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By Mayo Clinic staffLeft ventricular hypertrophy occurs as a result of one or more things making your heart work harder than normal to pump blood to your body. For example, if you have high blood pressure, the muscles of the left ventricle must contract more forcefully than normal in order to counter the effect of the elevated blood pressure.
The effect of the stronger contraction on your heart is similar to the response of other muscles to an increased workload. If you add weight to a dumbbell for arm curls, your biceps become larger. Similarly, the work of adapting to high blood pressure may result in larger muscle tissue in the walls of the left ventricle. Unlike weight training, however, the increased workload on the heart is constant with each heartbeat and with little time for the heart muscles to relax. The increase in muscle mass causes the heart to function poorly.
Factors that can cause your heart to work harder include the following:
- High blood pressure (hypertension) is the most common cause of left ventricular hypertrophy. A blood pressure reading is given in a unit of measure called millimeters of mercury (mm Hg). Hypertension is generally defined as systolic pressure greater than 140 mm Hg and a diastolic pressure greater than 90 mm Hg, or 140/90 mm Hg. Systolic pressure is blood pressure while the heart contracts, and diastolic pressure is blood pressure while the heart rests between beats.
- Aortic valve stenosis is a narrowing of the aortic valve, the flap separating your left ventricle from the aorta, the large blood vessel that delivers oxygen-rich blood to your body. This partial obstruction of blood flow requires the left ventricle to work harder to pump blood into the aorta.
- Aortic valve regurgitation is a condition in which the heart valve separating the left ventricle and the aorta doesn't close properly, resulting in some blood flowing backward into the left ventricle. This condition increases the volume of blood in the left ventricle and requires more force to pump it out.
- Dilated cardiomyopathy is enlargement of the left ventricle and, in some cases, other chambers of the heart. Because the space inside the left ventricle is large, it fills with more blood and requires the muscle to contract more forcefully when pumping the blood out.
- A heart attack usually causes the loss or scarring of muscle tissue. To compensate for this loss, the surviving muscles may need to pump harder.