Wall tension or stress in ischemic heart disease

Abstract

Wall stress or wall tension is a conception derived from physics (Laplace's law) and represents the systolic force or work per surface unit. It is the systolic force made by myocardial tissues. Stress increase indicates enlargement of the left ventricle or increase of intracavitary pressure. This investigation included 170 subjects; control group consisted of 50 patients (pts) with normal coronary angiographic finding without valvular anomalies and the examination group included 120 pts with coronary disease. Transthoracic echocardiography was performed in the left lateral position using computerized Hewlett Packard SONOS 1000 apparatus. Invasive hemodynamic procedure was performed using GENERAL ELETRICS CGR 300. Meridional and equatorial systolic and diastolic stress were calculated according to Grossman formula. The meridional end-diastolic equatorial stress was 18.55 +/- 12.12 dyn/cm2 x 10(3) in the control group, while in coronary patients it was 28.15 +/- 13.42 dyn/cm2 x 10(3). In healthy persons the meridional end-systolic stress established by echocardiography was 190.37 +/- 23.15 dyn/cm2 x 10(3), while in coronary patients 203.82 +/- 17.88 dyn/cm2 x 10(3). End-diastolic equatorial stress was 34.32 +/- 17.18 dyn/cm2 x 10(3) in the control group and 46.13 +/- 17.82 dyn/cm2 x 10(3) in coronary patients. Systolic equatorial stress in the control group was 357.42 +/- 32.15 dyn/cm2 x 10(3) and in coronary patients 385.34 +/- 35.72 dyn/cm2 x 10(3). The same parameters determined by invasive hemodynamic procedure were slightly higher, but without statistical significance in relation to the values determined by echocardiography (P > 0.05). Values of equatorial and particularly meridional stress were higher in coronary patients in relations to healthy persons, but without significant difference. The correlation coefficients of all investigated parameters established by noninvasive 2D echocardiography and invasive hemodynamic procedure were in one domain of medium high and high values. Meridional stress increases in coronary patients, equatorial in hypertensive patients or valvular anomalies with severe myocardial hypertrophy. In regard to high correlation between these two techniques, echocardiography may be considered a highly reliable method in evaluation of wall tension.