HEPATIC BLOOD-FLOW AND RIGHT-VENTRICULAR FUNCTION DURING CARDIAC-SURGERY ASSESSED BY TRANSESOPHAGEAL ECHOCARDIOGRAPHY

Objective: To determine the effect of cardiopulmonary bypass (CPB) on hepatic blood flow (HBF) and the hepatic venous flow pattern. Design: Single-arm prospective study. Setting: University hospital operating r oom and intensive care unit. Participants: Eight patients ranging in a ge from 57 to 73 years undergoing cardiac surgery. Interventions: Tran sesophageal echocardiography (TEE) was used to assess HBF before, duri ng, and after CPB by pulsed-wave Doppler ultrasound recordings of hepa tic venous flow velocity and two-dimensional recordings of the hepatic vein diameter. Hepatic vein oxygenation was monitored by hepatic vein catheterization, and gastric intramucosal pH (pH(i)) was followed by tonometry. Measurements and Main Results: The HBF was unchanged after the start of CPB but was reduced from the baseline value 415 (standard error of the mean 40) mL/min to 225 (25) mL/min during hypothermic CP B (p < 0.05). Cardiac index, right ventricular ejection fraction, and arterial and tonometric pH were essentially unchanged during the study period. Hepatic vein and mixed venous saturation were unchanged compa red to control during CPB and were reduced at 2 and 3 hours after CPB (p < 0.01). Six of the patients had a normal predominant systolic flow pattern before surgery. In the postoperative period, seven patients s howed an abnormal predominant diastolic filling pattern. Conclusions: TEE represents a useful tool in assessing changes in the hepatic blood flow. The HBF was reduced during hypothermic CPB, but this was not ac companied by a reduced pH(i). The changes in the venous flow pattern w ith a reduction in systolic flow could be explained by impaired atrial relaxation. Copyright (C) 1996 by W.B. Saunders Company.