What does cardiac hypertrophy refer to?

Cardiac hypertrophy refers to the thickening of the heart walls, specifically the myocardium, in response to increased workload or stress on the heart. This adaptation often occurs without a proportional increase in the size of the heart's chambers, meaning the functional capacity for pumping blood may not be enhanced despite the thicker walls. This condition can arise from various factors, such as high blood pressure or athletic training, and it alters the heart's structure to handle higher demands, which can ultimately lead to complications if not managed properly. This differentiation makes option A the accurate definition of cardiac hypertrophy.

The other options describe different cardiac conditions that are not accurately encapsulated by the definition of cardiac hypertrophy.