Vascular complications after living donor liver transplantation are one of the most feared problems which frequently result in graft and patient loss. The leading causes of these complications are mostly due to challenging anatomical problems in the living donor. These problems can be divided into four groups.

1. Problems regarding vena cava inferior:
Retrohepatic vena cava may not exist in the recipient. The venous circulation of the lower extremity and kidney is provided by the collateral veins. In these cases the venous drainage of the partial liver graft is generally assured by the vena cava inferior present at the level of diaphragm. On the other hand if the venous circulation of the kidney of the patient is supplied by v. azygous system, an attempt to recreate the vena cava inferior should not be done (1).

2. Problems regarding hepatic venous system:
The necessity of providing venous drainage to the right anterior sector of a right lobe graft is controversial (2,3). The middle hepatic vein was included in the right lobe graft in the original design (4), but many transplant centers avoided this procedure assuming that the risk to the donor would substantially increase (5,6). However congestion and failure in the graft did occur without provision of the hepatic venous drainage to the right anterior sector(4,5). Therefore the crucial point in the venous drainage of the anterior sector in right lobe living donor liver transplantation is direct or indirect anastomosis of the segment V and VIII hepatic veins to the inferior vena cava by variable reconstruction methods (5,7,8).

3. Problems regarding vena porta:
Adult-to-adult right lobe living donor liver transplantation (LDLT) has become popular, because it provides a larger size liver graft that is necessary for adult recipients. However anomalous portal venous branching (APVB) resulting in two venous openings in a right lobe graft is one of the most common anatomic variations encountered during evaluation of a living donor candidate. Several authors reported the incidence of anatomic variations of the portal vein as 6% - 22% (9,10). Reconstruction of these vessels during transplantation can be challenging and even donors with such APVB had often been disqualified as right lobe donors (11). Several reconstruction methods have been attempted for this anomaly and thus donors with such APVB became available for right lobe liver grafts (12,13). However, all these surgical techniques have their pitfalls.

4. Problems regarding hepatic artery:
Hepatic artery reconstruction is one of the crucial steps for living donor liver transplantation. Arterial complications including thrombosis, stenosis and aneurysm formation are life threatening in living donor liver transplantation leading to graft failure and irreversible biliary damage. Arterial reconstruction has remained as a major problem in living donor liver transplantation due to small diameter until introduction of microvascular anastomosis techniques by surgical microscopes or loupes. The incidence of arterial thrombosis has declined dramatically from 25% without a microscope to 0-3.8% with a microscope (14,15,16). Nevertheless, technical failure of the reconstruction usually leads to retransplantation or even death and the procedure is complicated by anatomical variations (e.g. two hepatic erteries to the right lobe), vascular consistency and the hemodynamic situation of the recipients during the operations.

References:

1. Hatipoglu S, Olmez A, Ozgor D, Kayaalp C, Yilmaz S. Living donor liver transplantation in the absence of inferior vena cava: a case report. Transplant Proc. 2012 Jul-Aug;44:1761-3.
2. Yu PF, Wu J, Zheng SS. Management of the middle hepatic vein and its tributaries in right lobe living donor liver transplantation. Hepatobiliary Pancreat Dis Int. 2007 Aug;6(4):358-63.
3. Lee S, Park K, Hwang S, Lee Y, Choi D, Kim K, Koh K, Han S, Choi K, Hwang K, Makuuchi M, Sugawara Y, Min P. Congestion of right liver graft in living donor liver transplantation. Transplantation. 2001 Mar 27;71:812-4.
4. Fan ST, Lo CM, Liu CL, Wang WX, Wong J. Safety and necessity of including the middle hepatic vein in the right lobe graft in adult-to-adult live donor liver transplantation. Ann Surg. 2003 Jul;238:137-48.
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8. Hwang S, Jung DH, Ha TY, Ahn CS, Moon DB, Kim KH, Song GW, Park GC, Jung SW, Yoon SY, Namgoong JM, Park CS, Park YH, Park HW, Lee HJ, Lee SG. Usability of ringed polytetrafluoroethylene grafts for middle hepatic vein reconstruction during living donor liver transplantation. Liver Transpl. 2012 Aug;18:955-65.
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13. Xu M, Yan L, Zhao J, Li B, Wen T, Zeng Y, Ma Y, Wang W, Yang J, Chen Z. U-graft anastomosis for anomalous portal venous branching reconstruction in right lobe living donor liver transplantation. Liver Transpl. 2007 Jul;13:1062-4.
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16. Enne M, Pacheco-Moreira L, Balbi E, Cerqueira A, Alves J, Valladares MA, Santalucia G, Martinho JM. Hepatic artery reconstruction in pediatric living donor liver transplantation under 10 kg, without microscope use. Pediatr Transplant. 2010 Feb;14:48-51.