EP0253505A2
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EP
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Cardiac stimulator
Assignee: Intermedics Inc
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Filing: 1987-06-15
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Granted: —
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Expires: 2007-06-15
Abstract
Abstract A cardiac stimulator is provided for detecting and treating ventricular tachyarrhythmias of a patient's heart. The stimulator includes means for selectively dividing the heart rate continuum into regions including at least two classes of tachycardia (TACH-1, TACH-2, TACH-3), contiguous to each other and of progressively higher heart rate ranges, the lowest and highest of the tachycardia classes being bounded respectively by a sinus rate region (SINUS) and a fibrillation region (FIB) of the continuum. Means are provided for selectively adjusting the boundaries between the tachycardia classes and between the lowest and highest of those classes and the respective sinus rate and fibrillation regions, to correspondingly adjust the rate ranges of the classes in a desired manner. Cardiac events are selectively detected anywhere within the continuum and a distinction made between normal and abnormal tachycardias among the detected events. A detected abnormal tachycardia is then treated with any of a multiplicity of therapy regimens of differing degrees of aggressiveness, toward terminating the detected tachycardia.
Inventors
- 👤 Edward A. Haluska
- 👤 Stephen J. Whistler
- 👤 Ross G. Baker, Jr.
- 👤 Richard V. Calfer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 23:51
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/18; A61N1/32; A61N1/36; A61N1/362; A61N1/3621
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
159 words
A cardiac stimulator for detecting and treating ventricular tachyarrhythmias of a patient's heart, characterized in that the stimulator includes means for selectively dividing the heart rate continuum into regions including at least two classes of tachycardia, contiguous to each other and of progressively higher heart rate ranges, the lowest and highest of the tachycardia classes being bounded respectively by a sinus rate region and a fibrillation region of the continuum; means for selectively adjusting the boundaries between the tachycardia classes and between the lowest and highest of those classes and the respective sinus rate and fibrillation regions, to correspondingly adjust the rate ranges of the classes in a desired manner; means for selectively detecting cardiac events anywhere within the continuum and for distinguishing between normal and abnormal tachycardias among the detected events; and means for selectively treating a detected abnormal tachycardia with any of a multiplicity of therapy regimens of differing degrees of aggressiveness, toward terminating the detected tachycardia.
Claim 2
Dependent Claim
159 words
A cardiac stimulator for detecting and treating ventricular tachyarrhythmias of a patient's heart, characterized in that the stimulator includes means for selectively dividing the heart rate continuum into regions including at least two classes of tachycardia, contiguous to each other and of progressively higher heart rate ranges, the lowest and highest of the tachycardia classes being bounded respectively by a sinus rate region and a fibrillation region of the continuum; means for selectively adjusting the boundaries between the tachycardia classes and between the lowest and highest of those classes and the respective sinus rate and fibrillation regions, to correspondingly adjust the rate ranges of the classes in a desired manner; means for selectively detecting cardiac events anywhere within the continuum and for distinguishing between normal and abnormal tachycardias among the detected events; and means for selectively treating a detected abnormal tachycardia with any of a multiplicity of therapy regimens of differing degrees of aggressiveness, toward terminating the detected tachycardia.
Claim 3
Dependent Claim
34 words
A cardiac stimulator according to Claim 1, characterized in that the treating means is responsive to acceleration of a detected tachycardia into the fibrillation region to automatically apply defibrillation therapy to the patient's heart.
Claim 4
Dependent Claim
48 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the detecting means also senses a loss of electrical activity of the patient's heart, and in response the treating means applies stimulating pulses to pace the heart until it resumes its normal electrical activity.
Claim 5
Dependent Claim
41 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means also selectively controls the sequence in which therapy regimens are applied in response to detection of an abnormal tachycardia within any of the classes.
Claim 6
Dependent Claim
67 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the detecting means also selectively redetects the presence or absence of an abnormal tachycardia in any of the classes after each application of a therapy regimen by the treating means, and in doing so applies less than the number of criteria used for the initial detection of the tachycardia, to expedite the redetection.
Claim 7
Dependent Claim
55 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the detecting means also senses a transition of a detected abnormal tachycardia to a higher or a lower class, and the treating means is responsive to the transition to apply a therapy regimen preselected for a tachycardia of the new class.
Claim 8
Dependent Claim
52 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means treats any abnormal tachyarrhythmia detected within the continuum, and the therapies available from the treating means include pacing and shock therapies which differ at least in the level of electrical energy applied to the heart.
Claim 9
Dependent Claim
37 words
A cardiac stimulator according to Claim 7, characterized in that each of the pacing and shock therapies is represented by a respective electrical waveform having at least one parameter which is selectively variable by the treating means.
Claim 10
Dependent Claim
28 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the detecting means also senses reversion of the patient's heart rate to sinus rhythm.
Claim 11
Dependent Claim
51 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the detecting means applies different criteria for detecting tachyarrhythmias in different regions of the heart rate continuum, the detection criteria being most stringent for the lowest tachycardia class and progressively less stringent with each higher rate range.
Claim 12
Dependent Claim
23 words
A cardiac stimulator according to Claim 5, characterized in that the criteria used for initial detection are selectively modifiable for purposes of redetection.
Claim 13
Dependent Claim
35 words
A cardiac stimulator according to Claim 6, characterized in that the detecting means also distinguishes false indication of acceleration from actual acceleration of the detected tachyarrhythmia to a higher rate range region of the continuum.
Claim 14
Dependent Claim
43 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is programmable to repetitively deliver the same therapy regimen in response to repeated redetection of a tachyarrhythmia within the same region of the heart rate continuum.
Claim 15
Dependent Claim
59 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is programmable to deliver a therapy regimen upon redetection of an abnormal tachyarrhythmia as having undergone a change of rate to a new region of the continuum, which differs from the therapy regimen that was delivered in response to the previous detection.
Claim 16
Dependent Claim
35 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is programmable to modify the aggressiveness of the selected therapy regimen during treatment of a detected abnormal tachyarrhythmia.
Claim 17
Dependent Claim
41 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is programmable to preclude return to a therapy less aggressive than that last delivered, upon acceleration of the abnormal tachcardia to a higher class.
Claim 18
Dependent Claim
45 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is programmable to reapply a therapy identical to that previously applied in response to detection of an abnormal tachyarrhythmia, upon the very next incidence of an abnormal tachyarrhythmia.
Claim 19
Dependent Claim
31 words
A cardiac stimulator according to Claim 17, characterized in that the reapplied therapy is identical to the last therapy of the overall therapy regimen last successful to terminate an abnormal tachycardia.
Claim 20
Dependent Claim
27 words
A cardiac stimulator according to Claim 17, characterized in that the reapplied therapy is identical to the entire last therapy regimen successful to terminate an abnormal tachycardia.
Claim 21
Dependent Claim
35 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is programmable to repeat the least aggressive therapies within a therapy regimen before redelivering the entire therapy regimen.
Claim 22
Dependent Claim
36 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the detecting means selectively establishes criteria to detect each of the cardiac events of bradycardia, tachycardia, fibrillation, and reversion to sinus rate.
Claim 23
Dependent Claim
40 words
A cardiac stimulator according to Claim 21, characterized in that the criteria selectively established by the detecting means to detect tachycardias includes high heart rate, sudden onset of the high rate, stability of the high rate, and sustained high rate.
Claim 24
Dependent Claim
52 words
A cardiac stimulator according to Claim 21, characterized in that the criteria selectively established by the detecting means to detect fibrillation includes high heart rate exceeding the highest rate for detecting tachycardias, and the occurrence of at least x fibrillation intervals out of y consecutive intervals, where x and y are selectible.
Claim 25
Dependent Claim
105 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is controllable to selectively alter any therapy consisting of either cardioverting shocks or defibrillating shocks by altering any of the features in the group consisting of (i) the number of shocks to be delivered, (ii) the delay time interval between detection of the cardiac event and delivery of the shock, (iii) the amplitude of the shocks on the first attempt and on each subsequent attempt to arrest the tachyarrhythmia, and (iv) the phasic structure of the shock waveform including pulse width, polarity, presence and absence of each phase.
Claim 26
Dependent Claim
142 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means is controllable to selectively alter any pacing therapy by altering any of the features in the group consisting of (i) number of attempts to arrest the detected tachyarrhythmia, (ii) number of pulses in a pacing stimuli burst, (iii) delay time between detection and initial pulse in the pacing stimuli burst, (iv) interval between pulses in a pacing stimuli burst, (v) automatic decrementing or alternate incrementing and decrementing of either of the delay time or the interval between pulses, (vi) variation of each of those intervals as a percentage of the tachyarrhythmia rate, (vii) amount by which each of the intervals is increased or decreased for each successive burst, and (viii) number of times any sequence defined by (v), (vi) or (vii) is to be repeated.
Claim 27
Dependent Claim
73 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the stimulator includes a microprocessor for processing and storing digital data to develop control signals for operation of the heart rate continuum dividing means, the detecting means, and treating means; and the detecting means includes a sense amplifier to receive analog signal information representative of the patient's ECG and convert same to digital data for transmission to the microprocessor.
Claim 28
Dependent Claim
33 words
A cardiac stimulator according to Claim 26, characterized in that the sense amplifier enhances the ECG signal information to track the rapidly varying amplitude of signals indicative of fibrillation of the patient's heart.
Claim 29
Dependent Claim
25 words
A cardiac stimulator according to Claim 27, characterized in that the sense amplifier has automatic gain control, and bandpass filtering of the ECG signal information.
Claim 30
Dependent Claim
47 words
A cardiac stimulator according to Claim 28, characterized in that the bandpass filtering reduces the amplitude of signals outside the tachyarrhythmia frequency band of interest, and amplifies low frequency signals within that frequency band in the absence of normal R-waves, indicative of fibrillation of the patient's heart.
Claim 31
Dependent Claim
43 words
A cardiac stimulator according to Claim 28, characterized in that the automatic gain control is provided by a feedback circuit which includes the microprocessor, to adjust the gain of the sense amplifier to sense rapidly varying low amplitude signals indicative of ventricular fibrillation.
Claim 32
Dependent Claim
167 words
A cardiac stimulator according to Claim 30, characterized in that the feedback circuit defines inner and outer voltage levels, selectively sets the ratio between the inner and outer voltage levels, compares the sense signal levels which have been processed by the amplification and filtering with the inner and outer voltage levels, responds to the processed sense signal levels exceeding the inner voltage levels by generating logic signals indicative of valid sense signals, and responds to the processed sense signal levels exceeding the outer voltage levels by applying further logic signals to the microprocessor to adjust the gain of the sense amplifier; and in that the microprocessor responds to the further logic signals and to components of the ECG signal information to decrease the amplifier gain in the presence of a QRS complex indicative of either sinus rate or a tachycardia, and to increase the amplifier gain in the absence of a T-wave within a predetermined time interval following application of a pacing stimulus to the patient's heart.
Claim 33
Dependent Claim
36 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the treating means also generates high voltage levels for developing cardioverting shocks and defibrillating shocks to be applied to the patient's heart.
Claim 34
Dependent Claim
56 words
A cardiac stimulator according to Claim 32, characterized in that the high voltage levels are generated by the treating means using high voltage capacitors, a high voltage oscillator, and an isolation circuit coupling the high voltage oscillator to the capacitors to charge them to the high voltage levels suitable for the cardioverting shocks and defibrillating shocks.
Claim 35
Dependent Claim
57 words
A cardiac stimulator according to Claim 33, characterized in that the treating means also includes an output circuit to deliver the high voltage shocks to the patient's heart, and switches selectively operated under the control of the microprocessor to apply the high voltages on the capacitors as pulses of desired amplitude and polarity to the output circuit.
Claim 36
Dependent Claim
35 words
A cardiac stimulator according to Claim 34, characterized in that a short circuit protection circuit is provided to open the output circuit in response to current flow in the output circuit exceeding a predetermined level.
Claim 37
Dependent Claim
75 words
A cardiac stimulator according to any one of the preceding claims, characterized in that the stimulator is battery powered with all components except electrodes and associated leads housed in a biocompatible case of sufficiently small size for implantation in the patient, the electrodes and associated leads being part of the detecting means and the treating means for respectively sensing electrical activity of the patient's heart and delivering the selected therapy regimens to the patient's heart.
References Cited (Backward Citations)
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