Division of Cardiology, 1st Department of Medicine, University Hospital of Jena, Erlanger Allee 101, 07740 Jena, Germany.
Int J Cardiovasc Imaging. 2013 Mar;29(3):561-70. doi: 10.1007/s10554-012-0117-2. Epub 2012 Aug 24.
Aim of this study was to evaluate the influence of normobaric hypoxia on myocardial function in healthy humans. Fourteen subjects underwent two-dimensional speckle tracking echocardiography (2D-STE) examination during normoxia and in a normobaric hypoxia chamber. Examinations were performed at rest and during bicycle exercise test. The following parameters were quantified in both atria and ventricles by 2D-STE: Global Strain (S), systolic strain rate (SRS), early (SRE) and late (SRA) diastolic strain rate. During hypoxia SRS and SRE increased significantly in both ventricles compared to baseline. The increase of LV SRS and SRE during normoxic exercise was significantly higher when compared with exercise under hypoxia (for SRS -0.55 ± 0.22 vs. -0.34 ± 0.24 1/s, p = 0.024; for SRE 0.56 ± 0.29 vs. 0.23 ± 0.29 1/s, p = 0.005). For the right ventricle (RV) no significant difference of exercise induced increase of systolic contractility was found (SRS -1.07 ± 0.53 under normoxia vs. -1.28 ± 0.24 1/s under hypoxic conditions, p = 0.47). A shift from passive conduit (SRE) to active contraction (SRA) phase during hypoxia was noted for the right atrium (RA) (SRE/SRA 0.72 ± 0.13 under hypoxia vs. 1.17 ± 0.17 under normoxia). The ratio SRE/SRA of RA was closely related to pulmonary systolic pressure (r = -0.78, p < 0.001). Exposure to normobaric hypoxia leads to an increase of regional myocardial deformation in both ventricles. The contractile reserve during hypoxic exercise is reduced in LV, whereas RV systolic deformation rate is maintained. In addition, hypoxia had an impact on the ratio of passive conduit to active contraction phase in right atrium.
本研究旨在评估常压缺氧对健康人体心肌功能的影响。14 名受试者在常氧和常压缺氧室内接受二维斑点追踪超声心动图（2D-STE）检查。检查在休息时和自行车运动试验期间进行。通过 2D-STE 定量评估心房和心室的以下参数：整体应变（S）、收缩期应变率（SRS）、早期（SRE）和晚期（SRA）舒张期应变率。与基础值相比，缺氧时 SRS 和 SRE 在两个心室均显著增加。与缺氧下的运动相比，在常氧运动下 LV 的 SRS 和 SRE 增加更为显著（SRS：-0.55 ± 0.22 比-0.34 ± 0.24 1/s，p = 0.024；SRE：0.56 ± 0.29 比 0.23 ± 0.29 1/s，p = 0.005）。对于右心室（RV），收缩期收缩力的运动诱导增加无显著差异（SRS：常氧下 1.07 ± 0.53 比缺氧下 1.28 ± 0.24 1/s，p = 0.47）。在缺氧时，右心房（RA）从被动传导（SRE）向主动收缩（SRA）阶段的转变（SRE/SRA：缺氧下 0.72 ± 0.13 比常氧下 1.17 ± 0.17）。RA 的 SRE/SRA 比值与肺动脉收缩压密切相关（r = -0.78，p < 0.001）。暴露于常压缺氧会导致两个心室的局部心肌变形增加。在 LV 中，缺氧运动时的收缩储备减少，而 RV 收缩变形率保持不变。此外，缺氧对右心房被动传导与主动收缩阶段的比值有影响。
