What is pulmonary arterial hypertension?
Pulmonary hypertension means raised blood pressure in the arteries that carry blood from the right side of the heart to the lungs. It is not the same as ordinary high blood pressure measured at the arm. Pulmonary hypertension has several causes, grouped by the ESC/ERS guidelines into five groups. The most common causes are left heart disease and chronic lung disease such as COPD or interstitial lung disease.
Pulmonary arterial hypertension (PAH) is Group 1, a rare form in which the small pulmonary arteries themselves become thickened and narrowed. The right ventricle has to pump against increasing resistance and, over time, it enlarges and can fail. PAH can affect people of any age but is often diagnosed in younger and middle-aged women.
PAH is managed jointly with cardiology, and patients who need advanced therapies are cared for in close coordination with specialist pulmonary hypertension and transplant centres.
Symptoms of PAH
Early symptoms are non-specific, and the diagnosis is frequently delayed by a year or more.
- Breathlessness on exertion: the most common first symptom, gradually progressive.
- Fatigue and weakness: because the heart cannot increase its output during activity.
- Chest pain or tightness on effort.
- Dizziness or fainting on exertion, which is an important warning sign.
- Swelling of the ankles and abdomen: a sign of right heart strain.
- Palpitations and, in advanced disease, bluish lips.
Because these symptoms are often attributed to asthma, anaemia, anxiety or being unfit, breathlessness that cannot be explained by routine tests should prompt an echocardiogram.
Causes and risk factors
PAH may occur without an identifiable cause (idiopathic PAH), run in families (heritable PAH, often linked to the BMPR2 gene), or be associated with another condition. Associated forms include:
- Connective tissue diseases, particularly systemic sclerosis
- Congenital heart disease with shunts, such as atrial or ventricular septal defects
- Portal hypertension due to liver disease
- HIV infection
- Certain drugs and toxins, including some appetite suppressants and methamphetamine
Rarer conditions that closely resemble PAH, such as pulmonary veno-occlusive disease, need to be recognised because they respond differently to treatment.
How PAH is diagnosed
Diagnosis is a stepwise process. Echocardiography suggests the likelihood of pulmonary hypertension, a series of tests then searches for the cause, and right heart catheterisation confirms the diagnosis and measures its severity.
| Test | What it shows |
|---|---|
| Echocardiogram | Estimated pulmonary pressure and the size and function of the right heart |
| Right heart catheterisation | Direct measurement of pulmonary pressures and resistance, which is required to confirm PAH and to test vasoreactivity in selected patients |
| Ventilation-perfusion (V/Q) scan | Excludes chronic blood clots (CTEPH), which have a different treatment |
| Lung function tests and HRCT | Underlying lung disease as a cause |
| Blood tests including NT-proBNP | Heart strain, autoimmune markers, liver disease and HIV |
| Six-minute walk test | Exercise capacity, used for risk assessment and follow-up |
A V/Q scan is essential in every patient with unexplained pulmonary hypertension, because CTEPH is potentially curable and can otherwise be missed.
PAH treatment
Treatment is guided by a formal risk assessment that combines symptoms, walk distance, blood tests, echocardiography and catheter findings. The goal is to reach and maintain a low-risk status.
Targeted PAH medicines
Three pathways are targeted by current medicines:
- Endothelin receptor antagonists: ambrisentan, bosentan and macitentan
- Nitric oxide pathway drugs: phosphodiesterase-5 inhibitors such as sildenafil and tadalafil, or the soluble guanylate cyclase stimulator riociguat
- Prostacyclin pathway drugs: oral selexipag, inhaled iloprost, and injectable or infused prostacyclins for higher-risk disease
Most patients start with a combination of two oral medicines. A small group who respond to vasoreactivity testing at catheterisation may be treated with high-dose calcium channel blockers instead. Newer agents acting on the activin signalling pathway, such as sotatercept, have been added to treatment in eligible patients where available.
Supportive care
Diuretics for fluid retention, oxygen when levels are low, iron replacement if deficient, supervised exercise training and vaccinations all help. Pregnancy carries a high risk in PAH, so reliable contraception and counselling are essential. Lung transplantation is considered for patients who remain high risk despite maximal therapy.
Outlook and follow-up
PAH remains a serious, long-term condition, but outcomes have improved considerably with combination therapy and early treatment. Regular follow-up every three to six months with walk tests, NT-proBNP and echocardiography allows treatment to be stepped up promptly if risk increases.
Patients are advised to avoid heavy straining, high altitudes without advice, and dehydration, and to check with their team before taking new medicines or undergoing surgery.
When to seek urgent care
Seek emergency medical attention for fainting or near-fainting, chest pain, breathlessness at rest, coughing up blood, rapidly increasing swelling of the legs or abdomen, a fast or irregular heartbeat, or blue lips. Patients on infused prostacyclin should seek help immediately if the infusion stops or the line becomes red, painful or infected.
Frequently asked questions
Is pulmonary hypertension the same as high blood pressure?
No. Ordinary high blood pressure affects the arteries of the body and is measured at the arm. Pulmonary hypertension affects the arteries of the lungs and needs an echocardiogram and right heart catheterisation to assess.
Why do I need a right heart catheterisation?
An echocardiogram can only estimate pulmonary pressure. Right heart catheterisation measures pressures directly, confirms the type of pulmonary hypertension, and guides the choice of medicines. It is performed through a vein under local anaesthetic.
Can PAH be cured?
PAH cannot currently be cured with medicines, but targeted therapies improve symptoms, exercise capacity and survival. Lung transplantation is an option for selected patients whose disease progresses despite treatment.
Is it safe to become pregnant with PAH?
Pregnancy carries a high risk for both mother and baby in PAH and is generally advised against. Some PAH medicines can also harm an unborn baby, so effective contraception is discussed with every woman of child-bearing age.
Will I need to take medicines for life?
Most patients need lifelong treatment. Doses and combinations are adjusted over time according to regular risk assessment.
Can I exercise with pulmonary hypertension?
Gentle, supervised exercise is beneficial and safe for most stable patients. Heavy lifting, straining and exercise that causes dizziness or chest pain should be avoided.
Related conditions and procedures
Consult Dr. Gogineni Ratnakara Rao
Apollo Hospitals, Financial District: Monday to Saturday, 8:30 AM to 5:00 PM. Anything in Lung Clinic, Chanda Nagar: Monday to Saturday (Thursday closed), 6:00 PM to 9:00 PM.