Potassium dynamics are attenuated in hyperkalemia and a determinant of QT adaptation in exercising hemodialysis patients

Abstract

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.

Protection against severe hypokalemia but impaired cardiac repolarization after intense rowing exercise in healthy humans receiving salbutamol

“…We show for the first time, to our knowledge, a correlation between the decrease in arterial [K ϩ ] in early recovery and the postexercise QT hysteresis. This extends a similar finding in patients with end-stage renal failure, during [K ϩ ] lowering by hemodialysis (67). A relationship existed between the uncorrected QT interval and the decrease in [K ϩ ] a during recovery.…”

“…During exercise, cardiac repolarization duration reflected by the QT interval becomes shorter during an increase in the heart rate but is prolonged in recovery as the heart rate returns to resting values; however, the QT interval during recovery is shorter than at the same heart rate during exercise, defined as QT hysteresis (38,55,67). The causes of QT hysteresis are not well understood, but an interplay between the sympathetic and parasympathetic nervous system during early recovery (55,64), K ϩ channel disruptions (66), and K ϩ disturbances (67) have been identified.…”

“…The causes of QT hysteresis are not well understood, but an interplay between the sympathetic and parasympathetic nervous system during early recovery (55,64), K ϩ channel disruptions (66), and K ϩ disturbances (67) have been identified. Prolongation of the QT interval reflects abnormal cardiac repolarization and has been reported in both clinical (3,60,67) and healthy populations (19,59). Both hyperkalemia ([K ϩ ] Ͼ 5.0 mM) and hypokalemia ([K ϩ ] Ͻ 3.5 mM) can affect cardiac repolarization (21,41), with hypokalemia being the greater trigger of adverse cardiac events, including ventricular fibrillation (41).…”

A question to the physician from a patient on hemodialysis: Would it be safe to run a marathon? A case report

“…When exercise discontinues the muscles will regain the K by the sodium-potassium-adenosintriphosphatase (N-K-ATPase) mediated K uptake. 11,12 In patients with ESKD the Na-K-ATPase activity is reduced, 13 which may cause an F I G U R E 1 Potassium levels. Run 1 + 2: 22-23 km on the second day after hemodialysis (HD).…”

“…A concern for patients with ESKD is whether K will be accumulated due to insufficient excretion. When exercise discontinues the muscles will regain the K by the sodium‐potassium‐adenosintriphosphatase (N‐K‐ATPase) mediated K uptake 11,12 . In patients with ESKD the Na‐K‐ATPase activity is reduced, 13 which may cause an even higher pK than in healthy individuals.…”