Overview

The high prevalence of cardiac disease in patients presenting for noncardiac operations poses a considerable challenge to the anesthesia provider. Many of these patients have pacemakers, which are being used with increasing frequency to treat conduction problems, arrhythmias, and ventricular dysfunction. More than 500,000 people in the United States have pacemakers, and nearly 115,000 new devices are implanted each year.

Early pacing systems consisted of a single-lead asynchronous pacemaker, which paced the heart at a fixed rate. Over the years, technologic advances have revolutionized pacemakers; today’s sophisticated multiprogrammable devices have dramatically increased the number of indications for the use of pacing. Care of the patient with a pacemaker during surgery, therefore, requires an understanding of the pacemaker and of the associated anesthetic and surgical implications.

Generic codes of pacemaker

Developed originally by the International Conference on Heart Disease and subsequently modified by the NASPE/BPEG (North American Society of Pacing and Electrophysiology/British Pacing and Electrophysiology Group) alliance, the NASPE/BPEG code consists of five letters of the alphabet that describe the five programmable functions of the pacing system (Box 151-1). The first letter of the code indicates the chamber being paced; the second, the chamber being sensed; and the third, the response to sensing (I and T indicate inhibited or triggered responses, respectively). An R in the fourth position indicates that the pacemaker incorporates a sensor to modulate the rate independently of intrinsic cardiac activity, such as with activity or respiration. A P in the fifth position, for example, indicates that the pacemaker “paces” to treat a tachyarrhythmia. However, letters in the fourth and fifth positions are uncommonly used. Table 151-1 summarizes commonly used configurations.

Preoperative evaluation

Preoperative (and postoperative, if electrocautery was used) evaluation of the patient and the pacemaker is an important aspect of the anesthetic management of a patient with a permanent pacemaker who is undergoing a noncardiac operation. The patient should be asked about the initial indication for the pacemaker and preimplantation symptoms. The location of the pulse generator should be noted. Generally, the generator for endocardial electrodes is placed subcutaneously in the left lateral subclavicular region, and the generator for epicardial electrodes is placed subcutaneously in the abdomen.

Routine biochemical and hematologic investigations should be performed as indicated on an individual basis. A 12-lead electrocardiogram, chest radiograph (for visualization of continuity of leads), and measurement of serum electrolytes (especially K⁺) should be performed.