Left-Sided Portal Hypertension - SASSiT

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1142 Dig Dis Sci (2007) 52:1141–1149 major splanchnic veins was 13%, with the splenic vein being occluded in 8% of patients, the portal vein in 4%, and the superior mesenteric vein in 1% [10]. Synonyms LSPH has also been referred to as segmental [11], sinistral [7], regional [4], localized [12], compartmental [13], lineal [14], or splenoportal hypertension [15]. Anatomy The splenic vein is a large and nontortuous vessel formed by five or six tributaries from the spleen. It lies inferior to the splenic artery and, after leaving the splenic hilus, runs behind the tail and the body of the pancreas. It is approximately 0.5 cm in diameter and 12 cm long. The splenic vein crosses anterior to the left kidney, being separated from the left sympathetic trunk and crus by the left renal vessels and from the abdominal aorta by the superior mesenteric artery and left renal vein [16]. The tributaries of the splenic vein include the short gastric, left gastroepiploic, pancreatic, and inferior mesenteric veins. Behind the neck of the pancreas the splenic vein joins the superior mesenteric vein to form the portal vein. Since the splenic vein is contiguous with the pancreas throughout that organ’s entire length, pancreatic disorders contribute the main etiology, and any significant pancreatic pathology may be complicated with venous obstruction (Fig. 1). There is also close approximation between the splenic vein and the neighboring pancreatolienal lymph nodes. Therefore, even retroperitoneal diseases may contribute to splenic vein occlusion [17–21]. Fig. 1 Illustration of splenic venous thrombosis and fundal varices. CV, coronary veins; GEV, gastroepiploic vein; PV, portal vein; SV, splenic vein; SMV, superior mesenteric vein Pathophysiology Blood flow through the splenic vein may be blocked secondary to either thrombosis formation or neighboring mass effect. Splenic vein occlusion results in venous hypertension in collateral pathways that carry splenic arterial blood to the superior mesenteric and portal veins including the short gastric, coronary, and gastroepiploic veins and the veins located in the upper half of the stomach. Following obstruction, splenic blood typically drains through the short gastric veins to the stomach. In the gastric wall veins of the fundus, blood flow and pressure increase and submucosal structures consequently dilate, producing gastric varices. Eventual decompression into the portal system occurs through the coronary and epiploic veins. The coronary vein drains to different parts of the portal system (directly to the portal vein, to the junction of the splenic and portal veins, and to the splenic vein). When the coronary vein drains distal to the obstruction in the splenic vein, esophageal varices may occur alone or in combination with gastric varices [2, 7, 22]. However, due to several anatomic variations, obstruction of the splenic vein may not always result in portal hypertension or formation of varices. Etiology The main cause of LSPH is splenic vein thrombosis (SVT). Rare causes of LSPH include compression of the splenic vein by other organs, edema, enlarged lymphadenopathies, and splenic artery aneurysm. There is a strong association between pancreatic disorders and SVT because of the splenic vein’s location. Because the splenic vein is posterior to the pancreas and in direct contact with it, any type of pancreatic disease is likely to involve the splenic vein [3, 8, 16]. Acute and chronic pancreatitis and pancreas neoplasms are the most common causes of SVT [3, 8, 10, 16, 23–26]. In an early report in 1970, Sutton et al. found that 35% of their cases of isolated SVT were caused by tumors and only 17% by pancreatitis [4]. More recent reviews have found acute or chronic pancreatitis to be the probable cause of isolated SVT in the majority of cases [2]. In a study by Moosa et al., pancreatitis—diagnosed with biopsy or operation—was the etiology in 87 (60%) of 144 cases, while pancreas malignancy was detected in only 13 (9%) of the patients [16]. The reason for this difference may be due to increases in the incidence of pancreatitis and in diagnostic activities, as well as to improvements in diagnostic procedures [27]. Single episodes of acute pancreatitis may lead to SVT, and the risk of SVT does not correlate with the severity of pancreatitis. Also, SVT may occur silently, as a complication of mild pancreatitis [7, 8]. Springer
Dig Dis Sci (2007) 52:1141–1149 1143 Table 1 Etiologies of splenic vein obstruction 1. Pancreatic diseases a. Pancreatitis Acute pancreatitis [3, 16, 23, 34] Chronic pancreatitis [3, 8, 10, 16, 23, 28] Familial pancreatitis [16, 29] Traumatic pancreatitis [13] b. Pancreas malignancies Adenocarcinoma [3, 5, 24] Islet cell carcinoma [30–32] Cystadenoma [5, 33] Pancreatic lymphoma [16] c. Other pancreatic causes Pancreatic pseudocysts [3, 5, 23, 26, 35] Pancreatic abscess [1] Pancreatic divisum [23] Pancreatic transplantation [16] Congenital cyst [36] Pancreatic pseudotumor [37] 2. Nonpancreatic disorders a. Surgical procedures Umbilical vein catheterization [38] Partial gastrectomy [39] Distal splenorenal shunt [16] Splenectomy [2, 16] Selective venous catheterization [16] b. Metastatic carcinoma Lymphoma [3, 16] Oat cell carcinoma [5] Retroperitoneal liposarcoma [16] Renal cancer [3, 40] Gastric cancer [22] Colon cancer [3, 22] c. Miscellaneous Retroperitoneal fibrosis [12] Splenic artery aneurysms [16] Gastric ulcer [1] Hepatoportal sclerosis [22] Hereditary thrombocytemia [41] Myeloproliferative disorders [41] Protein S deficiency [22] Systemic lupus erythematosus [22] Renal abscess [17] Tuberculous adenitis [42] Retroperitoneal abscess [17, 21] Benign renal cysts [1] Various disorders other than pancreatic diseases can cause isolated SVT. However, they are rare and have a wide spectrum in terms of their mechanisms of splenic vein obstruction (Table 1) [1–5, 8, 10, 12, 13, 16, 17, 21–42]. Presenting signs/symptoms The major clinical consequences of portal hypertension in general are the formation of gastroesophageal varices, ascites, and splenomegaly. Patients with portal hypertension frequently form varices [43]. When only a segment of the portal venous bed is obstructed, varices develop only in areas that decompress the corresponding segment. For example, segmental portal hypertension within the splenic vein (SVT) is associated with the formation of isolated gastric varices in the fundus of the stomach. Most commonly, LSPH is asymptomatic and is found incidentally on investigation. In symptomatic cases, the first clinical manifestation of LSPH is generally acute or chronic GI bleeding from ruptured esophageal or gastric varices, and rarely from colonic varices [44]. Usually the bleeding is serious. Patients may also present with chronic anemia due to portal hypertensive gastropathy. Gastrointestinal bleeding is the presenting symptom in 45% [16] to 72% [3] of patients with LSPH. The number of patients that bleed varies from series to series (Table 2) [5, 10, 16, 22, 44, 45]. Based on prospective studies, it appears that most patients with SVT do not bleed, suggesting that adequate low-pressure collateral flow develops without the formation of varices. Splenomegaly is a hallmark of long-standing portal hypertension and is frequently seen in patients with LSPH. The degree of splenomegaly in patients with presinusoidal portal hypertension including isolated SVT is often greater than in those with cirrhosis [46]. The mechanisms are not fully understood but are related to increased venous congestion and splenic arterial flow. Although up to 71% of patients have splenomegaly, few patients suffer from splenic pain and develop leukopenia or thrombocytopenia [3]. Abdominal pain without bleeding can be caused in different patients by a variety of conditions, such as chronic pancreatitis, pseudocyst, carcinoma, and splenomegaly. It may be the presenting symptom in 25%–38% of patients [3, 16, 22]. Patients with LSPH typically do not have significant ascites unless they develop acute dilutional hypoalbuminemia during fluid resuscitation for a variceal bleed or have associated cirrhosis. Therefore, development of ascites is a rare presenting manifestation in LSPH [47]. Diagnosis The diagnosis of LSPH is based on clinical, biochemical, and radiological evaluation. Ultrasonography may show normal liver architecture. When the diagnosis is in doubt, a liver biopsy may be performed to rule out cirrhosis. Esophageal varices can be seen both radiologically and endoscopically. In contrast, gastric varices are often difficult to diagnose by either technique. On barium contrast studies, gastric varices appear as thick and tortuous mucosal folds, filling defects or distorted mucosal configurations anywhere along the greater curvature toward the cardia [48]. Although Springer
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Left-Sided Portal Hypertension - SASSiT

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