A 69-year-old Caucasian man was admitted to the hospital for reimplantation right total hip replacement. He had undergone a resection right hip arthroplasty 5 months prior to this admission for a hardware infection from a previous right hip fracture repair. His past medical history included coronary artery disease s/p right coronary artery bare metal stent 12 years ago, congestive heart failure, diabetes mellitus, hypertension, and depression. Medications included carvedilol 3.125 mg two times a day, furosemide 40 mg two times a day, glargine insulin 13 units every bedtime, escitalopram 20 mg once daily, pravastatin 40 mg daily, and omeprazole 20 mg daily. Preoperative laboratory studies were all within normal limits. A transthoracic echocardiogram was performed 2 weeks prior to surgery, which showed moderate left ventricular hypertrophy with low–normal left ventricular systolic function without any valvular abnormalities. His preoperative ECG was read as sinus rhythm with a rate of 74 beats per minute (bpm), left-bundle branch block, and probable left atrial abnormalities. On closer examination of his ECG, he was noted to have split P waves, most distinct in leads I and AVL, appearing like two distinct P waves (Fig. 1). PR interval was 204 milliseconds, and P wave duration about 150 milliseconds. He had been evaluated by his cardiologist, who cleared him for surgery and did not require any further testing. There was no comment about the split P waves on ECG by the cardiologist. The patient was also evaluated by the pre-anesthesia clinic, who deemed him appropriate to proceed with anesthesia and surgery. The patient requested spinal anesthesia, but given that the reimplantation surgery was scheduled to take up to 3–4 hours, we elected to proceed with a combination spinal and general anesthesia. The decision to proceed with spinal anesthesia was to be able to use intrathecal morphine as the primary analgesic and thus minimize the need for intravenous opioids. The local anesthetic with spinal anesthesia would also then allow for a lighter general anesthetic, which would still be needed given the potential length of the surgery.
On the day of surgery, the patient was taken to the operating room and standard ASA monitors were applied. His mean arterial pressure (MAP) was 66 mmHg, and his heart rate was 50 bpm. The patient’s bradycardia was thought to likely be due to his beta-blocker medication. Prior to surgery, he denied any recent symptoms including chest pain, palpitations, or syncopal events. The patient’s previous medical records showed that his heart rate was usually in the 50–70 bpm range. Given the patient’s recent cardiac evaluations and the anesthesiologist being unaware of the significance of split P waves, it was assumed that the patient’s bradycardia would be responsive to medications if it worsened with anesthesia. A subarachnoid block was performed at the L3–4 interspace, and 1.3 ml 0.75% bupivacaine with 200 mcg preservative-free morphine was injected. The patient was placed supine, and a T10 sensory level was demonstrated. His MAP was 55 mmHg with a heart rate of 45 bpm. The display monitor demonstrated sinus bradycardia, left-bundle branch block, and widely split-P waves. He was given two doses of glycopyrrolate without increase in heart rate, although his MAP increased with an IV fluid bolus. Given improvement in hemodynamics, a decision was made to proceed with the operation and general anesthesia. Following preoxygenation, anesthesia was induced with fentanyl and propofol, and rocuronium was given for muscle relaxation. The patient’s trachea was intubated without difficulty, and he was mechanically ventilated with oxygen and sevoflurane. Within minutes after anesthetic induction, his heart rate dropped to 30–40 bpm, while his MAP ranged between 60 and 68 mmHg. He was given two doses of atropine and then ephedrine without an increase in heart rate. At this time, a Mobitz type II heart block first appeared on the display monitor. A 12-lead ECG obtained in the operating room confirmed this diagnosis (Fig. 2). The risk of proceeding was discussed with the surgeon, and a decision was made to cancel the surgery. Cardiology was consulted in the operating room, and given stable blood pressures, the cardiologist recommended proceeding with anesthesia emergence and extubation with plans to further evaluate the patient in the recovery room. They recommended against transcutaneous or transvenous pacing at this time. Muscle relaxation was reversed, the sevoflurane was discontinued, and the patient’s trachea was extubated. His MAP remained at 60–70 mmHg with a heart rate of 35–45 bpm.
In the post-anesthesia care unit, he was seen by a cardiologist, who confirmed the Mobitz type II heart block and discussed the need for pacemaker implantation with the patient and his wife. The patient was then immediately taken to the electrophysiology laboratory, where a permanent dual-chamber pacemaker was implanted under conscious sedation. He tolerated this procedure without problems. During the remainder of his hospitalization, he required 100% pacing, atrial-sensed ventricularly paced. The cardiologist noted that the cause of heart block was likely due to an ischemic versus infiltrative process as suggested by his history of right coronary artery myocardial ischemia requiring stenting. He was discharged home 2 days later. He returned to the hospital and underwent a reimplantation right total hip replacement 1 week later under a combined spinal plus general anesthetic technique without any perioperative complications.
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