Idiopathic and Familial Pulmonary Arterial Hypertension

Also known as: Primary Pulmonary Hypertension


Hypertension is the medical term for an abnormally high blood pressure and pulmonary hypertension refers to abnormally high blood pressure in the lung circulation. Idiopathic (meaning there is no known cause) and heritable (meaning that the condition is genetic) pulmonary arterial hypertension (IPAH and HPAH, or I/HPAH) are rare progressive disorders in which blood pressure in the lungs rises far above normal levels. They may affect individuals at any age, including new born babies and infants of either gender, and all races and ethnic origins.


Medical text written April 2003 by Contact a Family. Approved April 2003 by Dr S Gibbs. Last updated April 2016 by Dr S Gibbs, Consultant Cardiologist, Hammersmith Hospital, London, UK.

Although great care has been taken in the compilation and preparation of all entries to ensure accuracy, we cannot accept responsibility for any errors or omissions. Any medical information is provided is for education/information purposes and is not designed to replace medical advice by a qualified medical professional.

What are the symptoms?

The most common presenting symptom of I/HPAH is breathlessness (dyspnea) and this is often associated with tiredness. Dizziness and fainting spells (syncope) are also typical early symptoms. Individuals may experience chest pain, palpitation (a feeling of rapid heartbeats in the chest) and a dry cough. The range and severity of symptoms varies between individuals and can occur at rest, whilst walking or during periods of mild exercise. In the more advanced stages, an individual is able to perform only minimal activity and has symptoms even when resting. Ankle or abdominal swelling may occur. In general, the more severe the symptoms, the more advanced the disease.

Pulmonary hypertension may be associated with other conditions such as pulmonary embolism (blood clots in the lungs)lung disease and heart disease. Pulmonary arterial hypertension may be associated with drugs and toxins (typically the anorexigens which are drugs used to cause weight loss in the past), some types of congenital heart disease, autoimmune disorders, portal hypertension, HIV and schistosomiasis (an infection caused by a parasitic worm).

What are the causes?

IPAH occurs when no cause is found. Normally, oxygen-poor blood is pumped from the right ventricle, one of the pumping chambers of the heart, to the lungs via a blood vessel known as the pulmonary artery. When blood reaches the lungs, it collects oxygen and flows to the left ventricle, another pumping chamber of the heart. Oxygenated blood is pumped to the rest of the body through a blood vessel known as the aorta.

In an individual with I/HPAH, the blood pressure in the pulmonary artery (the blood vessel which carries oxygen-poor blood from the heart to the lungs) is far higher than normal. The high blood pressure is a consequence of the disease of the blood vessels in the lungs. This causes a high resistance to blood flow. In order to maintain adequate blood flow through the lungs, the heart works harder to try to force blood through the lungs. This places a strain on the right ventricle of the heart, which ultimately fails.

Changes in genes (of which BMPR2 is the commonest) have been associated with HPAH and some people with IPAH. However, many people who have the mutation do not develop pulmonary hypertension and so it has been suggested that an environmental trigger may be necessary.

How is it diagnosed?

The symptoms of I/HPAH are non-specific – in other words, they may be due to a number of other conditions. I/HPAH is therefore difficult to diagnose at both early and later stages. A number of imaging tests are required as well as measurement of the pressures in the heart and blood vessels (cardiac catheterisation).

How is it treated?

I/HPAH are treated with specialist drug therapies which in the UK are prescribed by specialist pulmonary hypertension centres. There are 3 groups of drugs: prostacyclins, endothelin receptor antagonists and phosphodiesterase 5 inhibitors and they may be used in combination. These drugs improve symptoms and survival. Some patients who deteriorate on drug therapies may be considered for lung transplantation.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
Patients with I/HPAH should be advised about the availability of genetic testing and counselling. Genetic counselling and genetic testing is offered by specialist pulmonary hypertension centres to patients with IPAH considered to be sporadic or induced by anorexigens as well as to patients with a family history of pulmonary arterial hypertension.

Prenatal diagnosis
None at present.

Is there support?

Pulmonary Hypertension Association (PHA UK)

Tel: 01709 761 450

The Association is a Registered Charity in England and Wales No. 1120756. It provides information and support to people affected by pulmonary hypertension. The Association offers events including family weekends and conferences.  

Group details last updated April 2016.

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