Source: http://www.patentsencyclopedia.com/app/20140074178
Timestamp: 2018-11-17 23:55:32
Document Index: 281020735

Matched Legal Cases: ['art 115', 'art 115', 'art 115', 'art 115', 'art 115', 'art 115', 'art 115', 'art 115']

CARDIAC RHYTHM MANAGEMENT SYSTEM SELECTING BETWEEN MULTIPLE SAME-CHAMBER ELECTRODES FOR DELIVERING CARDIAC THERAPY - Patent application
Patent application title: CARDIAC RHYTHM MANAGEMENT SYSTEM SELECTING BETWEEN MULTIPLE SAME-CHAMBER ELECTRODES FOR DELIVERING CARDIAC THERAPY
Inventors: Jiang Ding (Shoreview, MN, US) Julio C. Spinelli (Lakewood Ranch, FL, US) Julio C. Spinelli (Lakewood Ranch, FL, US) Andrew P. Kramer (Marine On St. Croix, MN, US)
Patent application number: 20140074178
A cardiac rhythm management system selects one of multiple electrodes associated with a particular heart chamber based on a relative timing between detection of a depolarization fiducial point at the multiple electrodes, or based on a delay between detection of a depolarization fiducial point at the multiple electrodes and detection of a reference depolarization fiducial point at another electrode associated with the same or a different heart chamber. Subsequent contraction evoking stimulation therapy is delivered from the selected electrode.
2. A system, comprising: two or more electrostimulation electrodes configured to be associated with a first heart chamber; a sensing circuit coupled to the two or more electrostimulation electrodes, the sensing circuit configured to detect from each of the two or more electrostimulation electrodes a respective detection timing at which each of the two or more electrostimulation electrodes receives a first cardiac depolarization of the first heart chamber; and a controller coupled to the sensing circuit, the controller configured to: identify a late-responsive electrode among the two or more electrostimulation electrodes, the late-responsive electrode detecting the first cardiac depolarization no earlier than other of the two or more electrostimulation electrodes; and generate an indication for delivering an electrostimulation therapy using a recommended electrostimulation electrode configuration, the recommended electrostimulation electrode configuration including the late-responsive electrode for use in providing an electrostimulation to the first heart chamber.
3. The system of claim 2 wherein the controller is further configured to generate an indication of an order of the detection timings from the two or more electrostimulation electrodes.
4. The system of claim 2, further comprising a therapy circuit, wherein the controller is configured to selectively couple the recommended electrostimulation electrode configuration to the therapy circuit, the therapy circuit configured to deliver an electrostimulation using the recommended electrostimulation electrode configuration for evoking a heart contraction.
5. The system of claim 2, wherein the two or more electrostimulation electrodes are configured to be associated with the first heart chamber including one of a left ventricle or a right ventricle.
6. The system of claim 2, wherein the two or more electrostimulation electrodes are configured to be disposed at two or more non-identical locations associated with the first heart chamber.
7. The system of claim 6, wherein the two or more electrostimulation electrodes are respectively differently individually disposed at one of a base, a midregion, or an apex of a free wall of a first heart ventricle.
8. The system of claim 6, wherein the two or more electrostimulation electrodes are respectively differently individually disposed at one of a base, a midregion, or an apex of an anterior wall of a first heart ventricle.
9. The system of claim 2, further comprising a sensing electrode coupled to the sensing circuit, the sensing electrode configured to be associated with a second heart chamber different from the first heart chamber, wherein: the sensing circuit, using the sensing electrode, is configured to detect a reference timing at which the sensing electrode receives a second depolarization of the second heart chamber; and the controller is configured to identify the late-responsive electrostimulation electrode using a comparison of the detection timings and the reference timing.
10. The system of claim 9, comprising a timer circuit configured to measure time intervals between the reference timing and each of the detection timings from the two or more electrostimulation electrodes, wherein the controller is configured to identify the late-responsive electrostimulation electrode using a comparison of the measured time intervals.
11. The system of claim 9, wherein the sensing circuit is configured to detect, during a cardiac cycle, the reference timing and the detection timings from the two or more electrostimulation electrodes, and wherein the timer circuit is configured to measure the time intervals between the reference timing and each of the detection timings during the cardiac cycle.
12. The system of claim 9, wherein the sensing circuit is configured to detect, during a plurality of cardiac cycles, two or more reference timings from the sensing electrode and the detection timings from the two or more electrostimulation electrodes, and wherein the timer circuit is configured to measure the time intervals if one of the two or more reference timings and one or more of the detection timings are within same one of the plurality of cardiac cycles.
13. The system of claim 9, wherein the sensing electrode is configured to be disposed at a location in one of a left atrium or a right atrium, and wherein the sensing circuit is configured to detect the reference timing including a P wave.
14. The system of claim 9, wherein the two or more electrostimulation electrodes are each disposed at locations in a first heart ventricle, and wherein the sensing electrode is configured to be disposed at a location in a second heart ventricle different from the first heart ventricle.
15. The system of claim 2, wherein: the sensing circuit is configured to detect from each of the two or more electrostimulation electrodes a respective plurality of detection timings over a plurality of cardiac cycles; and the controller is configured to compute for each of the two or more electrostimulation electrodes a timing statistic using the respective plurality of detection timings, and to identify the late-responsive electrostimulation electrode using a comparison of the timing statistics.
16. The system of claim 15, wherein the controller is configured to identify the late-responsive electrode, the timing statistic of the late-responsive electrode indicating the late-responsive electrode receives the fast cardiac depolarization statistically later in a cardiac cycle than other of the two or more electrostimulation electrodes by at least a specified threshold amount of time.
17. The system of claim 15, wherein the controller is configured to identify the late-responsive electrode using a comparison of relative spatial locations of a subset of the two or more electrostimulation electrodes with respect to a heart apex, the late-responsive electrode being closer to the heart apex than other electrostimulation electrodes in the subset, the timing statistics indicating the subset of electrodes detecting the fast cardiac depolarization at approximately the same time in a cardiac cycle,and statistically later in a cardiac cycle than other of the two or more electrostimulation electrodes.
18. The system of claim 2, further comprising an external programmer communicatively coupled to the controller, the external programmer configured to display at least one of the late-responsive electrode or the recommended electrostimulation electrode configuration.
19. A method, comprising: providing two or more electrostimulation electrodes associated with a first heart chamber; detecting, from each of two or more electrostimulation electrodes, a respective detection timing at which each of the two or more electrostimulation electrode receives a first cardiac depolarization of the first heart chamber; identifying a late-responsive electrode among the two or more electrostimulation electrodes, the late-responsive electrode detecting the first cardiac depolarization no earlier than other of the two or more electrostimulation electrodes; and generating an indication for delivering an electrostimulation therapy using a recommended electrostimulation electrode configuration, the recommended electrostimulation electrode configuration including the late-responsive electrode for use in providing an electrostimulation to the first heart chamber.
20. The method of claim 19, further comprising: providing a sensing electrode associated with a second heart chamber different from the first heart chamber; detecting a reference timing at which the sensing electrode receives a second depolarization of the second heart chamber; and measuring time intervals between the reference timing and each of the detection timings, wherein identifying the late-responsive electrostimulation electrode includes identifying the late-responsive electrode using a comparison of the measured time intervals.
21. The method of claim 19, comprising generating an indication of an order of detection timings from the two or more electrostimulation electrodes.
[0001] This application is a continuation of U.S. patent application Ser. No. 13/646,720, filed on Oct. 7, 2012, which is a continuation of U.S. patent application Ser. No. 13/369,189, filed on Feb. 8, 2012, now issued as U.S. Pat. No. 8,301,253, which is a division of U.S. patent application Ser. No. 13/026,917, filed on Feb. 14, 2011, now issued as U.S. Pat. No. 8,121,686, which is a division of U.S. patent application Ser. No. 11/742,655, filed on May 1, 2007, now issued as U.S. Pat. No. 7,890,169 which is a division of U.S. patent application Ser. No. 10/706,436, filed on Nov. 12, 2003, now issued as U.S. Pat. No. 7,239,913, which is a division of U.S. patent application Ser. No. 09/862,181, tiled on May 23, 2001, now issued as U.S. Pat. No. 6,704,598, each of which are incorporated herein by reference and the priority of each of which is claimed herein.
[0006] Cardiac rhythm management systems include, among other things, pacemakers, also referred to as pacers. Pacers deliver timed sequences of low energy electrical stimuli, called pace pulses, to the heart, such as via an intravascular leadwire or catheter (referred to as a "lead") having one or more electrodes disposed in or about the heart. Heart contractions are initiated in response to such pace pulses (this is referred to as "capturing" the heart). By properly timing the delivery of pace pulses, the heart can be induced to contract in proper rhythm, greatly improving its efficiency as a pump. Pacers are often used to treat patients with bradyarrhythmias, that is, hearts that beat too slowly, or irregularly. Such pacers may also coordinate atrial and ventricular contractions to improve pumping efficiency.
[0007] Cardiac rhythm management systems also include defibrillators that are capable of delivering higher energy electrical stimuli to the heart. Such defibrillators also include cardioverters, which synchronize the delivery of such stimuli to portions of sensed intrinsic heart activity signals. Defibrillators are often used to treat patients with tachyarrhythmias, that is, hearts that beat too quickly. Such too-fast heart rhythms also cause diminished blood circulation because the heart isn't allowed sufficient time to fill with blood before contracting to expel the blood. Such pumping by the heart is inefficient. A defibrillator is capable of delivering a high energy electrical stimulus that is sometimes referred to as a defibrillation countershock, also referred to simply as a "shock." The countershock interrupts the tachyarrhythmia, allowing the heart to reestablish a normal rhythm for the efficient pumping of blood. In addition to pacers, cardiac rhythm management systems also include, among other things, pacer/defibrillators that combine the functions of pacers and defibrillators, drug delivery devices, and any other implantable or external systems or devices for diagnosing or treating cardiac arrhythmias.
[0008] One problem faced by physicians treating cardiovascular patients is the treatment of congestive heart failure (also referred to as "CHF"). Congestive heart failure, which can result from long-term hypertension, is a condition in which the muscle in the watts of at least one of the right and left sides of the heart deteriorates. By way of example, suppose the muscle in the walls of left side of the heart deteriorates. As a result, the left atrium and left ventricle become enlarged, and the heart muscle displays less contractility. This decreases cardiac output of blood through the circulatory system which, in turn, may result in an increased heart rate and less resting time between heartbeats. The heart consumes more energy and oxygen, and its condition typically worsens over a period of time.
[0014] In another embodiment, a reference first chamber depolarization fiducial point is detected. A second chamber depolarization fiducial point is detected at each of multiple second chamber electrodes during the same cardiac cycle as the reference fiducial point. Time intervals are measured between the reference fiducial point and each of the second chamber fiducial points. The electrode corresponding to the longest such time interval is selected for subsequent deliver of contraction-evoking stimulations.
[0015] In a further embodiment, a first depolarization fiducial point is detected from the first heart chamber. During the same cardiac cycle, a second depolarization point is detected from a first electrode associated with the second heart chamber. A first time interval is measured between the first and second fiducial points. During a subsequent cardiac cycle, a third fiducial point, of the same nature as the first fiducial point, is detected from the first heart chamber. During the same cardiac cycle, a fourth fiducial point, of the same nature as the second fiducial point, is detected from second electrode associated with the second heart chamber. A second time interval is measured between the third and fourth fiducial points. The electrode corresponding to the longer of the first and second time intervals is selected for subsequent delivery of contraction-evoking stimulations.
[0016] In yet a further embodiment, a reference fiducial point is detected, over one or more cardiac cycles, from one of a plurality of electrodes associated with a heart chamber. During the one or more cardiac cycles, corresponding fiducial points associated with heart depolarizations are detected at the electrodes, and time intervals are measured between the heart depolarization fiducial points and the respective reference fiducial points. The electrode associated with the longest time interval is used for subsequent delivery of stimulations. Other aspects of the present system and methods will become apparent upon reading the Mowing detailed description of the invention and viewing the drawings that form a part thereof.
[0026] The present methods and apparatus are described with respect to implantable cardiac rhythm management (CRM) devices, such as pacemakers, cardioverter/defibrillators, pacer/defibrillators, and multi-chamber and/or multi-site (in a single or multiple heart chambers) cardiac resynchronization therapy (CRT) devices. Such CRT devices are included within CRM devices even though the CRT devices need not necessarily modulate heart rate. Such CRT devices may instead provide contraction-evoking stimulations that establish or modify the conduction path of propagating depolarizations to obtain more efficient pumping of the heart. Moreover, the present methods and apparatus also find application in other implantable medical devices, and in un implanted (external) devices, including, but not limited to, external pacemakers, cardioverter/defibrillators, pacer/defibrillators, multi-chamber and/or multi-site CRT devices, monitors, programmers and recorders, whether such devices are used for providing a diagnostic, a therapy, or both.
[0028] In one embodiment, lead 110A includes an electrode associated with right atrium 115A, such as tip electrode 120 and/or ring electrode 125. The electrode is "associated" with the particular heart chamber by inserting it into that heart chamber, or by inserting it into a portion of the heart's vasculature that is close to that heart chamber, or by epicardially placing the electrode outside that heart chamber, or by any other technique of configuring and situating an electrode tier sensing signals and/or providing therapy with respect to that heart chamber. Lead 110B, which is introduced into coronary sinus 1.15E and/or the great cardiac vein or one of its tributaries, includes one or a plurality of electrodes associated with left ventricle 115D, such as electrodes 130 and 135. Device 105 may also include other electrodes, such as housing electrode 150 and/or header electrode 155, which are useful for, among other things, unipolar sensing of heart signals or unipolar delivery of contraction-evoking stimulations in conjunction with one or more of the electrodes 120, 125, 130, and 135 associated with heart 115. Alternatively, bipolar sensing and/or therapy may be used between electrodes 120 and 125, between electrodes 130 and 135, or between one of electrodes 130 and 135 and another closely situated electrode.
[0029] Device 105 includes a sensing module 169, which is coupled to one or more of the electrodes for sensing electrical depolarizations corresponding to heart chamber contractions. Such electrical depolarizations of the heart tissue include atrial depolarizations, referred to as P-waves, and ventricular depolarizations, referred to as QRS complexes. The QRS complex is a rapid sequence of several signal excursions away from a baseline in sequentially switching polarity, with the largest excursion referred to as an R-wave. Peak detector 165 is coupled to sensing module 160 for detecting the P-wave peak from right atrium 115A, obtained by bipolar sensing between electrodes 120 and 125 or by any other sensing technique. Peak detector 165 also senses the R-wave peak at a plurality of different sites associated with left ventricle, such as at each of electrodes 130 and 135. In one example, electrode 130 is located near the left ventricular apex and electrode 135 is located near the left ventricular base region, i.e., closer to the left atrium 115C. In another example, one of these two electrodes 130 and 135 (or an additional third electrode) is located in a middle portion ("midregion") of left ventricle 115D between the left ventricular apex and the left ventricular base region. In another example, electrodes 130 and 135 are located in a middle cardiac vein and closer to a septum region. The electrodes are located either on the free wall and/or the anterior wall of the ventricle. Sensing at electrodes 130 and 135 is either unipolar (e.g., the electrode 139 and/or 135 is sensed in combination with a relatively distant electrode, such as one or both of housing electrode 150 and/or header electrode 155) or bipolar (e.g., the electrode 130 and/or 135 is sensed in combination with another relatively close electrode, such as another electrode disposed on lead 1108 and associated with left ventricle 115D, or another electrode disposed on lead 110A and associated with right atrium 115A). System 100 also includes a telemetry transceiver 185 in device 105, which is communicatively coupled to an external programmer 190.
[0030] FIG. 1, and the graph of FIG. 2, illustrates an embodiment in which timer 170 measures a first right atrium to left ventricle (RA-LV) time interval between the detection of an intrinsic P-wave at time to at electrode 120 and the subsequent detection during the same cardiac cycle of an intrinsic R-wave peak at time t1 at first left ventricular electrode 130. A cardiac cycle includes both an atrial and the resulting ventricular heart contraction, and may be measured between P-waves, between R-waves, or between any other fiducial points on a heart signal, where the fiducial point occurs once per cardiac cycle. Timer 170 also measures a second RA-LV time interval between the detection of the intrinsic P-wave at time t0 at electrode 120 and the subsequent detection during the same cardiac cycle of an intrinsic R-wave peak at time t2 at a second left ventricular electrode 135. Controller 175 is coupled to timer 170 to receive these first and second time intervals (t1-t0) and (t2-t0), respectively.
[0031] Based on a comparison between these time intervals, controller 175 selects one of electrodes 130 and 135 to which therapy module 180 is coupled for delivering subsequent contraction-evoking stimulation therapy to left ventricle 115D. In this example, controller 175 selects the one of electrodes 130 and 135 that corresponds to a longer detected time interval between the detection of the P-wave associated with the right atrium 115A and the detection of the R-wave associated with left ventricle 115D. Thus, if (t1-t0)>(t2-t0), then electrode 130 is selected for delivering contraction-evoking stimulations. If (t1-t0)<(t2-t0), then electrode 135 is selected for delivering contraction-evoking stimulations. If (t1-t0)=(t2-t0), then, in one example, the electrode that is closest to the apex of heart 115 (e.g., electrode 130) is selected for delivering contraction-evoking stimulations. In a further example, a threshold time difference, Δt, is used for making the comparison. In this example, if (t1-t0)>[(t2-t0)+Δt], then electrode 130 is selected for delivering stimulations. If [(t1-t0)+Δt]<(t2-t0), then electrode 135 is selected for delivering stimulations. Otherwise, electrode 130, or other electrode closest to the apex of heart 115, is selected for delivering stimulations. In one example, Δt is approximately between 0 milliseconds and 20 milliseconds inclusive, such as about 10 milliseconds. In a further example, an indication of which of electrodes 130 and 135 was selected is communicated from device 105 by transceiver 185 to external programmer 190 for display to a user.
[0032] In an alternate embodiment, the reference time t0 is not used, but the relative times t1 and t2 are instead compared directly. If t1>t2, then electrode 130 is selected for delivering contraction-evoking stimulations, if t1<t2, then electrode 135 is selected for delivering contraction-evoking stimulations, if t1=t2, then electrode 130, or other electrode closest to the apex of heart 115, is selected for delivering contraction-evoking stimulations. In a further example, a threshold time difference, Δt, is used for making the comparison. For example, if t1>Δt), then electrode 130 is selected for delivering stimulations, if (t1+Δt)<t2, then electrode 135 is selected for delivering stimulations, otherwise electrode 130, or other electrode closest to the apex of heart 115, is selected for delivering stimulations.
[0033] In another alternate embodiment, a reference time is used, but this reference time and the times t1 and t2 are measured during different cardiac cycles. During a first cardiac cycle, a P-wave is detected at electrode 120 at time t0A and an R-wave is detected at electrode 130 at time t1, and a time interval (t1t0A) is measured based on these detections. During a second cardiac cycle, another P-wave is detected at electrode 120 at time t0B, and an R-wave is detected at electrode 135 at time t2, and a time interval t2-t0B is measured. The time intervals (t1-t0A) and (t2-0B) are then compared, as discussed above, for selecting one of electrodes 130 and 135 for delivering stimulations.
[0038] FIG. 4 is a schematic/block diagram of one alternate embodiment including right ventricular electrodes, such as tip electrode 400 and ring electrode 405. FIG. 4, and the graph of FIG. 5, illustrates an embodiment in which timer 170 measures a first right ventricle to left ventricle (RV-LV) time interval between the detection of an intrinsic R-wave peak at time t0 at right ventricular electrode 400 and the subsequent detection during the same cardiac cycle of an intrinsic R-wave peak at time t1 at first left ventricular electrode 130. Timer 170 also measures a second RV-LV time interval between the detection of the intrinsic R-wave peak at time t0 at right ventricular electrode 400 and the subsequent detection during the same cardiac cycle of an intrinsic R-wave peak at time t2 at a second left ventricular electrode 135. Controller 175 is coupled to timer 170 to receive these first and second time intervals (t1-t0) and (t2-t0), respectively.
[0039] Based on a comparison between these time intervals, controller 175 selects one of electrodes 130 and 135 to which therapy module 180 is coupled for delivering subsequent contraction-evoking stimulation therapy to left ventricle 115D. In this example, controller 175 selects the one of electrodes 130 and 135 that corresponds to a longer detected RV-LV time interval between the detection of the R-wave associated with the right ventricle 115B and the detection of the R-wave associated with left ventricle 115D. Thus, if (t1-t0)>(t2-t0), then electrode 130 is selected for delivering contraction-evoking stimulations. If (t1-t0)<(t2-t0), then electrode 135 is selected for delivering contraction-evoking stimulations. If (t1-t0)=(t2-t0), then the electrode closest to the heart apex, such as electrode 130, is selected fur delivering contraction-evoking stimulations. As discussed above, in a further example, a threshold time difference, Δt, is used fur making the comparison. Thus, if (t1-t0) [(t2-t0)+Δt], then electrode 130 is selected for delivering stimulations. If [(t1-t0)+Δt]<(t2-t0), then electrode 135 is selected for delivering stimulations. Otherwise the electrode closest to the heart apex, such as electrode 130, is selected for delivering stimulations.
[0040] As discussed above, the time intervals (t1-t0) and (t2-t0) need not be measured during the same cardiac cycle, as illustrated in the graph of FIG. 6. In the example of FIG. 6, a time interval (t1-t0A) is measured during a first cardiac cycle and a time interval (t2-t0B) is measured during a second (consecutive or nonconsecutive) cardiac cycle. In this example, if (t1-t0A)>(t2-t0B), then electrode 130 is selected for delivering contraction-evoking stimulations. (t1-t0A)<(t2-t0B), then electrode 135 is selected for delivering contraction-evoking stimulations. If (t1-t0A)=(t2-t0B), then the electrode that is closest to the apex of heart 115, such as electrode 130, is selected for delivering contraction-evoking stimulations. In a further example, as discussed above, a threshold time difference, Δt, is used for making the comparison. Thus, if (t1-t0A)>(t2-t0B), then electrode 130 is selected for delivering stimulations. If [(t1-t0A)+Δt]<(t2-t0B), then electrode 135 is selected for delivering stimulations. Otherwise, the electrode closest to the heart apex, such as electrode 130, is selected fur delivering stimulations. By measuring the time intervals during different cardiac cycles, a single sense amplifier can be multiplexed between electrodes 130 and 135 for detecting the depolarization fiducial points. In certain embodiments, this advantageously allows for reduced circuitry. Although FIG. 6 illustrates an embodiment in which a right ventricular depolarization fiducial point is used as a reference point for measuring the time intervals, such techniques for measuring time intervals separately during different cardiac cycles is equally applicable to the other techniques discussed herein using other fiducial points.
[0041] Moreover, as discussed above, with respect to FIG. 3, in a further embodiment, data is acquired over a plurality of cardiac cycles, and a statistical comparison of RV-LV time intervals, with or without using Δt fur the comparison, is used to select the particular LV electrode for delivering contraction-evoking stimulations. In one embodiment, the subsequent contraction-evoking stimulation therapy is delivered without corresponding contraction-evoking stimulations delivered to right ventricle 1158. However, in another embodiment, each subsequent contraction-evoking stimulation therapy delivered by the selected one of left ventricular electrodes 130 and 135 is accompanied by a corresponding appropriately timed stimulation delivered by right ventricular electrode 400. This is referred to as biventricular cardiac resynchronization therapy. The stimulation delivered at the selected one of left ventricular electrodes 130 and 135 may be simultaneous to, or different from, the time of the corresponding stimulation delivered by right ventricular electrode 400.
[0042] FIG. 7 is a graph example of selecting one of the electrodes associated with the same heart chamber, such as left ventricle 115D, using time intervals measured from a reference fiducial point obtained from one of the same electrodes associated with that heart chamber. In this example, a reference fiducial point is obtained at time t0A by the first one of LV electrodes 130 and 135 to detect an onset of a QRS complex. This onset of the QRS complex, which is referred to as serves as the reference fiducial point. One example of detecting Q* is discussed in Ding et al. U.S. Pat. No. 6,144,880, entitled "Cardiac Pacing Using Adjustable Atrio-Ventricular Delays," assigned to Cardiac Pacemakers, Inc., the entirety of which is incorporated herein by reference. The R-wave peak, or other fiducial point associated with a QRS complex, is detected at time t1 at electrode 130. A first time difference t1-t0A is measured. In this example, the same reference fiducial point is again detected, during a subsequent consecutive or nonconsecutive cardiac cycle, at time t0B by the first one of LV electrodes 130 and 135 to detect Q*. The R-wave peak, or the other fiducial point similar to the fiducial point measured from electrode 130 at time t1, is detected at time t2 at electrode 135. A second time difference t2-t0B is measured. In this example, if (t1-t0A)>(t2-t0B), then electrode 130 is selected for delivering contraction-evoking stimulations. If (t1-t0A)<(t2-t0B), then electrode 135 is selected for delivering contraction-evoking stimulations. If (t1-t0A)=(t2-t0B), then the electrode closest to the apex of heart 115, such as electrode 130, is selected for delivering contraction-evoking stimulations. In a further example, as discussed above, a threshold time difference, Δt, is used for making the comparison. Thus, if (t1-t0A)>[(t2-t0B)+Δt], then electrode 130 is selected for delivering stimulations. If [(t1-t0A)+Δt]<(t2-t0B), then electrode 135 is selected for delivering stimulations. Otherwise, the electrode closest to the heart apex, such as electrode 130, is selected for delivering stimulations. Although the example illustrated in FIG. 7 relates to using multiple cardiac cycles, it is understood that this technique could be carried out during a single cardiac cycle using a single reference point t0 substituted for the above reference points t0A and t0B. Moreover, because Q* typically occurs substantially simultaneously at multiple electrodes associated with the same heart chamber, the Q* reference fiducial point can typically be detected from any one of the multiple electrodes associated with the same heart chamber.
[0044] Moreover, in an alternative embodiment, for a heart 115 in which the electrical pathways cause the left ventricle to contract before the right ventricle, a left ventricular to right ventricular (LV-RV) delay is measured at a plurality of right ventricular electrodes, and subsequent contraction-evoking stimulations are delivered from that right ventricular electrode corresponding to the longest LV-RV delay. Thus, in a broader sense, a particular electrode from a plurality of electrodes associated with a first ventricle is selected for subsequent therapy delivery based on that electrode having a later detected depolarization than the other electrodes in the plurality of electrodes. In a further embodiment, system 100 not only selects between multiple electrodes associated with the same heart chamber, but also selects between right ventricle 115B and left ventricle 155D fur delivering the contraction-evoking stimulations, such as described in Ding et al. U.S. patent application Ser. No. 09/738,407, now issued as U.S. Pat. No. 6,622,040, assigned to Cardiac Pacemakers, Inc., the disclosure of which is incorporated herein by reference in its entirety.
Patent applications by Julio C. Spinelli, Lakewood Ranch, FL US
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