Physiologic, naturally occurring hypertrophy usually rep¬resents as an adaptation to increased functional demands, and a similar principle dominates pathologic hypertrophy. Hypertrophy of the heart affects the left ventricle and left ventricular hypertrophy is a feature of many forms of heart disease. The left atrium may, however, hypertrophy to assist a left ventricle that is under stress and strain imposed by pressure or volume overload. The right ven¬tricle may hypertrophy in patients with pulmonary artery hypertension or pulmonary valve stenosis. The right atrium may hypertrophy to assist the right ventricle and also be hypertrophied in patients with chronic obstructive pulmonary disease.
A. Compensatory Hypertrophy
Compensatory hypertrophy occurs in response to abnor¬mal functional demands imposed on the heart and the processes are similar to the physiologic adaptation described above. The heart muscle is capable of great hypertrophy when its workload is increased — such as when it has to pump against a pressure overload (systolic overload) – as may occur with obstruction to the aortic valve, aortic stenosis, or with chronic sustained hyperten¬sion. Hypertension is the most common cause of left ventricular hypertrophy.

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