Background

Changes in left ventricular (LV) torsion have been related to LV geometry in patients with concomitant long-standing myocardial disease or pulmonary hypertension (PH). We evaluated the effect of acute high altitude-induced isolated PH on LV geometry, volumes, systolic function, and torsional mechanics.

Methods

Twenty-three volunteers were prospectively studied at low altitude and after the second (D3) and third night (D4) at high altitude (4,559 m). LV ejection fraction, multidirectional strains and torsion, LV volumes, sphericity, and eccentricity were derived by speckle-tracking on three-dimensional echocardiographic data sets. Pulmonary pressure was estimated from the transtricuspid pressure gradient (TRPG), LV preload from end-diastolic LV volume, and transmitral over mitral annular E velocity (E/e′).

Results

At high altitude, oxygen saturation decreased by 15%–20%, heart rate and cardiac index increased by 15%–20%, and TRPG increased from 21 ± 2 to 37 ± 9 mm Hg (P < .01). LV volumes, preload, ejection fraction, multidirectional strains, and sphericity remained unaffected, but diastolic (1.04 ± 0.07 to 1.09 ± 0.09 on D3/D4, P < .05) and systolic (1.00 ± 0.06 to 1.08 ± 0.1 [D3] and 1.06 ± 0.07 [D4], P < .05) eccentricity slightly increased, indicating mild septal flattening. LV torsion decreased from 2.14 ± 0.85 to 1.34 ± 0.68 (P < .05) and 1.65 ± 0.54 (P = .08) degrees/cm on D3/D4, respectively. Changes in torsion showed a weak inverse relationship to changes in systolic (r = −0.369, P = .013) and diastolic (r = −0.329, P = .032) eccentricity but not to changes in TRPG, heart rate or preload.

Conclusions

High-altitude exposure was associated with mild septal flattening of the LV and reduced ventricular torsion at unchanged global LV function and preload, suggesting a relation between LV geometry and torsional mechanics.

中文翻译：

---

高海拔诱发的肺动脉高压中左心室几何形状和扭转力学的改变：三维超声心动图研究

背景

伴有长期心肌病或肺动脉高压（PH）的患者左心室（LV）扭转的变化与LV几何形状有关。我们评估了急性高原引起的孤立的PH对LV几何形状，体积，收缩功能和扭转力学的影响。

方法

前瞻性研究了23位志愿者在低海拔地区以及在高海拔地区（4,559 m）进行的第二天（D3）和第三天晚上（D4）之后的研究。通过在三维超声心动图数据集上进行斑点跟踪，得出左室射血分数，多向应变和扭转，左室体积，球形度和偏心率。肺压由经皮三尖瓣压力梯度（TRPG），舒张末期LV容积的LV预负荷和二尖瓣环E速度的经皮传递（E / e'）估算。

结果

在高海拔地区，血氧饱和度降低15％–20％，心率和心脏指数提高15％–20％，TRPG从21±2毫米汞柱升高至37±9毫米汞柱（P  <.01）。左心室容积，预负荷，射血分数，多向应变和球形度均不受影响，但舒张期（D3 / D4时为1.04±0.07至1.09±0.09，P  <.05）和收缩期（1.00±0.06至1.08±0.1 [D3]和1.06±0.07 [D4]，P  <.05）偏心率略有增加，表明轻微的中隔扁平。 在D3 / D4上，LV扭转分别从2.14±0.85度/ cm降低至1.34±0.68（P  <.05）和1.65±0.54（P = .08）度/ cm。扭转的变化与收缩期的变化呈微弱的反比关系（r  = -0.369，P  = .013）和舒张期（r  = -0.329，P = .032）， 但与TRPG，心率或预紧力的变化无关。

结论

高海拔暴露与LV的轻度间隔变平和在未改变整体LV功能和预紧力的情况下降低心室扭转有关，这提示LV几何形状与扭转力学之间的关系。