An Analysis of the Pulsatile Hemodynamic Responses of the Pulmonary Circulation to Acute and Chronic Pulmonary Venous Hypertension in the Awake Dog

SUMMARY In this study we measured high fidelity pulsatile pressure and flow waveforms at the inlet to the pulmonary vascular bed to assess the differences in adaptation to acute and chronic pulmonary venous hypertension in awake dogs. Acute elevations in left atrial pressure (Pia) were effected by inflation of left atrial balloons, while chronic elevations were accomplished by placement of aorta to left atrial shunts. Pulmonary artery hydraulic impedance was calculated and analysis of these data revealed marked differences between the responses to acute and chronic elevations of left atrial pressure. The acutely stressed dogs (n = 12) had significantly decreased pulmonary vascula