Small-diameter H-graft Research Articles

Partial portacaval shunt with H-grafts to treat portal hypertension

Partial portosystemic shunts have been popularized because of a reported low rate of mortality and morbidity (especially encephalopathy, liver failure and occlusion). The results of partial portacaval shunts [small-diameter expanded polytetrafluoroethylene (ePTFE) H-graft portacaval shunt] were retrospectively reviewed to evaluate the clinical efficacy in the treatment of portal hypertension. Forty-three patients with portal hypertension were treated by small-diameter H-graft of ePTFE portacaval shunt from May 1995 to April 2006. Thirty-three had externally ringed grafts and ten had non-ringed ones. Ten had grafts of 10 mm in diameter and 33 had grafts of 8 mm. The left gastric artery and coronary vein were ligated in all the cases. Six had pericardial devascularization and splenectomy was performed in 42. An average decrease of free portal pressure (FPP) from (33.24 ± 4.78) cmH2O before shunting and (13.65 ± 5.65) cmH2O after shunting was observed. The portal blood flow was reduced by one-third of that before shunt. Thirty-eight patients survived and no upper gastro-intestinal rebleeding occurred in the follow-up period (50.5 months in average). Two were out of contact. Color Doppler ultrasonography and/or portography revealed the shunts were patent in 38 cases and were occluded in three cases (3/41, 7.3%). Encephalopathy developed in five cases (5/41, 12.2%). Partial (small-diameter ePTFE H-graft) portacaval shunting can reduce the portal pressure effectively. Majority of the hepatic flow from the portal vein can be maintained adequately. The shunts with reinforced grafts can keep a higher rate of patency. The morbidity of encephalopathy was lower than those with total shunt. The partial portacaval shunt is effective in preventing recurrent variceal bleeding.

The effect of small-diameter H-graft portacaval shunts on portal blood flow

Small-diameter prosthetic H-graft portacaval shunts have been shown to promote preservation of total hepatic blood flow relative to large-diameter H-graft shunts. Nonetheless, specific changes in portal hemodynamics occurring with small-diameter H-graft shunting are unknown. This study was undertaken to evaluate changes in portal flow that occur with these shunts. Portal vein and inferior vena cava (IVC) blood flow were determined intraoperatively in 36 consecutive adults before and after prosthetic H-graft portacaval shunting using color-flow Doppler ultrasound. Postshunt measurements were made immediately cephalad and caudad to the shunt. Comparisons were undertaken using a paired Student's t-test with 95% confidence. Portal pressures decreased in all (P < 0.001), but never to normal. Postshunt portal flow cephalad and caudad to the shunt were not different from preshunt flow (P = 0.09, P = 0.28, respectively), although they were different from each other (P = 0.004). Postshunt IVC flow cephalad to the shunt was greater than caudad IVC flow (P = 0.004) and greater than preshunt IVC flow (P < 0.001), reflecting high flow through the shunt into the IVC. Small-diameter prosthetic H-graft portacaval shunts divert a significant amount of blood from the portal vein and significantly decrease portal pressures. The decreases in portal pressures with shunting are significant whereas changes in portal blood flow into the liver are not. These findings help explain the low incidence of variceal rebleeding and hepatic dysfunction after these shunts.

The effect of small diameter H-graft portacaval shunts on portal blood flow

BACKGROUND: Small-diameter prosthetic H-graft T he traditional end-to-side portacaval shunt is assoportacaval shunts have been shown to promote ciated with a prohibitive risk of severe hepatic dyspreservation of total hepatic blood flow relative to function and, therefore, has been abandoned as a large-diameter H-graft shunts. Nonetheless, spefirst choice treatment option in the management of variceal cific changes in portal hemodynamics occurring hemorrhage due to portal hypertension.’ This shunt diverts with smalldiameter H-graft shunting are unknown. all portal blood flow from the liver and achieves complete This study was undertaken to evaluate changes in portal decompression. Partial portal decompression incomportal flow that occur with these shunts. pletely decompresses the portal vein and allows prograde porMETHODS: Portal vein and inferior vena cava (IVC) tal blood flow.* Different extremes of partial portal decomblood flow were determined intraoperatively in 36 pression have been compared through study of largeand consecutive adults before and after prosthetic Hsmall-bore prosthetic H-graft portacaval shunts.3*4 Compared graft portacaval shunting using color-flow with large-bore shunts, small-bore shunts less completely deDoppler ultrasound. Postshunt measurements compress the portal vein and divert less nutrient hepatic were made immediately cephalad and caudad to blood flow. The relative maintenance of nutrient hepatic the shunt. Comparisons were undertaken using a blood flow by small-diameter prosthetic H-graft portacaval paired Student’s t-test with 95% confidence. shunts is presumed to be the basis by which these shunts RESULTS: Portal pressures decreased in all (P lead to superior clinical outcomes.’ <O.OOl), but never to normal. Postshunt portal Surprisingly, hemodynamic changes in the portal system ocflow cephalad and caudad to the shunt were not curring with small-diameter prosthetic H-graft portacaval different from preshunt flow (P = 0.09, P = 0.26, . shunts are poorly understood. Studies have been undertaken respectively), although they were different from to determine changes in portal and hepatic blood flo~,~ each other (P = 0.004). Postshunt IVC flow changes in the direction of portal blood flow:” and changes cephalad to the shunt was greater than caudad in portal pressures with small-diameter H-graft shunting.*s IVC flow (P = 0.004) and greater than preshunt The results of these studies are often conflicting and difficult IVC flow (P <O.OOl), reflecting high flow through to correlate with clinical outcomes, leaving many questions the shunt into the IVC. about portal hemodynamic changes with H-graft shunting. CONCLUSIONS: Small-diameter prosthetic H-graft This study was undertaken to measure portal vein and inportacaval shunts divert a significant amount of ferior vena cava (IVC) blood flow to determine the size of blood from the portal vein and significantly dethe reduction in portal blood flow that occurs with partial crease portal pressures. The decreases in portal portal decompression attained through small-diameter prospressures with shunting are significant whereas thetic H-graft portacaval shunting and to determine the volchanges in portal blood flow into the liver are ume of blood shunted from the portal system. Our hypotheses not. These findings help explain the low inciin undertaking this study were that portal blood flow into dence of variceal rebleeding and hepatic dysthe liver was well maintained after partial portal decomfunction after these shunts. Am J Surg. 1996; 171 :154-l 57. pression achieved by small-diameter prosthetic H-graft shunting, that loss of portal blood flow into the liver was small compared with reduction in portal pressures, and that the volume of blood shunted from the portal system was large, although compensated for by an increase in blood flow into the portal system.

Long-term follow-up of poor-risk patientsundergoing small-diameter portacaval shunts

The small-diameter portacaval H-graft has been shown to be a reliable method of controlling variceal hemorrhage. However, little has been written about the long-term follow-up of poor-risk patients treated by this method. Over the last 11 years, we have performed 38 portacaval H-grafts; 79% of the patients were Child's B or C, and 79% were alcoholic. The mean age was 52 years, and the mean period of follow-up was 44 months. Over 37% of the grafts were performed in patients who were bleeding at the time of operation. Our 30-day operative mortality was 13%. Postoperatively, the small-diameter H-graft was associated with mild to moderate encephalopathy in 33% of the patients and ascites in 42%. Both these conditions were easily controlled with diet and medication. Early recurrent variceal bleeding was seen in 13% of patients. However, on late follow-up, recurrent hemorrhage and encephalopathy have been seen in only 12% and 14% of patients, respectively. We conclude that the portacaval H-graft is a reliable and lasting method for controlling variceal bleeding with an acceptable postoperative morbidity and mortality.

Prospective study of a prosthetic H-graft portacaval shunt

This study was undertaken to prospectively evaluate the 8-mm Gore-Tex interposition H-graft portacaval shunt. Thirty-six high-risk patients at the University of South Florida-affiliated hospitals received small-diameter shunts because of bleeding esophagogastric varices over a recent 2-year period. Portal vein and portal vein-inferior vena cava gradients were significantly reduced after shunting. These pressure changes were manifested clinically by the absence of variceal rebleeding and improvement of ascites; in addition, the incidence of encephalopathy was low. The 8-mm graft maintained hepatopedal flow in 67% of the patients, but reversal of flow did not result in complications commonly associated with poor portal perfusion. Graft thrombosis occurred in four (11%) patients. All grafts were successfully revised, three by operative revision and one by an interventional radiologist. Operative mortality was low (11%), and morbidity was unusual. The small-diameter H-graft portacaval shunt is a safe and effective method of treatment for bleeding esophagogastric varices.