Apparatus and method for capture detection in a cardiac stimulator

A method of verifying cardiac capture by sensing via a pacing electrode a cardiac signal evoked in response to a cardiac stimulation pulse delivered via said same pacing electrode, comprising the steps of:

• sensing a waveform signal at said pacing electrode following delivery of said cardiac stimulation pulse;
• bandpass filtering said sensed waveform signal through a pass band selected to pass a band of frequencies characteristic of the evoked cardiac signal;
• processing said bandpass-filtered waveform signal to render a waveform signal representing the absolute value of said bandpass-filtered signal;
• integrating said absolute value processed waveform signal over a selected window of time beginning at a selected time delay following delivery of said cardiac stimulation pulse;
• and
• comparing said integrated waveform signal to a reference value during said selected window of time and generating a capture detect signal if said integrated waveform signal exceeds said reference value during said selected window of time.

A method of verifying cardiac capture by sensing via an electrode a cardiac signal evoked in response to a cardiac stimulation pulse, comprising the steps of:

• sensing a waveform signal at said electrode following delivery of said cardiac stimulation pulse;
• highpass filtering said sensed waveform signal through a filter selected to pass frequencies characteristic of the evoked cardiac signal;
• processing said highpass-filtered waveform signal to render a waveform signal representing the absolute value of said bandpass-filtered signal;
• integrating said absolute value processed waveform signal over a selected window of time beginning at a selected time delay following delivery of said cardiac stimulation pulse;
• and
• comparing said integrated waveform signal to a reference value at the end of said selected window of time and generating a capture detect signal if said integrated waveform signal exceeds said reference value during said selected window of time.

A method of verifying cardiac capture by sensing via an electrode a cardiac signal evoked in response to a cardiac stimulation pulse, comprising the steps of:

• sensing a waveform signal at said electrode following delivery of said cardiac stimulation pulse;
• bandpass filtering said sensed waveform signal through a pass band selected to pass a band of frequencies characteristic of the evoked cardiac signal;
• processing said bandpass-filtered waveform signal to render a waveform signal representing the absolute value of said bandpass-filtered signal;
• integrating said absolute value processed waveform signal over a selected window of time beginning at a selected time delay following delivery of said cardiac stimulation pulse;
• and
• comparing said integrated waveform signal to a first reference value at the end of said selected window of time, and comparing said integrated waveform signal to a second reference value at the end of said selected window of time, and generating a capture detect signal if said integrated waveform signal exceeds said first reference value during said selected window of time, but does not exceed said second reference value during said selected window of time.

A method of verifying cardiac capture by sensing via an electrode a cardiac signal evoked in response to a cardiac stimulation pulse, comprising the steps of:

• sensing a waveform signal at said electrode following delivery of said cardiac stimulation pulse;
• bandpass filtering said sensed waveform signal through a pass band selected to pass a band of frequencies characteristic of the evoked cardiac signal;
• processing said bandpass-filtered waveform signal to render a waveform signal representing the absolute value of said bandpass-filtered signal;
• integrating said absolute value processed waveform signal over a selected window of time beginning at a selected time delay following delivery of said cardiac stimulation pulse;
• and
• comparing said integrated waveform signal to a first reference value at the end of said selected window of time, and comparing said integrated waveform signal to a second reference value at the end of said selected window of time, and if said integrated waveform signal exceeds said first reference value during said selected window of time, but does not exceed said second reference value during said selected window of time, continuing to integrate said absolute value processed waveform signal over an extended window of time, and generating a capture detect signal if said integrated waveform signal does not exceed said second reference value during said extended window of time.