Laboratory for Molecular Cardiology, The Heart Centre, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
J Appl Physiol (1985). 2013 Aug 15;115(4):498-504. doi: 10.1152/japplphysiol.01019.2012. Epub 2013 May 30.
Disturbances in plasma potassium concentration (pK) are well known risk factors for the development of cardiac arrhythmia. The aims of the present study were to evaluate the effect of hemodialysis on exercise pK dynamics and QT hysteresis, and whether QT hysteresis is associated with the pK decrease following exercise. Twenty-two end-stage renal disease patients exercised on a cycle ergometer with incremental work load before and after hemodialysis. ECG was recorded and pK was measured during exercise and recovery. During exercise, pK increased from 5.1 ± 0.2 to 6.1 ± 0.2 mM (mean ± SE; P < 0.0001) before hemodialysis and from 3.8 ± 0.1 to 5.1 ± 0.1 mM (P < 0.0001) after hemodialysis. After 2 min of recovery, pK had decreased to 5.0 ± 0.2 mM and 4.1 ± 0.1 mM (P < 0.0001) before and after hemodialysis, respectively. pK increase during exercise was accentuated after hemodialysis. The pK increase was negatively linearly correlated with pK before exercise (β = -0.21, R(2) = 0.23, P = 0.001). QT hysteresis was negatively linearly correlated with the decrease in pK during recovery (β = -28 ms/mM, R(2) = 0.36, P = 0.006). Thus, during recovery, low pK was associated with relatively longer QT interval. In conclusion, new major findings are an accentuated increase in pK during exercise after hemodialysis, an attenuated increase in pK in hyperkalemia, and an association between pK and QT interval adaptation during recovery. The acute pK shift after exercise may modulate QT interval adaptation and trigger cardiac arrhythmias.
血浆钾浓度（pK）紊乱是心律失常发展的已知危险因素。本研究旨在评估血液透析对运动时 pK 动力学和 QT 滞后的影响，以及 QT 滞后是否与运动后 pK 下降有关。22 例终末期肾病患者在血液透析前后在功率自行车上进行递增负荷运动。在运动和恢复期间记录心电图并测量 pK。在运动过程中，pK 从血液透析前的 5.1±0.2 增加到 6.1±0.2 mM（平均值±SE；P<0.0001），从血液透析后的 3.8±0.1 增加到 5.1±0.1 mM（P<0.0001）。恢复 2 分钟后，pK 分别降低到血液透析前和后的 5.0±0.2 mM 和 4.1±0.1 mM（P<0.0001）。血液透析后运动时 pK 增加更加明显。运动时 pK 增加与运动前 pK 呈负线性相关（β=-0.21，R²=0.23，P=0.001）。QT 滞后与恢复期间 pK 的下降呈负线性相关（β=-28 ms/mM，R²=0.36，P=0.006）。因此，在恢复期间，低 pK 与相对较长的 QT 间期相关。总之，新的主要发现是血液透析后运动时 pK 明显增加，高钾血症时 pK 增加减弱，以及恢复期间 pK 和 QT 间期适应之间的关联。运动后 pK 的急性变化可能调节 QT 间期适应并引发心律失常。
