Echocardiographic evaluation of pulmonary artery distensibility

The aim of this study was to verify the hypothesis that pulmonary artery (PA) distensibility may modify the pattern of right ventricular ejection. Pulmonary artery distensibility was evaluated with M-mode measurements of right pulmonary artery diameter from suprasternal notch simultaneous with pulmonary pressure measurements. Pulmonary artery pressure was measured in 19 subjects, 29 to 75 years old (mean age, 49 years). Pulmonary artery systolic pressure was 22 to 108 mm Hg (mean, 52 mm Hg). Pulmonary artery pressure strain modulus (Ep) was calculated as follows: PADD x (PASP-PADP)/PADD-PADS (PADS-PA diameter in systole, PADD-PA diameter in diastole, PASP-PA systolic pressure, PADP-PA diastolic pressure) was 6 +/- 8 10(5) dynes/cm2. Right ventricular outflow tract velocity was recorded with pulsed Doppler echocardiography and acceleration times (AT) and ejection times (ET) were measured. Log Ep was correlated with pulmonary artery systolic and mean pressure (r = 0.90 and r = 0.87, p < 0.0001) but not with age (r = 0.30, p = NS). Acceleration time and AT/ET ratio were correlated with log Ep (r = 0.73 and r = 0.76, p < 0.001) and with pulmonary artery mean pressure (r = 0.91 and r = 0.89, p < 0.0001). When pulmonary artery pressure was included in multiple analyses, the relationships between Doppler indices and elastic modulus did not prove to be significant. These findings emphasize the independence of Doppler right ventricular outflow tract velocity indexes used for noninvasive evaluation of pulmonary hypertension from pulmonary artery distensibility in a clinical setting.