Interventional procedure overview of leadless cardiac pacemaker implantation for bradyarrhythmias

The condition

Bradyarrhythmias are abnormal heart rhythms that can result in a slow heart rate (bradycardia), usually defined as less than 60 beats per minute. There are a range of causes including diseases such as sick sinus syndrome or atrioventricular (AV) block. The most common causes are the natural ageing process, ischaemic heart disease, heart valve disorders and heart failure. If untreated, bradycardia may lead to fatigue, fainting, palpitations, dizziness, heart failure and an increased risk of death.

Current practice

The treatment depends on the underlying cause and the symptoms. If treatment is needed, bradyarrhythmias are usually managed with pacemakers as described in NICE technology appraisal guidance on dual-chamber pacemakers for symptomatic bradycardia due to sick sinus syndrome and/or atrioventricular block and dual-chamber pacemakers for symptomatic bradycardia due to sick sinus syndrome without atrioventricular block. Dual-chamber pacing is recommended for symptomatic bradycardia caused by sick sinus syndrome, AV block, or a combination of both. Single-chamber ventricular pacemakers may be used for AV block alone or with sick sinus syndrome in people with continuous atrial fibrillation (AF), or people who have specific factors such as frailty or comorbidities that influence the balance of risks and benefits in favour of single-chamber pacing.

Unmet need

Bradyarrhythmias are usually managed with transvenous pacemakers (TVPs). However, these are associated with lead and generator-related complications, including lead failure and infection, which contribute to long-term morbidity.

Leadless pacemakers (LPs) provide an option for people who cannot have a conventional TVP. There are also some groups of people who might particularly benefit from LPs, such as those with previous device infection or endocarditis, vascular access issues, or high risk of infection.

The procedure

The aim of implanting a LP is to detect cardiac bradyarrhythmias and deliver electric pulses to help regulate the heartbeat. LPs can provide single-chamber (right ventricle pacing) or dual-chamber pacing (atrial pacing or AV pacing). 

The procedure is usually done under local anaesthesia in a cardiac catheterisation laboratory. Fluoroscopic guidance is used and intracardiac echocardiography or contrast may be needed to assist or guide implantation in the desired location in the heart chamber (right ventricle or atrium). For single chamber LP implantation, the proximal end of an LP is attached to a deflectable delivery catheter system and is usually inserted percutaneously via the femoral or jugular vein using an introducer sheath. It is then advanced into the right atrium through the tricuspid valve, into the right ventricle and positioned near the apex or lower septum. Once positioned, the LP is securely implanted into the endocardial wall using a fixation mechanism. Electrical measurements are taken and, if satisfactory, the LP is released from the catheter and the catheter is removed. If the position is suboptimal, the LP can be detached from the endocardium and repositioned before the release of the delivery catheter. 

The pacemaker delivers electrical impulses that pace the heart through an electrode at the distal end of the device and is adjusted using an external programming system. A catheter retrieval system is used for removal and replacement of the LP when needed. 

A dual chamber LP system consists of 2 devices implanted percutaneously in a single procedure into the target chamber - 1 in the right atrium and another in the right ventricle.