|front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |21 |22 |23 |24 |review|
1 Normal heart
2 Hypertrophied heart
3 Comparising of hypertrophy tipes
4 Eccentric LV hypertrophy
5 Concentric LV hypertrophy
|Ventricular hypertrophy (i.e.,
increased ventricular mass) is an adaptation by the ventricle to increased stress, such as
chronically increased volume load (preload) or increased
pressure load (afterload).
It is a physiological response that enables the heart to adapt to increased stress;
however, the response can become pathological and ultimately lead to a deterioration in
function. For example, hypertrophy is a normal physiological adaptation to exercise
training that enables the ventricle to enhance its pumping capacity. This type of
physiologic hypertrophy is reversible and non-pathological. Chronic hypertension also
causes ventricular hypertrophy. This response enables the heart to maintain a normal
stroke volume despite the increase in afterload. However, over time, pathological
changes occur in the heart that lead to a functional degradation and heart failure.
If the precipitating stress is volume overload, the ventricle responds by adding new sarcomeres in-series with existing sarcomeres. This results in ventricular dilation while maintaining normal sarcomere lengths. The wall thickness normally increases in proportion to the increase in chamber radius. This type of hypertrophy is termed eccentric hypertrophy.
In the case of chronic pressure overload, the chamber radius may not change; however, the wall thickness greatly increases as new sarcomeres are added in-parallel to existing sarcomeres. This is termed concentric hypertrophy. This type of ventricle is capable of generating greater forces and higher pressures, while the increased wall thickness maintains normal wall stress. This type of ventricle becomes "stiff" (i.e., compliance is reduced) which can impair filling and lead to diastolic dysfunction.