UMPS-CERCOM, Faculte de Medecine Université, 2 Blv tonnelle, 37032, Tours, France.
Politecnico di Milano, Electronic, Information and Bioengineering Department, p.zza L. da Vinci 32, 20133, Milan, Italy.
Eur J Appl Physiol. 2019 Dec;119(11-12):2477-2486. doi: 10.1007/s00421-019-04228-0. Epub 2019 Sep 17.
To evaluate functional myocardial contractility after 21 days of head-down bed rest (HDBR) in sedentary control (CON) or with a resistive vibration exercise (RVE) countermeasure (CM) applied, by using 4D echocardiographic (4D echo) imaging and speckle tracking strain quantification.
Twelve volunteers were enrolled in a crossover HDBR design, and 4D echo was performed in supine position (REST) at BDC-2 and at R + 2, and in - 6° HDT at day 18, and during the first and the last minute of the 80° head-up step of tilt test performed at both BDC-2 and R + 2. Radial (Rad-Str), longitudinal (Lg-Str) and twist (Tw-Str) strains were measured by 4D speckle tracking, as well as left ventricle diastolic volume (LVDV) and mass (LVmass).
On HDT 18: in the CON group, LVDV and LVmass were reduced (p < 0.05), the Rad-Str decreased (p < 0.05) and Tw-Str showed a tendency to increase (p < 0.11), with no changes in Lg-Str. In RVE group, LVDV and LV mass, as well as all the strain parameters remained unchanged. On R + 2: in the CON group, LVDV and LVmass were not recovered in all subjects compared to pre-HDBR (p < 0.08) and Rad-Str was still decreased (p < 0.05), while Tw-Str tended to increase (p < 0.09). These parameters remained unchanged in the RVE group. Tilt 80°: Rad-Str and Lg-Str values at 80° tilt were similar post-HDT in both groups.
The 4D echo and speckle tracking analysis showed that in the CON group, Rad-Str decreased concomitant with LVmass and LVDV with HDBR, but this observation did not allow concluding if HDBR induced a real remodeling or a muscle atrophy. RVE was able to preserve LVmass, LVDV and contractility during HDBR, thus proving its effectiveness to this aim. Nevertheless, the significant HDBR-induced changes observed in the CON group had only a limited effect on the cardiac contractile response as observed during post-HDBR tilt test. The level of contractility at 80° Tilt position was not affected either by HDBR or by RVE CM.
通过 4D 超声心动图（4D 回声）成像和斑点追踪应变定量评估 21 天头低位卧床（HDBR）后久坐对照组（CON）或应用抗阻振动运动（RVE）对策（CM）后的功能性心肌收缩力。
12 名志愿者参与了 HDBR 交叉设计，在仰卧位（REST）时在 BDC-2 和 R + 2 进行 4D 回声检查，并在第 18 天进行 - 6°HDT 检查，以及在 BDC-2 和 R + 2 进行 80°头高位倾斜试验的第 1 和最后 1 分钟进行。通过 4D 斑点追踪测量径向（Rad-Str）、纵向（Lg-Str）和扭转（Tw-Str）应变，以及左心室舒张末期容积（LVDV）和质量（LVmass）。
在 HDBR 18 天：在 CON 组中，LVDV 和 LVmass 减少（p < 0.05），Rad-Str 减少（p < 0.05），Tw-Str 呈增加趋势（p < 0.11），Lg-Str 无变化。在 RVE 组中，LVDV 和 LVmass 以及所有应变参数均无变化。在 R + 2：在 CON 组中，与 HDBR 前相比，所有受试者的 LVDV 和 LVmass 均未恢复（p < 0.08），Rad-Str 仍降低（p < 0.05），而 Tw-Str 呈增加趋势（p < 0.09）。在 RVE 组中，这些参数没有变化。80°倾斜：两组 HDBR 后，在 HDBR 后，Rad-Str 和 Lg-Str 在 80°倾斜时的值相似。
4D 回声和斑点追踪分析表明，在 CON 组中，Rad-Str 随 HDBR 而降低，同时伴有 LVmass 和 LVDV，这一观察结果不能确定 HDBR 是否导致真正的重构或肌肉萎缩。RVE 能够在 HDBR 期间保持 LVmass、LVDV 和收缩力，从而证明其对该目的的有效性。然而，在 CON 组中观察到的与 HDBR 相关的显著变化仅对 HDBR 后倾斜试验期间观察到的心脏收缩反应产生有限的影响。80°倾斜位置的收缩力水平也不受 HDBR 或 RVE CM 的影响。
