Although pulmonary hypertension (PH) can be caused by many underlying conditions, in some cases, there is no known cause. This may sometimes be referred to as primary pulmonary hypertension, although this term was more widely used in the past. The condition is now more commonly referred to as idiopathic pulmonary arterial hypertension (IPAH). A condition is considered idiopathic if the cause of the disease is not known.

PH causes a person to have high blood pressure in the blood vessels of the lungs, called the pulmonary arteries. Blood is normally pumped through the right side of the heart and picks up oxygen in the lungs, then is pumped back through the left side of the heart.

In a person with PH, blood cannot properly flow through the pulmonary arteries, leading to enlargement of the right side of the heart and, ultimately, right heart failure. PH is a rare and progressive disease, meaning it worsens over time.

Common symptoms of PH include dyspnea (shortness of breath) during physical activity, chest pain, and fatigue. If you are experiencing symptoms, communicate promptly with your doctor to help figure out the cause.

Causes of Pulmonary Hypertension

In addition to IPAH, there are several more forms of PH that are caused by or associated with other underlying conditions. In order to diagnose the disease as idiopathic, other diseases must be ruled out first. Below are examples of health conditions that can lead to PH.

Connective Tissue Diseases

Organs and tissues throughout the body are supported by connective tissue, which helps provide structure. The connective tissue can be affected by several autoimmune disorders caused by the immune system inappropriately attacking the tissue. Conditions that can lead to PH include:

• Scleroderma — A disease that causes scar tissue to form on the skin and organs
• Systemic lupus erythematosus — Also called lupus, which causes inflammation in organs throughout the body
• Mixed connective tissue disease — A complex disease that shares features with lupus, scleroderma, and RA

Genetic Factors

Mutations in certain genes, including the BMPR2 gene, are associated with an increased risk of PH. Genetic mutations can be inherited, which can cause PH to be more prevalent in some families.

HIV Infection

Another known risk factor for PH is human immunodeficiency virus (HIV) infection. HIV is thought to contribute to lung disease and other health problems that may lead to the development of PH.

Liver Disease

High pressure in the liver caused by portal hypertension is linked to PH.

Heart Disease

PH is often associated with chronic heart disease. In some cases, this is congenital heart disease, which is a condition present at birth caused by defects in the heart.

One of the most common causes of PH is left heart disease, which causes a buildup of pressure in the pulmonary arteries due to left-side heart dysfunction. PH associated with left heart disease may also be called pulmonary venous hypertension or postcapillary pulmonary hypertension.

Chronic Lung Disease

Conditions that negatively affect lung function can also cause PH. PH-associated lung diseases include:

• Interstitial lung disease
• Chronic pulmonary obstructive disease (also referred to as COPD)
• Sleep apnea (improper breathing during sleep)
• Chronic high-altitude exposure
• Physical abnormalities of the lungs
• Alveolar hypoventilation disorder, a breathing disorder that results in hypoxia (low oxygen) and high levels of carbon dioxide in the blood

Some of these conditions can cause pulmonary fibrosis, a secondary lung disease that occurs from tissue damage and scarring.

Blood Clots

Blood clots may cause a form of PH called chronic thromboembolic pulmonary hypertension (CTEPH). In many cases, CTEPH is caused by a pulmonary embolism, which occurs when a blood clot from a deep vein in the leg breaks off and travels to the lungs, leading to an increase in pulmonary artery pressure.

Rare Conditions

Several rare diseases are linked to PH in a way that isn’t well understood. This includes conditions such as:

• Metabolic disorders
• Blood disorders, also called hematologic diseases
• Systemic diseases that affect the lungs
• Kidney failure
• External factors or tumors that prevent pulmonary circulation

Categories of Pulmonary Hypertension

There are several different types of PH associated with various causes. To better categorize PH and its associated causes, the World Health Organization (WHO) has classified PH into five different groups depending on the cause:

• Group 1 — Pulmonary arterial hypertension (PAH)
• Group 2 — PH related to heart disease
• Group 3 — PH related to lung disease
• Group 4 — PH caused by blood clotting disorders
• Group 5 — PH related to other miscellaneous conditions

IPAH is included in the group 1 category and is distinguished from other forms of PAH associated with known diseases.

Treatment for Primary Pulmonary Hypertension

Although there is no cure for IPAH, the condition can be managed with treatment. A common treatment approach involves drugs called vasodilators that widen the pulmonary arteries and allow for easier blood flow.

Prostacyclin and phosphodiesterase inhibitors are two different types of therapies that can act as vasodilators. If drug therapy fails to work, lung transplantation may be considered as a last resort. A health care provider will go over available therapies and devise a suitable treatment plan for a person’s condition.

Talk With Others Who Understand

MyPHteam is the social network for people with pulmonary hypertension and their loved ones. On MyPHteam, more than 46,000 members come together to ask questions, give advice, and share their stories with others who understand life with pulmonary hypertension.

Are you or a loved one living with primary pulmonary hypertension? Share your experience in the comments below, or start a conversation by posting on MyPHteam.