Iron sufficient to cause hepatic fibrosis and ascites does not cause cardiac arrhythmias in the gerbil

Chronic iron overload associated with hereditary hemochromatosis or repeated red cell transfusions is known to cause cardiac failure. Cardiac arrhythmias have been incidentally noted in patients with iron overload, but they are often dismissed as being related to comorbid conditions. Studies with anesthetized iron-loaded gerbils using short recordings suggest a role for iron in the development of arrhythmias. Our goal was to characterize iron-induced arrhythmias in the chronically instrumented, untethered, telemetered gerbil. Electrocardiograms were recorded for 10 s every 30 min for approximately 6 months in iron-loaded (n = 23) and control (n = 8) gerbils. All gerbils in both groups showed evidence of frequent sinus arrhythmia. There was no difference in heart rate, electrocardiographic parameters, or number of arrhythmias per minute between groups. Gerbils rarely showed significant arrhythmias. Body weight and heart weight were not significantly different between groups, whereas liver weight increased with increasing iron dose in the treated group. Cardiac and hepatic iron concentrations were significantly increased in iron-loaded gerbils. Eight of 14 gerbils loaded to 6.2 g/kg body weight developed ascites. We conclude that an iron load sufficient to cause clinical liver disease does not cause cardiac arrhythmias in the gerbil model of iron overload.