Evaluation of septal hypertrophy and systolic function iu diseases that cause left ventricular hypertrophy: A 3-dimensional echocardiography study

Objectives: The goals of this study were to determine regional systolic fun ction of the septum and to relate it to regional wall thickness and wall st ress. Background: Wall thickening, a parameter of systolic function: is determine d by wall thickness and wall stress. In patients with hypertrophic obstruct ive cardiomyopathy (HOCM), hypertrophic nonobstructive cardiomyopathy (HNCM ), and hypertensive heart disease (HHD), regional systolic function of norm al and hypertrophic septal regions has been incompletely characterized by 3 -dimensional echocardiography. Thus, multiplane transesophageal echocardiog raphy with 5-dimensional reconstruction of the septum was used. Methods and Results: In 49 patients (15 controls, II with HOCM, a with HNCM , and 15 with HHD) 4 parallel (2 basal and 2 apical) equidistant short-axis cross sections from base to apes were obtained from the reconstructed sept um. Ln each short-asis cross section. 6 wall-thickness measurements were ma de in 15 degrees intervals at end diastole and end systole, for a total of 48 measurements in each patient. Fractional thickening was calculated as wa ll thickening divided by end-diastolic wall thickness. wall thickness of th e basal cross sections was significantly thicker (P < .001) in HOCM and HNC M than in HHD. However, circumferential wall thickness was more evenly dist ributed in HOCM and HHD when compared with HOCM. In tile basal cross sectio ns, fractional thickening was similarly reduced in all hearts, though basal wall stress was significantly different in all groups (P < .001). In the a pical cross sections, R all thickness was similar in all diseased hearts, b ut fractional thickening was better (P < .001) and wall stress lower (P < . 001) ill HNCM than in HOCM and HHD. Conclusions: In septal regions without or with only mild hypertrophy, regio nal systolic function is preserved and appears to he determined bp hemodyna mic factors such as wall stress. However, in regions with moderate to sever e hypertrophy, systolic function is markedly and uniformly impaired in all groups, which seems not to be caused by differences in mall thickness and w all stress but by the degree of the myocardial disease process.