Pulmonary stenosis is a congenital heart disorder where blood flow is blocked between the right ventricle and pulmonary artery. This blockage is in the valve (pulmonary valve) that separates the right ventricle and the arteries that deliver blood with low oxygen to the lungs.
The Problem
In a healthy heart, the right atrium receives (oxygen depleted) blood from the body and then passes it to the right ventricle. Form the right ventricle then passes it to the pulmonary artery, which carries blood into the lungs. The blood becomes oxygenated in the lungs and then it re-circulates and delivers oxygen to the body by the pumping mechanism of the left ventricle. The pulmonary valve is the valve between the right ventricle and the pulmonary artery. If this valve is obstructed, blood cannot properly flow to the lungs.
Usually, the problem is with the leaflets in the valve. In a healthy valve, three flexible leaflets move aside easily to enable the blood to pass through. In a defective valve, the leaflets may be molded together or stiffened, so they are not as pliable as usual. As a result, he narrowing of the valve obstructs blood flow.
Since PVS prevents enough blood from flowing in to the lungs, the right ventricle has to work harder to compensate for the obstruction. This cause an increase of pressure to the right ventricle and the right ventricle muscle compensate by becoming enlarged, a condition known as hypertrophic cardiomyopathy. This shouldn’t present a problem in itself, but reflects the obstructive defect on the pulmonary valve. PVS can also cause blood to pass straight from the right atrium to the left atrium, which leads to a condition called cyanosis. PVS does not usually cause heart failure (a defect of the right ventricle to maintain the pumping ability due to increase of pressure)
