Use of transesophageal echocardiography for postoperative evaluation of right ventricular function

Background. No method has been available to assess the right ventricular (RV) pressure–volume relation in the operating room or intensive care unit. Left ventricular cross-sectional area measured by echocardiography using the technology of automated border detection has been used to construct left ventricular pressure–area (P-A) loops. In the human right ventricle, however, this approach has not been validated. Methods. We recorded RV P-A loops in 14 patients in the intensive care unit using transesophageal echocardiography. Multiple RV P-A loops were obtained by reducing preload with intravenous nitroglycerin, thereby elucidating the end-systolic P-A relation. Results. With an incremental dose of dobutamine, the slope of the RV end-systolic P-A relation increased (from 4.56 ± 2.42 to 7.34 ± 3.62 mm Hg/cm2, p< 0.01), with no change in the x-axis intercept, which implied increased contractility. Furthermore, in the operating room we validated the use of RV cross-sectional area as a surrogate for RV volume by demonstrating the close correlation between the stroke area (maximal RV area minus minimal RV area) and stroke volume (r = 0.962; p< 0.0001). Conclusions. Tranesophageal echocardiography with automated border detection is a promising tool for elucidating RV function through the analysis of RV P-A loops.