The number of permanent pacemaker insertions in the United States has been steadily increasing.^[1] 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, 3 approaches to permanent cardiac pacing are in common use:

• Single-chamber pacemaker – With this device, 1 pacing lead is implanted in the right atrium or ventricle
• Dual-chamber pacemaker – With this device, 2 pacing leads are implanted (1 in the right ventricle and 1 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 cardiac resynchronization 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 Epicardial lead implantation by thoracotomy has largely been replaced by transvenous placement of right atrial and right ventricular leads, as well as left ventricular epicardial pacing lead placement via the coronary sinus.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.^[2]

Published guidelines that outline indications for cardiac pacing are available from both the American Heart Association (AHA) and the European Society of Cardiology.^{[3, 4]} 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:

• Class I – The procedure should be performed
• Class IIa – It is reasonable to perform the procedure, but additional studies with focused objectives are needed
• Class IIb – The procedure may be considered, but additional studies with broad objectives are needed
• Class III – The procedure should not be performed; it is not helpful and may be harmful

In 2008, the American College of Cardiology (ACC), the AHA, and the Heart Rhythm Society (HRS) jointly published guidelines.^[5] For further details on the following indications, see the ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities.

Class I indications include the following:

• Sinus node dysfunction
• Acquired atrioventricular block in adults
• Chronic bifascicular block
• After acute myocardial infarction
• Hypersensitive carotid sinus syndrome and neurocardiogenic syncope
• After cardiac transplantation
• Pacing to prevent tachycardia
• Patients with congenital heart disease

Class IIa indications include the following:

• Sinus node dysfunction
• Acquired atrioventricular block in adults
• Chronic bifascicular block
• Hypersensitive carotid sinus syndrome and neurocardiogenic syncope
• Patients with congenital heart disease
• Pacing to prevent tachycardia
• Permanent pacemakers that automatically detect and pace to terminate tachycardia

Class IIb indications include the following:

• Sinus node dysfunction
• Acquired atrioventricular block in adults
• Chronic bifascicular block
• After acute myocardial infarction
• Hypersensitive carotid sinus syndrome and neurocardiogenic syncope
• After cardiac transplantation
• Pacing to prevent tachycardia
• Patients with congenital heart disease

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 2 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.^[6]

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.

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. Be sure the line hubs are always 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 left side of the heart. 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 is due to mechanical irritation of the heart by the wire or catheter tip. 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.