RIGHT ATRIAL ISCHEMIA EXACERBATES HEMODYNAMIC COMPROMISE ASSOCIATED WITH EXPERIMENTAL RIGHT VENTRICULAR DYSFUNCTION

To determine the importance of right atrial function with acute right ventricular dysfunction, sequential right ventricular and right atrial ischemia were induced in 15 dogs. Right ventricular ischemia resulted in right ventricular free wall dyskinesia, right ventricular dilation by ultrasound, elevated right ventricular filling pressure and paradoxic septal motion. There were decrements in right ventricular systolic pressure (28.9 +/- 5.5 to 25.5 +/-4.6 mm Hg) (p < 0.05 for these and all subsequent values) and stroke work (5.66 +/- 0.94 to 2.66 +/- 0.62 g.m/m2), resulting in reductions in left ventricular preload, systolic pressure (123 +/- 11 to 97 +/- 12 mm Hg) and stroke volume (24.2 +/- 4.3 to 19.1 +/- 5.2 ml). Right atrial contractility was augmented, as indicated by increases in peak A wave amplitude (ratio of peak A wave to mean right atrial pressure 1.22 +/- 0.02 to 1.46 +/- 0.3) and right atrial stroke work (0.11 +/- 0.02 to 0.25 +/- 0.05 g.m/m2). Right atrial ischemia depressed right atrial contraction, as indicated by decreased A wave amplitude (ratio of peak A wave to mean right atrial pressure 1.46 +/- 0.3 to 1.04 +/- 0.2) and stroke work (0.25 +/- 0.05 to 0.04 +/- 0.01 g.m/m2). Right ventricular end-diastolic area decreased, right ventricular free wall dyskinesia increased and there were significant decreases in right ventricular systolic pressure (25.5 +/- 4.6 to 22.1 +/- 4.5 mm Hg) and stroke work (2.66 +/- 0.62 to 1.92 +/- 0.53 g-m/m2), with associated decrements in left ventricular systolic pressure (97 +/- 12 to 80 +/- 10 mm Hg) and stroke volume (19.1 +/- 5.2 to 15.2 +/- 4.9 ml). Therefore, ischemia renders right ventricular performance dependent on augmented right atrial transport. Ischemic depression of right atrial contractility compromises biventricular performance and exacerbates the hemodynamic compromise associated with right ventricular dysfunction.