Effectiveness of A-C Bypass Operation for Improvement of Sinus Bradycardia for Patients with Right Coronary Disease and Preoperative Pacing

Summary

We found various types of right coronary lesion on coronary angiograms in patients who complained of sinus bradycardia and angina pectoris and suspected a blood stream disturbance to the sinus node artery. We experienced improvement of bradycardia after A-C bypass surgery on those patients and also noted in the case of several patients to whom pacemaking was preoperatively indicated, this became unnecessary after A-C bypass. Nineteen patients were entered into study. Four patients were preoperatively indicated for pacemaking due to sinus bradycardia. In one patient to whom a permanent pacemaker was implanted preoperatively for 2 years, all the pacemaker systems were removed during A-C bypass surgery. Inferior infarction was found in 65% of the patients. Permanent pacemakers were implanted in two patients. Preoperative evaluation of conduction system in sinus bradycardic patients revealed AH-time to be 93 ± 21 ms, HV-time 37 ± 8 ms, SNRT 1297 ± 283 ms, ARP 407 ± 99 ms. But there were no statistical differences compared to non-bradycardic patients except HV-time (p < 0.05). Total occlusion of the right coronary artery and subsequent disturbance of blood supply for sinoatrial node were noted in 21% of the patients. Sclerotic changes of the sinus node artery were noted in 58% of the patients. Coronary artery spasm was observed in two patients on cineangiogram. RR-interval was found to have improved after A-C bypass from 1.273±0.226 sec to 0.770±0.l35 sec. A-C bypass surgery was useful for patients with sinus bradycardia associated with sinus node artery disease and pacemakers were not always needed after A-C bypass surgery.