Quantitation of left ventricular myocardial fiber hypertrophy and interstitial tissue in human hearts with chronically increased volume and pressure overload

Abstract

Using new techniques, the left ventricular myocardial fiber hypertrophy together with the interstitial tissue was quantitated in 4 groups of autopsied hearts free of coronary disease. 22 normal hearts; 20 hearts from patients with mitral incompetence (NYHA clas II-III) who died early after mitral valve replacement from causes other than cardiac failure; 22 hearts from patients with mitral incompetence (NYHA class III IV) who died early after mitral valve replacement from cardiac failure with low cardiac output syndrome; and 22 hearts from patients with hypertensive heart disease (NYHA class II-III). Myocardial fiber hypertrophy was measured on the basis of the cross sectional myocardial fiber diameter; while the proportion of interstitial tissue was quantitated by using a computerized, high resolution video image digitizing system. The myocardial fiber average diameter in groups 2, 3 and 4 was significantly higher than in group I. The proportion of interstitial tissue was significantly increased in group 3. In chronic mitral incompetence an increase in left ventricular interstitial tissue may play a role in the development of severe cardiac failure.