Left ventricular weight above 250 g was associated with a significantly higher number of myocytes, indicating that myocyte hyperplasia occurs in severe cardiac hypertrophy.
Observational (n=103)
This post-mortem morphometric study provides evidence that significant cardiac enlargement (LV weight > 250 g) involves myocyte hyperplasia in addition to cellular hypertrophy.
In 103 hearts with various forms of cardiac muscle hypertrophy the following parameters were estimated: diameter, length, volume, density and number of myocytes, and density of myocyte nuclei. The values of all histometric parameters correlated well with left ventricular (LV) weight up to 350 g. In heavier hearts these parameters remained approximately of the same magnitude. The number of myocytes was significantly higher in hearts with LV weight above 250 g. The influence on LV weight of age, coronary artery diameters, degree of atherosclerosis, weight and percent of fibrous tissue was also evaluated. On the basis of a linear discriminant function, hearts were divided into three classes: (1) LV weight 350 g (marked signs of hyperplasia). The percent of fibrosis increased proportionally to LV weight. Where LV weight was above 250 g there was a subsequent increase in the mean percent of fibrosis (approx. 26%). This phenomenon (plateau of percent fibrosis) is the result of an increased number of myocytes (myocyte hyperplasia). We suggest that, independent of aetiology, in all hearts above 350 g (patients with congestive heart failure) hyperplasia phenomenon exists.
Grajek et al. (Fri,) conducted a observational in Cardiac muscle hypertrophy (n=103). Left ventricular weight > 250 g vs. Left ventricular weight ≤ 250 g was evaluated on Myocyte parameters (diameter, length, volume, density, number) and fibrosis. Left ventricular weight above 250 g was associated with a significantly higher number of myocytes, indicating that myocyte hyperplasia occurs in severe cardiac hypertrophy.