Mitra shunt (spleen preserving, side to side lieno-renal shunt) for portal hypertension with hypersplenism in early infancy.

Extrahepatic portal vein obstruction (EHPVO) is the commonest cause of portal hypertension presenting with gastrointestinal bleeding and splenomegaly. Medical management of this condition may provide relief, but involves repeated hospital visits and endoscopic procedures. Surgery is an effective curative solution by lowering portal venous pressure with effective shunting of venous blood from splanchnic to systemic circulation. Shunt surgery for such a small baby has not been previously reported and splenectomy has its own problems. Similarly, banding or sclerotherapy in such babies is not without risk. Among the various shunt options, Mitra shunt (spleen preserving, side-to-side lienorenal shunt), developed and standardized in our own country, stands out as the most optimum surgical treatment for EHPVO in early infancy. We report a 4-month-old baby, youngest recipient of Mitra shunt reported in literature with successful outcome.

INTRODUCTION

Portal hypertension can present with gastrointestinal bleeding in early childhood. It is usually associated with various grades of splenomegaly and hypersplenism. There are a few series published from our country, limited to few centers.[1] The traditional management of the gastrointestinal bleeding due to this etiology has been conservative management with blood transfusion, balloon tamponade of varices, and drugs to lower splanchnic pressure followed by sclerotherapy or banding. In refractory cases, splenectomy and devascularization in emergency situation or shunt surgery in elective situation is the surgical treatment. However, when this situation presents in early infancy with gastrointestinal bleeding and hypersplenism, the management option is complicated by lack of established protocols. Further, it is known that the gastrointestinal bleed due to portal hypertension is severe and repetitive, particularly in infancy.

CASE REPORT

A 4-month-old male child was referred to us with repeated episodes of melena and progressive abdominal distension. The baby had umbilical sepsis at 3rd week, treated with intravenous antibiotics for 7 days. At 2 months of age, baby developed progressive abdominal distension, associated with a low grade fever, and repeated bouts of melena. During hospitalization in a remote district Hospital, he was found to have low hemoglobin (5 g/dl), leukopenia, and thrombocytopenia requiring blood transfusion. A second admission for melena prompted the physician treating the baby to refer the baby for further investigation and management.

At admission, the baby was mildly dehydrated, had pallor with marked abdominal distension. Massive splenomegaly was present along with ascites and melena. Blood investigations revealed hemoglobin levels of 6.5 g/dl, total leukocyte count of 2,800/mm3 and a platelet count of 39,000/mm3. The liver function tests were normal. A complete coagulation profile done to rule out any congenital coagulation defects was found to be normal. The endoscopic examination revealed Grade 4 esophageal varices with daughter varices, with a normal stomach and duodenum.

Ultrasonography (USG) [Figure 1], contrast computed tomography (CT) scan, magnetic resonance imaging (MRI) abdomen [Figures 2 and 3] and endoscopy were done in another hospital before admission to our center. The diagnosis at this stage was established as extrahepatic portal venous obstruction (EHPVO) leading to portal hypertension and esophagogastric varices with hypersplenism. The parents were offered medical or surgical management for the condition highlighting the outcome of both approaches. Since they were from a remote district with no local medical facility and baby was small, they opted for surgical management.

Figure 1

Ultrasonography abdomen at the level of porta, portal vein not visualized, multiple collaterals seen

Figure 2

Magnetic resonance imaging axial section at the level of porta hepatis showing absence of portal vein

Figure 3

MR angiography coronal plane showing collaterals along inferior mesenteric vein and splenomegaly

On midline exploration, he was found to have ascites, large congested spleen. Splenic vein was identified by lifting the transverse colon cranially so that the pancreas got rotated along the whole body and tail. Pancreaticosplenic vein disconnection was done with individual ligation of tributaries and a good segment of splenic vein dissected for side-to-side anastomosis with left renal vein. The rest of the surgery was performed as the original description of Mitra et al., several years ago from Chandigarh.[2] It was possible to construct a 1 cm long patent wide anastomosis despite the splenic vein being 5 mm across. The spleen was visibly changing on the operating table itself after the shunt was allowed to function. Postoperatively, the child required 1 day of ventilatory support without any inotropic support. Intravenous anticoagulation was started in the perioperative period and continued till the 10th postoperative day. Oral feeds were started by day 7 after surgery.

In the postoperative period, the hematological parameters steadily kept improving and spleen gradually regressed to half its size. The platelet count had reached over 100,000/mm3, total leukocyte count had risen to 6,400/mm3 and hemoglobin was 10.5 g/dl. Doppler evaluation was done on the 10th postoperative day to confirm shunt patency. At 6 months follow-up, spleen is just palpable with no features of hypersplenism and esophageal varices have regressed.

DISCUSSION

Most Indian studies have highlighted EHPVO to be the major cause of portal hypertension and the commonest cause of major upper gastrointestinal bleeding in children.[3] The cause of EHPVO is unknown in majority of cases, but congenital malformation of the portal vein or acquired thrombosis following umbilical sepsis, umbilical vein catheterization, and pyelephlebitis following intestinal infection are some of the risk factors.

The management of acute hemetemesis in portal hypertension consists of resuscitation with blood and endoscopic banding and/or sclerotherapy, which controls the bleeding in 95%. These nonsurgical procedures, that is, endoscopic banding and sclerotherapy in pediatric age group requires state of art instruments and expertise which is not universally available and is followed by significant incidence of rebleed. These episodes are well-tolerated in the majority; however, mortality rates up to 31% have been reported.[4] There is no universally acceptable guideline on the management in case of recurrence of such bleeds and furthermore, there is controversy regarding best therapeutic option with endoscopic management on one side and surgery with or without splenectomy on the other. The timing and indication to give up the medical management and opt for shunt surgery is not clear with most of the series on shunt surgery reporting on average three to four bleeding episodes before the patients are taken up for surgery. Bismuth et al., had suggested surgical option even with one episode of variceal bleeding especially in infants as there are high chances of rebleeding in this age group. The longest follow-up study following shunt surgery has reported 5 and 10 year survival rates greater than 95% in children with negligible rebleeding rates.[5]

Endoscopic band ligation requires expertise and these patients need to be followed-up much longer to record the incidence of rebleed from ectopic varices (fundal, duodenal, and ileal varices) and reappearance of new varices.[6]

Surgical management of EHPVO may be nonselective shunts or selective shunts, partial shunts, and the more recently introduced Rex shunt. Nonselective shunts enable complete decompression of portal system by diverting total portal blood flow away from liver. Selective shunts divert blood of gastroesophageal-splenic segment and maintain blood flow in mesenteric segment which enables portal decompression with maintenance of hepatopetal portal perfusion, mesenteric venous pressure, and hepatotropic factors. Distal splenorenal shunt has lower chance of post-shunt encephalopathy. Mitra et al., published the first major report of successful treatment in portal hypertension patients by side-to-side lienorenal shunt. The youngest baby reported in literature treated by a shunt surgery was a 7-month-old.[7]

The risk and complications arising from thrombosis can be more catastrophic in a Rex shunt than the Mitra's lienorenal shunt as the venous drainage of entire small bowel is at risk in the Rex shunt as opposed to Mitra's shunt where only the ipsilateral kidney is at risk. Mitra's shunt has proven efficacy in several large series over the years.

Rex shunt had demonstrated increase in growth spurt thought to be due to increased blood supply of liver and probable release of growth factors and insulin like growth factors.[8] However, similar improvement in somatic growth after side to side lieno-renal shunt for portal hypertension has been reported in two separate prospective studies from Chandigarh.[9] The mechanism of this growth spurt in children after surgery remains unclear. Endoscopic treatment has not been able to demonstrate growth spurt in babies and children seen after shunt surgery[10] and requires babies and children having enough blood volume to withstand bleed, proximity to facility for blood transfusion, and center where rebleeding episode can be managed.

Our baby demonstrates a direct cause and effect relationship between umbilical sepsis and EHPVO. He had serious and recurrent gastrointestinal bleeding leading to need for several admission and blood transfusion. In view of the life-threatening risk of the condition, we had to offer treatment which has been well-tolerated by the baby with significant improvement.

The shunt surgery for portal hypertension essentially depends on the presence of a shuntable vein which is defined by the size across and tortuosity of the vein allowing downward mobilization towards the renal vein. In the technique described by Mitra, since it is a side to side shunt it can be done in small caliber splenic vein in small babies with the dual advantage of preserving the spleen.

CONCLUSION

Mitra shunt (spleen preserving side-to-side lienorenal shunt) is an ideal option for the surgical management of symptomatic portal hypertension in early infancy.