Temporary pacemakers for non-cardiac surgery

Abstract

EDITOR: Indications for permanent pacemaker implantation have changed considerably in the last two decades. The American Heart Association (AHA) and the American College of Cardiology (ACC) latest guidelines [1] deny the need for permanent pacemaker implantation in moderate sinus node or conduction disturbances (e.g. asymptomatic sinus bradycardia). Other guidelines provide the indications for electrophysiological examinations, e.g. the presence of Mobitz type I atrioventricular block (AVB) [2]. Furthermore, in some cases the permanent pacemaker implantation is based on pure haemodynamic considerations when an individually programmed permanent pacemaker generator, with a short atrioventricular delay, can improve the quality of life of patients with a failing left ventricle and prolonged PQ time [3]. Frequently, the anaesthetist is the first doctor who examines the patient's electrocardiograph recording and suspects the potential for intraoperative dysrhythmias during the preoperative visit. Some rhythm disturbances have no effect on the everyday life of the patient - nevertheless, they may present a potential danger during surgery and anaesthesia or in the postoperative period [4-6]. Therefore, it is of prime importance to select the patients who need further cardiac examination before surgery. We implemented a diagnostic algorithm for the identification of patients who might produce potentially dangerous rhythm problems during non-cardiac surgical operations (Fig. 1).Figure 1: Diagnostic protocol for the selection of patients for perioperative temporary pacemaker therapy. HR: heart rate; AVB: atrioventricular block.Between January 1997 and April 1999, 14090 elective surgical operations were performed under general or regional anaesthesia in our department. Among them, 104 patients (0.17%) were identified as having either bradycardia (resting heart rate < 50 beats min−1) or intraventricular conduction disturbance (first- or second-degree AVB with QRS complexes >100 ms). Patients were subjected to an atropine test or carotid massage (Fig. 1). Twenty-four patients (23%) met the criteria for the insertion of a temporary pacemaker electrode preoperatively. The distribution of dysrrhythmia diagnoses is shown in Table 1. Forty-nine patients (47%) received atropine premedication (1.0 mg subcutaneously 30 min before operation) to prevent episodes of critical bradycardia (<45 beats min−1) during anaesthesia. The remaining 31 patients (29%) were regarded as low risk and neither temporary pacemaker insertion nor atropine premedication were used and the standard intraoperative monitoring was considered as sufficient. Three other patients who were not subjected to the diagnostic procedure shown in Figure 1 also needed temporary pacemaker treatment: one patient had third-degree AVB and narrow QRS complexes; two had first-degree AVB and a bifascicular block.Table 1: Indications for preoperative temporary pacemaker insertion.The electrodes were inserted through the basilar vein at the antecubital fossa in nine patients and central veins were used (internal jugular or subclavian vein) in 15 cases. Following the AHA/ACC guidelines, permanent pacemakers were implanted in four patients in the postoperative period. The negative chrono- and dromotropic effects of drugs used for the induction and maintenance of general anaesthesia can significantly worsen existing rhythm disturbances. Our protocol has to be applied cautiously since not only the dysrhythmia, but also the type of the operation, as well as patients' concomitant diseases, need to be taken into account [7] (e.g. atropine cannot be administered to glaucoma patients, and operations with severe blood loss or thoraco-abdominal procedures require temporary pacing more frequently). The benefit of our protocol is supported by the fact that patients without permanent pacemakers did not develop any rhythm disturbances that would have needed admission to an intensive care unit. The temporary pacemakers were set to a rate limit of 60 beats min−1 and all of them triggered the myocardium during the surgical intervention. Patients with temporary pacemakers had no complications related to their insertion. We conclude that when using our algorithm, the patients scheduled for non-cardiac surgery can be classified into different risk categories for perioperative heart rhythm complications. Further prospective clinical trials are warranted to examine the false-positive and -negative results of the diagnostic protocol. Cs. Csontos L. Bogar L. Melczer Department of Anaesthesia and Intensive Care; University of Pécs and Heart Institute; Pécs, Hungary