Pulmonary Hypertension (cont.)
George Schiffman, MD, FCCP
Dr. Schiffman received his B.S. degree with High Honors in biology from Hobart College in 1976. He then moved to Chicago where he studied biochemistry at the University of Illinois, Chicago Circle. He attended Rush Medical College where he received his M.D. degree in 1982 and was elected to the Alpha Omega Alpha Medical Honor Society. He completed his Internal Medicine internship and residency at the University of California, Irvine.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- Pulmonary hypertension definition and facts
- What is pulmonary hypertension?
- Signs and symptoms of pulmonary hypertension
- Which diseases are common in people with the condition?
- Classification of primary and secondary pulmonary hypertension
- What causes pulmonary hypertension?
- How is pulmonary hypertension diagnosed?
- What is the treatment for pulmonary hypertension?
- Is there a cure?
- What is the life expectancy?
- Which types of doctors treat pulmonary hypertension?
- Find a local Cardiologist in your town
What causes pulmonary hypertension?
There are many causes of pulmonary hypertension. Often more than one mechanism is involved in a specific disease process. This can also change as the disease progresses.
- Diseases that affect flow out of the heart to the rest of the body result in backflow of blood (stacking of blood) that raises pulmonary venous pressures leading to pulmonary hypertension.
- Hypoxic pulmonary vasoconstriction is the process in which the lung vessels narrow in attempt to divert blood from poorly functioning segments of the lung. For instance, when pneumonia develops, a portion of lung becomes inflamed and works poorly in performing the functions of the lung (to add oxygen and remove carbon dioxide from the blood). This process diverts blood from these poorly working areas and sends it to better functioning lung tissue. However, a problem develops when all the blood has a low oxygen level (hypoxia). This causes constriction of the vessels on the pulmonary arterial side and hence raises the pressure.
- Remodeling of blood vessels also occurs in some diseases whereby the inner lining (lumen) of the vessel becomes narrowed due to inappropriate growth of the tissue within and around the vessel. Masses and scarring from other diseases can compress and narrow vessels causing increased resistance to flow resulting in elevation of pressures.
- In a fairly common parasitic infection in the Middle East (schistosomiasis), the blood vessels in the lung become blocked by the parasites causing pulmonary artery hypertension.
- Some substances cause constriction of the blood vessels. Pulmonary hypertension has been rarely reported with the use of anti-obesity drugs, such as dexfenfluramine (Redux) and Fen/Phen. These medications have seen been removed from the market. Some street drugs such as, cocaine and methamphetamines can cause severe pulmonary hypertension.
- Some diseases raise pulmonary pressures to cause pulmonary artery hypertension for unclear reasons. Perhaps an unknown toxin or chemical effects the blood vessels by causes constriction or inappropriate growth of the tissue within or around the vessel. For example, there is a condition known as portopulmonary hypertension that is result of liver failure. When these individuals receive a liver transplant, the pulmonary hypertension disappears suggesting that the failing liver is unable to clear some biochemical that leads to pulmonary artery hypertension.
What causes idiopathic pulmonary hypertension?
Primary pulmonary hypertension has no identifiable underlying cause. This term is mainly a historical name and no longer used. The current term used to describe this condition is idiopathic pulmonary hypertension. Idiopathic pulmonary hypertension is more common in young people and more common in females than males.
Idiopathic pulmonary hypertension unusually is an aggressive and often fatal form of pulmonary hypertension. Whereas it is known that the arterial obstruction is caused by a building up of the smooth muscle cells that line the arteries, the underlying cause of the disease has long been a mystery.
A genetic cause of the familial form of idiopathic pulmonary hypertension, now referred to as Heritable PAH, has been discovered. It is caused by mutations in a gene called BMPR2. BMPR2 encodes a receptor (a transforming growth factor beta type II receptor) that sits on the surface of cells and binds molecules of the TGF-beta superfamily. Binding triggers conformational changes that are shunted down into the cell's interior where a series of biochemical reactions occur, ultimately affecting the cell's behavior. The mutations block this process. This discovery may provide a means of genetic diagnosis and a potential target for the therapy of people with familial (and possibly also sporadic) primary pulmonary hypertension.
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