A VIDEODENSITOMETRIC STUDY OF TRANSMURAL HETEROGENEITY OF CYCLIC ECHOAMPLITUDE VARIATION IN HUMAN MYOCARDIUM

The aims of this study were: (1) to assess whether variations in cycli c echo amplitude might be detected across the human myocardium by vide odensitometric analysis of images obtained with epicardial echocardiog raphy; and (2) to explore the possible relation between cyclic gray le vel variation and left ventricular [LV) hypertrophy and function. Expe rimental studies show that transmural differences in contractile perfo rmance across the normal myocardium are paralleled by differences in t he cyclic (diastolic-to-systolic) variation of myocardial echo amplitu de, Thirty-three patients (aged 60 +/- 11 years) undergoing cardiac su rgery were studied by intraoperative epicardial echocardiography. LV m ass index was normal (< 110 g/m(2) in women, < 131 g/m(2) in men) in 1 0 patients and increased in 22. Two-dimensional echocardiographic imag es were obtained with a 5 MHz transducer and digitized off-line. Video densitometric analysis was performed at end-diastole and end-systole w ith regions of interest across the septal and posterior wall, The cycl ic variation was more pronounced in the left than in the right septal subendocardium (31% +/- 14% vs 16% +/- 14%, p < 0.01) and higher in th e subendocardial than in the subepicardial layer of the posterior wall (30% +/- 21% vs 23 +/- 18%, p < 0.01). Cyclic variation of the left s eptal subendocardium wets higher in 11 patients with nonhypertrophic v entricles than in 22 with hypertrophic left ventricles (42% +/- 15% vs 27% +/- 12%; p < 0.01). The percent cyclic variation of the left sept al subendocardium appeared to be much more tightly related to percent systolic thickening in patients with eccentric LV hypertrophy (r = 0.8 0 p < 0.01) than in patients with concentric LV hypertrophy (r = 0.27, p = 0.9) or normal LV mass (r = 0.43, p = 0.2). A cyclic gray level v ariation can be consistently detected in different human myocardial re gions and layers. it is more obvious in the subendocardial than in the subepicardial layer, and in nonhypertrophic than hypertrophic ventric les. The cyclic subendocardial variation is tightly related to regiona l systolic thickening in patients with eccentric LV hypertrophy.