Hypertrophy

Hypertrophy is an increase in the volume of tissue or an organ due to an increase in the size of the cells it consists of. This process occurs without an increase in the number of cells themselves, and is a form of cellular adaptation to increased stress.

Hypertrophy is typical for tissues where cells have lost their ability to divide, primarily muscle tissue (myocardium, skeletal muscles). The increase in cell size is achieved through enhanced synthesis of protein structures and organelles.

Aetiology and pathophysiology

There are two types of hypertrophy: physiological and pathological.

• Physiological hypertrophy. It is a normal response to an adequate increase in stress. Classic examples are skeletal muscle hypertrophy in athletes and uterine hypertrophy during pregnancy.
• Pathological hypertrophy. It develops as a result of chronic stress on the organ caused by disease. The most significant example is left ventricular (myocardial) hypertrophy in hypertension or aortic valve stenosis.

Clinical Significance

Pathological hypertrophy is an important clinical marker indicating long-standing disease and organ stress. For example, myocardial hypertrophy detected on an ECG or US is a risk factor for heart failure, arrhythmias, and sudden cardiac death.

Unlike physiological one, pathological hypertrophy can eventually lead to decompensation, dystrophic changes and decreased organ function.

Differential Diagnosis

Hypertrophy (increase in cell size) must be distinguished from hyperplasia (increase in cell number). In some tissues capable of division, these two processes can occur simultaneously.