Continuous electrocardiographic recordings on magnetic tape were made in 100 patients undergoing surgery during general anesthesia; 84 of the patients had supraventricular or ventricular arrhythmias. Arrhythmias were particularly common at the time of intubation and extubation. While the incidence of supraventricular arrhythmias was similar in patients with cardiac disease and those without cardiac disease, the group with cardiac disease had a higher incidence of disturbances in ventricular rhythm (60% vs 37%); 24 of 25 patients with cardiac disease had some type of arrhythmia during the study period. All known patients with cardiac disease should be monitored during surgery.
Bertrand CA, Steiner NV, Jameson AG, Lopez M. Disturbances of Cardiac Rhythm During Anesthesia and Surgery. JAMA. 1971;216(10):1615-1617. doi:10.1001/jama.1971.03180360061008