Can hepatic vein flow study with transesophageal echocardiography during orthotopic liver transplantation predict early allograft dysfunction?

It was a pleasure to read the letter by Morita et al1 about the new hepatic vein flow index (HVFi) using intra-operative transesophageal echocardiography (TEE) during orthotopic liver transplant (OLT) as a predictor of early allograft dysfunction (EAD) and time for normalizing total bilirubin (TIME t-bil). Prompt recognition of EAD is crucial to improve survival in the post-transplant phase, the function of the new liver is followed by surgeons and intensivists through the monitoring of clinical signs and symptoms and laboratory blood test, even though they are well-known to have reduced sensitivity and specificity.2 Meanwhile, there is a growing interest in the literature in assessing other parameters with TEE as a part of the comprehensive evaluation during OLT.3-5 With this technique, Morita et al1 were able to show that a value of systolic HVFi of 23 and a value of diastolic HVFi of 15.7 predict EAD with an area under the receiver operative curve (ROC) of 0.751 and 0.782, respectively, while the cutoff levels to predict prolonged TIME t-bil were 27.7 and 17.9 for HVFi sys and HFVi dia, respectively, with an area under the curve of 0.751 and 0.782 in the first and second case. We congratulate the authors for these new data, and we would like to share some thoughts with them. First, the measurement of HVF should be done at the end of reperfusion phase and with the patient in stable hemodynamic condition; hypovolemia, postreperfusion syndrome, or the use of a high dose of vasoconstrictor could alter the measurements. As well as, a cardiac problem in relation to right or left ventricle can influence HVF. For the future, it would also be essential to clarify which kind of donors were studied, because the hemodynamic parameters of living or deceased donor after a brain or circulatory death can be different and the reconstruction of the outflow tract during living donor liver transplant is complex. Here, it is a vast field for research in liver transplant where the integration of the liver evaluation by intra-operative TEE can give information during surgery and potential postoperative prognosis. We hope that soon, this new index HVFi will be correlating with other noninvasive measurements such as the use of indocyanine green dye clearance test.2,6