General anesthesia in a patient with asymptomatic second-degree two-to-one atrioventricular block

The major perioperative concern in patients with second-degree atrioventricular (AV) block is the progression to complete AV block. Therefore, the prophylactic implantation of a temporary pacemaker prior to surgery is recommended, especially in symptomatic patients. However, as no quantitative preoperative risk assessment from progression to complete AV block is available, there is currently no established indication for preoperative prophylactic pacemaker implantation. Here, we present a case of progression from asymptomatic second-degree two-to-one (2:1) AV block to complete AV block following the induction of general anesthesia.

A 69-year-old female with degenerative spinal stenosis was scheduled for transforaminal lumbar interbody fusion surgery under general anesthesia. She had no cardiac symptoms, but routine preoperative resting 12-lead electrocardiogram revealed second-degree 2:1 AV block. After discussion with the surgeon and referring cardiologist, we scheduled the surgery without implantation of a temporary pacemaker before surgery for the following reasons: (1) asymptomatic, (2) no evidence of underlying cardiac disease, and (3) a narrow QRS complex. On the day of surgery, general anesthesia was induced with 150 mg of intravenous thiamylal and 25 μg of fentanyl, followed by intravenous administration of 50 mg of rocuronium to facilitate endotracheal intubation. Sevoflurane (1.0-2.0%) was used to maintain anesthesia. A few minutes after induction, the 2:1 AV block progressively converted to complete AV block, and the surgery was postponed. During emergence from anesthesia, the third-degree AV block recovered to 2:1 AV block, similar with the preoperative pattern. The patient was monitored in the intensive care unit for 2 days and then transferred to the normal orthopedic ward uneventfully. One month later, the surgery was rescheduled with preoperative implantation of a temporary pacemaker. A slow mask induction using sevoflurane with oxygen was started. Upon loss of consciousness during the inhalation of initial sevoflurane, complete AV block developed and temporary pacing was immediately initiated. Subsequent anesthesia and surgery were uneventful. The patient made an uncomplicated recovery from surgery with stable hemodynamics. The temporary pacemaker was not required after surgery, and the pacemaker catheter was removed 1 day after surgery.

The present case indicates that a prophylactic pacemaker should be implanted preoperatively in patients who have 2:1 AV block even without symptoms.