One hundred patients were monitored by telecardiography during routine sigmoidoscopy; 40 patients had heart disease, and 60 patients had no clinical evidence of heart disease. Electrocardiographic changes in rhythm, depolarization, and repolarization occurred in both patients with and without heart disease. There was a significantly greater frequency (40% vs 17%) in the development of or increase in ectopic beats in those patients with heart disease; however, no catastrophic arrhythmias occurred. These findings do not contraindicate sigmoidoscopy either in patients with or without heart disease; however, one must be aware of the potential hazard of cardiac arrhythmias and be prepared for their management.
Fletcher GF, Earnest DL, Shuford WF, Wenger NK. Electrocardiographic Changes During Routine Sigmoidoscopy. Arch Intern Med. 1968;122(6):483-486. doi:10.1001/archinte.1968.00300100017004