Pulmonary Veno-Occlusive Disease
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- heritable pulmonary arterial hypertension
- idiopathic pulmonary arterial hypertension
- pulmonary veno-occlusive disease
Article, see p 2022
When caring for our patients with pulmonary arterial hypertension (PAH), how many times have we wondered, could this patient really have pulmonary veno-occlusive disease/pulmonary capillary hemangiomiatosis (PVOD/PCH)? This question typically arises if there is a suggestive computed tomography scan, a low diffusing capacity of the lungs for carbon monoxide, substantial hypoxemia, or, certainly, a poor response to PAH-specific medications or development of pulmonary edema (PVOD/PCH versus unsuspected diastolic dysfunction). In fact, we recently were referred such a patient: the computed tomography scan showed septal thickening and lymphadenopathy, the diffusing capacity of the lungs for carbon monoxide was low, hypoxia requiring 8 to 10 L of supplemental oxygen was present, and marked clinical deterioration occurred after being started on PAH therapy with ambrisentan and tadalafil. Ultimately, the patient underwent lung biopsy to prove what we were certain was PVOD/PCH. To our surprise, histologically, there was no venous involvement, and she was diagnosed with idiopathic PAH (IPAH). However, based on the study by Hadinnapola and colleagues in this issue of Circulation,1 which found significant overlap in clinical, radiological, and in 1 case even histological findings, could she still have had EIF2AK4 mutations and thus PVOD/PCH genetically?
In contrast to IPAH, which involves small pulmonary arteries, vascular remodeling in PVOD/PCH affects predominantly septal veins and venules, as well as capillaries.2 PVOD and PCH, previously thought to be separate conditions, are now felt to represent variable expression of the same disease.2,3 Initial clinical presentation is …