24: Portopulmonary Hypertension



Overall Bottom Line


  • PPHTN is the presence of pulmonary arterial hypertension in the setting of portal hypertension.
  • The cause is unknown but appears to be related to cytokine-induced remodeling of the pulmonary arterial anatomy and possibly intravascular thromboses.
  • The diagnosis is suspected on echocardiography and confirmed by right heart catheterization.
  • Several medications can be used to treat PPHTN but need to be given for several months or years with periodic monitoring of pulmonary artery pressure.
  • Liver transplantation is an option for selected patients with PPHTN and is associated with improvement of pulmonary arterial hypertension.






Section 1: Background



Definition of disease



  • PPHTN is defined by pulmonary arterial hypertension in the setting of portal hypertension in the absence of other causes of pulmonary hypertension.


Disease classification



  • There is no standard disease classification for PPHTN although it can be useful to separate the disease into mild (30–44 mmHg), moderate (45–59 mmHg) and severe (60 mmHg and over) based on the degree of pulmonary arterial hypertension.


Incidence/prevalence



  • The prevalence of PPHTN ranges from less than 1% up to 16%.
  • The prevalence appears to be higher in patients with more severe liver disease.
  • The highest prevalence has been seen in patients being evaluated for liver transplantation.


Etiology



  • The cause of the disease is unknown.
  • PPHTN only occurs in the setting of portal hypertension.
  • This is typically due to cirrhosis but can also occur in non-cirrhotic portal hypertension.


Pathology/pathogenesis



  • The pathogenesis of PPHTN is unclear but may occur on the background of genetic susceptibility as there are cases of familial pulmonary hypertension related to dysfunction of the bone morphogenetic protein receptor type II.
  • Some studies suggest that the underlying portal hypertension leads to porto-systemic collaterals and substances that normally would be metabolized in the liver mediate the pulmonary hypertension. Multiple cytokines and hormones have been implicated including serotonin, IL-1, vasoactive intestinal peptide, glucagon, endothelin-1 and thromboxane B2.
  • The hyperdynamic circulation seen in cirrhosis and chronic thromboembolism may also play a role.
  • Pulmonary histology in PPHTN demonstrates in situ thrombosis, pulmonary arteriopathy and vasoconstriction.


Section 2: Prevention






Bottom Line/Clinical Pearls


  • No interventions have been demonstrated to prevent the development of the disease.





Screening



  • Typically PPHTN is found in patients with cirrhosis undergoing liver transplant evaluation during pre-operative cardiac testing.
  • The clinical presentation of PPHTN can mimic other conditions seen in cirrhosis such as hepatopulmonary syndrome and ascites (with or without a pleural effusion). Hence cirrhotic patients presenting with dyspnea on exertion without an obvious cause should be screened for PPHTN.


Section 3: Diagnosis (Algorithm 24.1)






Bottom Line/Clinical Pearls


  • Patients with PPHTN can present without symptoms but typically complain of shortness of breath on exertion. Other symptoms can include chest pain, fainting or dizziness.
  • Physical examination findings in PPHTN can be limited to signs of portal hypertension but a loud pulmonary component of the second heart sound, a pansystolic murmur heard at the left sternal border in the fourth intercostal space (from tricuspid regurgitation) that increases during inspiration, a parasternal heave and ankle edema can sometimes be appreciated.
  • The diagnosis can be suspected by echocardiography and is confirmed by right heart catheterization.





Differential diagnosis













Differential diagnosis Features
Hepatopulmonary syndrome History can be similar but usually no unique physical findings except for those of portal hypertension. Investigations show a low arterial oxygen saturation and normal right-sided pressures on echocardiography and right heart catheterization
Tense ascites and/or a pleural effusion History of shortness of breath on exertion is usual. Physical findings demonstrate a fluid thrill or shifting dullness or decreased air entry (typically at the right lung base) with a stony dull percussion note. Ascites and effusions are readily seen on abdominal or chest imaging. Echocardiography and right heart catheterization should be normal


Typical presentation



  • The typical patient with PPHTN is first diagnosed during investigation for liver transplantation. The diagnosis of portal hypertension is usually already apparent in a cirrhotic patient with complaints including abdominal distension, ankle edema and fatigue and physical examination demonstrating spider nevi, ascites and splenomegaly. Patients can present with symptoms of PPHTN including dyspnea on exertion, orthopnea and occasionally unexplained syncope or light-headedness. An abnormal cardiac examination with a pansystolic murmur at the left sternal edge and a loud pulmonary component of the second heart sound can be suggestive of PPHTN. During the transplant evaluation process, an echocardiogram can demonstrate high right-sided pressure which then leads to confirmatory testing.


Clinical diagnosis



History



  • The history in PPHTN is notable for shortness of breath on exertion in most patients. It is important to ask about breathing difficulties when lying down (orthopnea) and any symptoms that might suggest right heart failure including chest pain, hemoptysis, ankle swelling and syncopal episodes.
  • Abdominal distension from ascites is a feature but can obviously be seen in cirrhotic patients without PPHTN.


Physical examination



  • On physical examination, signs of portal hypertension are invariably present including spider nevi, ascites splenomegaly and lower extremity edema.
  • Examination findings specific to PPHTN include those seen in right heart failure such as a loud pulmonary component to the second heart sound, a pansystolic murmur due to tricuspid valve regurgitation, and a right ventricular heave. With higher right-sided pressures the physiological splitting of the second heart sound increases and an early diastolic flow murmur of pulmonary regurgitation can be heard. All of these cardiac auscultatory findings are accentuated by inspiration which increases flow through the right-sided cardiac chambers.

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Related posts:

15: Hereditary Hemochromatosis 25: Pregnancy-Related Liver Disease 38: Liver Transplantation: A Pediatric Perspective 36: Approach to Jaundice in Infancy 53: Recurrent Disease Post-Liver Transplantation: Autoimmune Diseases, Hepatitis B and NASH 34: Diagnosis and Management of Acute Liver Failure: A Pediatric Perspective

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Aug 12, 2016 | Posted by in GASTROENTEROLOGY | Comments Off on 24: Portopulmonary Hypertension

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