Extraction of hemodynamic pulse pressure from fluid and myocardial accelerations
First Claim
1. A cardiac stimulating apparatus functioning in a preset pacing mode having preset pacing rates and timing intervals, and programmed to optimize cardiac performance of a patient'"'"'s heart, said cardiac stimulating apparatus comprising:
- a) a pulse generator;
b) an accelerometer electrically coupled to a controller of the cardiac stimulating apparatus, said accelerometer transmitting a signal associated with fluid and myocardial accelerations of the patient'"'"'s heart;
c) filtering means coupled to the accelerometer for filtering and conditioning the signal transmitted by the accelerometer to produce a waveform related to a pulse pressure within the patient'"'"'s heart; and
d) said controller including a timing means for identifying cardiac cycles of the patient'"'"'s heart, a linear prediction means for predicting values associated with the waveform, bandwidth determining means for determining a bandwidth from predicted values of the waveform, center frequency determining means for determining a center frequency from predicted values of the waveform, means for calculating an amount indicative of pulse pressure from the determined bandwidth and center frequency, and analyzing means for analyzing the amounts indicative of pulse pressure over corresponding cardiac cycles.
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Abstract
A cardiac stimulating apparatus and method is described that non-intrusively determines an amount indicative of hemodynamic pulse pressure from an accelerometer signal. The amount indicative of pulse pressure is determined over several cardiac cycles and is used to optimize cardiac performance by evaluating the amount indicative of pulse pressure over varying timing intervals. The timing intervals are measured between at least one of intrinsic and paced stimulations of pre-selected chambers of the heart and a maximum pulse pressure indicates the optimum timing interval under manipulation. The cardiac stimulating apparatus and method may be used in any of several pacing modes including A-V pacing, V-V pacing, or A-A pacing.
106 Citations
9 Claims
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1. A cardiac stimulating apparatus functioning in a preset pacing mode having preset pacing rates and timing intervals, and programmed to optimize cardiac performance of a patient'"'"'s heart, said cardiac stimulating apparatus comprising:
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a) a pulse generator; b) an accelerometer electrically coupled to a controller of the cardiac stimulating apparatus, said accelerometer transmitting a signal associated with fluid and myocardial accelerations of the patient'"'"'s heart; c) filtering means coupled to the accelerometer for filtering and conditioning the signal transmitted by the accelerometer to produce a waveform related to a pulse pressure within the patient'"'"'s heart; and d) said controller including a timing means for identifying cardiac cycles of the patient'"'"'s heart, a linear prediction means for predicting values associated with the waveform, bandwidth determining means for determining a bandwidth from predicted values of the waveform, center frequency determining means for determining a center frequency from predicted values of the waveform, means for calculating an amount indicative of pulse pressure from the determined bandwidth and center frequency, and analyzing means for analyzing the amounts indicative of pulse pressure over corresponding cardiac cycles. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of non-invasively measuring hemodynamic pulse pressure from an accelerometer signal electrically coupled to an implantable cardiac pacer, said pacer being of the type having a microprocessor-based controller having memory, a pulse generator, and an accelerometer for sensing fluid and myocardial accelerations of a patient'"'"'s heart, said method comprising the steps of:
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a) pacing a patient'"'"'s heart with the implantable cardiac pacer, wherein the cardiac pacer has a preset pacing mode, identifies cardiac cycles of the patient'"'"'s heart and controls a timing interval between at least one of intrinsic and paced stimulations of preselected chambers of the heart; b) receiving a signal from the accelerometer; c) filtering the signal to obtain a waveform related to a pulse pressure within the patient'"'"'s heart; d) performing a linear prediction to determine values from the waveform; e) determining a bandwidth from the values determined from the waveform, f) determining a center frequency from the values determined from the waveform; and g) calculating an amount indicative of pulse pressure from the determined bandwidth and center frequency. - View Dependent Claims (8, 9)
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Specification