Pulmonary arterial hypertension

Pulmonary arterial hypertension is a progressive disorder characterized by abnormally high blood pressure (hypertension) in the pulmonary artery, the blood vessel that carries blood from the heart to the lungs. Hypertension occurs when most of the very small arteries throughout the lungs narrow in diameter, which increases the resistance to blood flow through the lungs. To overcome the increased resistance, pressure increases in the pulmonary artery and in the heart chamber that pumps blood into the pulmonary artery (the right ventricle).

Signs and symptoms of pulmonary arterial hypertension occur when increased pressure cannot fully overcome the elevated resistance and blood flow to the body is insufficient. Shortness of breath (dyspnea) during exertion and fainting spells are the most common symptoms of pulmonary arterial hypertension. People with this disorder may experience additional symptoms, particularly as the condition worsens. Other symptoms include dizziness, swelling (edema) of the ankles or legs, chest pain, and a racing pulse.

In the United States, about 1,000 new cases of pulmonary arterial hypertension are diagnosed each year. This disorder is twice as common in females as in males.

Mutations in the BMPR2 gene cause pulmonary arterial hypertension.

The BMPR2 gene plays a role in regulating the number of cells in certain tissues. Researchers suggest that a mutation in this gene promotes cell division or prevents cell death, resulting in an overgrowth of cells in small arteries throughout the lungs. As a result, these arteries narrow in diameter, which increases the resistance to blood flow. Blood pressure in the pulmonary artery and the right ventricle of the heart increases to overcome the increased resistance to blood flow.

Other genes that have not yet been identified may also cause pulmonary arterial hypertension. In people with a BMPR2 mutation, other genes or environmental factors may contribute to the development of this disorder.

Read more about the BMPR2 gene.

This condition is inherited in an autosomal dominant pattern, which means each cell has one copy of an altered BMPR2 gene. In many cases, however, people with an altered BMPR2 gene never develop symptoms of pulmonary arterial hypertension.

Inherited cases of this disorder are known as familial pulmonary arterial hypertension. As the altered gene is passed down from one generation to the next, the disorder generally begins earlier in life. This phenomenon is called anticipation.

Most cases of pulmonary arterial hypertension, however, occur in individuals with no known family history of the disorder. These cases are known as idiopathic pulmonary arterial hypertension. Some idiopathic cases are due to mutations in the BMPR2 gene, but in most cases a gene mutation has not yet been identified.