Portal vein thrombosis is a potentially preventable complication in clinical islet transplantation

Abstract

Percutaneous transhepatic portal access avoids surgery but is rarely associated with bleeding or portal venous thrombosis (PVT). We herein report our large, single-center experience of percutaneous islet implantation and evaluate risk factors of PVT and graft function. Prospective data were collected on 268 intraportal islet transplants (122 subjects). A portal venous Doppler ultrasound was obtained on Days 1 and 7 posttransplant. Therapeutic heparinization, complete ablation of the portal catheter tract with Avitene paste and limiting packed cell volume (PCV) to <5 mL completely prevented any portal thrombosis in the most recent 101 islet transplant procedures over the past 5 years. In the previous cumulative experience, partial thrombosis did not affect islet function. Standard liver volume correlated negatively (r =-0.257, p < 0.001) and PCV correlated positively with portal pressure rise (r = 0.463, p < 0.001). Overall, partial portal thrombosis occurred after 10 procedures (overall incidence 3.7%, most recent 101 patient incidence 0%). There were no cases of complete thrombosis and no patient developed sequelae of portal hypertension. In conclusion, portal thrombosis is a preventable complication in clinical islet transplantation, provided therapeutic anticoagulation is maintained and PCV is limited to <5 mL.

Figure 1

Factors affecting acute change of portal venous pressure after islet transplantation A. Correlation between packed cell volume and change in portal vein pressure B. Correlation between standard liver volume and change in portal vein pressure

Figure 2

Cumulative risk of portal vein thrombosis and number of islet transplant procedures per year. Since 2005, Intravenous heparin (70u/kg) has been infused to keep the partial thromboplastin time >60 sec or 48 hr after transplant and packed cell volume has been kept < 5 ml. No portal vein thrombosis has been observed in the most recent 5 years.

Figure 3

Evaluation of transplanted islet cells in the livers with or without portal vein thrombosis by SUITO index. No significant difference was observed between no portal vein thrombosis patients and portal vein thrombosis patients at 5–7 days (A) and 1 month (B) after islet transplantation. Each symbol represents an individual case.

Figure 4

Comparison between the patients without portal vein thrombosis and those with portal vein thrombosis. The subjects that developed portal thrombosis had larger packed cell volume (A), and had a significantly increased portal venous pressure during the islet transplant (B). Each symbol represents an individual case.

Figure 5

Receiver operating characteristic curve assessment of (A) the packed cell volume and (B) portal venous pressure change to predict portal vein thrombosis after islet transplantation A. A cut off 5.5 ml was selected, providing sensitivity 50 %, specificity 84.5 % and area under the curve (AUC) 0.667. B. A cut off 4.5 mmHg was selected, providing sensitivity 70 %, specificity 73.2 % and area under the curve 0.716