Kinetics of Left Ventricular Strains and Torsion During Incremental Exercise in Healthy Subjects

Abstract

Background-The dynamics of systolic and diastolic strains and torsional mechanics of the left ventricle (LV) and their relation to diastolic filling never have been evaluated at various exercise intensities. Methods and Results-Speckle tracking echocardiography was performed in 20 healthy sedentary subjects at rest and during a progressive submaximal exercise test at 20%, 30%, and 40% of maximal aerobic power. LV twist increased progressively with exercise intensity (10.5Ϯ3.2 to 15.8Ϯ4.5°; PϽ0.001), whereas longitudinal strain remained unchanged after the first workload, underlining the key role of torsional reserve in systolic-diastolic coupling during exercise. The increase in diastolic untwisting (Ϫ88.7Ϯ34.2 to Ϫ182.9Ϯ53.5 deg ⅐ s Ϫ1 ; PϽ0.01) was correlated to enhanced systolic twist (Rϭ0.61; PϽ0.001), and its magnitude of increase was significantly higher compared to diastolic longitudinal and circumferential strain rates (119Ϯ64% versus 65Ϯ44% and 57Ϯ24%, respectively), emphasizing its contribution to diastolic filling. The timing of peak untwisting and the chronology of diastolic mechanical events were unchanged during effort. Untwisting was driven mainly by apical rotation and determined mitral opening and isovolumic relaxation time (Rϭ0.47 and 0.61, respectively; PϽ0.001), whereas basal rotation and longitudinal and circumferential diastolic strain rates were major determinants of increased early diastolic filling (Rϭ0.64, 0.79, and 0.81, respectively; PϽ0.001). Conclusions-The use of speckle tracking echocardiography gives new insights into physiological adaptive LV mechanics during incremental exercise in healthy subjects, underlining the key role of torsional mechanics. It might be useful to better understand the mechanisms of diastolic dysfunction and exercise intolerance in various pathological conditions. (Circ Cardiovasc Imaging. 2010;3:586-594.)

Exercise Response in Hypertrophic Cardiomyopathy

“…Intraobserver and interobserver variability for STE analysis has been previously assessed in our laboratory, yielding maximal coefficient of variation values Ͻ8% for strains and rotations during exercise. 18 Statistical analysis was performed using MedCalc for MS Windows, version 11.5.00 (MedCalc, Mariakerke, Belgium). Statistical significance was assumed at PϽ0.05.…”

“…18 LV longitudinal strain and strain rate were assessed using apical 2-and 4-chamber views from 12 segments with a mean number of analyzable segments per patient of 10.1Ϯ1.3 at rest and 9.5Ϯ1.8 during exercise (NS). Radial and circumferential strain and strain rates, LV rotation, and rotational velocities were assessed from short-axis views at basal and apical levels.…”

“…The time sequence was normalized to the percentage of systolic and diastolic duration (ie, AC represented 100% of systole, and end of cardiac cycle represented 100% of diastole) using linear interpolation to obtain 1 point per percentage of the cardiac cycle from 1% to 200%. 18 Net LV twist was calculated as the instantaneous difference between apical and basal rotations. Diastolic function was evaluated by UTR, the time to peak UTR, and the ratio of UTR normalized for maximal twist.…”

Exercise Physiology and Rehabilitation in Circulation and the Circulation Subspecialty Journals

“…It might be useful to better understand the mechanisms of diastolic dysfunction and exercise intolerance in various pathological conditions. 14 …”

Three-Dimensional Left Ventricular Torsion in Patients With Dilated Cardiomyopathy ― A Marker of Disease Severity ―

“…9 Twist motion and apical rotation are sensitive markers for changes in the state of cardiac function and contractility. 10, 11 However, as with all 2D speckle-tracking techniques used for quantification of the LV, deformation and twist are affected by incorrect acquisition.…”