Patent ID: 6217522
Filing Date: 2001-04-17
Classification: A61B

Abstract:
A method for the non-invasive determination of the pressure-volume loop (PVL) of a patient's heart, comprising the steps of:(a) connecting said patient to an electrocardiograph;(b) mounting the probe of an echo-Doppler device on the patient in a four-chamber position of the heart enabling it to sense the aortic root and to produce signals representative of the flow waves issuing from said aortic root;(c) 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;(d) applying a curve-fitting procedure to turn said data points into a flow curve resembling the flow wave issuing from said aortic root;(e) placing a pressure cuff on the patient's arm and inflating it to a point where all flow in the patient's brachial artery stops;(f) deflating said cuff at a controlled rate while measuring pressure inside said cuff throughout deflation;(g) 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;(h) obtaining a series of data points from peak systolic to diasystolic pressure, each point consisting of cuff pressure at penetration coupled with the time of its occurrence after the corresponding QRS complex;(i) applying a curve-fitting procedure to turn said data points into a pressure curve resembling the ascending limb of the aortic pressure wave;(j) calculating the end systolic pressure (ESP) using the expressionESP=DP+2/3 (PSP-DP)where:DP=diastolic pressure, andPSP=peak systolic pressure;(k) calculating volume at point ESP by integrating said flow curve throughout the ejection phase of the patient's heart; and(l) from data obtained in steps (a) through (k), forming said pressure-volume loop;viewing said pressure-volume loop on a monitor screen.