Splenic Arteriovenous Fistula: A Rare Cause of Portal Hypertension

Abstract

Purpose: Portal hypertension is a common condition encountered by gastroenterologists. While this is most commonly encountered in the setting of cirrhosis, other conditions affecting portal venous blood flow dynamics can present with findings consistent with portal hypertension. We present a rare case of portal hypertension caused by a splenic arteriovenous (SAV) fistula. A 69-year-old female presented with hematemesis after a prolonged bout of nausea and vomiting. Endoscopic evaluation showed large esophagogastric varices which were amenable to esophageal banding. There was no evidence for alcohol abuse, hepatotoxin exposure, or risk factors for viral hepatitis. Serologic studies for viral hepatitis, antinuclear antibody, antismooth muscle antibody, antimitochondrial antibodies, and iron studies were normal. Initial radiographic imaging did not suggest cirrhosis and a percutaneous liver biopsy was normal. She was referred to our center for further management. Following initial esophageal banding, she did not rebleed. Our review of the previous CT images suggested a possible splenic arteriovenous (SAV) fistula. CT angiography showed contrast in the splenic and portal veins during the arterial phase and aneurysmal splenic vein enlargement confirming the diagnosis of a SAV fistula. Transcatheter arterial embolization was done with only a small branch of the splenic artery still feeding the dilated splenic vein postembolization. Upon further questioning, she denied any major abdominal trauma and had two normal pregnancies. She did not experience any further bleeding and was discharged. SAV fistula is a rare cause of portal hypertension and should be suspected in female patients who present with variceal bleeding, but have no signs of chronic liver disease. In a SAV fistula, portal hypertension is due to enhanced arteriovenous flow as blood bypasses the capillary bed of the spleen. The hemodynamic changes that ensue lead to dramatic and rapid increases in portal venous pressures and subsequent clinical sequellae. The etiology of an acquired SAV fistula may be spontaneous, iatrogenic, or traumatic. A significant female predominance of spontaneous cases and relatively young presentations that are temporally associated with pregnancy have suggested that hormonal factors (perhaps associated with pregnancy) lead to arterial wall elastin weakening. Gastrointestinal hemorrhage has been the most common presentation in the literature. Our patient demonstrates that an SAV fistula should be considered as a cause of noncirrhotic portal hypertension in females even well beyond the child-bearing years.