.Pulmonary hypertension is a condition in which blood pressure in the arteries of the lungs (the pulmonary arteries) is abnormally high. Lung disorders can cause pulmonary hypertension in several ways.
When oxygen levels are low for a long time, pulmonary arteries constrict and their walls become thickened. This constriction and thickening increase the pressure in the pulmonary arteries. Lung disorders that damage or decrease the amount of lung tissue (for example, emphysema) also decrease the number of blood vessels in the lungs. The decreased number of blood vessels increases pressure in the remaining vessels.
The most common cause of cor pulmonale is
Other less common causes include
Once pulmonary hypertension develops, the right side of the heart has to work harder to pump blood through the lungs. The increased effort causes the heart muscle to become enlarged and thickened. If pulmonary hypertension continues long enough, the right side of the heart can no longer compensate by enlarging and thickening, and right-sided heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more develops.
The failing right ventricle places a person at risk of pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more because blood flow is abnormally low, so blood tends to pool in the legs. If clots form in the pooled blood, they may eventually travel to and lodge in the lungs, with dangerous consequences.
Symptoms of Cor Pulmonale
There may be few symptoms of cor pulmonale until the disorder is quite advanced. When symptoms do occur, people describe
Symptoms of heart failure, such as swelling (edema Swelling Swelling is due to excess fluid in the tissues. The fluid is predominantly water. Swelling may be widespread or confined to a single limb or part of a limb. Swelling is often in the feet and... read more 
) in the legs and progressively worse shortness of breath, also develop.
Diagnosis of Cor Pulmonale
A number of tests are available to help doctors diagnose cor pulmonale, but the diagnosis is often suspected on the basis of the physical examination. For example, by listening through a stethoscope, doctors can hear certain characteristic heart sounds that occur when the right ventricle becomes strained. The legs also become swollen, and veins in the neck enlarge.
Chest x-rays can show the enlarged right ventricle and pulmonary arteries.
Doctors evaluate the function of the left and right ventricles with echocardiography Echocardiography and Other Ultrasound Procedures Ultrasonography uses high-frequency (ultrasound) waves bounced off internal structures to produce a moving image. It uses no x-rays. Ultrasonography of the heart (echocardiography) is one of... read more 
, radionuclide studies Radionuclide Imaging of the Heart In radionuclide imaging, a tiny amount of a radioactive substance (radionuclide), called a tracer, is injected into a vein. The amount of radiation the person receives from the radionuclide... read more , and cardiac catheterization Cardiac Catheterization and Coronary Angiography Cardiac catheterization and coronary angiography are minimally invasive methods of studying the heart and the blood vessels that supply the heart (coronary arteries) without doing surgery. These... read more 
(to measure pressures in the heart chambers and lung arteries).
