Contents
Rare disorder characterised by raised pulmonary-artery pressure in the absence of secondary causes.
Pathophysiology
Characterised by intimal fibrosis, in situ thrombosis, and hypertrophy of the smooth muscle cells of the media.
Pathological subtypes:
- Plexogenic arteriopathy (50% cases, worst prognosis)
- Associated with the plexiform lesion, an unusual pathological entity consisting of a mass of disorganised vessels associated with endothelial cells, smooth muscle cells, and myofibroblasts (angiogenic response to underlying vascular injury).
- Thrombotic arteriopathy
- Similar pulmonary vascular histology with multiple thrombi (give the abnormal patchy appearance seen in a ventilation perfusion scan and may be a consequence of endothelial injury).
- Anticoagulants improve survival
- Pulmonary veno-occlusive disease (< 10% cases)
- Separate entity with intimal proliferation of the intrapulmonary veins rather than arteries.
Clinical features
It is a progressive disease usually affecting the arterial side of the pulmonary circulation and, if untreated, progresses to severe pulmonary hypertension and, finally, right heart failure.
- Breathlessness with no other obvious cause (M/C symptom at presentation)
Specific signs of pulmonary hypertension:
- Loud pulmonary second sound
- Right ventricular heave
- Pulmonary flow murmur
Signs of right heart dysfunction:
- Raised jugular venous pressure
- V-waves in the neck
- Hepatic pulsation
- Swollen ankles
Other features:
- Signs of co-existent disease: Primary pulmonary, cardiac, or liver disease
- Evidence of: venous thrombosis or connective tissue, thyroid or HIV disease).
Diagnosis
May take up to 18 months to diagnose and, following diagnosis, the median survival is under two years.
Right heart catheterization (DIAGNOSTIC):
Usually performed using a Swan Ganz triple lumen thermodynamic catheter inserted under fluoroscopic control via the right femoral vein.
- Mean PAP >25 mmHg at rest and >30 mmHg during exercise, with a normal pulmonary capillary wedge pressure.
Chest radiograph:
Of limited benefit but may show enlargement of the heart or main pulmonary artery or peripheral pruning of vessels.
Ventilation-perfusion scan:
May show the presence of mismatched defects indicating possible underlying thromboembolism, but defects may also be seen in pure intrinsic vascular disease, particularly the thrombotic variant. The ventilation scan will be normal but the perfusion scan may show patchy loss consistent with vascular obstruction.
Computed tomographic (CT) angiogram:
Exclude parenchymal lung disease but volume scans of the central pulmonary arteries after injection of contrast may help to demonstrate major intravascular clot.
Selective pulmonary angiography:
Management
Treatment aimed at lowering PAP, increasing cardiac output, and decreasing in situ thrombosis.
Anticoagulants (prevent in situ thrombosis):
- Long-term treatment with warfarin improves the prognosis in PPH.
- Treatment goal: To achieve an international normalised ratio (INR) of 2
Calcium channel blockers (CCB) (oral drug of choice as vasodilators):
- High-dose dihydropyridine blockers:
- Diltiazem (up to 720 mg daily)
- Nifedipine (up to 300 mg daily)
Other vasodilators:
- Diazoxide, captopril, and hydralazine
- Prostacyclins
Inotropic agents:
Used once maximum vasodilation has been achieved (particularly if there is concomitant use of CCBs which are known to be negatively inotropic) since right heart dysfunction is a sequel of severe pulmonary hypertension.
Lung transplantation
Last resort