Pulmonary veno-occlusive disease (PVOD) is considered an uncommon variant of primary pulmonary hypertension (PPH) that preferentially affects the postcapillary pulmonary vasculature. It is still controversial if this condition and pulmonary capillary haemangiomatosis (PCH) are varied expressions of the same condition or different entities.
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Epidemiology
It is thought to account for ~5-10% of cases initially considered to be idiopathic PAH 2.
It is rare but can potentially affect all age groups with no geographic predilection. The majority of affected patients are under 50 years of age 1.
in the paediatric population, both sexes are equally affected
in the adult population, the ratio of male to female patients is approximately 2:1
Clinical presentation
Its presentation can be similar to other forms of pulmonary arterial hypertension, such as progressive dyspnoea, cough, fatigue and also haemoptysis.
Pulmonary capillary wedge pressure (PCWP) is usually normal due to patchy involvement. This is in contrast to the elevated pressures commonly obtained in patients with obstructed or stenotic larger pulmonary veins, mitral stenosis or left ventricular failure 4.
Pathology
It is characterised by extensive occlusion of pulmonary veins by fibrous tissue in a patchy distribution. This may be loose and oedematous or dense and sclerotic 7.
Associations
PVOD is still considered an idiopathic disease, but innumerable associated conditions have been reported in the medical literature, which includes 2,4:
peripheral blood stem cell transplantation
after radiation therapy
-
after chemotherapy
including treatment with bleomycin, cisplatin, vincristine, carmustine, and mitomycin 4
Genetics
Biallelic mutations in the EIF2AK4 gene is a cause of an autosomal recessive form 9.
Radiographic features
In general, imaging features can be non-specific and a definitive diagnosis often requires a lung biopsy 1.
Plain radiograph
Usually demonstrates nonspecific features of pulmonary hypertension, such as an enlarged pulmonary trunk and main pulmonary arteries and prominent heart right chambers.
CT
Reported HRCT chest findings include 1,2,4,9:
-
regions of ground-glass opacities, which can be
diffuse multifocal 1,4
perihilar 4
patchy 4
centrilobular 2,4: most cases 8,9
mediastinal lymph node enlargement 9
normal calibre pulmonary veins
The normal appearances of the heart left chambers in the setting of these pulmonary findings favours that the transudation of fluid into the lung interstitium is possibly pulmonary veno-occlusive disease related.
Angiography (DSA)
PVOD pulmonary arteriographic findings include 4:
enlarged central pulmonary arteries
subtle narrowing of the distal arterial branches
no arterial filling defects
heterogeneous contrast blush in the parenchymal phase
prolonged lung circulation time
normal or small left atrium
Treatment and prognosis
Pulmonary veno-occlusive disease generally carries a poor prognosis (some report a 72% mortality at one year from diagnosis 1). Lung transplantation is the treatment of choice 2.
It is important to note that vasodilators commonly used to treat patients with primary pulmonary hypertension, such as calcium-channel blockers 1, epoprostenol (PGI2) 1 or prostacyclin 6 can lead to disastrous outcomes (severe pulmonary oedema) in patients with pulmonary veno-occlusive disease.
History and etymology
The first description of the condition is thought to have been first reported by J Hora (German physician) et al. in 1934 1. The term "pulmonary veno-occlusive disease" was thought to have been coined by Heath et.al in 1966 9.
Differential diagnosis
Possible differential considerations include
-
idiopathic pulmonary arterial hypertension
there is no thickening of the interlobular septa
peripheral lung oligaemia
-
chronic pulmonary thromboembolism
there is no thickening of the interlobular septa
presence of vascular pruning
See also
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