[MECHANISMS OF THE PULMONARY CIRCULATORY CHANGES FOLLOWING EXPERIMENTAL PULMONARY THROMBOEMBOLISM]

In acute experiments the pulmonary hemodynamics changes following pulmonary embolism were studied in rabbits with intact circulation and isolated lungs perfusion. In both cases the pulmonary vascular resistance increased to the same extent. The pulmonary artery pressure following pulmonary embolism in intact animals increased less, than in the case of isolated lungs perfusion, because the pulmonary artery flow decreased. The experiments with the restriction of the inferior vena cava flow have revealed that pulmonary artery pressure and flow decreased, where the pulmonary artery flow was reduced in the same level as following pulmonary embolism. At the same time the pulmonary vascular resistance was increased in two times less, than following pulmonary thrombosis. Thus we concluded, that following pulmonary embolism the pulmonary artery pressure is dependent on the pulmonary artery flow and pulmonary vascular resistance. The pulmonary artery flow changes are caused by the venous return and right ventricular contractility changes and not correlated with the pulmonary vascular resistance alterations.