Use of cadaveric superior mesenteric artery as interpositional vascular graft in orthotopic liver transplantation

Experimental results and clinical impact of using autologous rectus fascia sheath for vascular replacement

Vascular complications are major causes of graft failure in liver transplantation. The use of different vascular grafts is common but the results are controversial. The aim of this study was to create an 'ideal' arterial interponate for vascular replacements in the clinical field. An autologous, tubular graft prepared from the posterior rectus fascia sheath was used for iliac artery replacement in dogs for 1, 3, 6 and 12 months. Forty-one grafts were implanted and immunosuppression was used in separate groups. The patency rate was followed by Doppler ultrasound. Thirty-seven grafts remained patent, 2 cases with thrombosis and 2 cases with stenosis occurred. There was no evidence of necrosis or aneurysmatic formation. The histological analysis included conventional light microscopic and immunohistochemical examinations for CD34 and factor VIII. The explanted grafts showed signs of arterialisation, appearance of elastin fibres, and smooth muscle cells after 6 months. Electron microscopy showed intact mitochondrial structures without signs of hypoxia. In conclusion, the autologous graft presents acceptable long-term patency rate. It is easy to handle and the concept of beneficial presence of the anti-clot mesothelium until endothelialisation seems to work. The first clinical use was already reported by our group with more than 2 years survival.

Thrombotic and nonthrombotic hepatic artery complications in adults and children following primary liver transplantation with long-term follow-up in 1000 consecutive patients*

Arterial complications have a major impact on survival after liver transplantation (LTx). The aim of this study was to examine arterial complications in adults and children after LTx. A total of 1000 consecutive primary LTx patients [mean age 40.5 years: 600 males, 400 females, 834 adults; 166 children (age <18 years)] were studied. Forty-two patients (4.2%; 31 adults, 11 children) developed hepatic artery thrombosis (HAT). Thrombosis in children occurred significantly early (mean 5.4 days) compared with adults (mean 418.7 days, P = 0.0001). Nonthrombotic complications occurred in 30 patients (29 adults, one child). Overall, 13-year patient survival after HAT was 43.2% (72.7% children, 32.9% adults). For nonthrombotic complications, 54.3% of adults died and 69.4% grafts were lost. An overall incidence of 4.2% thrombotic and 3.2% nonthrombotic complications was observed. Rate of HAT was higher in children, but survival was better compared with adults.

ARTERIAL VASCULAR CONDUITS IN ADULT ORTHOTOPIC LIVER TRANSPLANT RECIPIENTS

BACKGROUND

Vascular conduits may be required to gain arterial inflow to the donor hepatic artery in orthotopic liver transplantation.

METHODS

From January 1986 to December 2003, arterial conduits were required in 31/582 (5.3%) adult liver transplant procedures.

RESULTS

Indications for the conduit included recipient hepatic artery problems (20); hepatic artery thrombosis previous allograft (7) and other (4). The conduits used in 28/31 cases (90%) were deceased donor iliac arteries and the remainder prosthetic grafts. Patients requiring conduits were more likely to be already hospitalized (P = 0.038) or undergoing a retransplant procedure (P = 0.001) than patients not requiring conduits. Both sepsis and haemorrhage caused death in 8/31 (26%) patients requiring conduits versus 42/551 (7.6%) patients not requiring conduits. Death from thrombosis of the iliac artery conduit occurred in two cases and from bacterial infection of a prosthetic conduit in one case. For retransplant procedures, allograft loss was seen in 11/13 (84%) conduit cases versus 11/28 (39%) non-conduit cases (P = 0.016). Overall allograft survival was significantly lower in the conduit cases than in the non-conduit cases (P = 0.0001), with 12/31 (39%) allografts being lost within the first 3 months post-transplantation for the conduit cases.

CONCLUSION

Arterial vascular conduits are more commonly required in adult liver transplant recipients who are hospitalized or undergoing retransplant procedures. Allograft survival is poorer in the conduit cases and is associated with complications, particularly sepsis and haemorrhage, following retransplantation procedures.

Back-Table Arterial Reconstructions in Liver Transplantation: Single-Center Experience

Anatomic variations of the arterial supply to donor liver grafts often require complex hepatic artery reconstructions on the back table. Therefore, because of the additional anastomoses, there is a greater risk of arterial thrombosis and graft loss. Among the 620 orthotopic liver transplantations (OLT) in 549 adult and pediatric patients performed from June 1983 through August 2004, the rates and types of donor hepatic artery variations (HAV) and the type of reconstructions were reviewed as well as the 1- and 5-year grafts and patient survival rates after OLT. At least 1 HAV was present in 133 liver grafts (21.4%). The most frequent variations were as follows: right hepatic artery (RHA) from superior mesenteric artery (SMA) (44 cases); RHA from aorta (4 cases); and RHA from SMA, combined with a left hepatic artery (LHA) from left gastric artery (3 cases). No graft was discarded. Fifty-six of 133 (42%) HAV required arterial reconstructions, generally a termino-terminal (TT) anastomosis between RHA and splenic artery (26 cases, 46.4%). Less frequently performed anastomoses were the "fold-over" technique (15 cases, 26.8%) and the anastomosis between the RHA and the gastro-duodenal artery (6 cases, 10.6%); rare reconstructions were performed in 9 cases (16.0%). The rate of hepatic artery thrombosis was 5.4% (3 of 56 OLT) in complex hepatic artery reconstructions and 2.2% in other grafts. One- and 5-years graft and patient actuarial survival rates have been respectively 73.2%- 71.4% in hepatic artery reconstructions and 78.6%-76.8% in the absence of an artery reconstruction, respectively.

Use of donor aorta for arterial reconstruction in paediatric liver and multivisceral transplantation

BACKGROUND

Arterial reconstruction remains the most important technical issue in paediatric transplantation. The arteries of paediatric donors as well as recipients are small and friable. The aim of this study was to assess the use of the donor aorta as a conduit for arterial reconstruction in paediatric liver and multivisceral transplantation.

METHODS

Between June 1994 and January 2002, 284 paediatric transplants, including 197 cadaveric liver and multivisceral transplants, were performed in children at this centre. Of these, 41 (20.8 per cent), including nine cadaveric liver transplants and 32 multivisceral transplants, were revascularized by donor aortic reconstruction. Patient demographics, types of donor arterial reconstruction, technical complications and incidence of hepatic artery thrombosis were reviewed.

RESULTS

None of the 41 donor aortic reconstructions used in revascularization of paediatric liver and multivisceral transplants thrombosed. There were no bleeding complications and no pseudoaneurysms developed.

CONCLUSION

Arterial reconstruction using donor aorta is a useful option with a low incidence of thrombosis in paediatric transplantation.

Experimental vascular graft for liver transplantation

Hepatic artery thrombosis is a major cause of graft failure in liver transplantation. Use of donor interponates are common, but results are controversial because of necrosis or thrombosis after rejection. Reperfusion injury, hypoxia and free radical production determinate the survival. The aim of the study was to create an 'ideal' arterial interponate. Autologous, tubular graft lined with mesothelial cells, prepared from the posterior rectus fascia sheath, was used for iliac artery replacement in eight mongrel dogs for six months under immunosuppression. Patency rate was followed by Doppler ultrasound. Eight grafts remained patent and another two are patent after one year. The patency rate was good (median Doppler flow: 370 cm/sec) and there was no necrosis, thrombosis or aneurysmatic formation. The grafts showed viable morphology with neoangiogenesis, appearance of elastin, smooth muscle and endothelial cells. Electron microscopy showed intact mitochondrial structures without signs of hypoxia. Tissue oxygenation was good in all cases with normal (< 30 ng/ml) myeloperoxidase production. In conclusion, this autologous graft presents good long-term patency rate. Viability, arterialisation and low thrombogenicity are prognostic factors indicating usability of the graft in the clinical practice without the risk of rejection. Further investigations such as cell cultures and standardisation are necessary.