Abstract 19690: Left Atrial Pressure and the Inotropic State Determine Right Ventricular Pulsatile Vascular Load in the Normal Pulmonary Circulation. A Wave-Intensity Analysis

Introduction: In chronic patients, the relationship between pulmonary vascular resistance (PVR) and pulmonary compliance (C) depends on their pulmonary wedge pressure values. However, whether this is a physiological reflex or a chronic consequence of type-2 pulmonary hypertension remains unknown. The present study characterized the acute determinants of the PVR-C relationship in the healthy pulmonary circulation using wave intensity analysis (WIA). Methods: In 22 open-chest pigs we measured high-fidelity pressure and transit-time pulmonary artery flow at baseline, during beta-adrenergic modulation (dobutamine 2.5 ug/Kg/min), acute volume loading, and LV myocardial ischemia. Wave speed was obtained from early P-Q linear relationship and used to compute WIA. Repeated measures within-subjects were analyzed using linear mixed effects models. Results: Hemodynamic interventions induced a wide range of left atrial pressures (LAP: 3 to 20 mmHg). PVR and C varied extensively by u003e 280 and 120%, respectively. Pulmon...