5th May 2025

Pacing

A pacemaker provides permanent treatment of a bradyarrhythmia. Overall, the commonest indication for pacemaker intervention is high degree AV-block, followed by SND. Patients with AV-block who are conservatively managed have been shown to have poorer survival, when compared with pacemaker-treated patients. In contrast, patients with SND often have an unpredictable prognostic trajectory without intervention; pacing is used for symptom control and to optimise quality of life . The 2021 ESC guidelines recommend that pacing in asymptomatic SND has not been shown to affect prognosis. 

Types of pacing

Pacing is classically done via an endocardial approach, whereby a pulse generator device is placed in the pectoral region with transvenous lead(s) implanted into the myocardium. Epicardial pacing, whereby lead(s) are placed onto the myocardial surface via minimally invasive techniques, may be used in certain circumstances – i.e. patients with congenital disease with difficult venous access. Permanent pacemakers (PPM) can be single chamber, dual chamber or leadless. Single chamber PPMs have one lead placed in the right ventricle (single lead right atrial pacing is no longer recommended). A single lead PPM may be used in AV-block or AF with bradycardia. Dual chamber pacemakers pace two cardiac chambers (usually the right atrium and the right ventricle) and are the preferred form of pacing for AV-block and SND. In cases where LV-impairment or a high RV-pacing burden may be seen, a biventricular pacemaker may be used which paces the LV and the RV. An extra atrial lead can be added in conditions with atrial asynchrony (AV-block/SND). Leadless pacing is a relatively new revolutionary form of pacing whereby a miniaturized intracardiac device is inserted via the femoral vein and implanted directly into the RV wall. Although in theory, this would reduce the risk of lead displacement, infection and generator defects, randomised controlled trials directly comparing leadless pacing with conventional pacing are still pending.

Complications

The commonest complications of pacemakers include device infection and lead failure. In the acute phase following PPM insertion, lead displacement, lead failure or perforation can occur and should be monitored for. Although most cardiac centres use a post-insertion antibiotic prophylaxis regime (based on local Trust guidelines), mostly covering for Gram positive bacteria (i.e. Staphylococci spp.), some patients can still experience ongoing pacemaker insertion site pain, discharge or otherwise unexplained fevers. In these patients, a pacemaker site infection should be considered and a decision made based on the clinical status of the patient if they can have ambulatory antimicrobial treatment or whether they require inpatient intravenous treatment and telemetry monitoring for any arrhythmias. Depending on the approach taken, subclavian vein or superior vena cava thrombosis or occlusion can occur. One of the risks of single chamber (i.e. right ventricular) pacing is a delay in activation of the left ventricle, as the RV lead bypasses the His-Purkinje system, causing an asynchrony similar to that of left bundle branch block. In some cases, this asynchrony between atrium-ventricle or ventricle-ventricle can cause a congestive cardiac failure-like clinical syndrome – known as pacemaker syndrome. This can be managed either medically (with diuretics) or by the addition of an atrial lead, or using biventricular pacing. Follow-up every 6–12 months in a pacing clinic is recommended to ensure PPM device integrity and function.