Cardiac arrhythmias and silent myocardial ischemia during hemodialysis

Cardiac arrhythmias are noted in a significant proportion of chronic renal failure (CRF) patients on hemodialysis (HD), and may contribute to cardiova scular mortality. A number of factors have been implicated in the genesis o f these arrhythmias. The role of silent myocardial ischemia (SMI), however, has not been evaluated systematically. We prospectively studied 38 unselec ted CRF patients on regular HD by continuous Holter monitoring starting 24 hours before HD, lasting through the dialysis session and continued for 20 hours thereafter. The recordings were analyzed for frequency, timing and se verity of supraventricular and ventricular arrhythmias and SMI as identifie d by ST-segment depression. Ventricular arrhythmias during HD were noted in 11 (29%) patients (group I), and were potentially life-threatening (Lown C lass III and IVa) in 13%. The remaining 27 patients (group II) had no ventr icular arrhythmias during HD. There was no difference in the age, sex ratio , duration of HD, blood pressure, fluctuations in weight, hematocrit, predi alysis creatinine, sodium, potassium, calcium or inorganic phosphate levels between patients in the two groups. The number of patients with clinical i schemic heart disease was significantly greater in group I. SMI was noted i n 72% and 33% of group I and II patients respectively (p = 0.026). 46% of t hose with and 25% of these without ST changes during HD developed ventricul ar arrthythmias during HD. Both SMI and ventricular arrhythmias were noted most frequently during the last hour of dialysis. Hypertension, diabetes me llitus and ischemic heart disease were observed more frequently amongst pat ients with SMI. Ventricular arrhythmias are detected ill a significant prop ortion of CRF patients on HD. These are probably related to coronary artery disease since silent myocardial ischemia is also noted more frequently dur ing HD in these patients. Further studies incorporating coronary angiograph y are needed in a larger number of patients to establish a definite causal relationship.