Pulmonary hypertension – high pressure in blood vessels of lung
Pulmonary hypertension is the technical term for high blood pressure in the blood vessels of the lung. Most often the increase in blood pressure in the vessels of the lung is due to some other cause – either lung disease or heart disease. Then it is considered secondary. If there is no primary cause like this, it is called primary pulmonary hypertension.
What are the common causes of secondary pulmonary hypertension?
Any disease which causes failure of the left side of the heart (left heart failure) can cause back pressure in the blood vessels of the lung like what happens in the catchment area of a dam. Obstruction to the valve between the left atrium and left ventricle (mitral stenosis) is an important cause in developing countries whererheumatic fever and rheumatic heart disease are common. Left ventricle can fail after and heart attack and increase back pressure in the left atrium, which in turn gets reflected back to the blood vessels draining the lungs (pulmonary veins).
Another group of important diseases which cause increase in pressure of lung vessels is defects in the partitions of the heart causing shunting of blood. Atrial septal defect (between the upper chambers of the heart), ventricular septal defect (between the lower chambers of the heart) and patent ductus arteriosusbetween the (pulmonary artery and aorta) are three such important defects. In these birth defects, excessive blood flow through the blood vessels of the lung increases the pressure and causes pulmonary hypertension.
Clots in blood vessels of legs (deep vein thrombosis) can move to the lungs and block the blood vessels of the lung (pulmonary embolism). If this occurs over long periods, it can cause chronic thromboembolic pulmonary hypertension. If large number of clots move over a short period of time, it may become fatal due to massive pulmonary embolism.
Those with severe diseases of the lung have associated damage to the blood vessels of the lung. This along with decrease in the oxygen level of blood due to lung disease increases the blood pressure in the lungs causing pulmonary hypertension.
How can pulmonary hypertension be treated?
Secondary pulmonary hypertension is reversible if the primary cause can be treated successfully. Primary hypertension is not reversible like that, but can be controlled by novel medications.
Chronic thromboembolic pulmonary hypertension can be treated with medications which prevent blood clotting. Those who have severe forms benefit from surgery (pulmonary thromboendarterectomy) done from specialized centers.