Pulmonary Arterial Hypertension (PAH)

Pulmonary arterial hypertension (PAH) signs and symptoms result from the restricted flow of oxygenated blood through the lungs to other parts of the body and the decreased ability of the heart to pump blood, which is caused by increased pulmonary resistance due to thickening and narrowing of the pulmonary arteries.1

Delayed Diagnosis of PAH

In the early stages, patients may not experience any symptoms or symptoms may be less numerous and severe. Symptoms of PAH can also be vague or nonspecific (such as breathing difficulty upon exertion, fatigue, weakness, and lightheadedness) and may also be masked by the underlying associated diseases. Thus, the diagnosis of PAH is often delayed by months or even years before the symptoms are noticed. Therefore, increased awareness of PAH among clinicians is essential to allow early diagnosis and subsequent treatment. Symptoms worsen and become more noticeable as the disease progresses.2

Early-Stage PAH Symptoms

The most common initial symptom experienced by patients is dyspnea after exertion, observed in more than 85% of patients.2 PAH should be considered in any patient who develops dyspnea without any signs of heart or lung disease.

Other common symptoms include excessive fatigue, weakness, fainting episodes, chest pain (caused by right ventricular angina), dizzy spells, palpitations, rapid heart rate, and exercise intolerance. Since these symptoms are also common in other cardiopulmonary disorders, PAH may result in misdiagnosis or delayed diagnosis.
Symptoms like chest pain, rapid heart rate, palpitations, or irregular heartbeat are caused by the weakening of the heart’s muscles, which result from persistently high blood pressure and overload on the heart.3

cardiomegaly pah
A chest x-ray of a patient with cardiomegaly
and bilateral lung congestion.

Other Symptoms of PAH

Some patients may experience coughing, enlargement of the heart and liver, or low systemic blood pressure. In rare cases, patients may have coughing with blood or hoarse voice due to compression of the nerves in the larynx by the enlarged pulmonary artery.1

Advanced-Stage PAH Symptoms

In some cases, patients with PAH are not diagnosed until they reach the advanced stage and are unable to continue with normal daily activities.

With progression of the disease, symptoms such as shortness of breath may occur at rest without any exertion as the right ventricular muscles progressively weaken due to continuously high pulmonary vascular resistance. Syncope/presyncope is also indicative of a severe form of PAH.

Another symptom that may be experienced by PAH patients who are in the advanced stage is edema of the face, ankles, abdomen, legs, and feet4 due to fluid retention within the fascial tissues.1

Patients in the advanced stages may also experience blue discoloration of the eyes, lips, or skin due to low levels of circulating oxygen in the blood (cyanosis).1 Most patients with severe PAH experience abnormal enlargement (hypertrophy) of the right ventricle of the heart, which affects the normal functioning of the right side of the heart and eventually right heart failure. Some cases may develop intrapulmonary shunts or a right-to-left shunt in the heart.6 In addition, the patients may have symptoms of the PAH-associated disease.

Functional Classification of PAH

The World Health Organization (WHO)-modified New York Heart Association (NYHA) functional classification describes 4 functional classes (FC) of PAH patients, in which the symptoms are related to the corresponding ability of the patients to perform daily activities.
The patients in the FC I can perform normal physical activities without experiencing any symptoms such as dyspnea, fatigue, near syncope, or chest pain. In contrast, the patients in the FC IV experience severe symptoms while performing any physical activity and may even experience symptoms at rest. Such patients often show signs of right heart failure and have a poor prognosis, with a median survival of 6 months if left untreated. The median survival is 2.5 years for patients in the FC III and 6 years for those in the FC I or FC II.7


  1. Pulmonary arterial hypertension. National Organization for Rare Disorders. Accessed June 3, 2021.
  2. Brown LM, Chen H, Halpern S, et al. Delay in recognition of pulmonary arterial hypertension: factors identified from the REVEAL registry. Chest. 2011;140(1):19-26. doi:10.1378/chest.10-1166
  3. Pulmonary arterial hypertension symptoms and diagnosis. American Lung Association. Updated October 23, 2020. Accessed June 3, 2021.
  4. Bordoni B, Mahabadi N, Varacallo M. Anatomy, fascia. In: StatPearls. StatPearls Publishing; 2021. Updated April 3, 2021. Accessed June 3, 2021.
  5. Pulmonary arterial hypertension. MedlinePlus Genetics. Updated August 18, 2020. Accessed June 3, 2021. 
  6. Hoendermis ES. Pulmonary arterial hypertension: an update. Neth Heart J. 2011;19(12):514-522. doi:10.1007/s12471-011-0222-1
  7. Sitbon O, Simonneau G. Optimal management of severe pulmonary arterial hypertension. Eur Respir Rev. 2011;20(122):254-61. doi:10.1183/09059180.00007011

Reviewed by Debjyoti Talukdar, MD, on 7/1/2021.