Pulmonary hypertension (PH) can be caused by anything that raises the blood pressure in the pulmonary arteries. Pulmonary arterial hypertension (PAH), a subtype of PH, is caused specifically by narrowing of the pulmonary arteries. PH can be caused by genetic variants, congenital (present at birth) defects, heart disease, lung disease, connective tissue diseases, blood cell disorders, blood clots, or the use of prescribed or illicit drugs. In many cases, the cause of PH is unknown — or as doctors say, idiopathic. Types of pulmonary hypertension are categorized by cause.
While researchers have established that both hereditary and environmental factors influence a person’s risk for developing pulmonary hypertension, no one is certain why some people get PH and some people don’t. Most scientists believe pulmonary hypertension is most likely caused by a combination of inherited and environmental factors.
In general, risk for pulmonary hypertension rises with age. However, even children can develop PH. Women 2.5 times more likely to develop PAH than men, especially during their childbearing years.
In some people, pulmonary hypertension — specifically pulmonary arterial hypertension — is directly caused by genetic variants inherited from one’s parents. In these cases, genes cause an overgrowth of cells in the pulmonary arteries that narrows the arteries and causes hypertension. For this reason, having family members with PH raises your risk for developing pulmonary hypertension yourself. In other people, PAH may be directly caused by a sporadic (random) genetic mutation not present in one’s parents.
For others with PH, genes inherited from parents may not cause PH directly, but a wide range of genetic variants may predispose you to develop the condition when exposed to environmental factors. Most researchers believe that many genes influence the risk for developing pulmonary hypertension and the severity of their PH.
Some people are born with congenital heart defects that increase their risk for developing pulmonary hypertension later on.
Living at high altitudes can cause some people to develop pulmonary hypertension due to chronic hypoxia (low oxygen). Oxygen levels fall as elevation increases. Different elevations may be problematic for different people.
In women who are predisposed to develop pulmonary hypertension, the risk for developing PH may be higher during pregnancy.
Pulmonary hypertension caused by another condition, a medical treatment, or exposure to a drug or toxin is called associated PH.
Drugs and toxins that can cause associated pulmonary hypertension include:
Diseases that can cause associated PH include:
Pulmonary hypertension can also be a late side effect of splenectomy (surgical removal of the spleen) or radiation therapy or chemotherapy for cancer.