Pulmonary vascular disease is a category of disorders. All affect the blood circulation in the lungs.  Basic information about the major types of pulmonary vascular disease follows: 

Pulmonary Embolism

A pulmonary embolism happens when the blood flow through the lung's artery is blocked suddenly. This is caused by a blood clot that traveled from somewhere else in the body—usually a leg or the pelvis—and has not broken up in the blood stream. Symptoms included difficulty breathing, chest pain, fainting and a rapid heart rate. A pulmonary embolism can damage the heart, and if not treated immediately, can cause death. 

Pulmonary embolisms can be prevented through drugs that break up blood clots before they reach the lung, physical activity, compression socks that improve blood circulation in the legs, and pneumatic compression (a massage or compression of the legs through use of an electronic cuff).

Chronic Thromboembolic Disease

This is a condition in which old blood clots remain in the arteries within the lungs. This can cause complications including pulmonary arterial hypertension.

Pulmonary Arterial Hypertension: This is a disease that causes stress on the heart when the blood pressure in a person's pulmonary arteries gets dangerously high.

Pulmonary Veno-occlusive Disease

This is an extremely rare form of high blood pressure in the lung area; in most cases, the cause is not known. It may be caused by a viral infection or occur as a complication of certain diseases, including lupus, leukemia, lymphoma, chemotherapy, or bone marrow transplantation. Symptoms may include shortness of breath, fatigue, fainting, coughing up blood and having difficulty breathing while you lie flat. 

As pulmonary veno-occlusive disease gets worse, it causes narrowed pulmonary veins, pulmonary hypertension, congestion, and swelling of the lungs. There is no cure for pulmonary veno-occlusive disease, but drugs that control the immune system's response to the disease, and drugs that widen the blood vessels are used to treat the disease.  

Arteriovenous Malformations

Arteriovenous malformations (AVMS) are congenital tangles within in the circulatory system. Your circulatory carries blood to and from the heart and includes arteries, veins and capillaries. The tangles of arteries and veins interfere with the blood circulation in an organ. They occur most often in the head but also happen in internal organs (including the lungs), limbs and torso. 

The cause is unknown. The greatest danger of an AVM is hemorrhage, which may be prevented by surgery or irradiation therapy.

Pulmonary Edema

Pulmonary edema occurs when fluid builds up in the air sacs (alveoli) of the lungs. It is usually caused by heart failure, with a rise in the vein's blood pressure going through the lungs. As the pressure in the blood vessels increases, fluid is pushed into the lungs and causes a shortness of breath.

Pulmonary edema may be caused by exercise at very high altitudes (high altitude pulmonary edema), direct damage to the lung (by poisonous gas or severe infection), as a side effect of medications, or from major trauma. Pulmonary edema may also be a complication of any heart disease that causes the heart muscle to weaken or become stiff.  

Taken from American Lung Association

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