Hemodynamic interaction between portal vien and hepatic artery flow in small-for-size split liver transplantation

Abstract

In split-liver transplantation, the entire portal flow is redirected through relatively smallfor-size grafts. It has been postulated that excessive portal blood flow leads to graft injury. In order to elucidate the mechanisms of this injury, we studied the hemodynamic interactions between portal veinand hepatic artery flow in an experimental model in pigs. Six whole pig liver grafts were implanted in Group 1 (n = 6) and six whole liver grafts were split into right and left grafts and transplanted to Groups 2 (n = 6) and 3 (n = 6), respectively. The graftto-recipient liver volume ratio was 1:1, 2:3 and 1:3 in Groups 1, 2 and 3 , respectively. Portal vein-and hepatic artery flows were measured with an ultrasonic flow meter at 60,120 and 180min after graft reperfusion. Portal vein pressure was also recorded at the same time intervals. Graft function was assessed at 3,6h and 12h, and morphological changes at 12h after reperfusion. Following reperfusion, portal vein flow showed an inverse relationship to graft size, while hepatic artery flow was reduced proportionately to graft size. The difference was significant among the three groups (P<O.O5). Portal vein pressure was significantly higher in group 3, compared to groups 1 and 2 (P < 0.05). Hepatic artery buffer response was significantly higher in Group 3, compared to Groups 1 and 2 in relation to preocclusion values (P < 0.05). Splitliver transplantation, when resulting in small-for-size grafts, is associated with portal hypertension, diminished arterial flow, and graft dysfunction. Arterial flow impairment appears to be related to increased portal vein flow.

Splenectomy improves survival by increasing arterial blood supply in a rat model of reduced-size liver

“…caused by associated suppression of the intrahepatic flow and thus less sinusoidal shear stress [7,19,32]. However, reduction in total hepatic inflow in simultaneously splenectomized and hepatectomized animals was marginal and not that pronounced what it would take to improve survival by reduced shear stress.…”

“…As a consequence of portal venous hyperperfusion in reduced-sizelivers, HABR may lead to hepatic arterial hypoperfusion [18,19]. For the reason that the regenerating liver requires an enormous amount of oxygen for its increased metabolic load and for DNA synthesis, suboptimal arterial inflow may be poorly tolerated in the reduced-size-liver and may increase the risk for organ dysfunction [20].…”

Tacrolimus dosage requirements in living donor liver transplant recipients with small-for-size grafts

“…The first possible mechanism is that as the graft size in group S was smaller than in group N, it did not meet the demands of metabolism. SFS grafts have a relatively small liver mass because the GRBW is less than 0.8% and severe ischemic injuries caused by decreased hepatic arterial inflow or even hepatic artery thrombosis can occur [13][14][15] . Fukatsu et al [8] reported that graft hepatic weight was significantly correlated with clearance of tacrolimus in adult patients who had undergone LDLT, and Sugawara et al [16] reported that the optimal tacrolimus dose was best correlated with GV/SV ratio.…”

Split liver transplantation: What’s unique?

“…Portal blood flow removes adenosine that has a local vasodilator effect on the arterial system [46,47] . However, an exaggerated HABR may contribute to ischemic injury in states of portal hyperfusion, as seen in small for size grafts [48,49] . Prophylactic splenic artery modulation [50,51] produced a significant reduction in portal flow causing a significant reduction in incidence of SFSS.…”