[Analysis of the pressure-surface relation of the left ventricle with automatic echocardiographic contour detection]

Echocardiographic automatic border detection is a new on-line technique 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 administration of nitrates. In 12 patients with normal left ventricular function pressure-area relation was studied after a Swan-Ganz thermodilution catheter was placed in the wedge position and a high fidelity pig tail catheter was placed in the left ventricle. Left ventricular pressure and cyclic changes of cavity area were simultaneously analysed and displayed together as waveforms on the echo screen using a computer interfaced with the echo machine. All measurements were done before and five minutes after administration of 0.8 mg nitroglycerin. Mean systolic and diastolic blood pressure decreased significantly from 145/12 mmHg to 127/8 mmHg (p < 0.05). Mean systolic area decreased slightly from 10 cm2 to 9 cm2 (n.s.) whereas mean enddiastolic area decreased significantly from 18 cm2 to 15 cm2 (p < 0.05). Accordingly there was a downward and leftward shift of the diastolic pressure-area relationship following administration of nitroglycerin.

Echocardiographic automated border recognition seems to be a promising new on-line method in the detection of left ventricular cavity area changes underlining its potential usefulness in the evaluation of left ventricular performance.