A systematic appraisal of portacaval H-graft diameters. Clinical and hemodynamic perspectives.

Over a period of 10 years, the authors have systematically reduced portacaval H-graft diameters. Their objective was to achieve partial shunting of portal flow without reversal of hepatic flow. This report summarizes their clinical and hemodynamic observations in 68 surviving patients with cirrhosis (mostly alcoholic) and variceal hemorrhage who underwent portacaval H-grafts ranging from 20 to 8 mm diameters. When shunt diameters were reduced to 10 and 8 mm and combined with aggressive portal collateral ablation, portal pressures increased significantly over larger H-grafts. Only 3% of patients with 20-12 mm H-grafts had prograde portal flow after operation, compared with 46 and 82% after 10 and 8 mm H-grafts, respectively (p less than 0.001). The incidence of encephalopathy diminished from 39% in the 20-12 mm H-graft group to 19 and 9% after 10 and 8 mm grafts, respectively (p less than 0.04). None of the patients with 10 or 8 mm PTFE grafts rebled from varices in the follow-up period (4-61 months). It is concluded that partial shunting of portal flow is hemodynamically feasible. It can be achieved in most patients using 8 mm polytetrafluoroethylene (PTFE) portacaval H-grafts combined with portal collateral ablation. Preserving prograde portal flow by partial shunting correlates with reduced encephalopathy rates after operation. Despite maintaining a relatively hypertensive portal system, partial shunts effectively prevent variceal hemorrhage.     

Predictability and maintenance of portal flow patterns after small-diameter portacaval H-grafts in man.

Patients undergoing small-diameter (8, 10, 12, and 14 mm) portacaval H-grafts were followed up to 3.5 years. Eight- and 10-mm grafts maintained prograde portal perfusion in 50% of the patients. Follow-up studies performed from 6 to 36 months after surgery show late shunt patency to be 97%. Recurrent variceal hemorrhage has not occurred in any patients. Direction of portal flow after a shunt was related to the size of the portal vein and the size of the shunt. If the shunt diameter was less than 50% that of the portal vein measured on the preoperative angiogram, portal flow was prograde. Encephalopathy rates remained significantly lower in patients with prograde flow after small diameter (8 and 10 mm) portacaval H-graft (p = .0.1). If thrombosis and encephalopathy rates remain low, the small-diameter, polytetrafluoroethylene portacaval H-graft is an attractive alternative to standard portacaval and mesocaval shunts.     

Computer analysis of portal hemodynamics after small-diameter portacaval H-grafts: the theoretical basis for partial shunting

We have previously reported on the clinical results of partial shunting using small-diameter portacaval H-grafts. In this study, we defined the theoretical basis for partial shunting using the Wheatstone bridge model of the splanchnic circulation. The model was modified to include a variable resistance for a portacaval shunt and was programmed as a computer simulation. We calculated portal flow as a function of shunt resistance to determine the resistance necessary to maintain prograde portal flow in patients with portal hypertension. The resistance of 8- and 10-mm portacaval H-grafts, as positioned clinically, was determined using a laboratory apparatus. The experimentally derived values for resistance were inserted into the graph of portal flow predicted by the computer program. Portacaval H-grafts 8 mm in diameter should produce prograde portal flow, 10-mm H-grafts should be borderline, and shunts larger than 10 mm should routinely result in reversed flow. These predictions were confirmed by clinical observations in 29 patients undergoing portacaval H-grafts.     

门腔静脉人工血管搭桥分流术治疗门静脉高压症

目的观察用门腔静脉间人工血管搭桥分流术治疗门静脉高压症患者的临床疗效,并与传统的门体分流术比较。方法采用带外支撑环的８ｍｍ口径聚四氟乙烯（ＧｏｒｅＴｅｘ）薄壁人工血管行门腔静脉间搭桥分流术,所用人工血管长度为２～３ｃｍ,共治疗２０例患者。结果搭桥分流术后门静脉压力下降幅度与同期１７例脾肾静脉分流术及１１例门腔静脉侧侧分流术相比差异无显著意义（０８３±０３１ｋＰａ,０８１±０５０ｋＰａ及１０２±０４５ｋＰａ,Ｐ＞００５）。三组患者全部获得随访,平均随访时间为１５～２８个月,手术死亡率及再出血率没有差别,但搭桥分流组术后脑病发生率显著低于门腔侧侧分流组（５０％及３６４％,Ｐ＜００５）。２０例患者术后近期均经下腔静脉行门静脉造影,人工血管通畅率为９５％,出院后１９例患者均经一次以上Ｂ超检查,随访已超过１５个月,人工血管均通畅。结论门腔静脉间小口径人工血管搭桥分流术对患者创伤小,操作简便,术后脑病发生率低,疗效比较确切     

Does portal pressure influence direction of portal flow and encephalopathy rates after 10-mm portacaval shunts in man?

Direction of portal flow after small diameter portacaval H graft has been found to significantly correlate with postshunt portasystemic encephalopathy rates. While some patients maintaining prograde portal flow were found to have a lower incidence of portasystemic encephalopathy, it has been suggested that high portal pressures are responsible for minimizing this complication. If both statements are true, then postshunt pressures should be higher in patients with prograde flow and in encephalopathy. Portal pressure and portal flow patterns were determined by shunt cannulation and fluoroscopy in 16 patients fully recovered from operation. Patients were screened for portasystemic encephalopathy over a 6- to 24-month period (average 12 months) at which time shunt patency was documented. Portal pressures were similar in patients with and without portasystemic encephalopathy and in patients with and without prograde flow. These results do not support the concept that portal pressure is an important determinant of portasystemic encephalopathy rates or flow patterns after 10-mm portacaval H graft.     

Partial portal decompression for variceal hemorrhage

To test the hypothesis that partial portal decompression in the treatment of variceal hemorrhage will diminish subsequent encephalopathy, 50 consecutive patients were studied after construction of a small-stoma (10 to 12 mm) side-to-side portacaval shunt, with the goal of a postoperative portacaval pressure gradient of 10 mm Hg. During follow-up averaging 26 months, six patients (12 percent) died. Four patients (8 percent) had episodes of rebleeding, only one from varices. All patients had patent shunts at subsequent angiography or ultrasonography. Despite consistent (100 percent) postoperative reversal or stagnation of portal flow on duplex scan, encephalopathy on clinical and psychometric grounds was observed in only three patients (6 percent). This study suggests that small-stoma portacaval shunt can be performed with reliably low rates of rebleeding and encephalopathy. That encephalopathy was rare despite loss of hepatic portal perfusion incriminates other factors besides portal flow in the genesis of postshunt hepatic failure.     

Partial portacaval shunt: renaissance of an old concept.

BACKGROUND. Partial diversion of the portal system aims to reduce portal pressure sufficiently to prevent variceal hemorrhage but still maintain adequate hepatic portal flow. METHODS. Partial portacaval shunts were performed in 25 patients with cirrhosis with portal hypertension and esophageal varices, either as a primary procedure (n = 16) or for failure of endoscopic sclerotherapy (n = 9), with ringed polytetrafluoroethylene prostheses (8, 10, or 12 mm). RESULTS. All patients have now been followed up for at least 1 year. The operative mortality rate (2 months) was 4%. In 24 patients who survived beyond the initial perioperative period, there was no recurrence of variceal bleeding. Cumulative shunt patency (up to 4 years) is 96%. Acute encephalopathy was detected in two patients (8%), but no patients had signs of chronic encephalopathy. Intraoperative pressure measurements revealed a significant correlation between decreasing diameter of the graft and the percentage reduction of the portacaval pressure gradient. Selective angiography, performed 1 year after surgery, revealed that hepatopetal flow was maintained in 70% of patients with a 10 mm shunt. CONCLUSIONS. It is possible to achieve a partial portacaval shunt, related to the diameter of the prosthesis, that preserves hepatopetal flow in the majority of patients and is associated with a very low incidence of shunt thrombosis. This effectively prevents recurrent variceal bleeding and significant postoperative encephalopathy. The performance of subsequent orthotopic liver transplantation is not compromised. The technique is recommended, either as a primary procedure or when sclerotherapy has failed, in patients with good liver function who are unlikely to require early liver transplantation (grade A and some grade B cirrhosis).     

Surgical treatment of complications of portal hypertension

This review defines the role of non-transplant surgery in portal hypertension. Surgical options for patients with portal hypertensive bleedings include portacaval shunt emergently and distal splenorenal shunt with splenopancreatic disconnection electively. There is currently renewed interest for calibrated portacaval H-grafts. Early results show a low encephalopathy rate and a good control of bleeding.     

Serial measurement of portal hemodynamics after partial portal decompression

In a serial analysis of splanchnic hemodynamics, we compared partial with total portal decompression in 16 alcoholic cirrhotic patients who underwent portacaval shunts for variceal hemorrhage. Partial decompression was achieved with 8 or 10 mm polytetrafluorethylene portacaval H grafts and aggressive collateral ligation. Total decompression was achieved with larger diameter H grafts (12 or 14 mm). Early and follow-up (mean interval, 18 months) postoperative studies of portal hemodynamics included: direct measurement of shunt gradients, scintigraphic quantitation of portal and mesenteric flow distribution to the liver, and a portal and splenic collateral scoring system developed from standardized splenic venography. Partial portal decompression reduced portal pressure by 43% +/- 8% compared with 81% +/- 5% after total decompression (p less than 0.01). Scintigraphy demonstrated that partial decompression provided a greater fraction of portal flow to the liver than did total decompression (57% +/- 9% versus 2% +/- 1% intrahepatic radioactivity) and mesenteric flow distribution (14.5% +/- 5.4% versus 1.2% +/- 0.7%). Only one patient with partial decompression had a significant loss of portal perfusion during the interval studies. Significantly more residual collaterals were visualized in patients with partial decompression than in those with total decompression, and interval studies showed no significant changes from early studies. We conclude that partial decompression maintains higher portal pressures, more residual collaterals, and a greater fraction of portal and mesenteric flow to the liver than does total decompression. A modest but uniform reduction of portal pressure minimizes stimulus for new collateral formation and further shunting of portal flow.     

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.     

Reevaluation of limited side-to-side portacaval shunt

Results of limited side-to-side portacaval shunt is better than other shunts, but, post-operative encephalopathy was still observed in 10.2% of the patients. Therefore, animal experiments and clinical observations were carried out to determine the relationship between the changes in size of anastomotic stomas and the development of post-operative encephalopathy. It was shown that significant augmentation of the size of anastomotic stomas developed in 50% of experimental animals in a period of three months after limited side-to-side portacaval shunt and in all post-operative patients with post-operative encephalopathy. In an effort to prevent the enlargement of the anastomotic stoma caused by blood flow under high pressure, a limiting ring of 10 mm in internal diameter was put around the anastomotic site during operation in 9 patients with portal hypertension. These patients now have been followed up to 5-11 months without evidence of post-operative encephalopathy and rebleeding. A ring of the same kind was put around the enlarged anastomotic stoma during exploration in 6 patients with post-operative encephalopathy, and all the cerebral symptoms and signs disappeared completely soon after the procedure.     

Partial versus total portacaval shunt in alcoholic cirrhosis. Results of a prospective,randomized clinical trial.

OBJECTIVE: Results of the first prospective randomized clinical trial comparing partial and total portacaval shunt for variceal hemorrhage are reported. SUMMARY BACKGROUND DATA: Total portacaval shunts produce subnormal portal pressures, completely diverting hepatic portal flow. Partial shunts maintain higher pressures and preserve hepatopedal flow. No randomized trials of these two approaches have been performed. METHODS: Alcoholic patients with cirrhosis (n = 30) and variceal hemorrhage treated at one institution were randomized to receive partial (8-mm diameter portacaval H grafts with collateral ablation, n = 14) or total shunts (16-mm diameter grafts, n = 16). Portography was performed after operation and then yearly. Investigators blinded to shunt type assessed encephalopathy; hospitalizations were reviewed. RESULTS: Child''s class, age, and operative urgency were similar for the two groups. Two patients (with total shunts) died within 30 days. Hepatopedal flow was maintained in 13 partial and 0 total shunt patients (p < 0.0001). Shunt gradients were 16 +/- 5 compared with 6 +/- 3 cm saline after partial and total shunts (p < 0.0001). There were no shunt thromboses or variceal hemorrhages. Encephalopathy-free survival was significantly greater after partial shunts (p = 0.013; life table analysis). Five total compared with zero partial shunt patients required hospitalization for coma (p = 0.02). Long-term survival was not different for the two groups of patients. CONCLUSIONS: Partial shunts control variceal hemorrhage while maintaining hepatopedal flow and elevated portal pressures. By minimizing encephalopathy rates, partial shunts provide improved quality of survival compared with total shunts.     

应用PTFE人造血管行门腔H型吻合治疗门静脉高压症

目的　了解血管移植物PTFE在H型门腔分流道的通畅率,分流口径对向肝血流的影响以及减压效果和并发症。方法　用内径10mm普通型PTFE和带支撑环的PTFE分别为12例及8例肝硬化门静脉高压症患者进行了门腔静脉间的H型分流术。其中肝功能ChildA级13例,B级5例,C级2例。平均年龄434岁。结果　无手术死亡。术后平均随访172个月,脑病Ⅰ～Ⅱ级2例,无曲张静脉破裂再出血。术后门脉系统彩色多普勒超声及血管造影检查,向肝血流量无明显影响,分流道通畅率90%。普通PTFE者血栓形成2例(167%);带支撑环PTFE者无血栓形成。结论　该技术在减低门静脉压力,维持向肝血流,预防再出血等方面均取得了良好结果,其中带支撑环者优于普通型。     

Selectivity of the distal splenorenal shunt.

The distal splenorenal shunt is less likely to provoke encephalopathy than conventional shunting procedures, and it may offer a survival advantage for certain cirrhotic individuals, presumably because of its selective nature. This study suggests that the distal splenorenal shunt, even with exceptional efforts to achieve portomesenteric-gastrosplenic (PM-GS) disconnection, is not nearly as selective as it originally was assumed to be. In 11 patients intraoperative pressure determinations showed a significant decrease in portal pressure after end-to-side distal splenorenal anastomosis and no restoration of portal pressure after PM-GS disconnection. Measurements of flow through the shunt were comparable to those reported for portacaval shunts, and shunt flow was not decreased significantly by PM-GS disconnection. Postoperative angiography showed some PM-GS collateral in 17 of 18 patients, and later angiographic studies showed a tendency for progressive collateral development and consequent loss of hepatopetal portal perfusion. The advantages of the distal splenorenal shunt must accrue from gradual, as opposed to abrupt, portal deprivation, rather than from lasting selectivity.     

Left renal vein ligation for large splenorenal shunt during liver transplantation

Adequate hepatopetal portal vein blood flow is obligatory to ensure proper liver function after liver transplantation. Large collateral veins as shunts impair portal vein flow and even cause hepatofugal blood flow and portal steal syndrome. In particular, splenorenal shunts in liver transplant recipients can lead to allograft dysfunction and possible allograft loss or hepatic encephalopathy. Restoration of portal flow through left renal vein ligation (LRVL) is a treatment option, which is much easier compared to splenectomy, renoportal anastomosis and shunt closure, but bears the risk of moderate and temporary impairment of renal function. In addition, a patent portal vein is mandatory for LRVL. However, although LRVL has been reported to be an effective, safe and easy method to control portacaval shunts and increase hepatopetal flow in some studies, indications and safety are still not clear. In this review, we summarize existing studies on LRVL during liver transplantation.     

Percutaneous control of a portacaval H-graft: Description of a new device and its initial clinical application

A percutaneously-controlled inflatable cuff which can change the diameter of a portacaval H-graft has been developed and used in 10 patients. When inflated, the cuff narrows the H-graft to increase portal pressure and reduce shunting. Use of the cuff has been of clinical significance in 3 of 7 long-term surviving patients. Narrowing the shunt improved the clinical state in 2 patients with encephalopathy, and reopening a closed shunt improved ascites in the third patient. Duplex ultrasound and deep Doppler have demonstrated an alteration of hepatic portal blood flow following inflation of the cuff after 6 months. It is concluded that further development of this controlled portacaval H-graft is warranted.     

Comparison between selective distal splenorenal shunt and small diameter H-graft portosystemic shunt

Although most commonly performed portal decompressive procedures control bleeding effectively, postoperative morbidity and mortality remains a serious problem in these patients. Both distal splenorenal shunts (DSRS) and small-diameter portacaval H-grafts (PCHG) are reported to produce decreased rates of postoperative encephalopathy. We prospectively evaluated 69 patients in whom 27 PCHG and 45 DSRS were performed over a seven-year interval. There were no significant preoperative differences between these groups. Operative mortality was 12.9% overall. DSRS was associated with decreased intraoperative blood transfusions and operative time. Postoperatively, DSRS was associated with significantly less encephalopathy, other postoperative complications, and ascites. Recurrent variceal bleeding was seen in three patients treated with PCHG and two patients with DSRS. We conclude that both DSRS and PCHG are effective in preventing recurrent variceal bleeding, but DSRS remains our procedure of choice because of its decreased rates of postoperative complications.     

Small-diameter portacaval H-graft for variceal hemorrhage

This report describes the steps in the development of the concept of partial shunting from its earliest stages to the 8-mm-diameter portacaval H-graft. Sequentially decreasing the diameter of the graft from 20 mm did not seem to affect hepatic hemodynamics until the 10-mm-diameter graft was used. At this point, we began to see some patients maintain prograde portal flow. Further reduction in diameter gave a higher rate of patients with prograde flow. Postoperative flow patterns correlate with lower encephalopathy rates and better long-term survival. Important nuances of the operative technique as well as pre- and postoperative management are described.     

How to handle a huge portosystemic shunt in adult living donor liver transplantation with a small-for-size graft: Report of a case

Little attention has been paid to a ligation of the spontaneous portosystemic shunt in adult living donor liver transplantation (LDLT). A 33-year-old Japanese man with cryptogenic liver cirrhosis accompanied by a huge splenorenal shunt underwent LDLT. Acute cellular rejection produced “to and fro” portal venous flow on postoperative day (POD) 10. Steroid bolus therapy reversed the rejection, but the recovery of the portal venous flow was incomplete and the recipient subsequently started to have episodes of encephalopathy. Angiography showed portal hypoperfusion and portal flow steal via a huge splenorenal shunt. The patient underwent a shunt occlusion on POD 58. Portography showed marked improvement of the portal hypoperfusion. The encephalopathy thereafter dramatically reversed and the patient was discharged with no complications related to shunt ligation on POD 110. This case suggested that a ligation of a huge portosystemic shunt should therefore be considered at the time of transplantation, even when a relatively small graft is implanted.     

Comparative study of portacaval and mesocaval interposition shunts

Portacaval and mesocaval interposition shunts using vascular prosthetic grafts were compared in 37 cirrhotic patients without portal vein thrombosis who were operated on for previous or active variceal hemorrhage. Operative indications and severity of liver disease were similar in the two groups of patients having one or the other procedure. The major difference in results was that none of the 23 patients with portacaval H-graft shunts had rebleeding, while 4 of 14 had rebleeding from varices after mesocaval interposition shunting. This contributed to the higher operative mortality associated with the latter procedure. The index of operative difficulty, as judged by blood loss and length of operation, and postshunt encephalopathy rates were similar for both procedures. Thus, while the mesocaval interposition shunt offers none of the reported theoretical advantages over portacaval H-graft shunt, it does place patients at greater risk of postoperative variceal rehemorrhage. It is concluded that the portacaval interposition shunt, because of its effectiveness and technical expediency, may be the operation of choice in cirrhotic patients with bleeding varices who are not otherwise candidates for other procedures which reduce portal flow less drastically.