Adaptation of myocardial twist in the remodelled athlete's heart is not related to cardiac output

Autor: Samuel Cooke, T. Jake Samuel, Stephen‐Mark Cooper, Eric J. Stöhr
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Experimental Physiology, Vol 103, Iss 11, Pp 1456-1468 (2018)
Druh dokumentu: article
ISSN: 1469-445X
0958-0670
DOI: 10.1113/EP087165
Popis: New Findings What is the central question of this study? What is the role of heart muscle function in the increased output of remodelled, larger hearts? What is the main finding and its importance? The greater stroke volume of endurance athletes is not associated with enhanced function of the heart muscle (i.e. left ventricular twist, torsion and twist‐to‐shortening) in normal and low‐oxygen environments. These data indicate that, in the process of cardiac adaptation, left ventricular twist may play an important role that is not related to generating a larger output. Since enlarged hearts with low output can develop in disease, the present findings may influence the future interpretation of heart muscle function in patients. Abstract Despite increased stroke volume (SV), ‘athlete's heart’ has been proposed to have a similar left ventricular (LV) muscle function – as represented by LV twist – compared with the untrained state. However, the underpinning mechanisms and the associations between SV/cardiac output and LV twist during exercise are unknown. We hypothesised that endurance athletes would have a significantly lower twist‐to‐shortening ratio (TwSR, a parameter that relates twist to the shortening of heart muscle layers) at rest, but significantly greater LV muscle function during exercise. Eleven endurance trained male runners and 13 untrained males were tested at rest and during supine cycling exercise in normoxia and hypoxia (increased cardiac output but unaltered SV). Despite the expected cardiac remodelling in endurance athletes, LV twist, torsion, TwSR, strain and strain rate (‘LV systolic mechanics’) did not differ significantly between groups (P > 0.05). Structural remodelling, as per relative wall thickness, and LV twist did not correlate (r2 = 0.04, P = 0.33). In normoxia and hypoxia, exercise increased LV systolic mechanics in both groups (P
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