Pulmonary hypertension (PH) is a condition where blood pressure rises in the lungs. The term PH is a broad one and defines a general condition. Pulmonary arterial hypertension (PAH), on the other hand, is more specifically, a chronic disease where the arteries of the lungs are narrowed. This puts pressure on the heart to pump harder to push one’s blood through these arteries. Let’s differentiate between the subsets PH and PAH according to their causes, for more clarity on the terms.

First, we’ll look at the causes of PH.

• Lung disease
  Lung diseases can cause PH. For instance, pulmonary fibrosis, which leads to a scarring of the lung tissues can increase blood pressure in the organ. Even obstructive sleep apnea (OSA), a disorder in which one stops and starts breathing while sleeping can lead to PH. So, unlike PAH, PH can be caused by breathing issues too.
• Blood clots due to DVT
  Conditions like deep vein thrombosis (DVT) cause blood clots, in the deep vein of the leg, that can travel to the lungs. This leads to a fatal condition called pulmonary embolism, wherein the blood clots enter the lungs and block major blood vessels. This increases the blood pressure in the lungs, which is known as PH. The difference between this and PAH would be that the latter would specifically mean that the arteries that carry one’s blood to the lungs from the right side of one’s heart are blocked or have grown narrower. While PH is essentially high blood pressure, PAH is a progressive chronic disorder.
• Left-sided heart disease
  Mitral valve disease is one of the left-sided heart valve diseases. The mitral valve lies in the middle of the left atrium and the left ventricle. The disease can cause the valve to not work optimally as it may hinder its ability to close properly. This causes one’s blood to leak backward, and can lead to PH. Aortic valve disease and left ventricle failure may also may cause PH.
• Other health conditions
  Few other conditions can increase one’s risk of PH. Inflammatory disorders like sarcoidosis that enlarge the lymph nodes in the body can cause PH. The same goes with metabolic disorders like glycogen storage disease. Also, add to this list chronic kidney disease. Kidney dysfunction can increase the blood pressure in one’s lungs.

Now that the causes of PH have been mentioned, knowing the causes of PAH will help understand the difference between them fully.

• Hereditary
  PAH may be inherited as it can be passed down through generations, and is known as heritable pulmonary arterial hypertension.
• Prescription medications
  Few medications such as diet drugs can have side effects and clause the pulmonary arteries to narrow, resulting in high-blood pressure in the lungs.
• Other health conditions
  Congenital heart disease, lupus, scleroderma, AIDs or cirrhosis can create blockage in the pulmonary arteries too.

In a nutshell, PAH is a disorder which leads to increased narrowing of the pulmonary arteries, resulting in high blood pressure in them, while PH is a more general form of the condition, also resulting in increased blood pressure in the arteries of the lungs and the heart.