Synchronous pacemaker with upper rate stabilization and method of use

Claim 2

In a synchronous heart pacemaker, including: means for selectively detecting natural electrical heart signals; means for generating an artificial pacing stimulus in timed synchronism with the detected heart signal; and means for applying the generated pacing stimulus to the heart to elicit a responsive heart beat; the improvement for stabilizing the synchronous pacing rate at an average rate approaching but not exceeding the upper pacing rate comprising: means for inhibiting the generation of a subsequent pacing stimulus for a predetermined time interval corresponding to an upper pacing rate; and means for varying the time elapsed from the detection of electrical heart signals recurring at a rate exceeding the upper pacing rate and the synchronous generation of artificial pacing stimulus to include the predetermined time interval.

Claim 3

The synchronous heart pacemaker of claim 1 further comprising: means for periodically interrupting the selective detection of natural electrical heart signals recurring at a rate exceeding the upper pacing rate so that the generation of a subsequent pacing stimulus is in timed synchronism with the detected heart signal.

Claim 4

In a method of operation of a synchronous heart pacemaker, comprising the steps of: selectively detecting natural electrical heart signals; generating an artificial pacing stimulus in timed synchronism with the detected heart signal; and applying the generated pacing stimulus to the heart to elicit a responsive heart beat; the improvement for stabilizing the synchronous pacing rate at an average rate approaching but not exceeding the upper pacing rate comprising the steps of: inhibiting the generation of a subsequent pacing stimulus for a predetermined time interval corresponding to an upper pacing rate; and varying the time elapsed from the detection of electrical heart signals recurring at a rate exceeding the upper pacing rate and the synchronous generation of artificial pacing stimulus to include the predetermined time interval.

Claim 5

In a method of operation of a synchronous heart pacemaker, comprising the steps of: selectively detecting natural electrical heart signals; generating an artificial pacing stimulus in timed synchronism with the detected heart signal; and applying the generated pacing stimulus to the heart to elicit a responsive heart beat; the improvement for stabilizing the synchronous pacing rate at an average rate approaching but not exceeding the upper pacing rate comprising the steps of: inhibiting the generation of a subsequent pacing stimulus for a predetermined time interval corresponding to an upper pacing rate; and varying the time elapsed from the detection of electrical heart signals recurring at a rate exceeding the upper pacing rate and the synchronous generation of artificial pacing stimulus to include the predetermined time interval.

Claim 6

The method of claim 3 further comprising the step of: inhibiting the detection of natural electrical heart signals for a further predetermined time interval upon the generation of a pacing stimulus so that the synchronous generation of the artificial pacing stimulus at the upper pacing rate is periodically interrupted for one pacing cycle to re-establish the time synchronism of generation of the artificial pacing stimulus.

Claim 7

The method of claim 3 further comprising the step of: periodically interrupting the selective detection of natural electrical heart signals recurring at a rate exceeding the upper pacing rate so that the generation of a subsequent pacing stimulus is in timed synchronism with the detected heart signal.

Claim 8

In a synchronous artificial cardiac pacemaker comprising pulse generator means operable to generate electrical pacing pulses applicable to the patient's heart to elicit a responsive heart beat in timed synchronism with a natural electrical heart signal detectable from the patient's heart at a synchronous rate extending between a lower, base pacing rate and an upper maximum pacing rate including timing circuit means controlling the generation of the pacing pulses at the lower, base pacing rate upon the failure of the pacemaker to detect such natural heart signals within a maximum time interval, the improvement comprising: upper rate limit circuit means for establishing the maximum pacing rate by inhibiting the generation of the pacing pulses for a predetermined minimum time interval following the generation of each such pacing pulse; means for varying the time elapsed from the detection of electrical heart signals recurring at a rate exceeding the maximum pacing rate and the synchronous generation of artificial pacing pulses to include the predetermined minimum time interval; and means for periodically interrupting the selective detection of natural electrical heart signals recurring at a rate exceeding the upper pacing rate so that the generation of a subsequent pacing pulse is in timed synchronism with the detected heart signal.

Claim 9

In a synchronous artificial cardiac pacemaker comprising pulse generator means operable to generate electrical pacing pulses applicable to the patient's heart to elicit a responsive heart beat in timed synchronism with a natural electrical heart signal detectable from the patient's heart at a synchronous rate extending between a lower, base pacing rate and an upper maximum pacing rate including timing circuit means controlling the generation of the pacing pulses at the lower, base pacing rate upon the failure of the pacemaker to detect such natural heart signals within a maximum time interval, the improvement comprising: upper rate limit circuit means for establishing the maximum pacing rate by inhibiting the generation of the pacing pulses for a predetermined minimum time interval following the generation of each such pacing pulse; means for varying the time elapsed from the detection of electrical heart signals recurring at a rate exceeding the maximum pacing rate and the synchronous generation of artificial pacing pulses to include the predetermined minimum time interval; and means for periodically interrupting the selective detection of natural electrical heart signals recurring at a rate exceeding the upper pacing rate so that the generation of a subsequent pacing pulse is in timed synchronism with the detected heart signal.

Claim 10

The synchronous artificial cardiac pacemaker of claim 6 further comprising: a first electrode coupled to said pulse generator means, said first electrode being adapted to be operatively connected to a patient's heart on or in the ventricle thereof to transmit the artificial pacing pulses to the patient's ventricle and to pick up natural ventricular electrical signals; and reset circuit means coupled to said timing circuit means and said first electrode and responsive to a ventricular electrical signal to restart the maximum time interval and prevent the pulse generator from stimulating the heart for the maximum time interval.

Claim 11

The synchronous artificial cardiac pacemaker of claim 7 further comprising: a second electrode coupled to said pulse generator, said second electrode being adapted to be operatively connected to a patient's heart on or in the atrium thereof to pick up natural atrial electrical signals; and trigger circuit means coupled to said pulse generator means and said second electrode and responsive to the atrial electrical signals to trigger said pulse generator means into generating a pacing pulse synchronously with a detected atrial electrical signal.

Claim 12

The synchronous artificial cardiac pacemaker of claim 8, wherein said periodically interrupting means further comprises: signal responsive means coupled to said second electrode and said trigger circuit means and responsive to atrial electrical signals picked up by said second electrode for rendering said trigger circuit means operable; and refractory circuit means coupled to said signal responsive means and said pulse generator means and responsive to a generated pacing pulse to inhibit said signal responsive means from responding to atrial electrical signals for a predetermined refractory time period so that as the synchronous pacing time interval increases as the atrial heart rate increases, an atrial signal will fall within the refractory time period and will not be sensed to produce a pacing pulse.

Claim 13

The synchronous artificial cardiac pacemaker of claim 6 further comprising: a second electrode coupled to said pulse generator, second electrode being adapted to be operatively connected to a patient's heart on or in the atrium thereof to pick up natural atrial electrical signals; and trigger circuit means coupled to said pulse generator means and said second electrode and responsive to the atrial electrical signals to trigger said pulse generator means into generating a pacing pulse synchronously with a detected atrial electrical signal.

Claim 14

The synchronous artificial cardiac pacemaker of claim 10 further comprising: time delay circuit means coupled to said second electrode and said trigger circuit means and adapted to respond to each detected atrial electrical signal for causing said trigger circuit to trigger said pulse generator means into generating a pacing pulse in timed synchronism, after an atrial-ventricular time delay, with the detection of the atrial electrical signal; and said varying means further comprises: p1 memory circuit means coupled to said second electrode and said time delay circuit means and responsive to the atrial electrical signal for maintaining the response of said time delay circuit for a time period exceeding the elapse of the predetermined time interval of said upper rate limit circuit means, so that said trigger circuit means will trigger said pulse generator into generating a pacing pulse in synchronism with the atrial electrical activity of the heart.

Claim 15

An atrial synchronous artificial cardiac pacemaker comprising: pulse generator means operable to generate electrical pacing pulses applicable to a patient's ventricle to elicit a responsive contraction of the heart in synchronism with a natural atrial electrical signal detectable from the patient's heart at a synchronous rate extending between a lower, base pacing rate and an upper maximum pacing rate; said pulse generator means including timing circuit means controlling the generation of the pacing pulses at the lower, base pacing rate upon the failure of the pacemaker to detect atrial or ventricular electrical signals within a maximum time interval, upper rate limit circuit means for establishing the maximum pacing rate by inhibiting the generation of the pacing pulses for a predetermined minimum time interval following the generation of each such pacing pulse; reset circuit means coupled to said timing circuit means and adapted to restart the maximum timing interval in response to atrial electrical signals, and trigger circuit means coupled to said pulse generator means and operable to trigger said pulse generator means into generating a pacing pulse independently of said timing circuit means; first and second electrodes coupled to said pulse generator means, said first electrode being adapted to be operatively connected to a patient's heart on or in the ventricle thereof to transmit the artificial pacing pulses to the patient's ventricle and to pick up natural ventricular electrical signals, said second electrode being adapted to be operatively connected to a patient's heart on or in the atrium thereof to pick up natural atrial electrical signals; first signal responsive means coupled to the first electrode and responsive to ventricular electrical signals picked up by the first electrode for producing a first signal; second signal responsive means coupled to the second electrode and responsive to atrial electrical signals picked up by the second electrode for producing a second signal; circuit means coupled to said first signal responsive means and said reset circuit means and responsive to the first signal to reset the timing circuit means to restart said maximum timing interval between pacing pulses; time delay circuit means coupled to said trigger circuit means and adapted to respond to each second signal for triggering said pulse generator means into generating a pacing pulse in synchronism, after an atrial-ventricular time delay, with the detection of the atrial electrical signal; and memory circuit means having input means coupled to said first and second signal responsive means and output means coupled to said time delay circuit means, said memory circuit means responsive to the second signal for maintaining the second signal at said time delay circuit for a time period exceeding the elapse of the predetermined time interval of said upper rate limit circuit means, whereby the pulse generator operates to produce a pacing pulse in synchronism with atrial electrical signals detected from the atrium but at an average rate not exceeding the maximum pacing rate.

Claim 16

An atrial synchronous artificial cardiac pacemaker comprising: pulse generator means operable to generate electrical pacing pulses applicable to a patient's ventricle to elicit a responsive contraction of the heart in synchronism with a natural atrial electrical signal detectable from the patient's heart at a synchronous rate extending between a lower, base pacing rate and an upper maximum pacing rate; said pulse generator means including timing circuit means controlling the generation of the pacing pulses at the lower, base pacing rate upon the failure of the pacemaker to detect atrial or ventricular electrical signals within a maximum time interval, upper rate limit circuit means for establishing the maximum pacing rate by inhibiting the generation of the pacing pulses for a predetermined minimum time interval following the generation of each such pacing pulse; reset circuit means coupled to said timing circuit means and adapted to restart the maximum timing interval in response to atrial electrical signals, and trigger circuit means coupled to said pulse generator means and operable to trigger said pulse generator means into generating a pacing pulse independently of said timing circuit means; first and second electrodes coupled to said pulse generator means, said first electrode being adapted to be operatively connected to a patient's heart on or in the ventricle thereof to transmit the artificial pacing pulses to the patient's ventricle and to pick up natural ventricular electrical signals, said second electrode being adapted to be operatively connected to a patient's heart on or in the atrium thereof to pick up natural atrial electrical signals; first signal responsive means coupled to the first electrode and responsive to ventricular electrical signals picked up by the first electrode for producing a first signal; second signal responsive means coupled to the second electrode and responsive to atrial electrical signals picked up by the second electrode for producing a second signal; circuit means coupled to said first signal responsive means and said reset circuit means and responsive to the first signal to reset the timing circuit means to restart said maximum timing interval between pacing pulses; time delay circuit means coupled to said trigger circuit means and adapted to respond to each second signal for triggering said pulse generator means into generating a pacing pulse in synchronism, after an atrial-ventricular time delay, with the detection of the atrial electrical signal; and memory circuit means having input means coupled to said first and second signal responsive means and output means coupled to said time delay circuit means, said memory circuit means responsive to the second signal for maintaining the second signal at said time delay circuit for a time period exceeding the elapse of the predetermined time interval of said upper rate limit circuit means, whereby the pulse generator operates to produce a pacing pulse in synchronism with atrial electrical signals detected from the atrium but at an average rate not exceeding the maximum pacing rate.

Claim 17

The synchronous artificial cardiac pacemaker of claim 12 further comprising: refractory circuit means coupled to said second signal responsive means and said pulse generator means and responsive to a generated pacing pulse to inhibit said second signal responsive means to periodically interrupt the production of the second signal when the atrial electrical signal recurs at a rate exceeding the maximum pacing rate, so that the predetermined minimum time interval of the upper rate limit circuit means will elapse before a succeeding atrial electrical signal is picked up by said second electrode.

Claim 18

The synchronous artificial cardiac pacemaker of claim 12 wherein: said input means of said memory circuit means is coupled to said circuit means; and said memory circuit means is responsive to the first signal for removing the second signal at said time delay circuit on the occurrence of the first signal.

Claim 19

An atrial synchronous cardiac pacemaker for pacing the ventricle portion of the heart at a rate in synchronism with the natural contraction of the atrium portion of the heart, but at a rate above a lower rate limit and below an upper rate limit, said pacemaker comprising: an oscillator responsive to a trigger signal for generating an electrical pulse signal adapted to be applied over a lead to the ventricle portion of the heart to elicit a responsive heart beat, said oscillator further being operable to generate said pulse signal upon the absence of any trigger signal for a designated time period, said oscillator including rate limit means for preventing said pulse signals from being generated at a rate exceeding an upper rate limit; sensing means responsive to the occurrence of a cardiac signal caused by the contraction of the atrium of the heart for providing a signal each time said atrium contracts, said sensing means further including means for inhibiting the response by said sensing means to an atrium contraction caused signal which occurs during a fixed time, less than said designated time, after the provision of each pulse signal; and memory means, which in response to said sensing means signal, provides said trigger signal to said oscillator until said pulse signal is generated, said memory means being reset each time a pulse signal is generated and set each time a sensing means signal is provided.

Claim 20

An atrial synchronous cardiac pacemaker for pacing the ventricle portion of the heart at a rate in synchronism with the natural contraction of the atrium portion of the heart, but at a rate above a lower rate limit and below an upper rate limit, said pacemaker comprising: an oscillator responsive to a trigger signal for generating an electrical pulse signal adapted to be applied over a lead to the ventricle portion of the heart to elicit a responsive heart beat, said oscillator further being operable to generate said pulse signal upon the absence of any trigger signal for a designated time period, said oscillator including rate limit means for preventing said pulse signals from being generated at a rate exceeding an upper rate limit; sensing means responsive to the occurrence of a cardiac signal caused by the contraction of the atrium of the heart for providing a signal each time said atrium contracts, said sensing means further including means for inhibiting the response by said sensing means to an atrium contraction caused signal which occurs during a fixed time, less than said designated time, after the provision of each pulse signal; and memory means, which in response to said sensing means signal, provides said trigger signal to said oscillator until said pulse signal is generated, said memory means being reset each time a pulse signal is generated and set each time a sensing means signal is provided.

Claim 21

The invention according to claim 15 wherein said pacemaker further comprises: second sensing means responsive to a cardiac signal caused by the contraction of the ventricle of the heart for providing a second sensing means signal each time said ventricle naturally contracts; and means for providing said second sensing means signal to reset said memory, to inhibit the response by said first sensing means for said fixed time and to reset said oscillator to commence said designated time period.

Claim 22

The invention according to claim 15 wherein said memory means include means for delaying the provision of said trigger signal to said oscillator for a selected time after the provision of said sensing means signal.