| 摘要 |
<p>A method and system incorporated into an IMD that detects changes in ventricular afterload using the morphology of a ventricular blood pressure wave. A peak positive pressure value Pb, peak positive and peak negative derivatives pressures dP/dtPP and dP/dtNP, and a decreasing pressure Pc are determined. The sample times tb, at Pb, ta at dP/dtPP and tc at dP/dtNP are determined. An index alpha of the relative timing of peak positive pressure Pb in the blood ejection phase is calculated from, alpha=(tb-ta)/(tc-ta), the severity of ventricular afterload is proportional to the value alpha in the range between o and 1. The slope of the early ejection pressure in the blood ejection phase is calculated from beta=(Pc-Pb)/(tc-tb), wherein the severity of ventricular afterload is proportional to the magnitude of the index beta.</p> |
