Acute right ventricular dilatation in response to ischemia significantly impairs left ventricular systolic performance

Background-Right ventricular (RV) dilatation that occurs as a consequence o f RV infarction is thought to produce hemodynamic instability by reducing l eft ventricular (LV) preload and compliance. We hypothesized that these geo metric changes may also adversely affect LV systolic performance. Methods and Results-Twelve 40-kg pigs were studied. Integrated conductance catheters and micromanometers were placed in both the LV and RV to allow si multaneous recordings of pressure and volume and derivation of indices of c ontractile function. RV ischemia was induced by balloon occlusion of the pr oximal right coronary artery (RCA) under 3 conditions: 1) with the pericard ium intact, 2) with the pericardium intact and inotropic support, and 3) wi th the pericardium wide open. With an intact pericardium, RCA occlusion pro duced a decrease in LV end-diastolic volume associated with a marked declin e in the contractile function. With the pericardium open, the same ischemic insult resulted in both LV and RV dilatation, which produced a significant ly smaller negative effect on cardiac output (P=0.03), LV systolic pressure (P=0.02), LV preload-recruitable stroke work (P<0.01), and LV end-systolic pressure-volume relations (P<0.01). Similarly, administration of dobutamin e during RCA occlusion decreased the ventricular volume changes and produce d a relative improvement in LV contractile performance. Conclusions-The hemodynamic compromise seen in association with acute RV di latation within an intact pericardium is partly attributable to impaired LV systolic performance and cannot be wholly ascribed to changes in LV preloa d or compliance.