Method and apparatus for continuous pulse contour cardiac output
First Claim
1. A system, comprising:
- means for sensing a cardiac electrogram (EGM) signal of the heart;
means for sensing a right ventricular pressure (RVP) signal;
means for computing an estimated stroke volume using the sensed EGM signal and the sensed RVP signal;
wherein the means for computing an estimated stroke volume comprises means for computing a RVP pulse contour integral by;
identifying an integration start time corresponding to an estimated time of pulmonic valve opening;
identifying an integration end time corresponding to an estimated time of pulmonic valve closure; and
computing a plurality of correction areas used to adjust the area under the right ventricular pressure signal between the integration start time and the integration end time; and
means for one of displaying and storing in a memory structure at least one of;
the RVP pulse contour, the estimated stroke volume, the right ventricular pressure signal, the area.
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Abstract
A system and method are provided for sensing cardiac electrogram (EGM) signals and ventricular pressure signals and for using the sensed EGM and sensed pressure signals for estimating stroke volume (SV). A measure of cardiac output can be computed from the estimated SV and a heart rate determined from the EGM signals. The sensed ventricular pressure signal and the sensed EGM signal are used to derive landmark points such as an estimated pulmonary diastolic pressure, a mean pulmonary artery pressure, a peak right ventricular pressure (RVP), and various time intervals used in computing an area or a pulse contour integral. The pulse contour integral is used to estimate SV. The estimated pulmonary diastolic pressure, mean pulmonary artery pressure and CO computed from the estimated SV can be used to compute a pulmonary vascular resistance.
31 Citations
14 Claims
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1. A system, comprising:
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means for sensing a cardiac electrogram (EGM) signal of the heart; means for sensing a right ventricular pressure (RVP) signal; means for computing an estimated stroke volume using the sensed EGM signal and the sensed RVP signal; wherein the means for computing an estimated stroke volume comprises means for computing a RVP pulse contour integral by; identifying an integration start time corresponding to an estimated time of pulmonic valve opening; identifying an integration end time corresponding to an estimated time of pulmonic valve closure; and computing a plurality of correction areas used to adjust the area under the right ventricular pressure signal between the integration start time and the integration end time; and means for one of displaying and storing in a memory structure at least one of; the RVP pulse contour, the estimated stroke volume, the right ventricular pressure signal, the area. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for monitoring the hemodynamic status of a patient, comprising:
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means for sensing a cardiac electrogram (EGM) signal of the heart; means for sensing a right ventricular pressure (RVP) signal; means for computing an estimated stroke volume using the sensed EGM signal and the sensed RVP signal; means for deriving a mean pulmonary artery pressure using the RVP signal and the EGM signal; and means for deriving an estimated pulmonary artery diastolic pressure using the right ventricular pressure signal and the EGM signal; and means for computing a pulmonary vascular resistance using the sensed EGM signal and the sensed RVP signal by; computing a pressure difference between the mean pulmonary artery pressure and the estimated pulmonary artery diastolic pressure; and computing a cardiac output metric using the estimated stroke volume and a heart rate derived from the EGM signal; dividing the pressure difference by the cardiac output; and means for one of displaying and storing in a memory structure at least one of; the cardiac output metric, the estimated stroke volume, the heart rate, the pressure difference, the pulmonary vascular resistance, the right ventricular pressure, the mean pulmonary artery pressure, the estimated pulmonary artery diastolic pressure.
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Specification