The human heart consists of four chambers: the two upper chambers, which receive blood and are known as the atria, and the two lower chambers, which pump blood and are known as the ventricles. The left ventricle pumps oxygenated blood into the aorta to circulate throughout the body. The right ventricle pumps oxygen-poor blood into the pulmonary veins to the lungs. Just like any muscle, when the heart works harder, it becomes larger. In the case of the heart; however, larger is not better. Many conditions affect the heart, causing it to pump harder and therefore resulting in an enlarged ventricle.
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Congenital Heart Defects
Congenital heart defects, problems with the structure of the heart present from birth, affect eight out of every 1,000 babies born in the United States, according to the National Heart Lung and Blood Institute. Congenital defects range from simple, meaning they require no treatment or fix easily, to complex, which require surgical intervention and lifelong medical care.
One type of congenital defect, known as stenosis, causes a heart valve to thicken, preventing it from opening. Pulmonary valve stenosis causes the right ventricle to work harder to pump blood to the lungs, leading to enlargement. Aortic stenosis affects the heart valve leading from the left ventricle to the aorta, causing the left ventricle to work harder, resulting in enlargement.
Pulmonary hypertension describes high blood pressure that affects the right side of the heart and the arteries leading to the lungs. The increased pressure in the arteries leading to the lungs raises the pressure within the right ventricle. This causes the right ventricle to work harder to pump blood, which weakens the muscle. When less blood flows to the lungs, the right ventricle tries to compensate by becoming thicker and larger, therefore holding more blood in hopes of increasing the amount of blood reaching the lungs. Over time, the enlarged ventricle fails due to the added strain, according to MayoClinic.com.
Hypertrophic cardiomyopathy describes a type of heart disease that causes the heart muscle, specifically the ventricles, to thicken and enlarge. Hypertrophic cardiomyopathy can occur due to a congenital defect or as a result of chronic high blood pressure. The Cleveland Clinic reports that hypertrophic cardiomyopathy affects approximately one in 500 people in the United States.
Hypertrophic cardiomyopathy causes the septum, the wall separating the right and left sides of the heart, to thicken. This reduces the flow of blood from the left ventricle to the aorta, therefore causing the left ventricle to work harder, leading to enlargement. The changes to the septum can also affect the right ventricle, causing it to become larger as well.