Wave transmission in the pulmonary arterial system in disease in man.

Pulmonary capillary blood flow was measured by the nitrous oxide-body plethysmograph technique in 21 patients with valvular heart disease or pulmonary thromboembolism during routine diagnostic cardiac catheterization. The studies were performed with a high-frequency phonocardiogram recorded from the pulmonary area to indicate the pulmonary valve opening at the beginning of right ventricular ejection. The pulmonary artery to capillary flow conduction time was measured from the time of pulmonary valve opening to the foot of the pulmonary capillary flow pulse. The conduction time was greater than 160 msec when the pulmonary artery pressure was normal. The fall in the conduction time in disease indicated elevated pulmonary arterial pulse wave velocity and this correlated well with the level of pulmonary arterial pressure (correlation coefficient 0.92, P < 0.001). This suggests that there is a reduced pulmonary arterial distensibility in the chronic pulmonary hypertension of valvular heart disease and thromboembolic disorders. ADDITIONAL