Myocardial hypertrophy and hyperplasia. A narrative of past, present and future.

The heart of man is noble, but then 'noblesse oblige'. Obligated to what? Obviously, the heart — a muscular pump driven by electricity — is obliged to maintain the driving force of circulation. Once circumstances change, necessitating the heart to increase work, its response will be to adapt. In adults, cardiac adaptation is achieved by hypertrophy, defined as an increase in volume of myocytes, mainly because the cells synthesize additional contractile proteins. The intracellular remodelling depends on the type of load.' Where there is an increase in pressure load the number of sarcomeres increase in a parallel fashion, thus creating a distinct increase in the cross-sectional diameter of the myocytes. In volume load hypertrophy, on the other hand, the increase in the number of sarcomeres is mainly longitudinal, thus causing the cells to elongate rather than to exhibit an increase in diameter. The heart is thus equipped to cope with an increase in demand, albeit under pathological conditions at the expense of an imbalance between energy consumption and production — a negative effect, which in part relates to a decrease in coronary vasodilator reserve'"'.