2023 FSA Podium and Poster Abstracts

P067: PLANNED VENOARTERIAL EXTRACORPOREAL MEMBRANE OXYGENATION FOR LIVER TRANSPLANTATION IN THE SETTING OF PULMONARY HYPERTENSION
Jennifer Lee, DO; Wesley Allen, MD; Ryan Chadha, MD; Stephen Aniskevich, MD; Courtney Scott, DO; Mayo Clinic Florida

Severe pulmonary hypertension is considered a contraindication to liver transplantation (LT) due to its high rate of mortality. The most dangerous stage of surgery is reperfusion of the donor graft since this is when significant hemodynamic instability and electrolyte abnormalities occur due to the release of inflammatory mediators, vasoactive substances, and potassium from the ischemic graft into the systemic circulation. During reperfusion, the heart is under enormous stress with risks for cardiac arrhythmias, profound hypotension, myocardial depression, and acute pulmonary artery hypertension. In this case, planned initiation of venoarterial extracorporeal membrane oxygenation (VA-ECMO) was used to bridge a patient with severe pulmonic valve stenosis through LT.

A 58-year-old male with end stage liver disease (ESLD), status post ross procedure and severe prosthetic pulmonic valve prosthesis with an estimated right ventricular systolic pressure (RVSP) of 61 mmHg with associated chamber dilation underwent liver transplantation. A high-risk multidisciplinary committee met prior to transplantation to discuss the intra-operative risks associated with the surgery and the patient’s comorbidities. Due to the high risk for right ventricular collapse, liver transplantation on planned VA-ECMO was done. After incision and exposure, 2000 units of heparin was administered, the arterial cannula placed into the right common femoral artery, and the venous cannula placed into the left common femoral vein. ECMO was initiated and maintained with flows at 2 liters/minute. Intraoperative transesophageal echo (TEE) showed severely enlarged right ventricle with normal systolic function, moderate tricuspid valve regurgitation, moderate-severe pulmonary valve stenosis, and preserved left ventricular ejection function. Upon reperfusion, acute right-sided chambers dilation and dysfunction and signs of right ventricular pressure overload was noted with concomitant reduced left ventricular filling as evidenced by atrial septal bowing, RV distention, ventricular septal flattening, and moderate RV dysfunction on TEE. 500mg of calcium was given with ECMO flows maintained at 2.0 liters/minute. Right ventricular function improved, returned to baseline 5 minutes post reperfusion, and patient remained hemodynamically stable through reperfusion. ECMO was subsequently discontinued and the patient decannulated prior to abdominal closure. No complications were noted with caval anastomosis or increased hemorrhage.

In this case, we report the successful use of VA-ECMO to manage a patient with severely elevated right ventricular afterload undergoing LT. VA-ECMO reduces ventricular workload by the equivalent of the programmed flow rate and provides support for the high-risk liver transplant population. The safety and logistics of this approach requires multidisciplinary coordination between anesthesiology, cardiothoracic and transplant surgery, cardiology, and critical care. Although VA-ECMO has the benefit of hemodynamic support/stability, it has intrinsic risks and planning for critical events is paramount. Treatment algorithms for managing severe coagulopathy, ECMO pump failure and intra-cardiac thrombus were established prior to transplantation. ECMO venous cannulation located in the inferior vena cava (IVC) can affect full clamping of the IVC prior to the anhepatic stage. Large volume shifts affect ECMO flow and anticoagulation increases bleeding. In summary, ECMO is a feasible option in high-risk patients, however, multidisciplinary planning and careful consideration of complications and risks with ECMO during liver transplantation is important.