Pulmonary hypertension (PH) is elevated pressure in the pulmonary arteries ≥ 20 mmHg at rest. It can be idiopathic or due to chronic pulmonary (e.g., COPD, chronic sleep apnea) and/or cardiac disease (e.g., mitral valve disease). Over time, the rise in pressure may result in structural changes (e.g., dilation or hypertrophy) or impaired function of the right ventricle. If these changes are secondary to diseases of the lungs or the pulmonary artery system, the condition is referred to as cor pulmonale. While PH and cor pulmonale are often asymptomatic in early stages, symptoms like dyspnea on exertion, fatigue, cyanosis, and syncope appear in later stages. In decompensated cor pulmonale, the risk of arrhythmias and death is high. Echocardiograms are used as an initial non-invasive test to estimate the pulmonary artery pressure and to demonstrate an altered structure of the right ventricle. Right heart catheterization provides the definite diagnosis and the exact mean pulmonary arterial pressure (mPAP). Treatment mainly consists of management of the underlying causes of PH and cor pulmonale. Supplemental oxygen, pulmonary vasodilators, and diuretics may be given to reduce pulmonary artery hypertension and improve blood oxygenation. Lung transplantation is the treatment of last resort in refractory cases.
Pulmonary hypertension 
- Chronically elevated mean pulmonary arterial pressure (mPAP) at rest ≥ 20 mmHg (normal: 10–14 mmHg) or > 30 mmHg with exercise due to chronic pulmonary and/or cardiac disease or unknown reasons
- Plus elevated pulmonary vascular resistance of ≥ 3 Wood units for patients with pre-capillary pulmonary hypertension (e.g., )
Cor pulmonale 
- Altered structure (hypertrophy, dilation) or impaired function of the right ventricle caused by pulmonary hypertension resulting from a primary disorder of the respiratory or pulmonary artery system
Chronic cor pulmonale
- Most common form
- Slow progression
- Acute cor pulmonale
- Sudden overload of the right ventricle
- Usually caused by acute
- Life-threatening condition
- PAH: more commonly affects female individuals
Epidemiological data refers to the US, unless otherwise specified.
Classification of pulmonary hypertension (WHO) by cause
- Group 1: pulmonary arterial hypertension (PAH)
- Group 2: left heart disease (e.g. ,
Group 3: chronic lung diseases and/or hypoxemia
- High altitude (e.g., high-altitude pulmonary hypertension)
- Group 4: chronic thromboembolic occlusion of the pulmonary vessels
- Group 5: unclear multifactorial mechanisms
Increased pulmonary vascular resistance
- Occlusive vasculopathy (e.g., idiopathic pulmonary arterial hypertension, )
- Hypoxic pulmonary vasoconstriction: chronic hypoxic pulmonary vasoconstriction → airway smooth muscle hypertrophy (medial hypertrophy) and pulmonary vascular bed destruction → ↑ pulmonary vascular resistance (e.g., ,
- Increased pulmonary vessel pressure → right heart hypertrophy → right heart failure (cor pulmonale) and arrhythmias → death
- Inflammation (e.g., ) →↑ inflammatory cell infiltration of intima → thickened endothelial wall → intimal fibrosis
- PAH associated with endothelial dysfunction: ↑ endothelin and ↓ vasodilators (e.g., NO, prostacyclins) → vasoconstriction → arteriosclerosis, plexiform lesions 
- Increased pulmonary venous pressure: volume or pressure overload from left-sided heart disease (e.g. )
- Increased pulmonary blood flow
- Common clinical features
- Less common clinical features
- Physical examination
Clinical symptoms may be inconspicuous, especially, in early stages (the symptoms of underlying diseases such as COPD may eclipse those of PH).
- Doppler echocardiography (best initial test)
- (confirmatory test)
- Electrocardiography: right axis deviation due to right ventricular hypertrophy
- Right heart hypertrophy
- Vascular changes
- Signs of underlying cause (e.g., nodular opacities in , in )
Treatment of the underlying cause
- Initial therapy should be directed at the underlying cause of PH or cor pulmonale (e.g., bronchodilators and inhalation corticosteroids for patients with COPD, CPAP for patients with obstructive sleep apnea)
- Patients with chronic pulmonary hypertension and cor pulmonale despite treatment of the underlying cause should be evaluated for pulmonary vasodilator therapy in a specialized center.
Therapy should be initiated early before irreversible changes in the pulmonary vessels occur.
- Physical exercise
- Oxygen therapy
Pulmonary vasodilator therapy: decreases pulmonary vascular resistance
- Calcium channel blockers
Long-acting synthetic prostacyclin (epoprostenol) or prostacyclin analogs (e.g., iloprost, treprostinil)
- Prostacyclin (PGI2) acts as a direct vasodilator (systemic and pulmonary) and inhibts platelet aggregation via prostacyclin receptors.
- Binding of prostacyclins or prostacyclin analogs to their receptor → ↑ intracellular cAMP→ inhibition of myosin light chain kinase → vascular smooth muscle relaxation.
- Endothelin receptor antagonists (e.g., bosentan, macitentan, ambrisentan)
- Phosphodiesterase-5 inhibitors (e.g., sildenafil)
Special patient groups
- Acute cor pulmonale: See “ .”
- Individuals refractory to medical treatment
- Individuals in cardiogenic shock