Author: Melissa Colizza - CHU Sainte-Justine - Montreal, Quebec
Which of the following types of circulatory support requires the LOWEST level of systemic anticoagulation during combined heart-liver transplantation?
Combined heart-liver transplantation (CHLT) was first performed in 1984 and has become more frequent in the last decade. Indications have evolved to include metabolic diseases resulting in cardiomyopathy and end-stage liver disease leading to secondary heart failure. The most common indication for CHLT in the last decade was congenital heart disease with secondary liver disease. This was largely due to the growing number of patients palliated with a Fontan surviving to adulthood with concomitant Fontan-associated liver disease (FALD).
CHLT is most commonly performed in sequential manner with cardiac transplantation on CPB first, followed by weaning from bypass and subsequent liver transplantation. Heparin may or may not be fully reversed prior to liver transplantation. Sequential cardiac then liver transplantation leads to hemodynamic derangements and additional stress on the cardiac allograft, particularly during inferior vena cava clamping and hepatic reperfusion. Several circulatory support strategies have been utilized to minimize central venous hypertension and optimize systemic cardiac output, including venovenous bypass and venoarterial extracorporeal membrane oxygenation (ECMO).
Venovenous bypass (VVB) is the process during which blood is diverted from the infrahepatic IVC and portal vein and returned to the right heart via the axillary, subclavian, or internal jugular veins. The VVB circuit consists of heparin-bonded access catheters, a nonheparinized circuit, a centrifugal pump, and a blood warmer. There are options for an oxygenator and renal support. Anticoagulation management varies greatly across centers; VVB without anticoagulation has been described in the 1980s in circuits without an oxygenator, although more recent reports describe ACT targets like those used in VA ECMO. VA ECMO offers the benefits of full circulatory support of the heart and lungs, at the cost of greater levels of anticoagulation. The exact strategy for CHLT will depend on patient anatomy, cardiac allograft function, hemodynamic response to IVC test clamping and institutional preference.
There are case reports of simultaneous cardiac and liver transplantation while on full cardiopulmonary bypass (CPB). The benefits of performing both on CPB include the following, 1) a single period of reperfusion, 2) greater level of hemodynamic stability, particularly during liver reperfusion, 3) shorter cold ischemic time for the liver allograft, and 4) hemodynamic support of the newly transplanted heart with decreased venous congestion of the liver. However, en bloc liver and heart transplantation exposes patients to longer CPB duration and higher heparin doses.
Anesthetic management of CHLT is challenging and has been comprehensively reviewed by Smeltz and colleagues. Patient preparation should include large bore venous access for fluid administration and blood product transfusion, arterial line placement in location(s) with consideration of the bypass cannulation plan, and central venous access above the IVC clamping site. If VVB is planned, central venous access should include the femoral vein in addition to a return cannula to the superior vena cava. Patients undergoing CHLT often have elevated pulmonary vascular resistance (PVR) secondary to cardiac disease or portopulmonary hypertension, which is a risk factor for right ventricular dysfunction. Thus, vasoactive agents with minimal effects on pulmonary vascular resistance, such as vasopressin and norepinephrine, and pulmonary vasodilators are advantageous. Significant vasoplegia and bleeding are expected along with administration of large quantities of blood products. Frequent laboratory assessment of hemostasis with point of care testing is necessary, especially in patients palliated with a Fontan and heavy collateral burden. Ideally, there must be a balance between adequate tissue perfusion and avoidance of volume overload, pulmonary edema, and right ventricular dysfunction. Thus, there should be major consideration of factor concentrate use to manage coagulopathy.
Venovenous bypass requires the least amount of anticoagulation, especially with heparin-bonded circuits. VA ECMO generally requires higher levels of anticoagulation, but not as high as the anticoagulation required for full CPB.
Reardon LC, Lin JP, VanArsdell GS, et al. Orthotopic Heart and Combined Heart Liver Transplantation: the Ultimate Treatment Option for Failing Fontan Physiology. Curr Transplant Rep. 2021;8(1):9-20. doi: 10.1007/s40472-021-00315-4
Tracy KM, Matsuoka LK, Alexopoulos SP. Update on combined heart and liver transplantation: evolving patient selection, improving outcomes, and outstanding questions. Curr Opin Organ Transplant. 2023;28(2):104-109. doi: 10.1097/MOT.0000000000001041
Hofer RE, Christensen JM, Findlay JY. Anesthetic considerations for combined heart--liver transplantation in patients with Fontan-associated liver disease. Curr Opin Organ Transplant. 2020;25(5):501-505. doi: 10.1097/MOT.0000000000000800
Griffith BP, Shaw BW Jr, Hardesty RL, Iwatsuki S, Bahnson HT, Starzl TE. Veno-venous bypass without systemic anticoagulation for transplantation of the human liver. Surg Gynecol Obstet. 1985;160(3):270-272.
Barbara DW, Rehfeldt KH, Heimbach JK, Rosen CB, Daly RC, Findlay JY. The perioperative management of patients undergoing combined heart-liver transplantation. Transplantation. 2015;99(1):139-144. doi: 10.1097/TP.0000000000000231
Smeltz AM, Kumar PA, Arora H. Anesthesia for combined heart and liver transplantation. J Cardiothorac Vasc Anesth. 2021; 35:3350-3361. doi.org/10.1053/j.jvca.2020.12.005