Abstract
Cardiovascular disease is one of the leading causes of death among hemodialysis patients. In 30% of hemodialysis patients who experience sudden death, arrhythmia is the final event, and QTc prolongation is considered a risk factor for sudden death due to arrhythmia. We therefore studied the effect of hemodialysis on the QTc interval. We examined the QTc interval, serum electrolytes, ionized Ca, plasma HANP, and blood gases of 32 hemodialysis patients (24 males, 8 females, age 55.5±11.2 years) before and after hemodialysis. The QTc interval was also measured in age- and sex- matched normal controls. The QTc interval in hemodialysis patients (0.439±0.025sec) was significantly longer than in the normal controls (0.396±0.021sec) (p<0.01), and the upper limit of QTc was defined as 0.438sec. ΔQTc was defined as QTc (after hemodialysis) minus QTc (before hemodialysis), and Δ serum electrolytes as serum electrolytes (after hemodialysis) minus serum electrolytes (before hemodialysis). ΔQTc was correlated with Δserum Ca, Δionized Ca, and ΔHCO3-. Hemodialysis patients were divided into group A (QTc>=0.438sec) and group B (QTc<0.438sec). There were 15 patients in group A and 17 patients in group B. There were no significant differences between the two groups in levels of serum electrolytes, ionized Ca, plasma HANP, or blood gas levels, only in serum Ca. Serum Ca levels in group A (8.8±1.0mg/dl) were higher than (9.8±1.2mg/dl) in group B (p<0.05). In group A, the level of serum Ca increased to 9.6mg/dl after hemodialysis, but QTc remained prolonged (0.450sec). These data suggest that in addition to serum Ca, autonomic nerve dysfunction and myocardial damage may be involved in the etiology of the QTc prolongation in hemodialysis patients.
