Right atrial ultrastructural in chronic rheumatic heart disease.

We studied with ultrastructure techniques portions of right atrium resected at operation from 12 patients with chronic rheumatic heart disease and 6 patients with non-rheumatic valvular heart disease. The right atrial pressures, duration of symptoms and age of the patients were comparable in both groups. Ten of the 12 rheumatic and 4 of the 6 non-rheumatic patients had atrial fibrillation. In the 12 rheumatic patients we found severe interstitial fibrosis, extensive cellular degeneration (17% of cells studied) and marked cellular hypertrophy (average cell diameter 16 micrometers). The six non-rheumatic patients showed evidence of cellular hypertrophy (average cell diameter 15 micrometers) but minimal interstitial fibrosis or cellular degeneration. The degenerative changes in the rheumatic group did not correlate with the degree of hypertrophy or the extent of the hemodynamic alterations. Atrial fibrillation, present in both rheumatic and non-rheumatic patients, did not correlate with the presence of cellular degeneration. We conclude that the structural changes in atria of patients with chronic rheumatic heart disease may be part of the rheumatic process and are not entirely secondary to altered hemodynamics.