idiopathic pulmonary hypertension
pulmonary hypertensionAn idiopathic condition more common in women age 20 to 40, which is characterised by increased pulmonary arterial blood pressure in absence of other heart or lung disease. The major effect of pulmonary hypertension is increased right ventricular load which, when prolonged, predisposes patients to right ventricular failure, syncope, precordial pain, sudden death.
Idiopathic, secondary to Eisenmenger’s complex, respiratory failure in cystic fibrosis and COPD, with inhibition of endothelium-dependent pulmonary arterial relaxation due to decreased synthesis of nitric oxide or endothelium-derived growth factor.
High-dose calcium channel blockers may induce decreased pulmonary artery pressure and pulmonary vascular resistance, which may be combined with warfarin.
Causes of death
Arrhythmias, right and left ventricular dysfunction, left main coronary artery compression, dissection of pulmonary artery.
The average lifespan post-diagnosis is 3 years without therapy. The prognosis is worse in those who have severe symptoms, are older than 45 when diagnosed, present with right-sided heart failure, and do not respond to treatment.
Pulmonary hypertension aetiology
Decreased cross-sectional area of the pulmonary vascular bed:
• Parenchymal lung diseases;
• Lung resection;
• Congenital hypoplasia.
Increased flow through the pulmonary arteries:
• Systemic to pulmonary shunts.
Increased resistance to flow through large pulmonary arteries:
• Chronic thromboembolic disease;
• Takayasu’s arteritis;
• Congenital pulmonary artery stenosis;
• Mediastinal processes (fibrosis, tumours);
• Pulmonary artery tumours.
Increased resistance to flow through small pulmonary arteries:
• Primary pulmonary arterial hypertension;
• Pulmonary vasculitides;
• Autoimmune diseases;
• Chemical/toxic damage;
• Increased resistance to pulmonary venous drainage.
Increased resistance to pulmonary venous drainage:
• Elevated left ventricular diastolic pressure;
• Elevated left atrial pressure;
• Pulmonary venous obstruction.
Chronic alveolar hypoxia
• Obesity-hypoventilation syndrome;
• Chest wall disorders;
• Neuromuscular disorders;
• Parenchymal lung disease.
• High altitude;
• Portopulmonary hypertension;
• HIV infection;
• Sickle haemoglobinopathies;
• Pulmonary capillary hemangiomatosis.
Pulmonary Hypertension types
Systemic congestion due to mitral stenosis, left ventricular failure, left atrial myxoma, anomalous drainage of the pulmonary circulation.
Due to increased blood flow through lungs secondary to congenital heart defects.
Due to recurring vessel obstruction, seen in IV drug abuse and patients associated with hypoxia, alveolar hypoventilation (mitral stenosis, coarctation of aorta, Eisenmenger’s complex, ventricular septal defect).
Comprises 10-20% of cases, treated by addressing the underlying disease—e.g., unilateral renal artery stenosis, coarctation of aorta, primary aldosteronism, pheochromocytoma.