Influence of hemodialysis on electrocardiographic wave forms.

Alterations in Frank lead electrocardiograms induced by hemodialysis were investigated in 19 patients with chronic renal failure. The most prominent findings after hemodialysis were marked increases in the magnitudes of the R wave in Leads X,Y, and Z, and of the maximal QRS vectors in the frontal, sagittal, and transverse planes. Echocardiographic and roentgenographic examinations revealed no evidence of pericardial effusion before and after hemodialysis. Although the true origin of these findings remains undetermined, it appears reasonable to speculate that the decreased intracavitary blood volume due to hemodialysis may cause an increase in the QRS voltage by a short-circuiting effect. It should be emphasized that a sudden increase in QRS amplitude after hemodialysis might lead to an erroneous diagnosis of left ventricular hypertrophy. The clinician should be aware of such voltage increases when examining the ECGs of patients who undergo hemodialysis.