Source: http://www.google.com/patents/US6453197?dq=6,202,008
Timestamp: 2016-02-11 20:08:43
Document Index: 426004831

Matched Legal Cases: ['art. 2', 'art.\n4', 'art. 12', 'art.\n14', 'art.\n18', 'art.\n19', 'art.\n20', 'art. 22', 'art.\n24', 'art.\n28', 'art.\n29', 'art.\n30', 'art 28']

Patent US6453197 - Implantable cardiac stimulation device including a system for and method of ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA system and method for use in an implantable cardiac stimulation device permits automatic induction of a tachyarrhythmia of a heart to permit the performance of an electrophysiological test of the heart. A pulse generator repeatedly delivers a group of first and second sets of pacing pulses to a chamber...http://www.google.com/patents/US6453197?utm_source=gb-gplus-sharePatent US6453197 - Implantable cardiac stimulation device including a system for and method of automatically inducing a tachyarrhythmiaAdvanced Patent SearchPublication numberUS6453197 B1Publication typeGrantApplication numberUS 09/552,299Publication dateSep 17, 2002Filing dateApr 18, 2000Priority dateApr 18, 2000Fee statusPaidAlso published asUS6954672, US6968233Publication number09552299, 552299, US 6453197 B1, US 6453197B1, US-B1-6453197, US6453197 B1, US6453197B1InventorsJohn Thomas Parry, Gary Robert Viviano, James Edward Gantz, Jr.Original AssigneePacesetter, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (13), Referenced by (12), Classifications (4), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetImplantable cardiac stimulation device including a system for and method of automatically inducing a tachyarrhythmia
US 6453197 B1Abstract
What is claimed is: 1. In an implantable cardiac stimulation device, a system that automatically induces a tachyarrhythmia of a heart to permit the performance of an electrophysiological test of the heart, the system comprising:
a pulse generator that repeatedly delivers a group of first and second sets of pacing pulses to a chamber of the heart, the pacing pulses being separated in time by pacing intervals to overdrive pace the chamber; and a processor, coupled to the pulse generator, that varies the pacing intervals according to a predetermined protocol after each group of pacing pulses is delivered to the chamber of the heart. 2. The system of claim 1 wherein the processor is programmed to detect the tachyarrhythmia of the heart and to terminate the delivery of the pacing pulses to the heart by the pulse generator when a group of the pacing pulses has induced the tachyarrhythmia.
3. The system of claim 1 wherein the processor is programmed to determine capture of the heart by each delivered pacing pulse and to terminate the delivery of the pacing pulses to the heart by the pulse generator when a predetermined number of successive pacing pulses fail to capture the heart.
4. The system of claim 3 wherein the predetermined number is two.
5. The system of claim 3 wherein the processor requires a minimum pacing interval to determine capture of the heart by a pacing pulse and is further programmed to terminate the delivery of the pacing pulses to the heart by the pulse generator when a pacing interval falls below the minimum pacing interval.
6. The system of claim 1 wherein the processor is programmed to vary the pacing intervals of the second set of pacing pulses according to the predetermined protocol.
7. The system of claim 1 wherein the processor is programmed to determine capture of the heart by each delivered pacing pulse, wherein the second set of pacing pulses includes a last pulse and a second-to-the-last pulse, and wherein the processor is programmed to decrement the pacing interval between the last pulse and the second-to-the-last pulse responsive to the last pulse capturing the heart according to the predetermined protocol.
8. The system of claim 1 wherein the processor is programmed to determine capture of the heart by each delivered pacing pulse, wherein the second set of pacing pulses includes a last pulse, a second-to-the-last pulse, and a third-to-the-last pulse, and wherein the processor is programmed to decrement the pacing interval between the second-to-the-last pulse and the third-to-the-last pulse responsive to the last pulse failing to capture the heart according to the predetermined protocol.
9. The system of claim 8 wherein the pacing interval between the last pulse and the second-to-the-last pulse is preset to an initial interval prior to delivery of the pacing pulses to the heart by the pulse generator and wherein the processor is further programmed to set the pacing interval between the last pulse and the second-to-the-last pulse to the initial interval response to the last pulse failing to capture the heart according to the predetermined protocol.
10. The system of claim 1 wherein the implantable cardiac stimulation device includes a telemetry circuit coupled to the processor and wherein the system further includes an external device that communicates with the telemetry circuit and provides the processor with initial pacing intervals.
11. In an implantable cardiac stimulation device, a system for automatically inducing a tachyarrhythmia of a heart for the performance of a test of the heart, the system comprising:
stimulation means for providing groups of stimulation pulses to the heart, the stimulation pulses being separated in time by pulse intervals having durations for overdrive stimulating the heart; and control means for adjusting the durations of the pulse intervals in a prescribed manner after the provision of each group of stimulation pulses to the heart. 12. The system of claim 11 wherein the control means includes means for detecting the tachyarrhythmia of the heart and means for terminating the provision of the stimulation pulses to the heart by the stimulation means when a group of the stimulation pulses has induced the tachyarrhythmia.
13. The system of claim 11 wherein the control means includes means for determining capture of the heart by each delivered stimulation pulse and means for terminating the provision of the stimulation pulses to the heart by the stimulation means when a predetermined number of successive stimulation pulses fail to capture the heart.
14. The system of claim 13 wherein the predetermined number is two.
15. The system of claim 13 wherein the control means requires a minimum pulse interval for determining capture of the heart by a stimulation pulse and further includes means for terminating the provision of the stimulation pulses to the heart by the stimulation means when a pulse interval falls below the minimum pulse interval.
16. The system of claim 11 wherein the control means adjusts the pulse intervals of a last set of stimulation pulses of each group of stimulation pulses in the prescribed manner.
17. The system of claim 11 wherein the control means includes means for determining capture of the heart by each stimulation pulse, wherein each group of stimulation pulses includes a last pulse and a second-to-the-last pulse, and wherein the control means includes means for decrementing the pulse interval between the last pulse and the second-to-the-last pulse responsive to the last pulse capturing the heart.
18. The system of claim 11 wherein the control means includes means for determining capture of the heart by each stimulation pulse, wherein each group of stimulation pulses includes a last pulse, a second-to-the-last pulse, and a third-to-the-last pulse, and wherein the control means includes means for decrementing the pulse interval between the second-to-the-last pulse and the third-to-the-last pulse responsive to the last pulse failing to capture the heart.
19. The system of claim 18 wherein the pulse interval between the last pulse and the second-to-the-last pulse is preset to an initial interval prior to provision of the stimulation pulses to the heart by the stimulation means and wherein the control means further includes means for setting the pulse interval between the last pulse and the second-to-the-last pulse to the initial interval responsive to the last pulse failing to capture the heart.
20. The system of claim 1 wherein the implantable cardiac stimulation device includes telemetry means coupled to the control means and wherein the system further includes external programming means for communicating with the telemetry means and providing the control means with initial pulse intervals.
21. In an implantable cardiac stimulation device, a method of automatically inducing a tachyarrhythmia of a heart for the performance of an electrophysiological test of the heart, the method including the steps of:
storing a predetermined induction protocol in the implantable device; applying groups of stimulation pulses to the heart, the stimulation pulses being separated in time by interpulse intervals for overdriving the heart; and adjusting the interpulse intervals in accordance with the stored induction protocol after applying each group of stimulation pulses to the heart. 22. The method of claim 21 including the further steps of detecting for the tachyarrhythmia of the heart after applying each group of stimulation pulses to the heart and terminating the application of the stimulation pulses to the heart responsive to detecting the tachyarrhythmia.
23. The system of claim 21 including the further steps of determining capture of the heart by each applied stimulation pulse and terminating the application of the stimulation pulses to the heart when a predetermined number of successive stimulation pulses fail to capture the heart.
24. The method of claim 23 wherein the predetermined number is two.
25. The method of claim 23 wherein the step of determining capture of the heart requires a minimum interpulse interval to determine capture of the heart by a stimulation pulse and wherein the method further includes terminating the application of the stimulation pulses to the heart when an interpulse interval falls below the minimum interpulse interval.
26. The method of claim 21 wherein the adjusting step includes adjusting the interpulse intervals of only a last set of stimulation pulses of each group of stimulation pulses in accordance with the stored induction protocol.
27. The method of claim 21 further including the step of determining capture of the heart by each stimulation pulse, wherein each group of stimulation pulses includes a last pulse and a second-to-the-last pulse, and wherein the method further includes decrementing the interpulse interval between the last pulse and the second-to-the-last responsive to the last pulse capturing the heart.
28. The method of claim 21 including the further step of determining capture of the heart by each stimulation pulse, wherein each group of stimulation pulses includes a last pulse, a second-to-the-last pulse, and a third-to-the-last pulse, and wherein the method further includes the step of decrementing the interpulse interval between the second-to-the-last pulse and the third-to-the-last pulse responsive to the last pulse failing to capture the heart.
29. The method of claim 28 including the further steps of presetting the interpulse interval between the last pulse and the second-to-the-last pulse to an initial interval prior to applying the stimulation pulses to the heart and setting the interpulse interval between the last pulse and the second-to-the-last pulse to the initial interval responsive to the last pulse failing to capture the heart.
30. The method of claim 21 including the further step of setting the interpulse intervals to initial values prior to the applying step.
The stimulation device 10 further includes a programmable microcontroller 60 which controls the various modes of stimulation therapy including a non-invasive programmed stimulation (NIPS) procedure in accordance with the present invention. As is well known in the art, the microcontroller 60 includes a microprocessor, or equivalent control circuitry, designed specifically for controlling the delivery of stimulation therapy and may further include RAM or ROM memory, logic and timing circuitry, state machine circuitry, and I/O circuitry. Typically, the microcontroller 60 includes the ability to process or monitor input signals (data) as controlled by a program code stored in a designated block of memory. The details of the design and operation of the microcontroller 60 are not critical to the present invention. Rather, any suitable microcontroller 60 may be used that carries out the functions described herein. The use of microprocessor-based control circuits for performing timing and data analysis functions is well known in the art. Representative types of control circuitry that may be used for embodying the invention include the microprocessor-based control system of U.S. Pat. No. 4,940,052 (Mann et al.), the state-machine of U.S. Pat. No. 4,712,555 (Sholder) and U.S. Pat. No. 4,944,298 (Sholder). For a more detailed description of the various timing intervals used within the stimulation device and their interrelationship, see U.S. Pat. No. 4,788,980 (Mann et al.). The '052, '555, '298 and '980 patents are incorporated herein by reference. As shown in FIG. 1, an atrial pulse generator 70 and a ventricular pulse generator 72 generate pacing stimulation pulses for delivery by the atrial lead 20 and the ventricular lead 30, respectively, via a switch bank 74. The pulse generators, 70 and 72, are controlled by the microcontroller 60 via appropriate control signals, 76 and 78, respectively, to trigger or inhibit the stimulation pulses. The microcontroller 60 further includes timing circuitry that controls the operation of the stimulation device timing of such stimulation pulses (e.g., pacing rate and atrio-ventricular (AV) delay), as well as keeping track of the timing of any refractory periods, PVARP intervals, noise detection windows, evoked response windows, alert intervals, marker channel timing, etc., that is well known in the art.
For arrhythmia detection, the device 10 utilizes the atrial and ventricular sense amplifiers, 82 and 84, to sense cardiac signals to determine whether a rhythm is physiologic or pathologic. As used herein “sensing” is reserved for the noting of an electrical depolarization, and “detection” is the processing of these sensed depolarization signals and noting the presence of an arrhythmia. The timing intervals between sensed events (e.g., the P-P and R-R intervals) are then classified by the microcontroller 60 by comparing them to a predefined rate zone limit (i.e., bradycardia, normal, low rate VT, high rate VT, and fibrillation rate zones) and various other characteristics (e.g., sudden onset, stability, physiologic sensors, and morphology, etc.) in order to determine the type of remedial therapy that is needed (e.g., bradycardia pacing, anti-tachycardia pacing, cardioversion shocks or defibrillation shocks, also known as “tiered therapy”). In accordance with the present invention, the microcontroller 60 may employ a high rate classification to determine if a tachyarrhythmia is present for terminating the NIPS procedure when the tachyarrhythmia has been induced by the NIPS procedure.
The microcontroller 60 is further coupled to a memory 94 by a suitable data/address bus 96, wherein the programmable operating parameters used by the microcontroller 60 are stored and modified, as required, in order to customize the operation of the stimulation device 10 to suit the needs of a particular patient. Such operating parameters define, for example, pacing pulse amplitude, pulse duration, electrode polarity, rate, sensitivity, automatic features, arrhythmia detection criteria, and the amplitude, waveshape and vector of each shocking pulse to be delivered to the patient's heart 28 within each respective tier of therapy. The memory 94 preferably also stores a NIPS protocol from which the microcontroller automatically controls the NIPS procedure.
The stimulation device additionally includes a battery 114 which provides operating power to all of the circuits show in FIG. 1. For the stimulation device 10, which employs shocking therapy, the battery must be capable of operating at low current drains for long periods of time and then be capable of providing high-current pulses (for capacitor charging) when the patient requires a shock pulse. The battery 114 must also have a predictable discharge characteristic so that elective replacement time can be detected. Accordingly, the device 10 may employ lithium/silver vanadium oxide batteries, as is common in many such device to date.
An important function of the device 10 is to function as an implantable cardioverter/defibrillator (ICD) device. That is, it is capable of detecting the occurrence of an arrhythmia, and automatically applying an appropriate electrical shock therapy to the heart aimed at terminating the detected arrhythmia. To this end, the microcontroller 60 further controls a shocking 130 by way of a control signal 132. The shocking circuit 130 generates shocking pulses of low (up to 0.5 Joules), moderate (0.5-10 Joules), or high energy (11 to 40 Joules), as controlled by the microcontroller 60. Such shocking pulses are applied to the patient's heart through at least two shocking electrodes, and as shown in this embodiment, using the RV and SVC coil electrodes, 36 and 38, respectively. In alternative embodiments, the housing 40 may act as an active electrode in combination with the RV electrode 36 alone, or as part of a split electrical vector using the SVC coil electrode 38 (i.e., using the RV electrode as common).
FIG. 2 illustrates a group 140 of stimulation or pacing pulses forming a pulse train which are provided to the right ventricle of the heart by the pulse generator 72 to implement a NIPS procedure in accordance with this preferred embodiment of the present invention. The group 140 of pulses includes a first set 142 of pulses and a second set 144 of pulses. Each pulse of the first set is referred to as an S1 pulse and may range in number from, for example, 3-20, the number of S1 pulses being a programmable parameter. Immediately successive S1 pulses have a programmable interpulse interval (S1—S1) on the order to 300-400 milliseconds to provide overdrive pacing of the heart. Each S1 pulse also preferably has a programmable amplitude and pulse width of, for example, 4.5 volts (v) and 0.5 milliseconds, respectively, to assure capture of the heart by each S1 pulse. It is the purpose of the first set 142 of pulses to overdrive capture the heart.
The second set 144 of pulses, commonly referred to as the extra pulses, includes pulse S2, pulse S3, and pulse S4. The number of extra pulses may also be a programmable parameter and vary from that described herein. Each of the S2, S3, and S4 pulses also preferably has a programmable amplitude and pulse width of, for example, 4.5 V and 0.5 milliseconds, respectively. The last S1 pulse and the extra pulses are separated in time by interpulse intervals S1-S2, S2-S3, and S3-S4 which are progressively decreasing. The extra pulse interpulse intervals may be initially set by the programmer 102 and may be 280 milliseconds, 260 milliseconds, and 240 milliseconds, respectively. The intended purpose of the extra pulses is to place the last extra pulse, pulse S4, in accordance with this embodiment, in an overdriven cardiac cycle of the heart where the stimulated heart tissue is only partially refractory for inducing the tachyarrhythmia.
To place the pulse S4 as described above, the microcontroller 60 in accordance with this preferred embodiment and the stored NIPS protocol, adjusts or varies the interpulse intervals S2-S3, and S3-S4 in a prescribed manner after each group 140 of pulses is delivered to the heart. After each adjustment of the interpulse intervals, the pulse train is reinitiated and delivered to the heart. The foregoing process continues until the tachyarrhythmia is induced.
The process of FIG. 3 initiates at an activity step 150 wherein initializing parameters are provided to the microcontroller 60 or memory 94 via the telemetry circuit 100. It is, of course, assumed that the NIPS protocol to be implemented has already been stored in the memory 94 in the same manner. The initializing parameters may be, for example, the initial S1-S1, S1-S2, S2-S3, and S3-S4 intervals, the amplitude and durations of the stimulation pulses, the time between successive pulse trains, and the interval by which each coupling interval will be decremented as called for by the protocol. Also, at this time, any normal automatic capture back-up pulse function is suspended while capture verification is enabled on a beat-to-beat basis.
After the initial parameters have been established, the process proceeds to activity step 152 wherein the microcontroller 60 causes the pulse generator 72 to deliver the first pulse train or first group of stimulation pulses as illustrated in FIG. 2 to the heart. After the first pulse train has been applied, the microcontroller next, in decision block 154 determines if the tachyarrhythmia has been induced. If the tachyarrhythmia is detected by the microcontroller, the process returns. However, if not, the process then advances to decision block 156. In decision block 156, the microcontroller determines if pulse S4 captured the heart. If pulse S4 captured the heart, the processor advances to activity step 158 to decrement the S3-S4 interpulse interval, by, for example, 10 milliseconds. If pulse S4 failed to capture the heart as determined in decision block 156, the process advances to activity blocks 160 and 162 in that order to decrement the S2-S3 interpulse interval and to reset the S3-S4 interval, if previously decremented, to its initial value. The process is now ready to reinitiate another pulse train with the adjusted intervals unless a termination condition exists to be described subsequently. Absence such a condition, the process will continue to adjust the interpulse intervals as described above after each pulse train. The pulse trains are reinitiated by the microcontroller until the tachyarrhythmia is detected in decision block 154.
From the foregoing, it may be seen that the present invention provides a new and improved procedure for inducing a tachyarrhythmia of the heart to support an electrophysiological study. The procedure, such as a NIPS procedure, may be used to induce either a ventricular or atrial tachyarrhythmia. Since the procedure is truly automated, the tachyarrhythmia may be induced in less time, with less anxiety to the patient, and with reduced clinical cost.
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