A Case of Pulmonary Arterial Hypertension Associated with Congenital Extrahepatic Portocaval Shunt
In October 2012, a 20-yr-old male was referred to our department with pulmonary hypertension of unknown etiology. He underwent surgical closure of ventricular septal defect (VSD) at 10 months of age. Eleven months before admission, the patient underwent laparoscopic appendectomy at another hospital. During the preoperative evaluation, screening abdominal ultrasound (US) showed multiple liver masses, and transthoracic Doppler echocardiography (TTE) showed pulmonary hypertension of unknown origin.\nOn admission, the patient had mild exertional dyspnea (New York Heart Association, NYHA class II). Physical examination revealed pectus excavatum but was otherwise unremarkable. The electrocardiogram demonstrated regular sinus rhythm with right bundle branch block (RBBB), and the chest X-ray showed mild cardiomegaly and increased pulmonary vascularity with bulged pulmonary conus (). At admission, the patient's laboratory values were within normal limits except for slightly reduced serum total protein (6.3 g/dL; reference range, 6.6-8.3) and mildly elevated direct bilirubin (0.53 mg/dL; reference range, 0.13-0.47) and blood ammonia (105 µg/dL; reference range, 20-80). Serologic markers for hepatits B and C virus and for AFP and CA-19 were negative.\nTTE showed a significantly dilated right ventricle (RV) chamber with a D-shaped left ventricle (LV). The LV chamber was mildly dilated, but the LV ejection fraction was normal. The estimated RV systolic pressure (RVSP), calculated as the maximal velocity of tricuspid regurgitation (TR Vmax), was 64 mmHg, which indicated moderate pulmonary hypertension (). We found no definite shunt flow through the inter-ventricular or inter-atrial septum and main pulmonary artery. In addition, there was no evidence of pulmonary thromboembolism or pericardial effusion. These findings were confirmed by transesophageal echocardiography (TEE).\nCardiac catheterization was performed to confirm the diagnosis and to classify the pulmonary hypertension based on the Dana Point classification recommended by the World Health Organization (WHO) (, ). Right catheterization, performed with a Cournand catheter, showed a pulmonary capillary wedge pressure (PCWP) of 7 mmHg, mean pulmonary arterial pressure (mPAP) of 44 mmHg (), pulmonary vascular resistance (PVR) of 608 dyn·s·cm-5 and a cardiac index (CI) of 2.89 L/min per m2. Consequently, pulmonary arterial hypertension (group 1 pulmonary arterial hypertension) was diagnosed by right heart catheterization (RHC). Interestingly, significant oxygen step-up was observed between the inferior vena cava (IVC) and the low level of right atrium (RA) during O2 saturation analysis of the right heart. This findings suggested significant arterial blood shunt in this area.\nAbdominal computed tomography (CT) and magnetic resonance imaging (MRI) were performed to further evaluate the multiple liver masses that were found incidentally at the patient's local hospital. CT showed ill-defined low-density nodular lesions in the bilateral hemiliver. These lesions exhibited hyperintensity on T1-weighted MR images, with the larger ones containing a central scar with a high signal intensity on T2-weighted MRI images and a low signal intensity on T1-weighted MR images (). Based on the CT and MR imaging results, initially we thought that the pulmonary arterial hypertension was caused by portal hypertension, which is known as portopulmonary hypertension associated with nodules of liver cirrhosis (LC). A percutaneous liver biopsy was performed under US guidance for histological diagnosis, which was multifocal nodular regenerative hyperplasia with no evidence of LC. Therefore, CT angiography and portal venography were performed to investigate whether intra- or extra-cardiac shunt was present and also to determine the anatomical relationship between the portal venous system and the right heart; both can cause pulmonary arterial hypertension.\nCT angiography demonstrated the presence of a portocaval shunt in which the left portal vein (PV) and left hepatic vein joined and drained directly into the suprahepatic IVC without passing through the liver (). Portal venography revealed abnormal communication between the left PV and IVC with obliteration of the right PV (Abernethy type 1b) (). The main PV and hepatic venous wedge pressure were both 6 mmHg. The superior mesenteric and splenic venous pressures were 6 mmHg and 9 mmHg, respectively. In addition, we reexamined the TTE that was not able to detect this communication at first, in which type 1 CEPS could be clearly visualized on the subcostal window ().\nWe confirmed the diagnosis as a pulmonary arterial hypertension caused by CEPS (Abernethy type 1b) and multifocal nodular regenerative hyperplasia of the liver. However, there was no deinite evidence of other cardiac, gastrointestinal or genitourinary anomalies that are also known to be associated with type 1 CEPS. The patient began inhalation of iloprost (40 µg/day) and was taught to use a nebulizer. The patient's condition improved and he was discharged on day 7. At a 5-month follow-up appointment, his 6-min walking test improved from 380 m to 525 m, and TTE showed a reduction in RVSP from 64 mmHg to 49 mmHg.