METHOD AND SYSTEM FOR DETERMINATION OF THE PRESSURE-VOLUME RELATIONSHIP OF THE HEART

摘要

A method for the non-invasive determination of the pressure-volume loop (PVL) of a patient's heart, comprising the steps of: connecting said patient to an electrocardiograph (2); mounting the probe of an echo-Doppler device (8) on the patient in a position enabling it to sense the aortic root and to produce signals representative of the flow waves issuing from said aortic root; analyzing said signals and obtaining a series of data points as pairs of flow and time, using the QRS complex of the electrocardiogram pattern as a time reference point; applying a curve-fitting procedure to turn said data points into a flow curve resembling the flow wave issuing from said aortic root; placing a pressure cuff (4) on the patient's arm and inflating it to a point where all 1223 כ" ג בתמוז התש" ס - July 26, 2000 flow in the patient's brachial artery stops; deflating said cuff at a cotrolled rate while measuring pressure inside said cuff throughout deflation; during deflation, sensing blood flow penetrating the barrier constituted by said pressurized cuff, with instantaneous pressure at the aortic root being equal to instantaneous pressure inside said cuff; obtaining a series of data points from peak systolic to diastolic pressure, each point consisting of cuff pressure at penetration coupled with the time of its occurrence after the corresponding QRS complex; applying a curve-fitting procedure to turn said data points into a pressure curve resembling the ascending limb of the aortic pressure wave; calculating the end systolic pressur (ESP) using the expression ESP = DP + 2/3 (PSP - DP) where: DP = diastolic pressure, and PSP = peak systolic pressure; calculating volume at point ESP by integrating said flow curve throughout the ejection phase of the patient's heart, and viewing said PVL on a monitor screen.