Background: The goal of this study was to identify the effect of body growth and aging, and normal limits of the relation of left ventricular endocardial and midwall shortening to wall stress.
Methods: Endocardial and midwall shortening and circumferential end-systolic stress were assessed in 388 normotensive, normal-weight adults (226 men, 162 women, age 18 to 85 years) and 332 children and adolescents (180 males, 152 females, age 4 to 17 years) by two-dimensional targeted M-mode echocardiography and cuff blood pressure measurements.
Results: End-systolic stress decreased with age in children and adolescents (p < 0.001), but not during adulthood and maturity. The negative relation of endocardial shortening to end-systolic stress was stronger in adults than in children and adolescents (slope difference p < 0.005). The negative relation of midwall shortening to end-systolic stress was negligible in children and adolescents (r = -0.07, p = 0.18), whereas it was more evident, although weak, in adults (r = -0.14, p < 0.007). For a given level of end-systolic stress, endocardial shortening decreased by 0.32%/year in children and adolescents (multiple r = 0.51, p < 0.0001) and by 0.05%/year in adults, whereas midwall shortening decreased by 0.26%/year during body growth and by 0.02%/year in adults.
Conclusions: In the presence of normal blood pressure and normal weight, the relations between left ventricular wall stress and both chamber and myocardial function are weakly but significantly influenced by age. Left ventricular chamber function is markedly influenced by wall stress, while this influence is reduced for left ventricular wall mechanics.