title: Effects of 5 days of head-down bed rest, with and without short-arm centrifugation as countermeasure, on cardiac function in males (BR-AG1 study).
abstract: This study examined cardiac remodeling and functional changes induced by 5 days of head-down (-6°) bed rest (HDBR) and the effectiveness of short-arm centrifugation (SAC) in preventing them in males. Twelve healthy men (mean age: 33 ± 7) were enrolled in a crossover design study (BR-AG1, European Space Agency), including one sedentary (CTRL) and two daily SAC countermeasures (SAC1, 30 min continuously; SAC2, 30 min intermittently) groups. Measurements included plasma and blood volume and left ventricular (LV) and atrial (LA) dimensions by transthoracic echocardiography (2- and 3-dimensional) and Doppler inflows. Results showed that 5 days of HDBR had a major impact on both the geometry and cardiac function in males. LV mass and volume decreased by 16 and 14%, respectively; LA volume was reduced by 36%; Doppler flow and tissue Doppler velocities were reduced during early filling by 18 and 12%, respectively; and aortic flow velocity time integral was decreased by 18% with a 3% shortening of LV ejection time. These modifications were presumably due to decreased physiological loading and dehydration, resulting in reduced plasma and blood volume. All these changes were fully reversed 3 days after termination of HDBR. Moreover, SAC was not able to counteract these changes, either when applied continuously or intermittently.
authors: Politecnico di Milano, Electronics, Information and Biomedical Engineering Department, Milano, Italy; enrico.caiani@polimi.it.
authors: E G
authors: EG
authors: Caiani
authors: University Hospital of Rangueil, Department of Cardiology, Toulouse, France;
authors: P
authors: P
authors: Massabuau
authors: University of Chicago, Noninvasive Cardiac Imaging Laboratory, Chicago, Illinois; and.
authors: L
authors: L
authors: Weinert
authors: Université de Bordeaux, Bordeaux, France.
authors: P
authors: P
authors: Vaïda
authors: University of Chicago, Noninvasive Cardiac Imaging Laboratory, Chicago, Illinois; and.
authors: R M
authors: RM
authors: Lang
mesh_terms: D000328:Adult; D016279:Atrial Function, Left / Q000502:physiology; D001510:Bed Rest; D001810:Blood Volume / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D018592:Cross-Over Studies; D004452:Echocardiography; D018475:Head-Down Tilt / Q000502:physiology*; D006321:Heart / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D016277:Ventricular Function, Left / Q000502:physiology; D018544:Weightlessness Countermeasures; D055815:Young Adult
keywords: cardiac function; echocardiography; head-down bed rest; short-arm centrifugation