What is Pulmonary Arterial Hypertension

Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare, chronic and progressive heart and lung disease. In PAH, the pulmonary arteries thicken and constrict, making blood transfer between the heart and lungs difficult. PAH results in elevated blood pressure in the arteries in the lungs and right side of the heart.

As pressure in the pulmonary arteries increase, the right side of the heart is forced to work at unsustainable levels to move blood through the lungs. PAH leads to right sided heart enlargement and failure and may cause premature death.

The cause of PAH is unknown. It is a serious illness which presently affects over 30,000,000 people worldwide. There is no present cure for PAH.   The disease does not discriminate between age, gender or race.

The World Health Organization (WHO) has classified pulmonary hypertension into five groups. PAH represents Group 1. There are four functional classes within WHO Group 1 pulmonary hypertension, each class representing the present functional stage and advancement of the disease within a PAH patient:

  • WHO Class I – Patients with pulmonary hypertension but without resulting limitation of physical activity. Ordinary physical activity does not cause undue dyspnea (shortness of breath) or fatigue, chest pain or near syncope (loss of consciousness).
  • WHO Class II - Patients with pulmonary hypertension resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity causes undue dyspnea or fatigue, chest pain, or near syncope.
  • WHO Class III - Patients with pulmonary hypertension resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary activity causes undue dyspnea or fatigue, chest pain, or near syncope.
  • WHO Class IV - Patients with pulmonary hypertension with inability to carry out any physical activity without symptoms. These patients manifest signs of right-heart failure. Dyspnea and/or fatigue may be present at rest. Discomfort is increased by any physical activity.[1]

[1] Classification cite to Rubin LJ. Diagnosis and management of pulmonary arterial hypertension: AACP Evidence Based Clinical Practice Guidelines. Introduction. Chest. 2004; 126:7S-10S.


PAH is known as one of the medical field’s “silent killers.” PAH is often misdiagnosed or mistaken for common conditions such as asthma or COPD, or other illnesses or ailments. The symptoms most often associated with PAH mirror those of more common conditions, including:

  • Chest Pain
  • Dizziness
  • Shortness of Breath
  • Fatigue
  • Edema or swelling
  • Cyanosis or skin discoloration

As the disease progresses, these symptoms may become more severe and be accompanied by an increased pulse, heart palpitations and irregular heartbeat.

While there are times when these symptoms may mean you have another condition, these symptoms may also mean you suffer from PAH.

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Pulmonary Hypertension Resources

Organizations across the United States and around the world are dedicated to education, awareness and patient support of PAH.   Below are links to resources and organizations dedicated to the (ph)ight against PAH.




Phaware is the world’s leading organization dedicated to pulmonary hypertension awareness. Through the use of innovative technology, state of art tools and creative content, phaware engages the global community in pulmonary hypertension awareness conversation, and heightens the universal knowledge base of the disease.





Pulmonary Hypertension Association

The Pulmonary Hypertension Association (PHA) is the oldest organization in the world dedicated to pulmonary hypertension education and patient support. The PHA funds many programs dedicated to patient advocacy, community support and research into a cure of the disease. In addition, the PHA has created a comprehensive accreditation process to certify PAH treating physicians and treatment centers in an area near you.



Pulmonary Hypertension News

Pulmonary Hypertension News is a digital publication offering news coverage of transformative science and medicine surrounding PAH.



European Pulmonary Hypertension Association

PHA Europe serves as a unifying organization for PAH patients residing throughout Europe.



Pulmonary Hypertension  of Canada

PHA Canada is an organization founded by a collection of patients, health professionals and caregivers to serve and promote the interests of PAH patients throughout Canada.