Clinical Pearls & Morning Reports
Published July 26, 2023
Group 1 pulmonary hypertension encompasses pulmonary arterial hypertension, which may be of an unknown cause, hereditary, or associated with drugs or toxins, connective-tissue disease, certain infections, portopulmonary hypertension, or congenital heart disease. Read the NEJM Case Records of the Massachusetts General Hospital here.
Q: What causes portopulmonary hypertension?
A: Although the exact mechanism of portopulmonary hypertension is unclear, the major driver is thought to be an imbalance between pulmonary vasodilators and vasoconstrictors. Portopulmonary hypertension typically occurs in patients with cirrhosis, but it can develop in patients without cirrhosis in the presence of a portosystemic shunt that allows blood to bypass the hepatic circulation.
Q: Describe a key component of care for patients with portopulmonary hypertension scheduled to undergo liver transplantation.
A: Without liver transplantation, patients with portopulmonary hypertension have a poor prognosis. Before liver transplantation, it is essential to ensure good hemodynamic control of portopulmonary hypertension. Uncontrolled portopulmonary hypertension is associated with a high risk of intraoperative death. In a retrospective analysis, mortality was 100% among patients with a mean pulmonary arterial pressure of 50 mm Hg or greater at the time of transplantation. Given this risk, assessment for portopulmonary hypertension is an essential part of the evaluation for liver transplantation, and patients with portopulmonary hypertension receive medical treatment and must have documented hemodynamic improvement before proceeding.
A: A congenital extrahepatic portosystemic shunt (CEPS), also called the Abernethy malformation, results in the diversion of portal venous blood flow directly into the systemic circulation, bypassing the liver. Most patients with a CEPS are asymptomatic, but 30% have symptoms, signs, or systemic complications. Such complications may include hepatic encephalopathy, portopulmonary hypertension, hepatopulmonary syndrome, and liver tumors. There are two types of CEPS: type 1, in which there is no portal blood flow to the liver, and type 2, in which only a portion of portal blood is shunted into the systemic circulation. The estimated incidence of CEPS is approximately 1 case in 30,000 to 50,000 live births. A CEPS is associated with other congenital malformations or syndromes in approximately one third of cases.
A: For asymptomatic patients, clinical observation is the preferred treatment approach. Prophylactic or preemptive shunt closure has not been proven to be beneficial. Definitive treatment is needed for patients with complications. For a type 1 CEPS, liver transplantation used to be the only option, given the absence of portal drainage to the liver. However, more recent studies have shown that in some patients with a type 1 CEPS, the hypoplastic intrahepatic portal vein can be visualized by means of a shunt occlusion test. In these patients, shunt closure with either an endovascular or a surgical approach has become the preferred option; liver transplantation is avoided, although it is still considered in patients with hepatocellular carcinoma, those with portopulmonary hypertension, or those in whom shunt closure is not possible. For type 2 CEPS, shunt closure is the first option.