Echocardiographic estimation of pulmonary artery pressure in transposition of the great arteries.

To determine their usefulness in estimating pulmonary artery pressure, left ventricular systolic time intervals (STI) were determined by echocardiography in 65 patients with dextro-transposition of the great arteries (TGA). The STI were measured from recordings of pulmonary valve motion at 100 mm/sec paper speed. The pre-ejection period (PEP) and the ratio of PEP to left ventricular ejection time (PEP/LVET) were directly related to pulmonary artery pressure. The strongest correlations were that between PEP/LVET and pulmonary artery diastolic pressure (r = 0.70) and that between PEP/LVET and the ratio of mean pulmonary pressure to mean systemic pressure (r = 0.71). A value of PEP/LVET of less than 0.26 was consistently associated with pulmonary artery diastolic pressures of less than 20 mm Hg and, in 28 of 31 patients, pulmonary artery pressure less than one-third of mean systemic arterial pressure. Pulmonary hypertension was present in 18 of 22 patients with PEP/LVET of 0.30 or greater; elevated PEP/LVET was also present in four patients with abnormalities of cardiac rhythm or conduction, two of whom also had angiographic evidence of myocardial dysfunction.