Abstract
PurposeFew data exist on the descriptions of LV myocardial mechanics and reserve during dynamic exercise of adolescent athletes. The aim of this study was to describe the LV myocardial and cardiopulmonary changes during exercise using 2-D strain deformation imaging.MethodsElite adolescent male football players (n = 42) completed simultaneous cardiopulmonary exercise testing (CPET) and exercise echocardiography measurement of LV myocardial deformation by 2-D strain imaging. LV longitudinal and circumferential 2-D strain and strain rates were analyzed at each stage during incremental exercise to a work rate of 150 W. Additionally, exercise LV myocardial deformation and its relation to metabolic exercise parameters were evaluated at each exercise stage and in recovery using repeated measures ANOVA, linear regression and paired t tests.ResultsLV peak systolic baseline 2-D strain (longitudinal: − 15.4 ± 2.5%, circumferential: − 22.5 ± 3.1%) increased with each exercise stage, but longitudinal strain plateaued at 50 W (mean strain reserve − 7.8 ± 3.0) and did not significantly increase compared to subsequent exercise stages (P > 0.05), whilst circumferential strain (mean strain reserve − 11.6 ± 3.3) significantly increased (P < 0.05) throughout exercise up to 150 W as the dominant mechanism of exercise LV contractility increase. Regression analyses showed LV myocardial strain increased linearly relative to HR, VO2 and O2 pulse (P < 0.05) for circumferential deformation, but showed attenuation for longitudinal deformation.ConclusionThis study describes LV myocardial deformation dynamics by 2-D strain and provides reference values for LV myocardial strain and strain rate during exercise in adolescent footballers. It found important differences between LV longitudinal and circumferential myocardial mechanics during exercise and introduces a methodology that can be used to quantify LV function and cardiac reserve during exercise in adolescent athletes.
Highlights
The adaptation of left ventricular (LV) morphology to athletic training in adults has been well described in several seminal publications and meta-analyses (Morganroth et al 1975; Nishimura et al 1980; Maron 1986; Utomi et al 2013)
We describe for the first time, the LV myocardial contractile response to exercise in elite adolescent footballers by 2-D strain imaging
Using a novel approach piloted previously by our group (Pieles et al 2015), which combines 2-D strain imaging with simultaneous metabolic evaluation using cardiopulmonary exercise testing (CPET), we investigated the mechanics of LV contraction under exercise stress, as well as the relationship of exercise LV function to metabolic exercise parameters
Summary
The adaptation of left ventricular (LV) morphology to athletic training in adults has been well described in several seminal publications and meta-analyses (Morganroth et al 1975; Nishimura et al 1980; Maron 1986; Utomi et al 2013). Exercise stress echocardiography has recently, been shown to differentiate physiological LV functional adaptive processes from myocardial disease, where function decreases, in adult athletes (La Gerche et al 2013; Sanz-de la Garza et al 2017) and it has been shown to unmask cardiac dysfunction that is not detectable at rest in the paediatric and adolescent congenital heart disease population (Roche et al 2011, Roche et al 2014). The gold standard methodology for LV myocardial performance assessment, during exercise, is contractility assessment by end-systolic elastance using conductance catheters, which is an invasive technique (Izawa et al 1996; Inagaki et al 1999) To overcome this problem and important in the paediatric population, myocardial deformation imaging by 2-D strain during exercise has recently been shown to present a more practical alternative. Proof of principle studies including reference values for 2-D strain during exercise in non-athlete adolescents have recently become available (Boissiere et al 2013; Pieles et al 2015; Cifra et al 2016)
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