Left Ventricular Mechanics In Healthy Females Are Not Significantly Altered In Response To Isometric Handgrip

Abstract

Left ventricular (LV) mechanics characterize myocardial deformation across the cardiac cycle and are sensitive to changes in cardiac load. Previous research in a predominantly male cohort showed reduced LV mechanics in an afterload challenge mediated by isometric hand grip (IHG). There are known differences between male and female cardiac structure and function; it is possible that LV mechanics in females may differ in IHG. PURPOSE: To quantify LV mechanics in females during IHG. METHODS: Healthy females (n=18, age 28±4 yrs) performed an IHG (30% maximal strength; 9±1 kg) for 5 min. Cardiac images were collected using echocardiography at REST, DURING and 5 min POST IHG and analyzed for longitudinal, circumferential and radial strain, rotation and twist. Blood pressure was measured continuously. Repeated measures ANOVA was used to detect significant differences. RESULTS: Without significant change in heart rate or cardiac output, systolic blood pressure was significantly increased DURING IHG compared to REST and POST (SBP: 123±13 vs. 113±12 vs. 114±13 mmHg respectively, P < 0.01). Similarly, systemic vascular resistance was increased DURING IHG compared to REST measurements (2306±361 vs. 2125±312 dynes⋅sec⋅cm-5P < 0.01, POST 2246±274 dynes⋅sec⋅cm-6) confirming IHG augmented afterload. Except peak basal circumferential strain, there were no significant differences in LV mechanics from DURING to POST IHG (Table 1). CONCLUSIONS: In contrast to previous investigations in a predominantly male cohort, LV mechanics in healthy females do not appear to be markedly altered in IHG. These findings suggest that LV mechanics in response to an acute afterload challenge may be different between sexes.Table 1: Peak LV mechanics in response to isometric hand grip. * P < 0.01 vs. POST.