“Pulmonary (arterial) hypertension” literally means “high blood pressure in the pulmonary artery”. This is a completely different condition to the common “high blood pressure” which can affect large numbers of people. Pulmonary hypertension is often abbreviated to PH or PAH. Pulmonary hypertension is a rare lung disorder in which the blood pressure in the pulmonary artery rises above normal. This abnormally high pressure affects the small blood vessels in the lungs, resulting in less blood getting to the lungs and less oxygen being carried into the blood stream. As a result the right side of the heart has to work harder to try and compensate for the difficulty with the blood vessels in the lungs.