Source: http://www.google.com/patents/US20010016759?dq=4316055
Timestamp: 2017-10-17 10:13:12
Document Index: 652375382

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

Patent US20010016759 - System providing ventricular pacing and biventricular coordination - Google Patents
A cardiac rhythm management system includes techniques for computing an indicated pacing interval, AV delay, or other timing interval. In one embodiment, a variable indicated pacing interval is computed based at least in part on an underlying intrinsic heart rate. The indicated pacing interval is used...http://www.google.com/patents/US20010016759?utm_source=gb-gplus-sharePatent US20010016759 - System providing ventricular pacing and biventricular coordination
Publication number US20010016759 A1
Also published as EP1185335A1, EP1185335B1, US6285907, US6411848, WO2000071202A1
Publication number 09837019, 837019, US 2001/0016759 A1, US 2001/016759 A1, US 20010016759 A1, US 20010016759A1, US 2001016759 A1, US 2001016759A1, US-A1-20010016759, US-A1-2001016759, US2001/0016759A1, US2001/016759A1, US20010016759 A1, US20010016759A1, US2001016759 A1, US2001016759A1
Inventors Andrew Kramer, Jeffrey Stahmann, Rene Wentkowski, Kenneth Baker, Jesse Hartley, David Krig
Referenced by (42), Classifications (12), Legal Events (3)
US 20010016759 A1
, in which computing the first indicated timing interval includes differently weighting at least one of (1) the most recent actual timing interval duration, or (2) the previous value of the first indicated timing interval, if the most-recent actual timing interval is concluded by a paced beat than if the most recent actual timing interval is concluded by a sensed beat.
, in which computing the first indicated timing interval includes summing a first addend based on the most recent actual timing interval duration and a second addend based on the previous value of the first indicated timing interval, wherein at least one of the first and second addends is different if the most recent actual timing interval is concluded by an intrinsic beat than if the most recent actual timing interval is concluded by a paced beat.
, in which computing the first indicated timing interval (Tn) is carried out according to Tn=A·EEn+B·Tn-1, where A and B are coefficients, EEn is the most recent actual timing interval between events, and Tn-1 is the previous value of the first indicated timing interval.
, in which computing the first indicated timing interval (Tn) is carried out according to: Tn=A·EEn+B·Tn-1 if EEn is concluded by an intrinsic beat, otherwise is carried out according to Tn=C·EEn+D·Tn-1 if EEn is concluded by a paced beat, where C and D are coefficients.
, in which at least one of A, B, C, and D is a function of heart rate.
, in which computing the first indicated timing interval (Tn) is carried out according to Tn=a·w·EEn+(1−w)·Tn-1 if EEn is concluded by an intrinsic beat, otherwise is carried out according to Tn=b·w·EEn+(1−w)·Tn-1, if EEn is concluded by a paced beat, where a, b, and w are coefficients, EEn is the most recent actual timing interval duration, and Tn-1 is the previous value of the first indicated timing interval.
, in which a is approximately between 1.0 and 2.0, b is approximately between 1.0 and 3.0, and w is approximately between 0 and 1.
, in which providing pacing therapy is also based on a second indicated timing interval that is based on a sensor.
, in which the first indicated timing interval is limited by at least one of a maximum value and a minimum interval value.
, in which providing pacing therapy is based on the first indicated timing interval if atrial tachyarrhythmia is present, and providing pacing therapy is independent of the first indicated timing interval if no atrial tachyarrhythmia is present.
, in which computing the first indicated timing interval is also based on a remotely user-programmable parameter that corresponds to a desired degree of paced beats vs. sensed beats.
, in which computing the first indicated timing interval is also based on a goal proportion of paced beats to sensed beats.
, further including providing to a first ventricle a pace pulse triggered by a sensed beat in a second ventricle different from the first ventricle.
, in which computing the first indicated AV interval includes differently weighting at least one of (1) the most recent AV interval duration, or (2) the previous value of the first indicated AV interval, if the most-recent AV interval is concluded by a paced beat than if the most recent AV interval is concluded by a sensed beat.
, in which computing the first indicated AV interval includes summing a first addend based on the most recent AV interval duration and a second addend based on the previous value of the first indicated AV interval, wherein at least one of the first and second addends is different if the most recent AV interval is concluded by an intrinsic beat than if the most recent AV interval is concluded by a paced beat.
, in which computing the first indicated AV interval (Tn) is carried out according to Tn=A·AVn+B·Tn-1 where A and B are coefficients, AVn is the most recent AV interval, and Tn-1 is the previous value of the first indicated AV interval.
, in which computing the first indicated AV interval (Tn) is carried out according to: Tn=A·AVn+B·Tn-1 if AVn is concluded by an intrinsic beat, otherwise is carried out according to Tn=C·AVn+D·Tn-1, if AVn is concluded by a paced beat, where C and D are coefficients.
, in which computing the first indicated AV interval (Tn) is carried out according to Tn=a·w·AVn+(1−w)·Tn-1 if AVn is concluded by an intrinsic beat, otherwise is carried out according to Tn=b·w·AVn+(1−w)·Tn, if AVn is concluded by a paced beat, where a, b, and w are coefficients, AVn is the most recent AV interval duration, and Tn-1 is the previous value of the first indicated AV interval.
, in which the first indicated AV interval is limited by at least one of a maximum AV interval value and a minimum AV interval value.
, in which providing pacing therapy is based on the first indicated AV interval if no atrial tachyarrhythmia is present, and providing pacing therapy is independent of the first indicated AV interval if atrial tachyarrhythmia is present.
, in which computing the first indicated AV interval is also based on a remotely user-programmable parameter that corresponds to a desired degree of shortening vs. lengthening of AV interval.
, in which computing the first indicated AV interval is also based on a goal proportion of paced ventricular beats to sensed ventricular beats.
, in which obtaining V-V intervals between ventricular beats includes obtaining the V-V intervals between ventricular beats of the same ventricle.
, in which obtaining V-V intervals between ventricular beats includes obtaining the V-V intervals between ventricular beats of different ventricles.
, in which obtaining V-V intervals between ventricular beats includes:
, in which computing the first indicated pacing interval includes differently weighting at least one of (1) the most recent V-V interval duration, or (2) the previous value of the first indicated pacing interval, if the most-recent V-V interval is concluded by a paced beat than if the most recent V-V interval is concluded by a sensed beat.
, in which computing the first indicated pacing interval includes summing a first addend based on the most recent V-V interval duration and a second addend based on the previous value of the first indicated pacing interval, wherein at least one of the first and second addends is different if the most recent V-V interval is concluded by an intrinsic beat than if the most recent V-V interval is concluded by a paced beat.
, in which computing the first indicated pacing interval (Tn) is carried out according to Tn=A·VVn+B·Tn-1, where A and B are coefficients, VVn is the most recent V-V interval duration, and Tn-1 is the previous value of the first indicated pacing interval.
, in which computing the first indicated pacing interval (Tn) is carried out according to: Tn=A·VVn+B·Tn-1, if VVn is concluded by an intrinsic beat, otherwise is carried out according to Tn=C·VVn+D·Tn-1, if VVn is concluded by a paced beat, where C and D are coefficients.
, in which computing the first indicated pacing interval (Tn) is carried out according to Tn=a·w·VVn+(1−w)·Tn-1 if VVn is concluded by an intrinsic beat, otherwise is carried out according to Tn=b·w·VVn+(1−w)·Tn-1, if VVn is concluded by a paced beat, where a, b, and w are coefficients, VVn is the most recent V-V interval duration, and Tn-1 is the previous value of the first indicated pacing interval.
, in which providing pacing therapy is also based on a second indicated pacing interval that is based on a sensor.
, in which providing pacing therapy is based on the first indicated pacing interval, if an atrial tachyarrhythmia is present, and providing pacing therapy is independent of the first indicated pacing interval if no atrial tachyarrhythmia is present.
, in which the atrial tachyarrhythmia is atrial fibrillation.
, in which providing pacing therapy is based on the first indicated pacing interval if the first indicated pacing interval is longer than a first predetermined value, and providing pacing therapy is independent of the first indicated pacing interval if the first indicated pacing interval is shorter than the first predetermined value.
, in which computing the first indicated pacing interval is also based on a remotely user-programmable parameter that corresponds to a desired degree of paced ventricular beats vs. sensed ventricular beats.
, in which computing the first indicated pacing interval is also based on a goal proportion of paced ventricular beats to sensed ventricular beats.
, in which the first indicated pacing interval is limited by at least one of a maximum interval value and a minimum interval value.
43. A cardiac rhythm management system, including:
a controller, obtaining timing intervals between events and computing a first indicated timing interval based at least on a most recent actual timing interval duration and a previous value of the first indicated timing interval; and
, including a filter that computes the first indicated timing interval by differently weighting at least one of (1) the most recent actual timing interval duration, or (2) the previous value of the first indicated timing interval, if the most-recent actual timing interval is concluded by a paced beat than if the most recent actual timing interval is concluded by a sensed beat.
, in which the filter includes coefficients A, B, C, and D, and the filter computes the first indicated timing interval (Tn) according to: Tn=A·EEn+B·Tn-1 if EEn is concluded by an intrinsic beat, otherwise is carried out according to Tn=C·EEn+D·Tn-1, if EEn is concluded by a paced beat, where EEn is the most recent actual timing interval duration and Tn-1 is the previous value of the first indicated timing interval.
, further including a sensor, and in which the controller computes a second indicated timing interval based on signals received from the sensor, and in which the therapy circuit provides pacing therapy that is also based on the second indicated timing interval.
, further including a selection module, selecting between the first and second indicated timing intervals to provide a selected timing interval.
, including a programmer remote from and communicatively coupled to the controller, and in which the controller includes a first parameter that is programmable by the programmer, and the programmer includes an indicator based on a second parameter received from the controller.
, in which the first indicated timing interval is also based on the remotely user-programmable first parameter, wherein the first parameter corresponds to a desired proportion of paced ventricular beats to sensed ventricular beats.
, in which the controller includes a goal proportion of paced ventricular beats to sensed ventricular beats, and the first indicated timing interval is also based on the goal.
51. A cardiac rhythm management system, including:
a filter, updating the first indicated pacing interval based on a most recent AV interval provided by the AV interval timer and previous value of the first indicated AV interval stored the first register; and
, in which the filter differently weighting at least one of (1) the most recent AV interval duration, or (2) the previous value of the first indicated AV interval, if the most recent AV interval is concluded by a paced beat than if the most recent AV interval is concluded by a sensed beat.
, in which the filter includes coefficients A, B, C, and D, and the filter computes the first indicated AV interval (Tn) according to: Tn=A·AVn+B·Tn-1 if AVn is concluded by an intrinsic beat, otherwise is carried out according to Tn=C·AVn+D·Tn-1, if AVn is concluded by a paced beat, where AVn is the most recent AV interval duration and Tn-1 is the previous value of the first indicated AV interval.
, in which the filter includes a switch that disables the filter when the atrial sensing circuit indicates that an atrial tachyarrhythmia is present.
, in which the first indicated AV interval is also based on the remotely user-programmable first parameter, wherein the first parameter corresponds to a desired degree of shortening vs. lengthening of the AV interval.
, in which the controller includes a goal proportion of paced ventricular beats to sensed ventricular beats, and the first indicated AV interval is also based on the goal.
, in which the filter differently weighting at least one of (1) the most recent VV interval duration, or (2) the previous value of the first indicated pacing interval, if the most recent AV interval is concluded by a paced beat than if the most recent AV interval is concluded by a sensed beat.
, in which the filter includes coefficients A, B, C, and D, and the filter computes the first indicated pacing interval (Tn) according to: Tn=A·VVn+B·Tn-1 if VVn is concluded by an intrinsic beat, otherwise is carried out according to Tn=C·VVn+D·Tn-1, if VVn is concluded by a paced beat, where VVn is the most recent VV interval duration and Tn-1 is the previous value of the first indicated pacing interval.
, further including a sensor, and in which the controller computes a second indicated pacing interval based on signals received from the sensor, and in which the therapy circuit provides pacing therapy that is also based on the second indicated pacing interval.
, further including an atrial sensing circuit, and in which the filter includes a switch that enables the filter when the atrial sensing circuit indicates that an atrial tachyarrhythmia is present.
, in which the first indicated pacing interval is also based on the remotely user-programmable first parameter, wherein the first parameter corresponds to a desired degree of paced ventricular beats vs. sensed ventricular beats.
, in which the controller includes a goal proportion of paced ventricular beats to sensed ventricular beats, and the first indicated pacing interval is also based on the goal.
, further including a first electrode associated with the first ventricle and a second electrode associated with the second ventricle.
This application is related to the following co-pending, commonly assigned patent applications: “Method and Apparatus for Treating Irregular Ventricular Contractions Such as During Atrial Arrhythmia,” serial number ______, (Attorney Docket No. 00279.112US1); “Cardiac Rhythm Management System Promoting Atrial Pacing,” serial number ______, (Attorney Docket No. 00279.113US1); and “Cardiac Rhythm Management System With Atrial Shock Timing Optimization,” serial number ______, (Attorney Docket No. 00279.142US1); each of which are filed on even date herewith, each of which disclosure is herein incorporated by reference in its entirety.
[0020]FIG. 1 is a schematic drawing illustrating generally one embodiment of portions of a cardiac rhythm management system and an environment in which it is used.
[0021]FIG. 2 is a schematic drawing illustrating one embodiment of a cardiac rhythm management device coupled by leads to a heart.
[0022]FIG. 3 is a schematic diagram illustrating generally one embodiment of portions of a cardiac rhythm management device coupled to a heart.
[0023]FIG. 4 is a schematic diagram illustrating generally one embodiment of a controller.
[0024]FIG. 5 is a schematic diagram illustrating generally one conceptualization of portions of a controller.
[0025]FIG. 6 is a signal flow diagram illustrating generally one conceptual embodiment of operating a filter.
[0026]FIG. 7 is a signal flow diagram illustrating generally another conceptualization of operating the filter.
[0027]FIG. 8 is a signal flow diagram illustrating generally a further conceptualization of operating the filter.
[0028]FIG. 9 is a schematic diagram illustrating generally another conceptualization of portions of a controller.
[0029]FIG. 10 is a schematic diagram illustrating generally a further conceptualization of portions of a controller.
[0030]FIG. 11 is a graph illustrating generally one embodiment of operating a filter to provide a first indicated pacing rate, such as a VRR indicated rate, for successive ventricular heart beats.
[0031]FIG. 12 is a graph illustrating generally another embodiment of operating a filter to provide the first indicated pacing rate, such as a VRR indicated rate, and delivering therapy based on the first indicated pacing rate and based on a second indicated pacing rate, such as a sensor indicated rate.
[0032]FIG. 13 is a graph illustrating generally another illustrative example of heart rate vs. time according to a VRR algorithm spreadsheet simulation.
[0033]FIG. 14 is a graph illustrating generally one embodiment of using at least one of coefficients a and b as a function of heart rate (or a corresponding time interval).
[0034]FIG. 15 is a schematic drawing, similar to FIG. 2, illustrating generally one embodiment of a cardiac rhythm management device coupled by leads to a heart, such as for providing biventricular coordination therapy.
[0035]FIG. 16 is a schematic drawing, similar to FIG. 3, illustrating generally one embodiment of portions of a cardiac rhythm management device including, among other things, left ventricular sensing and therapy circuits.
[0036]FIG. 17 is a schematic drawing, similar to FIG. 5, illustrating generally portions of one conceptual embodiment of a controller.
[0037]FIG. 18 is a schematic diagram, similar to FIG. 17, illustrating generally another conceptualization of portions of a controller used for regulating an AV interval based on a filter indicated AV delay.
This document describes, among other things, a cardiac rhythm management system providing a method and apparatus for treating irregular ventricular contractions during atrial arrhythmia by actively stabilizing the ventricular heart rate to obtain less potentially proarrhythmic conditions for delivering the atrial tachyarrhythmia therapy. One suitable technique for stabilizing ventricular heart rate is referred to as Ventricular Rate Regularization, described in Krig et al. U.S. patent application Ser. No. ______ entitled “Method and Apparatus for Treating Irregular Ventricular Contractions Such As During Atrial Arrhythmia,” which is filed on even date herewith, assigned to the assignee of the present patent application, and which is herein incorporated by reference in its entirety.
[0043]FIG. 1 is a schematic drawing illustrating, by way of example, but not by way of limitation, one embodiment of portions of a cardiac rhythm management system 100 and an environment in which it is used. In FIG. 1, system 100 includes an implantable cardiac rhythm management device 105, also referred to as an electronics unit, which is coupled by an intravascular endocardial lead 110, or other lead, to a heart 115 of patient 120. System 100 also includes an external programmer 125 providing wireless communication with device 105 using a telemetry device 130. Catheter lead 110 includes a proximal end 135, which is coupled to device 105, and a distal end 140, which is coupled to one or more portions of heart 115.
[0044]FIG. 2 is a schematic drawing illustrating, by way of example, but not by way of limitation, one embodiment of device 105 coupled by leads 110A-B to heart 115, which includes a right atrium 200A, a left atrium 200B, a right ventricle 205A, a left ventricle 205B, and a coronary sinus 220 extending from right atrium 200A. In this embodiment, atrial lead 110A includes electrodes (electrical contacts) disposed in, around, or near an atrium 200 of heart 115, such as ring electrode 225 and tip electrode 230, for sensing signals and/or delivering pacing therapy to the atrium 200. Lead 110A optionally also includes additional electrodes, such as for delivering atrial and/or ventricular cardioversion/defibrillation and/or pacing therapy to heart 115.
[0046]FIG. 3 is a schematic diagram illustrating generally, by way of example, but not by way of limitation, one embodiment of portions of device 105, which is coupled to heart 115. Device 105 includes a power source 300, an atrial sensing circuit 305, a ventricular sensing circuit 310, a ventricular therapy circuit 320, and a controller 325.
[0053]FIG. 4 is a schematic diagram illustrating generally, by way of example, but not by way of limitation, one embodiment of controller 325 that includes several different inputs to modify the rate at which pacing or other therapy is delivered. For example, Input #1 may provide information about left ventricular rate, Input #2 may provide an accelerometer-based indication of activity, and Input #3 may provide an impedance-based indication of respiration, such as minute ventilation. Based on at least one of these and/or other inputs, controller 325 provides an output indication of pacing rate as a control signal delivered to a therapy circuit, such as to ventricular therapy circuit 320. Ventricular therapy circuit 320 issues pacing pulses based on one or more such control signals received from controller 325. Control of the pacing rate may be performed by controller 325, either alone or in combination with peripheral circuits or modules, using software, hardware, firmware, or any combination of the like. The software embodiments provide flexibility in how inputs are processed and may also provide the opportunity to remotely upgrade the device software while still implanted in the patient without having to perform surgery to remove and/or replace the device 105.
[0054]FIG. 5 is a schematic diagram illustrating generally, by way of example, but not by way of limitation, one conceptualization of portions of controller 325. At least one signal from ventricular sensing circuit 310 is received by ventricular event module 500, which recognizes the occurrence of ventricular events included within the signal. Such events are also referred to as “beats,” “activations,” “depolarizations,” “QRS complexes,” “R-waves,” “contractions. ” Ventricular event module 500 detects intrinsic events (also referred to as sensed events) from the signal obtained from ventricular sensing circuit 310. Ventricular event module 500 also detects evoked events (resulting from a pace) either from the signal obtained from ventricular sensing circuit 310, or preferably from a ventricular pacing control signal obtained from pacing control module 505, which also triggers the delivery of a pacing stimulus by ventricular therapy circuit 320. Thus, ventricular events include both intrinsic/sensed events and evoked/paced events.
[0058]FIG. 6 is a signal flow diagram illustrating generally, by way of example, but not by way of limitation, one embodiment of operating filter 515. Upon the occurrence of a sensed or evoked ventricular beat, timer 510 provides filter 515 with the duration of the V-V interval concluded by that beat, which is referred to as the most recent V-V interval (VVn). Filter 515 also receives the previous value of the first indicated pacing interval (Tn-1) stored in register 520. The most recent V-V interval VVn and the previous value of the first indicated pacing interval Tn-1 are each scaled by respective constants A and B, and then summed to obtain a new value of the first indicated pacing interval (Tn), which is stored in register 520 and provided to pacing control module 505. In one embodiment, the coefficients A and B are different values, and are either programmable, variable, or constant.
[0063]FIG. 7 is a signal flow diagram, illustrating generally, by way of example, but not by way of limitation, another conceptualization of operating filter 515, with certain differences from FIG. 6 more particularly described below. In this embodiment, the pacing control module 505, which controls the timing and delivery of pacing pulses, provides an input to filter 515 that indicates whether the most recent V-V interval VVn was concluded by an evoked beat initiated by a pacing stimulus delivered by device 105, or was concluded by an intrinsic beat sensed by ventricular sensing circuit 310.
In one embodiment, operation of filter 515 is described by Tn=A·VVn+B·Tn-1, if VVn is concluded by an intrinsic beat, and is described by Tn=C·VVn+D·Tn, if VVn is concluded by a paced beat, where A, B, C and D are coefficients (also referred to as “weights”), VVn is the most recent V-V interval duration, Tn is the new value of the first indicated pacing interval, and Tn-1 is the previous value of the first indicated pacing interval. If no ventricular beat is sensed during the new first indicated pacing interval Tn, which is measured as the time from the occurrence of the ventricular beat concluding the most recent V-V interval VVn, then pacing control module 505 instructs ventricular therapy circuit 320 to deliver a ventricular pacing pulse upon the expiration of the new first indicated pacing interval Tn.
In another embodiment, these coefficients can be more particularly described using an intrinsic coefficient (a), a paced coefficient (b), and a weighting coefficient (w). In one such embodiment, A=a·w, B=(1−w), C=b·w, and D=(1−w). In one example, operation of the filter 515 is described by Tn=a·w·VVn+(1−w)·Tn, if VVn is concluded by an intrinsic beat, otherwise is described by Tn=b·w·VVn+(1−w)·Tn-1, if VVn is concluded by a paced beat, as illustrated generally, by way of example, but not by way of limitation, in the signal flow graph of FIG. 8. If no ventricular beat is sensed during the new first indicated pacing interval Tn, which is measured as the time from the occurrence of the ventricular beat concluding the most recent V-V interval VVn, then pacing control module 505 instructs ventricular therapy circuit 320 to deliver a ventricular pacing pulse upon the expiration of the new first indicated pacing interval Tn. In one embodiment, the coefficients a and b are different from each other, and are either programmable, variable, or constant.
The above-described parameters (e.g., A, B, C, D, a, b, w) are stated in terms of time intervals (e.g., VVn, Tn, Tn-1).However, an alternate system may produce results in terms of rate, rather than time intervals, without departing from the present method and apparatus. In one embodiment, weighting coefficient w, intrinsic coefficient a, and paced coefficient b, are variables. Different selections of w, a, and b, will result in different operation of the present method and apparatus. For example, as w increases the weighting effect of the most recent V-V interval VVn increases and the weighting effect of the previous first indicated pacing rate Tn-1 decreases. In one embodiment, w={fraction (1/16)}=0.0625. In another embodiment, w={fraction (1/32)}. Another possible range for w is from w=½ to w={fraction (1/1024)}. A further possible range for w is from w≈0 to w≈1. Other values of w, which need not include division by powers of two, may be substituted without departing from the present method and apparatus.
[0071]FIG. 9 is a schematic diagram illustrating generally, by way of example, but not by way of limitation, another conceptualization of portions of controller 325, with certain differences from FIG. 5 more particularly described below. In FIG. 9, controller 325 receives from sensor 330 a signal including information from which a physiologically desired heart rate (e.g., based on the patient's activity, respiration, or any other suitable indicator of metabolic need) can be derived. The sensor signal is digitized by an A/D converter 900. The digitized signal is processed by a sensor rate module 905, which computes a desired heart rate that is expressed in terms of a second indicated pacing interval stored in register 910.
[0076]FIG. 10 is a schematic diagram illustrating generally, by way of example, but not by way of limitation, another conceptualization of portions of controller 325, with certain differences from FIG. 9 more particularly described below. In FIG. 10, controller 325 includes an atrial tachyarrhythmia (AT) detection module 1000 that receives a signal from atrial sensing circuit 305. The received signal includes information about atrial events, from which AT detection module 1000 determines the presence or absence of one or more atrial tachyarrhythmias, such as atrial fibrillation.
AT Present? 1st Indicated Pacing 1st Indicated Pacing
Pacing Interval? Pacing Interval?
[0082]FIG. 11 is a graph illustrating generally, by way of example, but not by way of limitation, one embodiment of a VRR indicated rate for successive ventricular heart beats for one mode of operating filter 515. As discussed above, the VRR indicated rate is simply the frequency, between ventricular heart beats, associated with the first indicated pacing interval. Stated differently, the VRR indicated rate is the inverse of the duration of the first indicated pacing interval. If pacing is based solely on the VRR indicated rate, pacing control module 505 directs ventricular therapy circuit 320 to issue a pacing pulse after the time since the last ventricular beat equals or exceeds the first indicated pacing interval. However, as described above, in certain embodiments, pacing control module 505 directs ventricular therapy circuit 320 to issue a pacing pulse based on factors other than the VRR indicated rate such as for, example, based on the sensor indicated rate.
[0095]FIG. 12 is a graph illustrating generally, by way of example, but not by way of limitation, one embodiment of selecting between more than one indicated pacing interval. FIG. 12 is similar to FIG. 11 in some respects, but FIG. 12 includes a second indicated pacing interval. In one embodiment, the first indicated pacing interval is the VRR indicated pacing interval, described above, and the second indicated pacing interval is a sensor indicated pacing interval, from an accelerometer, minute ventilation, or other indication of the patient's physiological need for increased cardiac output.
[0099]FIG. 13 is a graph illustrating generally, by way of example, but not by way of limitation, another illustrative example of heart rate vs. time according to a spreadsheet simulation of the behavior of the above-described VRR algorithm. In FIG. 13, the VRR algorithm is turned off until time 130. Stable intrinsic lower rate behavior is modeled for times between 0 and 10 seconds. Erratic intrinsic ventricular rates, such as would result from atrial tachyarrhythmias including atrial fibrillation, are modeled during times between 10 seconds and 130 seconds. At time 130 seconds, the VRR algorithm is turned on. While some erratic intrinsic beats are subsequently observed, the VRR algorithm provides pacing that is expected to substantially stabilize the heart rate, as illustrated in FIG. 13. The VRR indicated pacing rate gradually decreases until intrinsic beats are sensed, which results in a slight increase in the VRR indicated pacing rate. Thus, the VRR algorithm favors the patient's intrinsic heart rate when it is stable, and paces at the VRR indicated heart rate when the patient's intrinsic heart rate is unstable. It is noted that FIG. 13 does not represent clinical data, but rather provides a simulation model that illustrates one example of how the VRR algorithm is expected to operate.
[0101]FIG. 14 is a graph illustrating generally, by way of example, but not by way of limitation, one embodiment of using at least one of coefficients a and b as a function of one or more previous V-V intervals such as, for example, the most recent V-V interval, VVn. In one such example, a is less than 1.0 when VVn is at or near the lower rate limit (e.g., 1000 millisecond interval or 60 beats/minute), and a is greater than 1.0 when VVn is at or near the upper rate limit (e.g., 500 millisecond interval or 120 beats/minute). For a constant b, using a smaller value of a at lower rates will increase the pacing rate more quickly for sensed events; using a larger value of a at higher rates increases the pacing rate more slowly for sensed events. In another example, b is close to 1.0 when VVn is at or near the lower rate limit, and b is greater than 1.0 when VVn is at or near the upper rate limit. For a constant a, using a smaller value of b at lower rates will decrease the pacing rate more slowly for paced events; using a larger value of b at higher rates decreases the pacing rate more quickly for paced events.
[0103]FIG. 15 is a schematic drawing, similar to FIG. 2, illustrating generally by way of example, but not by way of limitation, one embodiment of a cardiac rhythm management device 105 coupled by leads 110A-C to a heart 115. In one such embodiment, system 100 provides biventricular coordination therapy to coordinate right ventricular and left ventricular contractions, such as for congestive heart failure patients. FIG. 15 includes a left ventricular lead 110C, inserted through coronary sinus 220 and into the great cardiac vein so that its electrodes, which include electrodes 1500 and 1505, are associated with left ventricle 205B for sensing intrinsic heart signals and providing one or more of coordination paces or defibrillation shocks.
[0104]FIG. 16 is a schematic drawing, similar to FIG. 3, illustrating generally by way of example, but not by way of limitation, one embodiment of portions of a cardiac rhythm management device 105, in which the left ventricular lead is coupled by lead 110C to a left ventricular sensing circuit 1600 and a left ventricular therapy circuit 1605, each of which are, in turn, coupled by node/bus 327 to controller 325. This embodiment also includes an atrial therapy circuit 1610, and a right ventricular lead 110B coupling right ventricle 205A to right ventricular sensing circuit 310 and right ventricular therapy circuit 320, each of which are, in turn, coupled by node/bus 327 to controller 325.
[0105]FIG. 17 is a schematic drawing, similar to FIG. 5, illustrating generally by way of example, but not by way of limitation, portions of one conceptual embodiment of controller 325. In this embodiment, ventricular event module 500 receives input signals from right ventricular sensing circuit 310 and left ventricular sensing circuit 1600. Pacing control module 505 provides control signals to right ventricular therapy circuit 320 and left ventricular therapy circuit 1605. Operation of filter 515 is similar to the above description accompanying FIGS. 5-14, with certain differences discussed below, thereby allowing device 105 to provide biventricular coordination therapy at a VRR-indicated rate, a sensor-indicated rate, or a combination thereof.
In one embodiment, ventricular event module 500 detects sensed and paced ventricular beats from both right ventricular sensing circuit 310 and left ventricular sensing circuit 1600. An interval between successive ventricular events, referred to as a V-V interval, is recorded by a first timer, such as V-V interval timer 510. Ventricular event module 500 selects the particular ventricular events initiating and concluding the V-V interval timed by V-V interval timer 510. In a first mode of operation, the V-V interval is initiated by a right ventricular beat (paced or sensed), and the V-V interval is then concluded by the next right ventricular beat (aced or sensed). In a second mode of operation, the V-V interval is initiated by a left ventricular beat (paced or sensed), and the V-V interval is then concluded by the next left ventricular beat (paced or sensed). In a third mode of operation, the V-V interval is initiated by either a right or left ventricular beat, and the V-V interval is then concluded by the next right or left ventricular beat that occurs after expiration of a refractory period of approximately between 130 milliseconds and 500 milliseconds (e.g., 150 milliseconds). Left or right ventricular beats occurring during the refractory period are ignored. Using the refractory period ensures that the beat concluding the V-V interval is associated with a subsequent ventricular contraction, rather than a depolarization associated with the same ventricular contraction, in which the depolarization is merely sensed in the opposite ventricle from the initiating beat. Such a refractory period can also be used in conjunction with the first mode (V-V interval initiated and concluded by right ventricular beats) or the second mode (V-V interval initiated and concluded by left ventricular beats).
In a further embodiment, device 105 uses a mapping, such as illustrated in Table 3, in a feedback control loop to automatically select the “performance parameter” of Table 3 and corresponding coefficients. The user programs a mean pacing frequency goal. Device 105 measures the mean pacing frequency over a predetermined period of time or predetermined number of V-V intervals. The measured mean pacing is compared to the mean pacing frequency goal. If the measured mean pacing frequency is higher than the goal mean pacing frequency, the performance parameter in Table 3 is incremented/decremented toward less pacing. Conversely, if the measured mean pacing frequency is lower than the goal mean pacing frequency, the performance parameter in Table 3 is incremented/decremented toward more pacing. In a further embodiment, the measured mean pacing frequency is compared to values that are slightly offset about the goal mean pacing frequency (e.g., goal mean pacing frequency ± Δ) to provide a band of acceptable measured mean pacing frequencies within which the performance parameter is not switched.
[0113]FIG. 18 is a schematic diagram, similar to FIG. 17, illustrating generally by way of example, but not by way of limitation, another conceptualization of portions of controller 325 used for regulating the AV interval based on a filter indicated AV delay. In FIG. 18, atrial event module 1800 and ventricular event module 500 provide information about paced or sensed atrial events and paced or sensed ventricular events, respectively, to AV interval timer 1805. AV interval timer 1805 times an AV interval initiated by an atrial event, and concluded by a ventricular event, such as described above with respect to FIG. 17.
Cooperative Classification A61N1/3682, A61N1/3621, A61N1/395, A61N1/3962, A61N1/3987, A61N1/3627