This case presentation involves a 76-year-old man with a 60-year history of smoking one and a half packs of cigarettes per day, who presented for a transurethral resection of the prostate (TURP). A preadmission chest x-ray revealed a left upper lobe lung lesion that was suggestive of carcinoma by subsequent computerized axial tomography. The TURP procedure was postponed, and the patient was advised to undergo an open thoracotomy biopsy with possible left upper lobectomy. The patient consented, and an open thoracotomy biopsy confirmed carcinoma. A left upper lobectomy was then performed. The operative procedure was significant for a 12-second acute episode of atrioventricular standstill during post-thoracotomy thoracic irrigation with warm saline. Return of sinus rhythm occurred spontaneously after cessation of irrigation. The operative field was closed, and the patient's recovery was unremarkable. Postoperative evaluation was unremarkable, and the patient was discharged 1 week later. Anatomic and physiologic vagal mechanisms are reviewed, and application to this case presentation is discussed.