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 room and intensive care unit.

PARTICIPANTS

Eight patients ranging in age from 57 to 73 years undergoing cardiac surgery.

INTERVENTIONS

Transesophageal echocardiography (TEE) was used to assess HBF before, during, and after CPB by pulsed-wave Doppler ultrasound recordings of hepatic 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 (pHi) 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 CPB (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 compared 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 showed 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 accompanied by a reduced pHi. The changes in the venous flow pattern with a reduction in systolic flow could be explained by impaired atrial relaxation.