Porto-Pulmonary Venous Anastomosis: A Reversible Cause of Chronic Hypoxemia in Portal Hypertension

Abstract

The two main mechanisms of hypoxemia in portal hypertension (PH) are hepatopulmonary syndrome and portopulmonary hypertension which occur respectively in 15% and 2–5% of cirrhotic patients [1]. We describe a case of PH-related hypoxemia due to a porto-pulmonary venous anastomosis (PPVA), and its improvement after embolization. A 70-year-old woman with no underlying cardiovascular or pulmonary illnesses was admitted for Child Pugh B7 cirrhosis revealed by esophageal varices rupture. The patient had severe dyspnea with a modified Medical Research Council (mMRC) score of 3/4. Arterial blood gas (ABG) showed PaO2: 65 mmHg, PaCO2: 33 mmHg, pH: 7.49. Seven days after esophageal varices ligation, ABG showed a decrease in PaO2 from 65 to 54 mmHg with an alveolo-arterial oxygen gradient of 54 mmHg. Pulse oximetry revealed orthodeoxia with a drop in SpO2 from 92% while supine to 83% while upright. On pulmonary function tests, carbon monoxide diffusion capacity was 67% of predicted value with normal lung volumes. Transthoracic echocardiography showed normal left ventricular ejection fraction (68%) and systolic pulmonary arterial pressure (25 mmHg). Bubble contrast study detected microbubbles in the left heart chamber within 15 cardiac cycles after right atrial passage, suggesting intrapulmonary shunt. Pulmonary embolism was excluded by contrast enhanced computed tomography (CT). At portal venous phase, CT with maximal intensity projection reconstructions showed peri-splenic, peri-gastric and periesophageal varices. The latter communicated with the lower right lobar pulmonary vein (Fig. 1), resulting in a porto-pulmonary shunt. Considering the contribution of this shunt to hypoxemia, a selective embolization was proposed. Under general anesthesia with ultrasound guidance, the main portal vein was catheterized with a percutaneous access set (Neff percutaneous access set, Cook medical , Bloomington, IN, USA). The portography confirmed a large and tortuous portosystemic venous shunt from the left gastric vein into the right lower pulmonary vein (Fig. 2). This anastomosis was catheterized with a 2,7F microcatheter (Progreat, Terumo Europe N.V. , Leuven, Belgium) and successfully embolized with 7 detachable coils (Interlock Boston Scientific, Malborough, MA, USA; Azur, Terumo Europe N.V. , Leuven, Belgium). Complete occlusion of the venous shunt was observed on the final angiographic control (Fig. 3). One month after embolization, we noted a marked improvement in dyspnea (mMRC 1/4) and ABG (PaO2: 68 mmHg), and a complete resolution of orthodeoxia. Contrast enhanced CT confirmed the occlusion of PPVA but showed a partial portal thrombosis. At 15 months of therapeutic anticoagulation, the patient remained stable (mMRC1/4; PaO2: 66 & Pascaline Priou [email protected]