Trasplante hepático en pacientes con trombosis portal: manejo intraoperatorio y resultados / Hepàtico transplant in patients with thrombosis vestibule: intraoperating handling and results

Antedecentes: La trombosis de la vena porta (TVP) es una complicación del paciente cirrótico que previamente era considerada una contraindicación para el trasplante hepático. Objetivos: Describir los resultados y evolución alejada de una serie consecutiva de trasplantes hepáticos realizados en pacientes portadores de TVP y analizarlos comparativamente con pacientes trasplantados sin TVP. Lugar de aplicación: Programa de trasplante hepático de una hospital público. Diseño: Retrospectivo, longitudinal, descriptivo. Material y Método: Entre julio de 1995 y junio del 2006, se realizaron 26 trasplantes hepáticos en pacientes con TVP (8,7%). Se analizaron factores de riesgo para TVP, variables del trasplante y del postrasplante. Se realizó un análisis comparativo con 273 pacientes trasplantados sin TVP. Resultados: 53,8% varones, edad 40,7 años. La TVP fue un hallazgo intraoperatorio en el 65%. Etiologías: cirrosis postnecróticas 73%, hepatopatías colestáticas 23% y fibrosis hepática congénita 4%. El 61,5% Child-Pugh C. Se realizó trombectomia en 21 pacientes con TVP Grados I, II y IV e injerto mesentérico portal extra-anatómico en 5 pacientes con TVP Grado III. La morbilidad fue del 57,7% la recurrencia de la TVP de 7,7% y la mortalidad durante la internación 26,9%. El trasplante en TVP presentó un incremento en el requerimiento de hemoderivados y en el índice de reoperaciones. La supervivencia al año fue 59,6% 75,2% para el Grado I y 44,8% para el Grado 2, 3 y 4. Conclusiones: La TVP no es contraindicación para el trasplante, su variedad más frecuente es el grado 1 y la técnica más empleada es trombectomía. El trasplante en pacientes con TVP demostró mayor requerimiento de hemoderivados, incidencia de complicaciones y de retrombosis portal y se asoció a una menor supervivencia en TVP grados 2, 3 y 4.

Immunodepletion in xenotransplantation.

Xenograft transplantation is perhaps the most immunologically difficult problem in transplantation today. An overwhelming hyperacute rejection reaction (HAR) occurs within minutes of organ implantation. Preformed antibodies are thought to initiate this process. We used a pig-to-dog renal xenograft transplant model and investigated methods of decreasing the severity of hyperacute rejection. Female pigs weighing 15-20 kg were used as donors. Recipients were mongrel dogs weighing 15-25 kg. Experimental dogs were all given a number of treatments of IgG depletion using an antibody removal system (Dupont-Excorim). This machine immunoadsorbs plasma against a column containing immobilized staphylococcal protein A, which is known to bind the IgG Fc receptor. An 84% reduction in the IgG levels and a 71% reduction in IgM levels was achieved. Postoperative assessment was made of urine output, time to onset of HAR, and histopathological examination of the rejected kidneys. Although cross-matches between donor lymphocytes and recipient sera remained strongly positive in the treated dogs, there was a two- to fourfold reduction in the titers. The time to onset of HAR was prolonged in the experimental group, and the urine output was increased slightly. The histopathologic changes in the experimental group generally showed signs of HAR, but of less intensity than in the nonimmunodepleted control group.

The UW solution for canine kidney preservation. Its specific effect on renal hemodynamics and microvasculature.

The preservation effects of UW solution on renal hemodynamics and microvascular systems were studied in canine kidney autografts. In 72-hr UW-preserved kidneys, the microvessels of both cortex and medulla were completely visualized with silicon rubber compound 1 hr after reperfusion. Histology also showed extremely well-preserved arterioglomerular and tubular systems. These results were correlated with good renal blood flow, prompt recovery of posttransplant graft function, and 100% two-week survival of dogs. In contrast, kidneys preserved for 72 hr with Euro-Collins solution showed necrotic and obstructive changes of the microvasculature and deterioration of renal hemodynamics. In 120-hr UW-preserved kidneys, the microcirculation of the medullary region became poor after reflow when there was fairly intact perfusion of the cortical region, indicating an ischemia-related intrarenal blood flow maldistribution. The 120-hr kidneys subsequently failed in spite of having a good blood flow and morphologically well-maintained microvasculature after reperfusion. These data demonstrated that much, but not all, of the beneficial effect of UW solution in kidney preservation might be attributed to its remarkable protection of renal microvasculature. Correction of intrarenal blood maldistribution caused by a discrepancy in tolerance to ischemia of the vascular and tubular systems might be important in successfully preserving the kidney for 120 hr.

Comparison of UW with other solutions for liver preservation in dogs.

The efficacy of the University of Wisconsin (UW) solution was compared with conventional Euro-Collins solution, as well as with 3 variants of a silica gel solution developed at the University of Minnesota (UM). Protection of the liver grafts with UW was superior after 24 hour preservation, although the results were inferior to those with immediate transplantation, as judged by animal survival, liver function tests, coagulation, and histopathologic parameters. The UM-III solution allowed similar animal survival as with the UW solution. Lactobionate and raffinose that are contained in both the UW and UM-III solutions were thought to be essential constituents for long-term preservation of liver grafts. The study not only establishes, under controlled circumstances, the superiority of the UW solution, but it also provides insight about the reasons for its effectiveness as well as a caution against its over exploitation.