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 > 280 and 120%, respectively. Pulmonary C inversely correlated with PVR, and LAP (p< 0.0001 for both; Figure Panel A). Inotropic stimulation significantly increased the intensity of forward and backward compression waves (BCW; p< 0.001). The intensity of the BCW also independently determined C, in addition to PVR and LAP (p< 0.00001; Figure Panel B).
Conclusions: Beyond PVR, LAP and the inotropic state determine the RV pulsatile vascular load. This is a physiological effect in the healthy subject, and is not consequence of chronic pulmonary vascular or parenchymal remodeling. LAP contributes to RV dysfunction by acutely increasing pulmonary afterload.
Author Disclosures: C. Pérez del Villar: None. J. Bermejo: None. P. Martinez-Legazpi: None. D. Rodríguez-Pérez: None. J. Antoranz: None. M. Desco: None. E. Gutierrez: None. Y. Benito: None. A. Barrio: None. F. Fernández-Avilés: None. R. Yotti: None.
- © 2016 by American Heart Association, Inc.