Number and size of myocytes, amount of interstitial space and extent of disarray of the hearts in patients with systemic hypertension and asymmetric septal hypertrophy.

Wall thickness, the extent of disarray, the number and the size of myocytes and the amount of interstitial space were measured in the ventricular septum (VS) and left ventricular (LV) free wall in hearts of 6 patients with chronic systemic hypertension and asymmetric septal hypertrophy (ASH). Twenty-five subjects (15 with no cardiac disease, and 10 with systemic hypertension) without ASH served as the controls. In the six patients with ASH, the degree of ASH ranged from 1.3 to 1.6. The extent of disarray in VS was 20% in one heart and within normal limits (mean +/- SD = 3 +/- 3%) in the other 5. The size of myocytes increased both in the VS and LV free wall and the VS/LV ratio ranged from 0.9 to 1.0. There was no significant difference in the % area of interstitial space between hearts with ASH and controls, and the VS/LV ratio ranged from 0.9 to 1.1. The number of transmural muscle layers (number of myocytes) was 680 +/- 90 in the VS and 440 +/- 40 in the LV free wall of these with ASH, and 500 +/- 60 in the VS and 490 +/- 60 in the LV free wall of control subjects. The VS/LV ratio of the number of myocytes ranged from 1.3 to 1.7 and was correlated with the VS/LV ratio of wall thickness. Although the sample is small, our findings suggest that most hearts from patients with chronic systemic hypertension and ASH have no diffuse disarray in the VS and that ASH probably occurs secondary to pressure overload.(ABSTRACT TRUNCATED AT 250 WORDS)