Effects of acute hemodynamic alterations on pulmonic valve motion. Experimental and clinical echocardiographic studies.

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Abstract
The purpose of this study was to assess the effects of acute alterations of the pulmonary circulation on the pulmonic valve echocardiogram. We measured the pulmonic valve opening velocity (PVOV) and right-sided systolic time intervals (right ventricular preejection period-to-right ventricular ejection time ratio [RPEP/RVET] in 22 open-chest dogs subjected to acute hemodynamic alterations produced by inferior vena cava constriction, atrial pacing, isoproterenol infusion and microsphere embolization of the pulmonary artery. We found only fair correlations between PVOV and peak pulmonary artery flow (r = 0.56), right ventricular dp/dt (r = 0.43), stroke volume (r = 0.42), pulmonary artery systolic pressure (r = 0.33) and peak pulmonary artery acceleration (r = 0.31). RVET was shortened by reduced venous return (caval constriction) and by increases in heart rate (atrial pacing and isoproterenol), which resulted in increases in RPEP/RVET that did not correspond well to simultaneous changes in pulmonary artery pressure. In seven patients breathing 10% O2 to raise pulmonary artery pressure acutely, we found no change or a fall in PVOV. Thus, the pulmonic valve echocardiogram is influenced by multiple factors relating to parameters of pulmonary flow and right ventricular contractility, and may be of limited clinical usefulness in predicting pulmonary artery pressures.