Age dependency of myocardial structure: A quantitative two-dimensional echocardiographic study in a normal population

Histological changes of the myocardium occur with aging due to an increase in collagen content, hypertrophy of fibers, and patchy fibrosis. Quantitati ve analysis of conventional echocardiographic images provides an in vivo as sessment of myocardial structure by the evaluation of the gray level distri bution; with this technique, a relation. between myocardial fibrosis and pa thological ultrasonic response has been, documented. The aim of this study was to evaluate the relation between ultrasonically assessed myocardial str ucture and age in a normal population. Seventy-eight subjects (47 men; mean age, 51 years; age range, 23-87 years) without apparent cardiovascular and systemic disease underwent conventional two-dimensional echocardiographic examinations. Still frames at end-diastole fi om apical four-chamber view w ere digitized and converted in matrices of 256 x 256 pixels. First-order st atistical analysis was performed to describe a region of interest in the in terventricular septum. The following parameters were studied: mean (gray Le vel amplitude), standard deviation (overall contrast), uniformity (tonal or ganization), and entropy (tendency of gray Levels to be spread). Myocardial structure was assessed in 75 of 78 subjects, divided into three groups: I, age 23-40 years; II age 41-65 years; and III, > 65 years. Significant diff erences for all the parameters were found between the age groups. Age corre lated directly with mean. and entropy (r = 0.77 and 0.69, respectively) and inversely with uniformity (r 0.70). Our results suggest that quantitative echocardiography can reveal age-related changes in myocardial structure tha t are characterized by a greater echogenicity and loss in tonal organizatio n, possibly due to increased collagen content within the fibers.