Dissociation between Alterations in Myocardial Perfusion and R-Wave Amplitude after Hemodialysis

Volker Wizemann, MD, Medizinische Universitätsklinik, Klinikstrasse 36, D-63 Giessen (FRG) Dear Sir, We read with interest the paper by Ono et al. [1] on the effect of dialysate sodium on the appearance of ischemic patterns in ECG. Elevation of dialysate sodium from 133 to 141 mEq/1 in unselected patients did reduce the incidence of hypotensive episodes and related symptoms as well as the frequency of R-wave increase in ECG postdialysis. In contrast to Diskin et al. [2], they described a positive correlation between weight loss and changes in R-wave amplitude and suggested that the use of 141 m.Eq/1 sodium dialysate reduces the high incidence of myocardial ischemia. In a group of 7 selected patients with proved coronary artery disease (CAD) and stable angina pectoris, we assessed the effect of hemodialysis (4 h, sodium 140 mEq/1 on myocardial perfusion and left ventricular function in CAD. Combined radionucleotide ventriculography and thallium-201 perfusion imaging was performed at rest and during supine bicycle exercise preand postdialysis. The investigation included Holier recording with continuous S-T level monitoring as well as standard electrocardiograms to analyze the sum of R-wave variations (ΣR). Left ventricular ejection fraction (54.7 vs. 66.1%, p < 0.05) and seg-mental motion abnormalities (4.51 vs. 2.50, p < O.Ol) improved after dialysis. In accordance, exercise capacity increased, reflected by an improvement of exercise duration (178 vs. 415 s, p < O.Ol), maximal S-T segment depression (2.78 vs. 1.88 mm, p < 0.05) as well as angina score (2.57 vs. 1.42, p < O.Ol). Significant S-T segment depression (p < O.Ol) and increase of R (p < O.Ol) was a constant finding at pre-dialysis peak exercise and correlated well (r = 0.79) with exerciseinduced ischemia in thallium perfusion imgaging. However, despite augmentation of myocardial perfusion and LV function after volume removal, a significant increase in resting ΣR (p < O.Ol) was observed, while S-T segment remained unchanged (p < 0.05). This discordance between changes in LV performance and R-wave response excludes myocardial ischemia as the sole determinant of R-wave increase after dialysis. Since the role of left ventricular volume in determining R-wave change (Brody effect) has been challenged [3–6], other factors could have an important influence on R-wave amplitude variations, including abnormal myocardial conduction patterns, altered depolarization and repolarization patterns [3]. Our observation of improved LV function and R-wave increase are in good agreement with the study of Ishikawa et al. [7] who found that in heart failure of various etiologies a reduction in