[Case report of coronary artery bypass performed on a patient implanted with a single-lead atrial triggered ventricular VDD pacemaker].

Single-lead atrial synchronized ventricular pacing using a floating atrial sensing electrode enables physiologic pacing in patients with complete atrioventricular block and normal sinus function. Open heart surgery performed on patient implanted with a single-lead atrial triggered ventricular VDD pacemaker is rarely reported. A 71-year-old male had been implanted with a single-lead VDD pacemaker because of Mobitz II atrioventricular block. He had a history of old myocardial infarction and diabetes mellitus. Coronary angiography revealed stenoses in the left main trunk and two main vessels. Bypass grafting of two coronary vessels under cardiopulmonary bypass was performed. Just before surgery, the pacemaker was reset to VVI mode at minimum pacing rate (50 beats per minute). During surgery, precautions were taken to ensure that the lead was not touched and that the position of the atrial electrode was not altered by atrial cannulation. After surgery, temporary VVI pacing at 90 beats per minute was conducted using a temporary ventricular pacing lead. However, this temporary lead was not absolutely necessary because the VVD pacemaker could be used. If a temporary lead was to be placed during surgery, placing it in the atrium to utilize the VDD pacemaker would be preferable because it would contribute to the cardiac function. The patient recovered uneventfully and was discharged one month after the surgery. This case demonstrates that special precautions different to those needed for a fixed electrode are required for a floating electrode placed in the atrium.