Clinical Definition

Pulmonary hypertension (PH) is high blood pressure in the lungs. In PH, the blood vessels in the lungs and the right side of the heart are sites of higher-than-normal pressure. It is different from regular hypertension, which affects the entire body. This significant pressure strains the heart’s right ventricle so much it may lead to heart failure. Increased pressure in PH is due to chronic lung or heart disease, or other causes.

In Our Own Words

Pulmonary hypertension is different from regular (systemic) high blood pressure as measured with a cuff on the arm. Instead, PH reflects the pressure of the blood flow between your lungs and your heart. The heart’s right side receives oxygen-depleted blood from the body, then pumps it to the blood vessels in the lungs, where blood gathers oxygen, leaves the lungs and travels to the left side of the heart, which pumps oxygen-rich blood to the body.

PH can exist on its own due to genetic predisposition and can also result from other conditions, such as chronic liver disease, heart disease, or use of the appetite suppressant known as ”fen-phen” (dexfenfluramine and phentermine). When pressure becomes too elevated in the lung’s blood vessels, the heart has to work harder to push blood through the lungs. With the excess stress, the heart can enlarge and become less efficient. Scientists believe the problem begins with an injury to the layer of cells lining the lungs’ small blood vessels. If pressure is high due to direct disease of the lungs’ blood vessels, it is known as PAH, or pulmonary arterial hypertension.