Antitachyarrythmia pacemaker using pre-ejection period to distinguish physiologic from pathologic tachycardia
First Claim
1. Apparatus for detecting tachycardia in a living subject for initiating cardioversion means when determined to be pathologic rather than physiologic in nature, comprising:
- (a) means for measuring the pulse rate of a beating heart and developing a first control signal value proportional thereto;
(b) means for comparing said first control signal value to a pre-established heart rate value for said subject and developing a second control signal value when said first control signal value exceeds said pre-established heart rate value;
(c) means for sensing the pre-ejection period of said subject'"'"'s heart and developing a third control signal value proportional thereto;
(d) means for comparing said third control signal value with a fourth control signal value proportional to a rate corrected pre-ejection period value of said subject'"'"'s heart based upon its current heart rate and producing a fifth control signal value when said third control signal value exceeds said fourth control signal value; and
(e) means for sensing coincidence of said second and fifth control signal values for initiation of said cardioversion means.
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Abstract
A cardiac stimulator apparatus for effecting cardioversion or defibrillation in the event of pathologic tachycardia or ventricular fibrillation in which the rate of heart depolarization signals is compared to a predetermined heart rate value indicative of the onset of tachycardia while, simultaneously, the heart'"'"'s pre-ejection period is monitored to sense whether an increase in heart rate above the predetermined value is accompanied by a decrease in the pre-ejection period. If not, a pathologic rather than a physiologic episode is diagnosed and a cardioversion pulse protocol is initiated. By also monitoring the mechanical pulse of the heart, if an inordinately high heart rate is accompanied by a low or non-existing mechanical pulse, ventricular fibrillation is diagnosed and the cardioverter is triggered to shock the heart back into sinus rhythm. If the mechanical pulse rate tracks the electrical rate of depolarization, tachyarrythmia is confirmed. The diagnosis may be further confirmed by taking into account the rate at which the heart rate increases.
107 Citations
6 Claims
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1. Apparatus for detecting tachycardia in a living subject for initiating cardioversion means when determined to be pathologic rather than physiologic in nature, comprising:
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(a) means for measuring the pulse rate of a beating heart and developing a first control signal value proportional thereto; (b) means for comparing said first control signal value to a pre-established heart rate value for said subject and developing a second control signal value when said first control signal value exceeds said pre-established heart rate value; (c) means for sensing the pre-ejection period of said subject'"'"'s heart and developing a third control signal value proportional thereto; (d) means for comparing said third control signal value with a fourth control signal value proportional to a rate corrected pre-ejection period value of said subject'"'"'s heart based upon its current heart rate and producing a fifth control signal value when said third control signal value exceeds said fourth control signal value; and (e) means for sensing coincidence of said second and fifth control signal values for initiation of said cardioversion means.
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2. Antitachyarrythmia pacing apparatus for producing cardioverting pulse patterns for application to a subject'"'"'s heart upon detection of tachycardia of pathologic origin, comprising:
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(a) means coupled to the heart for sensing an existing pulse rate; (b) means coupled to said sensing means for comparing said pulse rate to a pre-established pulse rate value for said subject, with the comparing means providing an indication when the sensed pulse rate exceeds the pre-established pulse rate; (c) means for measuring the pre-ejection period of the subject'"'"'s heart; (d) means responsive to said measuring means for indicating whether said measured pre-ejection period exceeds a corrected value for the subject'"'"'s pulse rate; and (e) means coupled to said means for comparing and said means for indicating for initiating generation of said cardioverting pulse patterns only when said sensed pulse rate exceeds the pre-established pulse rate and said measured prejection period exceeds and expected value.
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3. Antitachyarrythmia pacing apparatus for producing cardioverting pulse patterns for application to a subject'"'"'s heart upon detection of tachycardia of pathologic origin, comprising:
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(a) means coupled to the heart for sensing an existing pulse rate; (b) rate of change detecting means coupled to said sensing means for determining the rate of increase of pulse rate over a predetermined time interval; (c) first comparison means coupled to said sensing means for comparing said pulse rate to a pre-established pulse rate value for said subject, with the first comparison means providing signal indication when the sensed pulse rate exceeds the pre-established pulse rate; (d) gating means for producing a given output when said first comparison means provides said signal indication and said rate of change detecting means senses a rate change exceeding a predetermined value; (e) means for measuring the pre-ejection period of the subject'"'"'s heart; (f) second comparison means responsive to said measuring means for indicating whether said measured pre-ejection period exceeds an expected value for the subject'"'"'s then pulse rate; and (g) means coupled to said gating means and said second comparison means for initiating generation of said cardioverting pulse patterns only when said gating means produces said given output and said measured pre-ejection period exceed said expected value.
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4. Antitachyarrythmia pacing apparatus for producing cardioverting pulse patterns for application to a subject'"'"'s heart upon detection of tachycardia of pathologic origin, comprising:
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(a) means for sensing heart depolarization signals; (b) first means coupled to said sensing means for measuring the total cycle length between a first predetermined number of successive heart depolarization signals; (c) second means coupled to said sensing means for measuring the total cycle length between a second predetermined number of successive depolarization signals, said second number being greater than said first number and the second measurement being delayed a predetermined time from the first measurement; (d) first comparator means for producing an output when said first measurement exceeds said second measurement; (e) second comparator means for producing an output when the rate at which heart depolarization signals being sensed exceeds a predetermined rate value; (f) first gating means coupled to receive the output from said first and second comparator means and producing an output only when said output from said first and second comparator means are simultaneously present; (g) pre-ejection period sensing means for measuring the pre-ejection interval of the heart; (h) means coupled to said first means and to the pre-ejection period sensing means for detecting changes in length of the pre-ejection period with changes in cycle length; (i) cardioverter pulse producing means for applying a predetermined pattern of electrical pulses to the heart; and (j) further gating means coupling said cardioverter pulse producing means to the output of said first gating means and said means for detecting changes in length of the preejection period.
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5. A method for detecting the occurrence of a pathologic tachycardia in a living subject comprising the steps of:
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(a) measuring the heart rate of said subject; (b) measuring the pre-ejection period of the subject'"'"'s heart; and (c) detecting when the heart rate exceeds a predetermined rate reference value while the pre-ejection period remains relatively fixed in length. - View Dependent Claims (6)
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Specification