Portal vein grafts in hepatic transplantation

Confirmation of patency of the portal vein by either ultrasound or angiography is a routine part of the evaluation of patients being considered for hepatic transplantation. Complete thrombosis of the portal vein usually has been viewed as precluding successful orthotopic hepatic replacement. In addition, some pediatric patients present with extremely small portal veins which, although patent, have proved to be thick walled and sclerotic. Our recent experience has shown that, in both of these situations, successful and complete revascularization of hepatic allografts is quite feasible by using a vein graft to ensure adequate portal venous flow

The asymptotic regimes of tilted Bianchi II cosmologies

In this paper we give, for the first time, a complete description of the dynamics of tilted spatially homogeneous cosmologies of Bianchi type II. The source is assumed to be a perfect fluid with equation of state $p = (\gamma -1) \mu$, where $\gamma$ is a constant. We show that unless the perfect fluid is stiff, the tilt destabilizes the Kasner solutions, leading to a Mixmaster-like initial singularity, with the tilt being dynamically significant. At late times the tilt becomes dynamically negligible unless the equation of state parameter satisfies $\gamma > {10/7}$. We also find that the tilt does not destabilize the flat FL model, with the result that the presence of tilt increases the likelihood of intermediate isotropization

Vascular complications after liver transplantation: A 5-year experience

During the past 5 years, 104 angiographic studies were performed in 87 patients (45 children and 42 adults) with 92 transplanted livers for evaluation of possible vascular complications. Seventy percent of the studies were abnormal. Hepatic artery thrombosis was the most common complication (seen in 42% of children studied, compared with only 12% of adults) and was a major complication that frequently resulted in graft failure, usually necessitating retransplantation. In six children, reconstitution of the intrahepatic arteries by collaterals was seen. Three survived without retransplant. Arterial stenosis at the anastomosis or in the donor hepatic artery was observed in 11% of patients. Portal vein thrombosis or stenosis occurred in 13% of patients. Two children and one adult with portal vein thrombosis demonstrated hepatopetal collaterals that reconstituted the intrahepatic portal vessels. Uncommon complications included anastomotic and donor hepatic artery pseudoaneurysms, a hepatic artery-dissecting aneurysm, pancreaticoduodenal mycotic aneurysms, hepatic artery-portal vein fistula, biliary-portal vein fistula, hepatic vein occlusion, and inferior vena cava thrombosis

Accuracy of computerized tomography in determining hepatic tumor size in patients receiving liver transplantation or resection

Computerized tomography (CT) of liver is used in oncologic practice for staging tumors, evaluating response to treatment, and screening patients for hepatic resection. Because of the impact of CT liver scan on major treatment decisions, it is important to assess its accuracy. Patients undergoing liver transplantation or resection provide a unique opportunity to test the accuracy of hepatic-imaging techniques by comparison of finding of preoperative CT scan with those at gross pathologic examination of resected specimens. Forty-one patients who had partial hepatic resection (34 patients) or liver transplantation (eight patients) for malignant (30 patients) or benign (11 patients) tumors were evaluable. Eight (47%) of 17 patients with primary malignant liver tumors, four (31%) of 13 patients with metastatic liver tumors, and two (20%) of 10 patients with benign liver tumors had tumor nodules in resected specimens that were not apparent on preoperative CT studies. These nodules varied in size from 0.1 to 1.6 cm. While 11 of 14 of these nodules were 1.0 cm. These results suggest that conventional CT alone may be insufficient to accurately determine the presence or absence of liver metastases, extent of liver involvement, or response of hepatic metastases to treatment

Percutaneous transhepatic balloon dilatation of benign biliary strictures.

Between February 1981 and June 1984, 15 patients with benign biliary strictures were treated with percutaneous transhepatic balloon dilatation. Three of these patients had received liver transplants. The treatment began with a course of balloon dilatation therapy, after which a stent catheter was left across the stricture. Six weeks later, after duct patency had been shown by cholangiography, the stent catheter was removed from all but two patients, both of whom had intrahepatic sclerosing cholangitis. After this procedure, six patients (40%), including two liver-transplant patients, were stricture-free after one treatment for periods ranging from 27 to 56 months, and were considered to be treatment successes. Nine patients (60%) suffered stricture recurrences. In eight of these patients, the stricture was heralded by symptoms of either cholangitis or jaundice; in one patient, who was on permanent catheter drainage, the stricture was discovered only on follow-up cholangiography. All successfully treated patients had only one stricture, while all patients with more than one stricture suffered recurrences. Our data also suggest a greater responsiveness for anastomotic strictures than for non-anastomotic strictures. Of the patients with recurrences, five had symptom-free intervals of 23 months or more (up to 31 months). The fact that strictures recurred after such long periods of time underscores the importance of long-term follow-up. In view of the number of patients helped, the favorable experience with post-liver-transplantation strictures, and the lack of any major complications in our series, percutaneous biliary balloon dilatation offers a viable alternative to surgical management of benign biliary strictures

Angiography of liver transplantation patients

Over 45 months, 119 angiographic examinations were performed in 95 patients prior to liver transplantation, and 53 examinations in 44 patients after transplantation. Transplantation feasibility was influenced by patency of the portal vein and inferior vena cava. Selective arterial portography, wedged hepatic venography, and transhepatic portography were used to assess the portal vein if sonography or computed tomography was inconclusive. Major indications for angiography after transplantation included early liver failure, sepsis, unexplained elevation of liver enzyme levels, and delayed bile leakage, all of which may be due to hepatic artery thrombosis. Other indications included gastrointestinal tract bleeding, hemobilia, and evaluation of portal vein patency in patients with chronic rejection who were being considered for retransplantation. Normal radiographic features of hepatic artery and portal vein reconstruction are demonstrated. Complications diagnosed using results of angiography included hepatic artery or portal vein stenoses and thromboses and pancreaticoduodenal aneurysms. Intrahepatic arterial narrowing, attenuation, slow flow, and poor filling were seen in five patients with rejection

Cholangiography and interventional biliary radiology in adult liver transplantation

Radiographic assessment of the biliary tract is often essential in patients who have undergone liver transplantation. T. or straight-tube cholangiography, percutaneous transhepatic cholangiography, and endoscopic retrograde cholangiography all may be used. A total of 264 cholangiograms in 79 adult liver transplant patients (96 transplants) was reviewed. Normal radiographic features of biliary reconstructive procedures, including choledochocholedochostomy and choledochojejunostomy, are demonstrated. Complications diagnosed by cholangiography included obstruction, bile leaks, and tube problems, seen in eight, 24, and 12 transplants respectively. Stretching and incomplete filling of intrahepatic biliary ducts were frequently noted and may be associated with rejection and other conditions. Transhepatic biliary drainage, balloon catheter dilatation of strictures, replacement of dislodged T-tubes, and restoring patency of obstructed T-tubes using interventional radiologic techniques were important in avoiding complications and additional surgery in selected patients

Optimality Clue for Graph Coloring Problem

In this paper, we present a new approach which qualifies or not a solution found by a heuristic as a potential optimal solution. Our approach is based on the following observation: for a minimization problem, the number of admissible solutions decreases with the value of the objective function. For the Graph Coloring Problem (GCP), we confirm this observation and present a new way to prove optimality. This proof is based on the counting of the number of different k-colorings and the number of independent sets of a given graph G. Exact solutions counting problems are difficult problems (\#P-complete). However, we show that, using only randomized heuristics, it is possible to define an estimation of the upper bound of the number of k-colorings. This estimate has been calibrated on a large benchmark of graph instances for which the exact number of optimal k-colorings is known. Our approach, called optimality clue, build a sample of k-colorings of a given graph by running many times one randomized heuristic on the same graph instance. We use the evolutionary algorithm HEAD [Moalic et Gondran, 2018], which is one of the most efficient heuristic for GCP. Optimality clue matches with the standard definition of optimality on a wide number of instances of DIMACS and RBCII benchmarks where the optimality is known. Then, we show the clue of optimality for another set of graph instances. Optimality Metaheuristics Near-optimal