Effects of respiratory cycle on pulmonary venous flow and cardiac cycle onpulmonary venous diameter of dogs: A transesophageal echocardiography study

We investigated 12 anesthetized normal dogs using transesophageal echocardi ography to understand the effects of respiration on the pulmonary venous fl ow. Additionally, we observed whether the diameter of the pulmonary vein ch anges with the heart beat. The pulsed Doppler wave form of pulmonary venous flow predominantly demonstrated two backward flows, with one peak occurrin g during ventricular systole and another during ventricular diastole. Somet imes a small forward flow occurred during left atrial contraction. In compa rison with expiration, the peak velocity and velocity-time integral of the flow wave under inspiration occurred during both systole and diastole were significantly smaller. The diameter of the pulmonary vein decreased during left atrial contraction and increased during left ventricular systole and d iastole.