Magnetic Anastomosis Rings to Create Portacaval Shunt in a Canine Model of Portal Hypertension.

PURPOSE: This study evaluated a novel magnetic compression technique (magnamosis) for creating a portacaval shunt in a canine model of portal hypertension, relative to traditional manual suture. METHODS: Portal hypertension was induced in 18 dogs by partial ligation of the portal vein (baseline). Six weeks later, extrahepatic portacaval shunt implantation was performed with either magnetic anastomosis rings, or traditional manual suture (n = 9, each). The two groups were compared for operative time, portal vein pressure, and serum biochemical indices. Twenty-four weeks post-implantation, the established anastomoses were evaluated by color Doppler imaging, venography, and gross and microscopic histological examinations. RESULTS: Anastomotic leakage did not occur in either group. The operative time to complete the anastomosis for magnamosis (4.12 ± 1.04 min) was significantly less than that needed for manual suture (24.47 ± 4.89 min, P < 0.01). The portal vein pressure in the magnamosis group was more stable than that in the manual suture group. The blood ammonia level at the end of the 24-week post-implantation observation period was significantly lower in the magnamosis group than in the manual suture group. Gross and microscopic histological examinations revealed that better smoothness and continuity of the vascular intima had been achieved via magnamosis than with manual suture. CONCLUSION: Magnamosis was superior to manual suture for the creation of a portacaval shunt in this canine model of portal hypertension.

Survival and variceal rehemorrhage after shunting support small-diameter prosthetic H-graft portacaval shunt.

This study was undertaken to report variceal rebleeding and survival after small-diameter prosthetic H-graft portacaval shunts (HGPCS) and to compare actual to predicted survival after shunting. Since 1987 we have prospectively followed patients after undergoing HGPCS to treat bleeding varices failing/not amenable to sclerotherapy/banding. One hundred and seventy patients underwent shunting. Cirrhosis was because of alcohol in 56%, hepatitis in 12%, both in 11%, and other causes in 21%. Child class was A for 10%, B for 28%, and C for 62%. Thirty-three patients died by 6 months, 54 by 24 months, 87 by 60 months, and 112 by 10 years, generally because of liver failure. Fifty-one patients are alive at a median of 48.3 months, 76 months +/- 57.8 (mean +/- SD). Variceal rehemorrhage was documented in 3 (2%) patients. By child class, 5-year/10-year survival rates were as follows: A 66.7/33.3%, B 48.6/15.6%, and C 29.2/7.0%. Actual survival was superior to predicted survival (Model for End-Stage Liver Disease [MELD]), (p < 0.001). Variceal rehemorrhage in patients undergoing small-diameter prosthetic H-graft portacaval shunting was very uncommon. Actual survival was superior to predicted survival (MELD). Long-term survival paralleled degree of hepatic function, although long-term survival was possible even with very advanced cirrhosis. Application of HGPCS is encouraged.

Intravascular ultrasound-guided direct intrahepatic portacaval shunt: description of technique and technical refinements.

PURPOSE: This is a prospective study designed to demonstrate the safety and feasibility of creating a direct inferior vena cava (IVC)-to-portal vein shunt with use of a new type of intravascular ultrasound (IVUS) to guide the puncture and completing the shunt with the use of a polytetrafluoroethylene (PTFE)-covered stent graft. MATERIALS AND METHODS: IVC-to-portal vein shunts were created in 31 sequential patients for ascites (n = 31) or bleeding (n = 8). Transfemorally placed IVUS transducers were positioned in the IVC to guide the puncture from the IVC to the portal vein, which was performed from a transjugular approach with a modified Rosch-Uchida liver access set. A 9-MHz axial imaging IVUS system was used for the first 11 patients, and a variable 5-10-MHz sagittal IVUS imaging system was used for the next 20 patients. The shunts were completed with the use of single (n = 11) or overlapping (n = 20) PTFE-covered Palmaz stent-grafts, deployed primarily at a diameter of 8 mm. Patients were followed clinically and with US, venography, and inspection at liver transplantation to establish 30-day patency rates. RESULTS: All direct intrahepatic portacaval shunts (DIPSs) were created successfully. Both IVUS systems were able to adequately guide the portal vein puncture. Resolution and operator confidence were subjectively superior with the sagittal IVUS imaging system compared to the axial IVUS system. Two extrahepatic portal vein punctures occurred during the procedures. Both were controlled by the placement of sheaths and subsequent placement of stent-grafts. Both patients remained asymptomatic, although one required transfusion of blood products. The mean portosystemic gradient was reduced from 24 mm Hg before DIPS creation to 10 mm after DIPS creation. Embolization of varices was also performed in eight patients with history of recent gastrointestinal bleeding. Two patients died in the first week of acute liver failure. Two patients with hepatocellular carcinoma refused further follow-up. Of the 27 remaining patients, patency was demonstrated in all DIPS at 30 days by US, venography, or direct inspection at liver transplantation. CONCLUSIONS: IVUS-guided direct IVC-to-portal vein shunts may be created successfully with minimal complications. The use of a stent-graft is recommended for this procedure. Modifications of current technique and IVUS systems are described.

Effectiveness of porto-intracaval shunt to reduce the negative effects of portal and caval clamping in the rabbit.

In performing experimental liver surgery, it is difficult to prolong anhepatic time because the animals do not tolerate prolonged portal and caval clamping. To counteract prolonged venous stasis, the authors previously developed a simple porto-intracaval shunt. The shunt consists of a self-constructed inverted Y silicone tube. The effectiveness of this shunt was studied comparing two groups of 10 rabbits with shunt (S) versus those with clamped portal and inferior caval vein (C). In the group of rabbits that underwent porto-intracaval shunt, the results concerning intraoperative mortality, intraoperative increase in distal portal vein pressure, and incidence of the histologic signs of gut damage were clearly improved. The proposed porto-intracaval shunt was therefore effective in reducing some principal negative effects of portal and caval clamping. This type of porto-intracaval shunt can be therefore useful allowing improvement of experimental models concerning liver surgery in little animals.

Preliminary experience with transluminal laser-induced intrahepatic portacaval shunts.

This study investigated the feasibility of performing an intrahepatic portacaval shunt (IHPCS) by means of transluminal laser angioplasty. In 10 anesthized dogs, a catheter was introduced into a mesenteric vein and threaded into the portal vein (PV). Under fluoroscopy, a Ross needle was passed through the PV catheter, liver, and into the intrahepatic IVC. Following guidewire exchange, a neodymium YAG laser hot-tip probe (power setting 8 W) was passed over the guidewire to accomplish a transluminal IHPCS. In five animals, an IHPCS could not be accomplished. Initial and subsequent patency was confirmed by fluoroscopy. These early data suggest that transvenous laser-induced intrahepatic portacaval shunts may be feasible as a means of decompressing portal hypertension. Further research is necessary, to investigate the long-term patency as well as this technique's ability to decompress the portal system.

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.

The emergency portacaval H graft in alcoholic cirrhotic patients: influence of shunt diameter on clinical outcome.

Emergency partial portal decompression was achieved with 8 or 10 mm portacaval H graft shunts combined with aggressive collateral ligation in 18 patients in whom bleeding esophageal varices could not be controlled medically. They were compared with 11 similar risk patients undergoing larger diameter portacaval H graft shunts (12 to 14 mm) for the same indications. Variables studied included 90 day operative mortality, hepatic encephalopathy rates, corrected portal pressure, and variceal re-bleeding. Operative mortality was similar in both groups and correlated strongly with Child's class. However, the incidence of portasystemic encephalopathy in survivors was significantly lower after partial decompression than after total decompression. No patient in either group rebled from varices. We conclude from our series of high risk alcoholic cirrhotic patients, that although mortality after partial and total portal decompression is similar, the lower incidence of encephalopathy in survivors suggests that partial decompression has advantages over total decompression when emergency control of variceal bleeding is necessary.

Portacaval H-graft: relationships of shunt diameter, portal flow patterns and encephalopathy.

Small-diameter protacaval H-grafts, 10, 12, or 14 mm, were constructed in 29 cirrhotic patients with previous or active variceal hemorrhage. When 10 mm grafts were used in combination with portal collateral outflow ligation, varying degrees of prograde portal flow were maintained in 50% of the patients. When shunt size was greater, prograde flow was lost in more than 90%. The incidence of spontaneous postoperative encephalopathy was 11% in patients with prograde flow, compared with 50% in those with retrograde flow (p = 0.05). It is concluded that maintaining prograde portal flow after portacaval shunt is essential in minimizing postoperative encephalopathy. Prograde portal flow may be achieved in 50% of patients using 10 mm PTFE portacaval H-grafts combined with portal collateral ligation.

[A new method for isolated regional perfusion of the liver in vivo. Experimental studies (author's transl)]. / Ein neues Verfahren zur isolierten regionalen Leberperfusion in vivo.

The canine liver was isolated from its blood supply and perfused for one hour normothermically be means of a new catheter and a perfusion system consisting of oxygenator, pump and heat-exchanger. Hemodynamic parameters, blood gas analyses, and tissue metabolites were evaluated during experiments. The venous return from the lower body and portal vein (1.113/1min) could be maintained with the catheter system so that the mean systemic arterial pressure was within normal limits. With a perfusion rate through the liver 0,55 ml/min/g and perfusion pressure of 10 cm H2O there was an adequate tissue perfusion; this was also shown by blood gas analyses and tissue metabolite concentrations. Using dye dilution methods the isolation of the liver was tested. This showed a leakage of 6-7% of the total perfusion volume. This new method makes it possible to carry out an isolated, normothermic, liver perfusion for one hour without irreversible tissue damage.

Alternative use of the interposition Dacron grafts in the treatment of portal hypertension. Clinical experience with 28 cases.

Twenty-eight patients suffering from esophageal bleeding due to portal hypertension were submitted to an "H" type shunt utilizing a 12 mm. wide knitted Dacron prosthesis. The series consists of 8 meso-caval, 12 porto-caval 8 spleno-renal shunts. Thrombosis of the spleno-portal axis was the main indication for the mesocaval shunt, while side-to-side porto-caval and spleno-renal "H" anastomoses were carried out in patients in whom enlarged lymphatics, edema of the porta hepatis or a too large gap between the two veins precluded the use of a direct shunt. The overall mortality rate was 7% including one operative and one late death. The long-term follow-up study included 26 patients and ranged from 6 to 34 months. In all patients patency of the shunt was evaluated by barium swallow x-ray and esophagogastroscopy. Four of them were further investigated by angiography. A good patency of the shunt was demonstrated in all cases. There was no recurrence of the variceal bleeding either in the post-operative period nor in the long-term follow-up. On the basis of our results we feel that the use of Dacron grafts as "H" type shunts is an effective alternative method in relieving portal hypertension in patients in whom it is difficult or impossible to perform a direct anastomosis and further this procedure can be extended with encouraging results to side-to-side spleno-renal shunts.

An improved nonsuture method for portacaval anastomosis in the rat.

A nonsuture technique is described for performing portacaval anastomoses in rats. Improvements include reduced clamping time on critical vessels, reduced blood loss, uniformly patent anastomoses, easily manufactured buttons, and decreased mortality rates. The new procedure allows a single operator to perform 25 such operations per day, thus substantially increasing the availability of these animals for studies in hepatic metabolism following portacaval anastomoses.