Assessment of hypertrophy in myocardial biopsies taken during correction of congenital heart disease.

Myocardial biopsies were obtained from 27 patients undergoing corrective cardiac surgery for congenital heart disease. Normal hearts of 18 autopsied patients were used as reference. The biopsy material was assessed for desoxyribonucleic acid (DNA) concentration and ploidy profile of cell nuclei in order to quantitate myocardial hypertrophy at the time of operation. DNA-concentration decreased significantly with age (r = -0.76; p less than 0.001). Ploidy profile of myocardial nuclei correlated with age: the relative number of diploid nuclei decreased (r = -0.67; p less than 0.001), the relative numbers of tetraploid and octoploid nuclei increased with age (r = 0.58; p less than 0.01 and r = 0.77; p less than 0.001 respectively). At 8 years of age the patients with congenital heart disease reached myocardial DNA-concentrations comparable with those in normal adult hearts. At higher age the patients with congenital heart disease exceeded normal adult values for myocardial DNA-concentration. These findings are interpreted to represent rapid development of hypertrophy with an early onset, reaching at 8 years of age values observed in normal adult hearts. Quantitation of myocardial hypertrophy by DNA-concentration and ploidy profile of nuclei may offer a means to explain some of the factors of influence on the outcome of corrective cardiac surgery for congenital heart disease in relation to its timing. Our data stress the need for preventing irreversible myocardial damage by timely (surgical) therapy.