US 5,855,594 A · Self-calibration system for capture verification in pacing devices

Abstract

A cardiac pacing and sensing system includes a body implantable unit for generating tissue stimulation pulses and manipulating information based on sensed signals, and a catheter for transmitting pulses from the unit to a pacing electrode adjacent myocardial tissue. The unit incorporates circuitry for generating response values, one associated with each stimulation pulse, based on a predetermined characteristic or parameter of the signals evoked by the pulses. To evaluate the efficacy of the parameter in distinguishing capture versus non-capture, the stimulation pulses are generated according to a protocol of high energy pulses guaranteed to effect capture interspersed with low energy pulses guaranteed not to effect capture. Data, accumulated and sorted into separate "capture" and "non-capture" sets, provides respective capture and non-capture composite values. The ratio of the composite values is compared to a predetermined threshold, to generate an indication either accepting or rejecting the chosen parameter. A parameter, once accepted, can be employed in a self-test that either increments or decrements stimulation of signals to evaluate the capture threshold. Optionally, two or more designated parameters can be screened simultaneously and compared, with the most favorable ratio then being compared to the threshold.

Claims34

Dependent claims

A process for testing the efficacy of a sensed parameter as an indication of tissue stimulation;

including:
applying a plurality of first pulses to tissue, each of the first pulses having at least a first level of intensity known to evoke a desired response in the tissue;
applying a plurality of second pulses to the tissue in a manner to intersperse said second pulses within the plurality of first pulses, each of the second pulses having at most a second level of intensity known to be insufficient to evoke said desired response, with each of the pulses temporally distinguishable from the other pulses;
after applying each of the pulses, sensing the tissue to generate a response value based on a selected parameter, each one of the response values corresponding to one of said first and second pulses;
accumulating and sorting the response values into a first set of the response values corresponding to the first pulses and a second set of the response values corresponding to the second pulses;
combining the response values of said first set into a first composite value, and combining the values of said second set into a second composite value;
comparing the first composite value and the second composite value to one another to produce a difference factor based on the comparison;
and
comparing the difference factor to a predetermined threshold, and alternatively:
(i) indicating an acceptance of the selected parameter responsive to determining that the difference factor is at least equal to the threshold;
and
(ii) indicating a rejection of the parameter responsive to determining that the difference factor is less than the threshold.

9 more elements

A system for automatically determining the efficacy of a detected response in tissue as an indication of tissue stimulation including:

a pulse generator;
a conductive pulse transmitting means coupled between the pulse generator and tissue, for delivering pulses to the tissue;
a control means operatively coupled to the pulse generator for selectively varying an intensity level of the pulses, and thereby causing the pulse generator to deliver the pulses according to a protocol in which:
(i) a plurality of first pulses having at least a first level of intensity known to achieve a desired response are interspersed among a plurality of second pulses having at most a second level of intensity known to be insufficient to achieve the desired response;
and (ii) each of the pulses is temporally distinct from the others;
a detecting means for sensing a response signal in said tissue following each of the first and second pulses, and adapted for generating at least a first response value associated with each response signal, based on a first characteristic of the response signals;
a storage means adapted for accumulating the response values;
a sorting means adapted for sorting the accumulated response values into a first set corresponding to the first pulses and a second set corresponding to the second pulses;
a first processing means for combining the response values to generate first and second composite values based on the first and second sets, respectively;
a second processing means operatively coupled to the first processing means, for comparing the first and second composite values and generating a difference factor based on the degree of difference between the first and second composite values;
a third processing means coupled to receive the output of the second processing means, adapted for comparing the difference factor to a threshold, and for providing, either:
(i) an indication of acceptance of the characteristic responsive to determining that the difference factor is at least as great as the threshold;
or
(ii) an indication of rejection of the characteristic responsive to determining that the difference factor is less than the threshold.

11 more elements

A process for comparatively determining the efficacy of two or more sensed parameters as indications of tissue stimulation;

including:
applying a plurality of first pulses to tissue, each of the first pulses having at least a first level of intensity known to evoke a desired response in the tissue;
applying a plurality of second pulses to the tissue in a manner to intersperse the second pulses within the plurality of first pulses, each of the second pulses having at most a second level of intensity known to be insufficient to evoke the desired response, and wherein each of the pulses is temporally distinguishable from the other pulses;
sensing the tissue for an evoked signal after applying each of the pulses, and using each evoked signal to generate a first response value based on a first selected parameter and a second response value based on a second selected parameter of the evoked signals, whereby each of the first response values and each of the second response values corresponds to one of the first and second pulses;
accumulating the response values and sorting the response values into:
(i) a first set including the first response values corresponding to the first pulse;
(ii) a second set including the first response values corresponding to the second pulse;
(iii) a third set including the second response values corresponding to the first pulse;
and (iv) a fourth set including the second response values corresponding to the second set;
combining the response values of these sets respectively into first, second, third and fourth composite values;
comparing the first composite value and the second composite value to one another to produce a first difference factor based on the comparison, and comparing the third and fourth composite values to one another to produce a second difference factor based on the comparison;
and
selecting one of the difference factors, thereby to select the parameter associated with the selected difference factor.

10 more elements

Dependencies are inferred from the claim text.

Self-calibration system for capture verification in pacing devices

Life of this patent

Self-calibration system for capture verification in pacing devices

Life of this patent

Abstract

Claims34