Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2001-04-25
2002-07-23
Jastrzab, Jeffrey R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C607S025000
Reexamination Certificate
active
06424866
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of methods and medical devices for modulating cardiac muscle activity and contractility and for cardiac pacing and more specifically to the field of methods for determining timing of delivery of non-excitatory excitable tissue control (ETC) signals to the heart.
BACKGROUND OF THE INVENTION
Excitable tissue control (ETC) devices are devices which modulate the activity of excitable tissues by application of non-excitatory electrical field signals to the excitable tissue through suitable electrodes in contact with the tissue. For example, ETC devices may be used, inter alia, to increase or decrease the contractility of cardiac muscle in vitro, in vivo and in situ., as disclosed in detail in PCT application PCT/IL97/00012 (International Publication Number WO 97/25098) to Ben-Haim et al., titled “ELECTRICAL MUSCLE CONTROLLER”, incorporated herein by reference. Other methods and applications of ETC devices are disclosed in PCT application PCT/IL97/00231 (International Publication Number WO 98/10828) titled “APPARATUS AND METHOD FOR CONTROLLING THE CONTRACTILITY OF MUSCLES” to Ben Haim et al., incorporated herein by reference, PCT application PCT/IL97/00232 (International Publication Number WO 98/10829) titled “DRUG-DEVICE COMBINATION FOR CONTROLLING THE CONTRACTILITY OF MUSCLES” to Ben Haim et al., incorporated herein by reference and PCT application PCT/IL97/00233 (International Publication Number WO 98/10830) titled “FENCING OF CARDIAC MUSCLES” to Ben Haim et al., incorporated herein by reference, PCT application PCT/IL97/00235 (International Publications Number WO 98/10831) to Ben Haim et al., titled “CARDIAC OUTPUT CONTROLLER”, incorporated herein by reference.
Further applications of the ETC including devices combining cardiac pacing and cardiac contractility modulation are disclosed in PCT Application, International Publication No. WO 98/10832, titled “CARDIAC OUTPUT ENHANCED PACEMAKER” to Ben Haim et al., co-assigned to the assignee of the present application. Such ETC devices function by applying to selected cardiac segments non-excitatory electrical signals of suitable amplitude and waveform, appropriately timed with respect to the heart's intrinsic electrical activity or with respect to paced cardiac electrical activity. The contraction of the selected segments can be modulated to increase or decrease the stroke volume of the heart. The timing of the ETC signals must be carefully controlled since application of the ETC signal to the myocardium at inappropriate times may be arrhythmogenic. The ETC signal must therefore be applied to the selected cardiac segment within a defined time interval during which the selected cardiac segment will not be stimulated by the ETC signal.
As disclosed in International Publication No. WO 98/10832, the ETC signal may be timed relative to a trigger signal which is also used as a pacing trigger, or may be timed relative to locally sensed depolarizing electrogram signals.
Timing of the delivery of ETC signals relative to the time of detection of locally sensed electrogram signals may present certain practical problems. For example, triggering of the ETC signal by any locally detected depolarizing signals irrespective of the time of detection of the depolarizing signal within the cardiac beat cycle, may increase the probability of spurious detection of noise signals or of ectopic beats such as premature ventricular contractions (PVCs) or the like, which may lead to delivery of improperly timed and potentially arrhythmogenic ETC signals. It is therefore desirable to have a method for determining proper timing of the delivery of ETC signals without unduly increasing the probability of delivering an improperly timed ETC signal caused by spurious noise detection or by detection of ectopic beats.
SUMMARY OF THE INVENTION
There is therefore provided, in accordance with a preferred embodiment of the present invention, a method for timing the delivery of a non-excitatory signal to a heart within a cardiac beat cycle. The method includes the steps of applying electrodes to a plurality of cardiac sites, sensing electrical activity in at least a first site of the plurality of cardiac sites through at least a first electrode of the electrodes for detecting a first electrical depolarization event within the beat cycle, sensing electrical activity in at least a second site of the plurality of sites through at least a second electrode of the electrodes for detecting at least a second electrical depolarization event within the beat cycle, and applying the non-excitatory signal to at least one of the cardiac sites through at least one of the electrodes in response to detecting the second electrical depolarization event within an alert window period. The alert window period starts at a first delay from the time of detection of the first electrical depolarization event and has a first duration. The applying is delayed from the time of detecting of the second electrical depolarization event.
Furthermore, in accordance with another preferred embodiment of the present invention, the method includes the step of inhibiting the applying of the cardiac non-excitatory signal of the step of applying in response to detecting at the second site a third electrical depolarization event preceding the second electrical depolarization event. The third electrical depolarization event is detected within an inhibition window period. The inhibition window period starts at a second delay from the time of detection of the first electrical depolarization event and terminates before or at the time of starting of the alert window period. The second delay is smaller than the first delay.
Furthermore, in accordance with another preferred embodiment of the present invention, the step of inhibiting includes the step of initiating an inhibition refractory period. The inhibition refractory period starts at the time of detecting of the third electrical depolarization event and has a second duration. The sensing of the electrical activity in the second site is disabled during the inhibition refractory period.
Furthermore, in accordance with another preferred embodiment of the present invention, the sensing of the second step of sensing at the second site starts after the end of a refractory time period. The refractory period begins at the time of detection of the first electrical depolarization event and has a refractory period duration.
Furthermore, in accordance with another preferred embodiment of the present invention, the method further includes the step of pacing the heart by applying at least one pacing pulse to the heart through the first electrode. The refractory period prevents the sensing of electrical artifact signals by the second electrode due to the pacing pulse.
Furthermore, in accordance with another preferred embodiment of the present invention, the first site is located in or about the right ventricle of the heart and the second site is located in or about the left ventricle of the heart.
Furthermore, in accordance with another preferred embodiment of the present invention, the first site is located in or about the right atrium of the heart and the second site is located in or about the left ventricle of the heart.
Furthermore, in accordance with another preferred embodiment of the present invention, the method further includes the step of pacing the heart by applying within the beat cycle a pacing pulse to at least one of the electrodes prior to second step of applying.
Furthermore, in accordance with another preferred embodiment of the present invention, the first site is located in or about the right ventricle of the heart and the at least second site is located in or about the left ventricle of the heart.
Furthermore, in accordance with another preferred embodiment of the present invention, the step of pacing includes pacing the right ventricle by applying a pacing pulse to the first electrode or to one of the electrodes applied to the right ventricle.
Furthermore, in accordance with another
Belsky Ziv
Kimchy Yoav
Mika Yuval
Prutchi David
Dippert William H.
Impulse Dynamics N.V.
Jastrzab Jeffrey R.
Reed Smith LLP
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