Permanent Pacemaker Insertion

Permanent pacemaker insertion plays a key role in the management of heart rhythm disorders and heart failure. ^[1] The number of permanent pacemaker insertions in the United States has been steadily increasing. ^[2] A pacemaker is an electronic device, approximately the size of a pocket watch, that senses intrinsic heart rhythms and provides electrical stimulation when indicated.

At present, three approaches to permanent cardiac pacing are in common use:

• Single-chamber pacemaker – With this device, one pacing lead is implanted in the right atrium or ventricle

• Dual-chamber pacemaker – With this device, two pacing leads are implanted (one in the right ventricle and one in the right atrium); this is the most common type of implanted pacemaker

• Biventricular pacing (cardiac resynchronization therapy [CRT]) – With this approach, in addition to single- or dual-chamber right heart pacing leads, a lead is advanced to the coronary sinus for left ventricular epicardial pacing

The first implantable pacemaker to be used in a human being was inserted by Dr. Ake Senning in 1958; it lasted for only a few hours. Since then, cardiac pacing has evolved to include single-chamber, dual-chamber, and CRT devices. Epicardial lead implantation by thoracotomy has largely been replaced by transvenous placement of right atrial and right ventricular leads, as well as left ventricular epicardial pacing lead placement via the coronary sinus.

Remarkable advances have been made in pacemaker technology, including reduced size, increased battery longevity, and remote monitoring capability, as well as the addition of magnetic resonance imaging (MRI)-safe pacemakers. ^[3]

Published guidelines that outline indications for cardiac pacing are available from both the American Heart Association (AHA) and the European Society of Cardiology. ^{[4, 5]} This article outlines the clinical indications for pacing, implant techniques, and common pacing system complications.

Indications for pacemaker implantation are categorized into the following classes ^[6] :

• Class I – These are conditions where implantation of a pacemaker is considered necessary and beneficial (benefits much greater than risks).

• Class II – These are conditions where placement is indicated, but there is conflicting evidence or divergence of opinion. In Class IIa weight of evidence is in favor of efficacy (benefits greater than risk), while in class IIb, the efficacy is less well established (benefits greater than or equal to the risks).

• Class III – These are conditions in which permanent pacing is not recommended, and in some cases, it may be harmful (risks greater than the benefits).

The most common indications for permanent pacemaker implantation are sinus node dysfunction and high-grade atrioventricular block. ^[6]

In 2008, the American College of Cardiology (ACC), the AHA, and the Heart Rhythm Society (HRS) jointly published guidelines for pacemaker implantation. ^[7] For further details on the following indications, see ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities.

Sinus node dysfunction

Class I indications include the following:

• Documented symptomatic sinus bradycardia including frequent sinus pauses which produce symptoms and symptomatic sinus bradycardia that results from required drug therapy for medical condition

• Symptomatic chronotropic incompetence (failure to achieve 85% of age-predicted maximal heart rate during formal or informal stress test or inability to mount age appropriate heart rate during activities of daily living)

Class II indications include the following:

• Sinus bradycardia with heart rate less than 40 bpm, but no clear association between the symptoms and bradycardia

• Unexplained syncope when clinically significant abnormalities of sinus node function are discovered or provoked in electrophysiological (EP) studies

• Minimally symptomatic patients with chronic heart rate less than 40 bpm while awake

Acquired atrioventricular (AV) block

Class I indications include the following:

• Complete third-degree AV block with or without symptoms

• Symptomatic second degree AV block, Mobitz type I and II

• Exercise-induced second or third degree AV block in the absence of myocardial infarction

• Mobitz II with widened QRS complex

Class II indications include the following:

• Asymptomatic Mobitz type II with the narrow QRS complex

• First degree AV block when there is a hemodynamic compromise

• Asymptomatic second degree AV block at Intra or Infra-His levels found in EP studies

Chronic bifascicular block​

Class I indications include the following:

• Advanced second-degree AV block or intermittent third-degree AV block

• Alternating bundle-branch block

• Type II second-degree AV block

Class II indications include the following:

• In patients having syncope not demonstrated to be due to AV block when other likely causes have been excluded, specifically ventricular tachycardia (VT)

• Incidental finding at EP study of a markedly prolonged HV interval (greater than 100 ms) or pacing-induced infra-His block in asymptomatic patients. (HV interval is conduction time from the His bundle which is located just below the AV node to first identifiable onset of ventricular activation)

• Can be considered in patients with neuromuscular disease such as myotonic muscular dystrophy, Erb dystrophy and peroneal muscular dystrophy with bifascicular block or any fascicular block, with or without symptoms

After acute phase of myocardial infarction

Class I indications include the following:

• Permanent ventricular pacing for persistent second degree AV block in the His-Purkinje system with alternating bundle branch block or third degree AV block within or below the His-Purkinje system after ST-segment elevation MI (STEMI)

• Permanent ventricular pacing for a transient advanced second or third-degree infranodal AV block and associated bundle branch block

• Permanent ventricular pacing for persistent and symptomatic second or third degree AV

Class II indications include the following:

• Permanent ventricular pacing may be considered for the asymptomatic persistent second or third degree AV block at AV node level

Neurocardiogenic syncope and hypersensitive carotid sinus syndrome

Class I indications include the following:

• Recurrent syncope caused by spontaneously occurring carotid sinus stimulation and carotid sinus pressure that induces ventricular asystole of more than 3 seconds

Class II indications include the following:

• Reasonable in patients having syncope without clear and provocative event, and with a hypersensitive cardio-inhibitory response of 3 seconds or longer

• Can be considered for significantly symptomatic neurocardiogenic syncope associated with bradycardia documented spontaneously or at the time of tilt-table testing

Hypertrophic cardiomyopathy (HCM)

Class I indications include the following:

• Patients with HCM having sinus node dysfunction and AV block

Class II indications include the following:

• Can be considered in medically refractory symptomatic patients with HCM and with significant resting or provoked left ventricular outflow tract obstruction

Congenital heart disease

Class I indications include the following:

• For advanced second or third-degree AV block associated with symptomatic bradycardia, ventricular dysfunction, or low cardiac output; also for advanced second or third-degree AV block which is not expected to resolve or persists for 7 days or longer after cardiac surgery

• For sinus node dysfunction with a correlation of symptoms during age inappropriate bradycardia

• Congenital third-degree AV block with a wide QRS escape rhythm, complex ventricular ectopy or ventricular dysfunction

• Congenital third-degree AV block in an infant with a ventricular rate < 55 bpm or with congenital heart disease with a ventricular rate of < 70 bpm

Class II indications include the following:

• For patients with congenital heart disease and sinus bradycardia for the prevention of recurrent episodes of intra-atrial re-entrant tachycardia; sinus node dysfunction may be intrinsic or secondary to antiarrhythmic treatment

• For congenital third-degree AV block beyond the first year of life with an average heart rate < 50 bpm, abrupt pauses in ventricular rate which are 2 or 3 times the basic cycle length, or associated with symptoms due to chronotropic incompetence

• May be considered for transient postoperative third-degree AV block that reverts to sinus rhythm with the residual bifascicular block

• Considered for asymptomatic sinus bradycardia after biventricular repair of congenital heart disease in patients with a resting heart rate < 40 bpm or with pauses in ventricular rate longer than 3 seconds

Contraindications for permanent pacemaker insertion include the following:

• Local infection at implantation site

• Active systemic infection with bacteremia

• Severe bleeding tendencies (relative contraindication)

• Active anticoagulation therapy (relative contraindication)

• Severe lung disease and positive end-expiratory pressure ventilation (relative contraindication for internal jugular and subclavian access)

Procedural planning

Cardiac pacing can be either temporary or permanent. Temporary pacing may be accomplished transcutaneously (ie, placing two external pacing pads over the chest wall in the anteroposterior or anterolateral location) or via transvenous placement of a temporary pacing wire in one or more of the right heart chambers. In a patient who has recently undergone cardiac surgery, temporary epicardial leads are often placed and removed before the patient is discharged from the hospital. ^[8]

Permanent pacing is most commonly accomplished through transvenous placement of leads to the endocardium (ie, right atrium or ventricle) or epicardium (ie, to the left ventricular surface via the coronary sinus), which are subsequently connected to a pacing generator placed subcutaneously in the infraclavicular region. In a patient without appropriate venous access, epicardial leads can be placed via a thoracotomy and tunneled subcutaneously to the pacing generator. Recently, a leadless permanent pacemaker lead (Micra, Medtronic Inc) has been approved as an alternative to conventional transvenous pacemakers.

Complication prevention

Multiple studies have shown that infection rates can be reduced by employing maximal sterile-barrier precautions, including mask, cap, sterile gown, sterile gloves, and large sterile drape.

Subclavian artery injury may occur during subclavian vein access, carotid artery puncture during jugular vein access, and femoral artery puncture during femoral vein access. The subclavian artery cannot be compressed; accordingly, the subclavian approach should be avoided in anticoagulated patients.

An air embolism may be caused by negative intrathoracic pressure during inspiration by the patient, which sucks air into an open line hub. Hence, line hubs should always be occluded. Placing the patient in the Trendelenburg position lowers the risk of this complication.

If air embolism occurs, the patient should be placed in the Trendelenburg position with a left lateral decubitus tilt; this may prevent the movement of air into the right ventricle and onward into the pulmonary artery. In addition, 100% oxygen should be administered to speed resorption of the air. If a catheter is located in the heart, aspiration of the air should be attempted.

Dysrhythmia due to mechanical irritation of the heart by the wire or catheter tip may occur. It can usually be terminated by simply withdrawing the equipment into the superior vena cava. Placing a central venous catheter without a cardiac monitor is unwise.

If the clinician is not conscientious about maintaining control of the guide wire, it may be inadvertently inserted fully into the vein and have to be retrieved.

Patients who are allergic to antibiotics may experience anaphylaxis upon insertion of an antibiotic-impregnated catheter.

A 2016 retrospective, observational study evaluated the long-term (1 year) utility of permanent pacemakers implanted early (≤30 days) in 247 patients with complete heart block after cardiac surgery. ^[9] By determining the frequency of ventricular pacemaker at each pacemaker interrogation visit, investigators found that most permanent pacemakers were not underutilized, and there was no association between longer delay from surgery to implantation of the device and a higher likelihood that there would long-term use of the permanent pacemaker. ^[9]

In another 2016 retrospective study (1984-2002; followed to 2014) comprising data from 995 consecutive patients who underwent dual-chamber (DDD) pacemaker implantation and had at least one follow-up visit, investigators reported an association between sex and indications to DDD pacing therapy. ^[10] ​ Although the rate of adverse events was similar between the sexes, women had significantly more incidences of sick sinus syndrome, a history of paroxysmal atrial fibrillation, and a similar percentage of atrioventricular block. Women also had significantly longer duration of follow-up despite markedly older age at implantation than men. ^[10]

Observational data (2001-2011) from the Spanish ARIAM registry (Analysis of Delay in AMI [acute myocardial infarction]) of 27,608 patients with acute coronary syndrome (ACS) found that in 62 of these patients who received permanent pacemakers, implantation of these devices was independently associated with death. ^[11] Other factors independently associated with permanent pacemaker implantation in the setting of ACS included older age, heart failure, arrhythmias, and left bundle branch block at admission to the intensive care unit.