Mechanical function of the main pulmonary artery

The relationship among the longitudinal strain, circumferential strain, lateral intravascular pressure, blood flow, and longitudinal motion was examined in the main pulmonary artery of living, open-chested dogs. Results indicate: 1) The mean value for longitudinal extensibility was 0.73% change in length per centimeter of water pressure (± .19 sd ± .04 sem). 2) The mean value for volume distensibility was 2.28% change in volume per centimeter of water pressure (± .9 sd ± .17 sem). 3) The magnitude of the radial vessel wall velocity is small. 4) The magnitude of the longitudinal vessel wall velocity, though small over most of the cardiac cycle, may become significant at the beginning of cardiac systole, especially during isoproterenol administration.