ANALYSIS OF LEFT-VENTRICULAR PRESSURE-ARE A RELATION USING AUTOMATED ECHOCARDIOGRAPHIC EDGE-DETECTION

Echocardiographic automatic border detection is a new on-line techniqu e determinating the interface between blood and myocardial tissue thus having the potential to calculate cyclic changes in left ventricular cavity area in real time. It was the main purpose of the current study to evaluate left ventricular pressure-area relationship after adminis tration of nitrates. In 12 patients with normal left ventricular funct ion pressure-area relation was studied after a Swan-Ganz thermodilutio n catheter was placed in the wedge position and a high fidelity pig ta il catheter was placed in the left ventricle. Left ventricular pressur e and cyclic changes of cavity area were simultaneously analysed and d isplayed together as waveforms on the echo screen using a computer int erfaced with the echo machine. All measurements were done before and f ive minutes after administration of 0.8 mg nitroglycerin. Mean systoli c and diastolic blood pressure decreased significantly from 145/12 mmH g to 127/8 mmHg (p < 0.05). Mean systolic area decreased slightly from 10 cm(2) to 9 cm(2) (n.s.) whereas mean enddiastolic area decreased s ignificantly from 18 cm(2) to 15 cm(2) (p < 0.05). Accordingly there w as a downward and leftward shift of the diastolic pressure-area relati onship following administration of nitroglycerin. Conclusion: Echocard iographic automated border recognition seems to be a promising new on- line method in the detection of left ventricular cavity area changes u nderlining its potential usefulness in the evaluation of left ventricu lar performance.