The Frequency and Significance of Portopulmonary Venous Anastomosis (PPVA) and Transvenous Obliteration for Gastric Varices

Abstract

A Portopulmonary Venous Anastomosis (PPVA) is a direct vascular connection between the portal venous system and the pulmonary veins, close to the left atrium. We describe a patient with advanced cirrhosis and moderately severe Hepatopulmonary Syndrome (HPS) in whom (PPVA) was demonstrated by a high resolution computed tomographic scan. In order to reduce the symptoms of hypoxia in our patient, we sequentially performed Transjugular Intrahepatic Portosystemic Shunt (TIPS) followed by a catheter based obliteration of the PPVA. The case raised three questions which were addressed through an extensive literature review. Among patients with advanced cirrhosis, what is the frequency of PPVA? Our literature review suggests that the frequency of finding a PPVA in patients with portal hypertension depends on the imaging technique used. Transhepatic or transvenous portal venography may demonstrate PPVA in about 20% of patients with cirrhosis and varices. Limited published experience with contrast enhanced (bubble) echocardiography suggests that PPVA may be present in about 30% of such patients. An increasing number of case reports of PPVA have been published in recent years. This observation indicates that routine use of High Resolution Computed Tomography (HRCT) and magnetic resonance imaging is able to identify PPVA in cirrhotic patients. The visualization of PPVA with HRCT depends on the timing of the contrast injection and the expertise of the viewer. The present report describes three patients with portopulmonary venous anastomosis (PPVA) in whom balloon-occluded retrograde transvenous obliteration (B-RTO) of gastric varices was attempted. No patients had a gastrorenal shunt. In one patient, after an approach from the inferior phrenic vein (IPV), the PPVA was embolized with the use of microcoils. Portopulmonary Venous Anastomosis Detected at Balloon-occluded Retrograde Transvenous Obliteration for Gastric Varices among cirrhotic patients with PPVA, what is the clinical significance of the PPVA? There are multiple causes of clinically significant hypoxia in patients with cirrhosis. A PPVA is a right to left shunt that, theoretically, could be associated with clinically significant systemic arterial hypoxemia or emboli. There is not definitive evidence in the published literature that PPVA alone causes clinically significant hypoxia in cirrhotic patients. PPVA is, however, a documented important risk factor for systemic emboli when needle or catheter techniques are used to treat or prevent bleeding from gastroesophageal varices.