Which medical conditions are the associated with idiopathic pulmonary arterial hypertension (IPAH)?

Updated: Jul 08, 2020
  • Author: Ronald J Oudiz, MD, FACP, FACC, FCCP; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Pulmonary vascular disease can be associated with portal hypertension (sometimes called portopulmonary hypertension), suggesting that patients with shunting of splanchnic blood, with or without liver disease, have a higher risk of developing PAH.

Additionally, exposure of the pulmonary circulation to substances from the splanchnic circulation that are normally detoxified via the liver may contribute to the development of pulmonary hypertension. More research is necessary to better understand this relationship.

Patients with connective-tissue diseases, namely the CREST (calcinosis cutis, Raynaud phenomenon, esophageal motility disorder, sclerodactyly, and telangiectasia) variant of scleroderma, systemic lupus erythematosus, and mixed connective-tissue disease, are also predisposed to developing IPAH-like disease. This is now termed associated PAH, or APAH.

The pathophysiologic nature of this predisposition is unclear. In the past, most experts used the term "secondary" pulmonary arterial hypertension for these diseases, indicating that, similar to IPAH, the process involves the precapillary circulation but is somehow caused by or at least associated with the underlying (predisposing) disease.

A study by Soon et al determined that unexplained iron deficiency is more prevalent in patients with idiopathic pulmonary artery hypertension than in those with chronic thromboembolic pulmonary hypertension (CTEPH). [7] Interleukin-6 (IL-6) may play a role in this difference in prevalence.

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