing pulse using the composite electrode. Both electrodes 214a and 214b may be composite electrodes, and pacing stimuli may be applied at both sites, for example synchronously (e.g., simultaneously, or with a set and / or adjustable delay between them). Other uses of the electrodes are described below.

[0043] Figure 6 is a plan view of an example in which an LCP100 is implanted within the LAA50. Furthermore, in this example, a second MD200 may be configured to be implanted in the chest (or other location), and a transvenous lead 212d may be implanted within the left atrium 16, or an epicardial lead 212a may be implanted, or, if desired, the left atrial lead may not be used. It is envisioned that the LCP100 may be positioned distal to the LAA50, although this is not mandatory. Other implantation sites may also be used within, on, or adjacent to the LAA50, as desired. Furthermore, it is envisioned that multiple leads may be attached to the left atrium 16, and / or multiple leads and / or multiple LCP100s may be attached to the LAA50. Furthermore, it is envisioned that additional leads may be attached to other parts of the heart 10. Although not explicitly shown, in some cases the LCP100 may be implanted in contact with the outer surface of the LAA50. In Figure 6, the lead 212a and the fixation mechanism 116 of the LCP 100 are shown to extend into the tissue of the heart 10 to position one or more electrodes 214a, 114 within the endocardial tissue. The system may be configured to stimulate both the left atrium 16 and the LAA 50 to increase blood flow to and / or from the LAA 50.

[0044] Figure 7 is a plan view of an exemplary MD device 200 configured to be implanted in the chest (or other area), with lead 212a or lead 212d implanted in the left atrium 16 and lead 212b extending to nearby myocardial or skeletal muscle 60 outside the LAA 50. In Figure 7, lead 212a or lead 212d is shown extending into the tissue of the heart 10 to position one or more electrodes 214a within the myocardium. Although not explicitly shown, additional leads or LCP 100 from the MD 200 may be positioned to contact the LAA 50. The system may be configured to stimulate both the left atrium 16 and the tissue adjacent to the LAA 50 to increase blood flow to and / or from the LAA 50.

[0045] Furthermore, it is conceivable that the LCP 100 may be guided to the heart 10 by being led to the right atrium 18 via the inferior vena cava 30. The LCP may then be delivered transseptally to the LAA 50. In other examples, the LCP may be delivered via a femoral approach, which does not require transseptal access. If necessary, visualization, such as by injection of contrast agent, may be used to assist in the placement of the LCP. In some examples, the pacing systems in Figures 5-7 may omit the lead 212a extending to the left atrium 16. For example, the LAA 50 may be stimulated independently or in response to other pacing systems.

[0046] The pacing systems in Figures 5-7 may be configured to simultaneously deliver pacing pulses to the left atrium 16 and LAA50 (or adjacent regions). In some cases, pacing treatment may be delivered sequentially to the left atrium 16 and LAA50. For example, in some cases, the left atrium 16 may be stimulated by a first pacing treatment, and after a predetermined delay, the LAA50 may be stimulated by a second pacing treatment. The delay between stimulation / pacing treatment may be selected to optimize or maximize blood flow to and / or from the LAA50. Blood flow to and / or from the LAA50 may be measured as flow velocity, peak velocity, mean velocity, flow rate, ejection fraction, etc. Echocardiography may include, but is not limited to, intracardiac echocardiography (ICE), transesophageal echocardiography (TEE), and transthoracic echocardiography (TTE). It may be performed during or after pacing system implantation and may be used to optimize the pacing delay between left atrium 16 and LAA 50. For example, the pacing delay may be customized for each patient.

[0047] Figure 8 is a schematic cross-sectional view of the heart 10 with an implanted MD200 and an exemplary ICE system 400. Although Figure 8 illustrates the ICE system, other echocardiographic systems such as TEE or TTE may be used as desired. The ICE system 400 may include a long shaft 402, such as a catheter shaft, and an ultrasound device 404 positioned adjacent to the distal end of the long shaft 402. Although not explicitly shown, the ICE system 400 is expected to include other components such as a steering wire and a guide sheath. The ICE system 400 may be a radial system, a rotational system, or a phased array system as desired.

[0048] The implanted MD200 may include leads 212a and 212b implanted in the left atrium 16 and LAA 50. While transvenous leads are not shown in the figure for easier visualization of the ICE system 400, it should be understood that the transvenous leads 212c and 212d described above may be used instead of the illustrated epicardial leads. In Figure 8, leads 212a and 212b are shown extending into the tissue of the heart 10 to position one or more electrodes 214a and 214b within the endocardial tissue. It should be understood that the imaging and pacing time delay selection techniques described in relation to Figure 8 may be applicable to any pacing system described herein. For example, the pacing system may include the MD200 and LCP 100. After implantation of the MD200, the ICE system 400 may be guided to the heart 10 by being led to the right atrium 18 via the inferior vena cava 30. When viewed from the anterior side of the patient, the distal portion of the ICE system 400 may include a rightward curve near its distal end, so that the ICE system 400 may curve toward the wall (e.g., the septum) between the right atrium 18 and the left atrium 16, although this is not mandatory. The wall (septum) between the right atrium 18 and the left atrium 16 is punctured, and the ICE system 400 is delivered through this wall to a position adjacent to the LAA 50. This is merely one example. It is envisioned that the ICE system 400 may be delivered to the left atrium 16 by other routes as desired.

[0049] Once the ICE system 400 is positioned, the ultrasound device 404 may be positioned relative to the LAA and / or activated and directed toward the LAA. The ultrasound device 404 may emit high-frequency sound waves 406 toward the LAA 50. The sound waves 406 may be used, for example, by color Doppler to measure blood flow to and / or from the LAA 50 as flow velocity, flow rate, and / or ejection fraction. Once the ICE system 400 is positioned, the MD200 may be set to configuration mode. For example, a clinician may select the configuration mode of the MD200 using a display device or user input. If multiple implantable devices are provided, as in the system in Figure 6, each implantable device 100, 200 may be set to configuration mode. In configuration mode, the MD200's processing module 210 may be configured to vary the time delay between pacing pulses at each lead (any of 212a, 212b, 212c, 212d, and / or electrodes of the LCP100) under the direction of an external programmer or independently in automatic mode. In some cases, the processing module 210 may automatically vary the time delay between pacing pulses at each lead. In other examples, the processing module 210 may be configured to vary the time delay between operations at each lead according to user input received via a display device or user input.

[0050] Referring further to Figure 9A, a schematic graph 500 of an exemplary pacing device stimulation protocol is shown, where the first lead may receive the first pacing treatment 502 at a first time point, and the second lead may receive the first pacing treatment 504 at a second time point. The second time point may be a first time length 506 after the first time point. It is assumed that each lead may be activated once during a single heartbeat 508, however, it is not necessary for the lead to be activated with every heartbeat. Furthermore, it is assumed that the first lead may be activated in response to a predetermined timing index. The time delay between the activation of the first lead and the activation of the second lead may be increased incrementally over multiple consecutive heartbeats. In other words, pacing treatments for the first lead and pacing treatments for the second lead may be supplied iteratively with varying time intervals between these pacing treatments. The gradual increase may, as desired, be a constant time amount or a variable time amount, may be performed for each heartbeat / pacing output, or may be changed every "N" heartbeats, where N is 1, 2, 3, 4, 5, etc., or a larger number. The first lead may have a second actuation 510 at a third time point, and the second lead may have a second actuation 512 at a fourth time point. The fourth time point may be a second time length 514 after the third time point, where the second time length 514 is greater than the first time length 506.

[0051] While the processing module 210 adjusts the pacing delay between the first and second leads, the ICE system 400 may determine and / or record the blood flow to and / or from the LAA50 (e.g., as peak velocity, mean velocity, flow rate, ejection fraction, etc.) for each iteration of pacing therapy. The processing module 210 or an external computer may record the blood flow to and / or from the LAA50 and the corresponding pacing delay. In some cases, the blood flow and pacing delay may be recorded and / or displayed as a graph 550, a table, or other data recording system, as shown in Figure 9B. Graph 550 may include a curve 552 showing the relationship between the velocity of blood flow to and / or from the LAA and the pacing time delay between the first and second leads. As shown in Figure 9B, the velocity of blood flow to and / or from the LAA50 may be maximized at a specific pacing time delay shown by line 554 in Figure 9B. Although Figure 9B shows blood flow as flow velocity, other variables such as peak velocity, mean velocity, flow rate, and ejection fraction may also be used to maximize or optimize blood flow from the LAA50. The processing module 210 may be configured to store the operational time interval between pacing treatments, or the operational pacing time delay at which blood flow to and / or from the LAA50 is maximized.

[0052] In some cases, the processing module 210 (or an external computer) may automatically determine and store the operational time interval between pacing treatments, or the operational pacing time delay that maximizes blood flow to and / or from the LAA50. In other cases, the user may input the pacing time delay that maximizes blood flow to and / or from the LAA50 into an external computer, which may then relay to the processing module 210 of the MD200. The processing module 210 may then automatically or in response to user input exit the configuration mode and transition to the operation mode, and the ICE system 400 may be removed from the body. If multiple pacing devices are provided, it is assumed that operational time intervals or operational pacing time delays between pacing treatments may be provided to each processing module, or that one of the multiple pacing devices may be the dominant device issuing operation commands to one or more sub-devices.

[0053] Upon entering the operating mode, the processing module 210 may be configured to deliver pacing therapy using parameters determined during the configuration mode procedure. For example, a first lead may be activated in response to a determined pacing indicator marker, and a second lead may be activated "x" seconds after the first lead. The predetermined pacing time delay "x" is expected to be in the range of milliseconds, for example, from 0.1 milliseconds to about 50 milliseconds.

[0054] In addition to maximizing blood flow to and / or from the LAA50, polarization and / or depolarization of the distal portion of the LAA50 may create motion and / or instability, thereby further reducing or preventing thrombus formation. In some cases, the MD200 may be configured to deliver pacing therapy in response to certain conditions. For example, the MD200 may not pace the LAA with each heartbeat, thereby extending the lifespan of the MD200. In some cases, the MD200 may be configured to pace when atrial fibrillation is detected. As described above, when atrial fibrillation is detected, the LAA50 may not contract properly, and blood may stagnate and accumulate there. By supplying pacing energy to the left atrium 16 and LAA50, the flow velocity and motion of blood entering and leaving the LAA50 are increased, thereby reducing stagnation and, consequently, thrombus formation. In another example, pacing therapy may be delivered in response to pressure in the left atrium 16, LAA 50, or other areas of the heart 10. For example, if the pressure is high, less stimulation of atrium 16 and / or LAA 50 may be required. For example, the duty cycle of LAA pacing may vary in response to one or more indicators, including the presence or absence of atrial fibrillation or atrial flutter, the presence or absence of detected P waves (the absence of P waves may indicate undetected atrial fibrillation or atrial flutter), whether the intraatrial blood pressure is above or below a threshold, the presence or absence of other arrhythmias, the presence of irregular heart sounds, or the absence of any of the heart sounds specified below in the description of Figure 4. Multiple such conditions may be monitored. The duty cycle of LAA pacing may vary linearly or stepwise, and may vary as shown below, for example.

[0055] If regular P waves are present, the duty cycle for LAA pacing is 10%. If no P wave is detected, the duty cycle for LAA pacing is 33%. If atrial fibrillation is detected, the duty cycle for LAA pacing is set to 100%. Other configurations may also be used. In some cases, the pressure difference in the left atrium can be detected to measure the change in left atrial pressure from minimum to maximum during the cardiac cycle. When the pressure difference is relatively large, the duty cycle of LAA pacing may be relatively low (e.g., less than 50%), and when the pressure difference is relatively small, the duty cycle of LAA pacing may be relatively high (e.g., greater than 50%).

[0056] Pacing therapy applied to LAA may use multiple different LAA pacing indicators. As used herein, an LAA pacing indicator refers to an event that triggers LAA pacing output immediately or after a delay. In some examples, detection of mitral valve opening 32 by monitoring heart sound S3 may be used as an LAA pacing indicator. In another example, the LAA pacing indicator may be detection of heart sound S4. Another LAA pacing indicator may be detection of a decrease in atrial pressure or a downward slope of atrial pressure. Yet another LAA pacing indicator may be detection of a pacing pulse by another implanted system or supply of pacing therapy by the same implanted system that outputs the LAA pacing therapy. Yet another LAA pacing indicator may be an electrical event such as the onset or peak of a P wave. For example, in a multi-chamber pacing system, a lead with an electrode in the right atrium may detect the onset of right atrial depolarization (onset of a P wave), which may be used as an indicator of LAA pacing.

[0057] When an LAA pacing indicator is detected, the LAA pacing pulse may be delivered immediately or after a predetermined delay. If the LAA and left atrium pacing pulses are delivered separately, the LAA pacing indicator can be used to trigger one pacing output first, and then the other. In some examples, the procedure of the configuration modes described above may be performed using multiple different LAA pacing indicators, resulting in multiple different optimized LAA-to-left atrium pacing delays. For example, the LAA pacing system may be configured to use either the detection of mitral valve opening or the detection of a P wave in the right atrium as the pacing indicator, and the delay to the first pacing pulse and the delay from the first pacing pulse to the second pacing pulse may be selected depending on which LAA pacing indicator triggers the pacing output.

[0058] It is assumed that the region of atrium 16 and / or LAA50 will be ablated before supplying pacing therapy to atrium 16 and / or LAA50. For example, ablation may isolate LAA50 from the rest of the atrial nerve pathway. This may isolate LAA50 from atrial fibrillation. However, ablation is not mandatory. If ablation is performed, LAA50 will be isolated from the atrial nerve pathway and will not receive the intrinsically generated electrical signals of the heart 10, so a pacing pulse can be supplied with each heartbeat. Alternatively, after LAA is electrically isolated from the cardiac nervous system, a pacing pulse may be supplied with a duty cycle of less than 100%, for example, using one of the duty cycle increasing or decreasing factors as described above.

[0059] In another example, the illustrations in Figures 9A and 9B may be used in a different way. In this case, elements 502 and 510 may be understood as detected events used to trigger pacing indices, i.e., LAA pacing outputs at 504 and 512. Here, only a single pacing output is generated and supplied directly to the LAA. Next, by varying the time delay from the detection of pacing indices 502 and 510 to the output of the LAA pacing outputs at 504 and 513, a graph as shown in Figure 9B may be created, and then the delay that maximizes the flow velocity may be selected as the delay from the pacing indices to the LAA pacing outputs. This method may be repeated for multiple different pacing indices. This method may further be repeated for systems with two pacing outputs, if necessary, by first optimizing the delay from the pacing indices to the initial pacing output, and then optimizing the delay between the two pacing outputs.

[0060] In some cases, conventional helical leads may not be suitable for use in the LAA50. In some cases, the lead used in the LAA50 may be configured to penetrate the outer surface of the LAA and contact the outer surface. Figures 10A–10C show schematic diagrams of exemplary alternative leads 600 delivered to the LAA50. In Figure 10A, the lead 600 is advanced to a target location within the delivery sheath 602. In the illustrated embodiment, the target location may be the wall 52 of the LAA50, although this is not mandatory. The exemplary lead 600 may also be used at other locations in the heart 10 as desired. The delivery sheath 602 may be guided to the heart 10 by being led to the right atrium 18 via the inferior vena cava 30. The delivery sheath 602 may extend to enter the LAA50 through a puncture site in the septum between the right atrium 18 and the left atrium 16.

[0061] As the delivery sheath 602 approaches the target implantation site, the punch needle 604 of the lead 600 may advance distally beyond the distal end of the delivery sheath 602 and penetrate the wall 52, as shown in Figure 10B. An adhesive growth pad 606 may be positioned between the punch needle 604 and the outer surface of the wall 52. The adhesive growth pad 606 may be configured to promote tissue growth and further secure the lead 600 to the tissue. The electrode 608 may be positioned proximal to the punch needle 604 and configured to contact the endocardial tissue when the punch needle 604 penetrates the wall 52. The conductive member 610 may extend proximal from the electrode 608 toward the pacing device. Finally, as shown in Figure 10C, the lead 600 may be pulled back proximal to radially expand the punch needle 604 and press the adhesive growth pad 606 against the tissue. The delivery sheath 602 and other delivery aids may be withdrawn proximal to the body.

[0062] Another possible approach involves entering the thoracic cavity through the intercostal space and advancing the lead from the outer surface of the LAA to a position adjacent to the LAA. The above description of lead fixation in Figures 10A-10C may be applied, but in this case, the placement system / catheter 602 would be positioned outside the LAA.

[0063] A more detailed description of Figures 2 to 4 is provided below. Figure 2 shows an exemplary leadless cardiac pacemaker (LCP) that may be implanted in a patient, and the LCP may operate to prevent, control, or terminate cardiac arrhythmias in the patient by appropriately using one or more therapies, for example, anti-tachycardia pacing (ATP) therapy, cardiac resynchronization therapy (CRT), bradycardia therapy, or other antiarrhythmic therapies. As shown in Figure 2, the LCP 100 may be a compact device in which all components are housed directly within the LCP 100 or on the housing 120. In the example shown in Figure 2, the LCP 100 may include a communication module 102, a pulse generation module 104, an electrical sensing module 106, a mechanical sensing module 108, a processing module 110, a battery 112, and electrodes 114. The LCP 100 may include more or fewer modules depending on the application.

[0064] The communication module 102 may be configured to communicate with sensors, other medical devices, and / or similar devices located outside the LCP 100. Communication may be performed using, for example, Bluetooth®, Bluetooth Low Energy, MedRadio, or other communication protocols, and the communication module 102 may include appropriate circuitry, including an antenna. Alternatively, or in addition to, communication may be performed using any of the inductive coupling, optical, acoustic, and / or conducted signals known to those skilled in the art. Communication can serve many purposes, such as enabling programming of the LCP by an external device, or enabling the LCP to report the device status and events to an external device.

[0065] In the example shown in Figure 2, the pulse generation module 104 may be electrically connected to a plurality of electrodes 114 and / or 114'. The pulse generation module 104 may be configured to generate an electrical stimulation signal, and may include, for example, appropriate circuitry for modulating or multiplying a power signal obtained from a battery 112, and the output may include, for example, a pacing pulse or other therapeutic signal.

[0066] In some examples, the LCP 100 may not include the pulse generation module 104, in which case the device 100 may be described as an implantable cardiac monitor. The device 100 may collect data on the electrical activity of the heart and / or the patient's physiological parameters, and may communicate such data and / or determination results to one or more other medical devices via the communication module 102.

[0067] In some examples, the LCP100 may include an electrical sensing module 106 and, optionally, a mechanical sensing module 108. The electrical sensing module 106 may be configured to detect the cardiac electrical activity of the heart. The mechanical sensing module 108 may include one or more sensors, such as an accelerometer, a blood pressure sensor, a heart sound sensor, a blood oxygen sensor, a temperature sensor, a flow sensor, and / or other suitable sensors configured to measure one or more mechanical and / or chemical parameters of a patient. Both the electrical sensing module 106 and the mechanical sensing module 108 may be connected to a processing module 110, which may provide signals representing the detected mechanical parameters. In Figure 2, these are described as separate sensing modules, but in some cases, the electrical sensing module 106 and the mechanical sensing module 108 may be integrated into a single sensing module as desired. Other sensors, such as a pulse oximetry module, may be included as desired.

[0068] The processing module 110 may be configured to control the operation of the LCP 100. For example, the processing module 110 may be configured to receive electrical signals from the electrical sensing module 106 and / or the mechanical sensing module 108. Based on the received signals, the processing module 110 may determine, for example, the occurrence of an arrhythmia, and possibly its type. Based on the determined arrhythmia, the processing module 110 may control the pulse generation module 104 to generate electrical stimulation according to one or more treatments for treating the arrhythmia. The processing module 110 may further receive information from the communication module 102. In some examples, the processing module 110 may use the information thus received to determine whether an arrhythmia is occurring and what type of arrhythmia it is, and / or to perform a specific action in response to that information. The processing module 110 may further control the communication module 102 to send and receive information with other devices.

[0069] In some examples, the processing module 110 may include a pre-programmed chip, such as a very large-scale integrated circuit (VLSI) chip and / or an application-specific integrated circuit (ASIC). In such embodiments, the chip may be pre-programmed with control logic for controlling the operation of the LCP 100. By using a pre-programmed chip, the processing module 110 can operate with less power than other programmable circuits (e.g., a general-purpose programmable microprocessor) while maintaining basic functionality, thereby improving the battery life of the LCP 100. In other examples, the processing module 110 may include a programmable microprocessor. Such a programmable microprocessor may allow the user to change the control logic of the LCP 100 even after implantation, thereby increasing the flexibility of the LCP 100 compared to using a pre-programmed ASIC. In some examples, the processing module 110 may further include memory, which may store and read information. In other examples, the LCP100 may include a separate memory (not shown) that communicates with the processing module 110, in which case the processing module 110 may read and write information to the separate memory.

[0070] Battery 112 can supply power to the LCP 100 for its operation. In some examples, battery 112 may be a non-rechargeable lithium-ion battery. In other examples, the non-rechargeable battery may be made of other suitable materials as desired. Since the LCP 100 is an implantable device, access to the LCP 100 may be restricted after implantation. Therefore, it is desirable to have a battery capacity sufficient to provide treatment over a treatment period of several days, weeks, months, years, or even decades. In some cases, battery 112 may be a rechargeable battery, which may contribute to extending the usable life of the LCP 100. In yet another example, battery 112 may be of other types of power sources as desired.

[0071] To implant the LCP100 into a patient's body, the operator (e.g., physician, clinician, etc.) may fix the LCP100 to the patient's cardiac tissue. To facilitate fixation, the LCP100 may include one or more anchors 116. The anchors 116 may include any of various fixation or locking mechanisms. For example, the anchor 116 may include one or more pins, staples, threads, screws, helices, tines, and / or similar. In some examples, although not shown, the anchor 116 may include threads extending along its outer surface for at least a portion of its length. These threads may create friction between the cardiac tissue and the anchor, contributing to the fixation of the anchor 116 within the cardiac tissue. In other examples, the anchor 116 may include barbs, spikes, or other similar structures to facilitate engagement with the surrounding cardiac tissue.

[0072] Figure 3 shows an example of another medical device (MD) 200, which may be used alone or in combination with LCP 100 (Figure 2) to detect and / or treat cardiac arrhythmias and other cardiac conditions. In the illustrated example, the MD 200 may include a communication module 202, a pulse generation module 204, an electrical sensing module 206, a mechanical sensing module 208, a processing module 210, and a battery 218. Each of these modules may be similar to modules 102, 104, 106, 108, and 110 of the LCP 100, respectively. Furthermore, the battery 218 may be similar to the battery 112 of the LCP 100. In some examples, the MD 200 may have a larger volume within the housing 220 than the LCP 100. In such examples, the MD 200 may include a larger battery and / or a larger processing module 210 capable of handling more complex operations than the processing module 110 of the LCP 100.

[0073] While the MD200 is assumed to be another leadless device as shown in Figure 2, in some cases the MD200 may include leads such as lead 212. Lead 212 may include electrical conductors that transmit electrical signals between one or more modules located within the housing 220 and electrodes 214. In some cases, lead 212 may be connected to the housing 220 of the MD200 or may extend from the housing 220. In some examples, lead 212 is implanted on, within, or adjacent to the patient's heart. Lead 212 may include one or more electrodes 214 located at various positions on lead 212 and, optionally, at various distances from the housing 220. Some leads 212 may include only a single electrode 214, while others may include multiple electrodes 214. Generally, the electrodes 214 are positioned on lead 212 such that one or more electrodes 214 perform the desired function when lead 212 is implanted in the patient.

[0074] In some cases, one or more of the electrodes 214 may come into contact with the patient's cardiac tissue, for example, by inserting the lead 212 through the patient's blood vessels and positioning it within the cardiac chambers (atria or ventricles) or within blood vessels on the heart where the lead can be fixed. In some cases, one or more of the electrodes 214 may be positioned substernal or subcutaneously adjacent to the patient's heart, or on the pericardium or epicardially on the heart itself. In some cases, the electrodes 214 may transmit intrinsically generated electrical signals, such as signals representing intrinsic cardiac electrical activity, to the lead 212. The lead 212 may then transmit the received electrical signals to one or more of the modules 202, 204, 206, and 208 of the MD200. In some cases, the MD200 may generate electrical stimulation signals, and the lead 212 may transmit the generated electrical stimulation signals to the electrodes 214. The electrodes 214 may transmit and supply (directly or indirectly) such electrical signals to the patient's heart.

[0075] The mechanical sensing module 208, like the mechanical sensing module 108, may include or be electrically connected to one or more sensors, such as an accelerometer, blood pressure sensor, heart sound sensor, blood oxygen sensor, acoustic sensor, ultrasonic sensor, and / or other sensors configured to measure one or more mechanical / chemical parameters of the heart and / or patient. In some examples, one or more of these sensors may be located on the lead 212, but this is not required. In some examples, one or more of these sensors may be located inside the housing 220.

[0076] Although not required, in some examples the MD200 may be an implantable medical device. In such examples the MD200 housing 220 may be implanted in, for example, the patient's chest region. For example, the pectoral muscle or axilla may be implantation sites. The housing 220 may contain various materials known to be safe for implantation in the human body, and during implantation, each component of the MD200 may be airtightly sealed from the patient's bodily fluids and tissues.

[0077] In some cases, the MD200 may be an implantable cardiac pacemaker (ICP). In this example, the MD200 may have one or more leads, such as lead 212, which are implanted on or inside the patient's heart. One or more leads 212 may include one or more electrodes 214 that come into contact with the patient's cardiac tissue and / or blood. The MD200 may be configured to detect intrinsically generated electrical signals of the heart and, based on the analysis of the detected signals, determine, for example, one or more cardiac arrhythmias. The MD200 may be configured to provide CRT, ATP therapy, bradycardia therapy, and / or other types of therapy via the leads 212 implanted inside the heart or in cooperation with the LCP by instructing the LCP to pace. In some examples, the MD200 may further be configured to provide defibrillation therapy.

[0078] In some cases, the MD200 may be an implantable cardioverter-defibrillator (ICD). In such cases, the MD200 may include one or more leads implanted in the patient's heart. The MD200 may also be configured to detect electrical signals from the heart, determine the occurrence of tachyarrhythmia based on the detected signals, and provide defibrillation treatment in response to the detection of tachyarrhythmia.

[0079] One or more LCP100s and / or one or more MD200s are envisioned to be used in combination as an exemplary medical device system. Each device 100, 200 may communicate through various communication paths, including using RF signals, inductive coupling, conduction coupling, optical signals, acoustic signals, or any other signal suitable for communication. The system may further include and communicate with a display device. The display device may be a personal computer, tablet computer, smartphone, laptop computer, or any other display device as desired. In some cases, the display device may include input means for receiving input from a user. For example, the display device may also include a keyboard, mouse, operable (e.g., pressable) buttons, or touchscreen display. These are merely examples.

[0080] Referring to Figure 4, it will be understood that the human heart is controlled by electrical signals passing through cardiac tissue, and these electrical signals can be detected by implanted devices such as the LCP100 and / or MD200 in Figure 2 or Figure 3. Figure 4 is a graphical representation of an exemplary electrocardiogram (ECG) 300 and mechanical signals 302, shown as sound signals, illustrating the temporal relationship between the electrical signals of the heart and the mechanical signs of cardiac contraction 302 (e.g., sound signals). As can be seen in the exemplary ECG 300, the heartbeat includes a P wave, which indicates atrial depolarization associated with atrial contraction to fill the ventricles with blood. The QRS complex, including the Q, R, and S waves, represents ventricular depolarization associated with ventricular contraction to pump blood to the body and lungs. The T wave indicates ventricular repolarization in preparation for the next heartbeat. In cases of heart disease, the timing of these individual events may be abnormal, and the shape, amplitude, and / or timing of each wave may differ from those shown. It will be understood that the ECG300 can be detected by implanted devices such as the LCP100 and / or MD200 shown in Figure 2 or Figure 3.

[0081] Characteristics or events in ECG300 may have corresponding events in mechanical signal 302. Mechanical responses are typically delayed because it takes a certain amount of time for the heart to respond to electrical signals. It will be understood that heart sounds may be considered an example of mechanical signs of the heartbeat. Other exemplary mechanical signs may include, for example, endocardial acceleration or wall motion detected by an accelerometer in LCP, wall acceleration or motion detected by an accelerometer in SICD, intracardiac pressure, pressure change or rate of pressure change detected by pressure sensors in LCP or other implantable devices, acoustic signals resulting from cardiac motion detected by acoustic sensors (e.g., accelerometer, microphone, etc.), cardiac torsion detected by a gyroscope in LCP or other implantable devices, and / or other appropriate indicators showing cardiac pulsation.

[0082] Referring to Figure 4, in some cases, there may be a first heart sound S1 generated by vibrations caused by the closure of the mitral and tricuspid valves during ventricular contraction, a second heart sound S2 generated by the closure of the aortic and pulmonary valves, a third heart sound S3 which is an early diastolic sound caused by the rapid inflow of blood from the right atrium to the right ventricle and from the left atrium to the left ventricle, and a fourth heart sound S4 which is a late diastolic sound corresponding to late ventricular filling during active atrial contraction. These are mechanical responses that can often be detected using various sensors (e.g., microphones, hydrophones, accelerometers, etc.).

[0083] Since heart sounds are the result of the myocardium contracting or relaxing in response to the heart's electrical signals, it will be understood that there is usually a delay between the electrical signals of the heart shown by the ECG 300 and the corresponding mechanical signs shown by the heart sound trace 302 in the illustrated example. For example, the P wave of the ECG 300 is the electrical signal of the heart that causes atrial contraction. Heart sound S4 is the mechanical signal produced by atrial contraction. In some cases, it may be possible to utilize this relationship between the P wave and heart sound S4. For example, if one of these signals can be detected, their expected temporal relationship can be used as a means to search for the other signal. For example, if the P wave can be detected, a window following the P wave can be defined and searched to help find and / or isolate the corresponding heart sound S4. In some cases, the detection of both signals may be an indicator of high confidence in the detected atrial contraction. In some cases, the detection of either one of the signals may be sufficient to identify atrial contraction. Identification of atrial contraction may be used to identify timing indicators of atrial contraction (e.g., atrial contraction timing markers). QRS signals and heart sounds S1 may also be used to identify ventricular contractions in a similar manner. Identification of ventricular contractions may be used to identify ventricular contraction timing indicators (e.g., ventricular contraction timing markers).

[0084] It should be understood that this disclosure is illustrative in many respects. Modifications may be made without departing the scope of this disclosure, particularly in terms of shape, dimensions, and process arrangement. Such modifications may include, to the extent appropriate, applying any feature of one embodiment to another embodiment. The scope of this disclosure is, of course, defined by the language set forth in the appended claims.

Claims

1. A pacing system configured to detect a patient's cardiac activity and to supply pacing therapy to the patient's heart, wherein the pacing system is A first electrode configured to be positioned in a first cavity of the heart and to supply a first pacing treatment to the first cavity, A second electrode is configured to be positioned adjacent to the left atrial appendage of the heart and to supply a second pacing treatment to the left atrial appendage. The processing module of the pacing system is configured to determine the timing of supplying at least a portion of the first pacing treatment by the first electrode, at least in part on a first timing index, and to determine the timing of supplying at least a portion of the second pacing treatment by the second electrode, at least in part on a determined pacing delay between the first pacing treatment and the second pacing treatment. A pacing system in which the determined pacing delay is configured to maximize blood flow to and / or from the left atrial appendage.

2. The pacing system according to claim 1, wherein the first electrode is coupled to a first lead extending from a pacemaker, and the second electrode is coupled to a second lead extending from the pacemaker.

3. The second lead mentioned above is A punch needle and Adhesive growth pads and, The first electrode 2, A conductor extending proximal to the second electrode and The pacing system according to claim 2, comprising:

4. The pacing system according to claim 3, wherein the punch needle and the adhesive growth pad are configured to penetrate the outer surface of the left atrial appendage and to be pressed against the outer surface.

5. The pacing system according to claim 1, wherein the first electrode is coupled to a first lead extending from a pacemaker, and the second electrode is coupled to a leadless cardiac pacemaker.

6. The pacing system according to claim 5, wherein the pacemaker communicates with the leadless cardiac pacemaker.

7. The pacing system according to any one of claims 1 to 6, wherein the first timing indicator includes heart sounds.

8. The pacing system according to any one of claims 1 to 6, wherein the first timing indicator includes the opening of a valve.

9. The pacing system according to any one of claims 1 to 6, wherein the first timing indicator includes a pressure drop.

10. The pacing system according to any one of claims 1 to 7, wherein the determined pacing delay is configured to be customized when the pacing system is implanted.

11. The pacing system according to any one of claims 1 to 8, wherein the first cavity is the left atrium.

12. The pacing system according to any one of claims 1 to 11, wherein the second electrode is configured to be positioned in the left atrial appendage.

13. The pacing system according to any one of claims 1 to 11, wherein the second electrode is configured to be positioned outside the left atrial appendage.

14. The pacing system according to any one of claims 1 to 13, wherein the determined pacing delay is based on the first timing index.

15. The pacing delay determined is based on the first pacing treatment, according to any one of claims 1 to 13.

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