Temporary cardiac pacing

INTRODUCTION — Temporary cardiac pacing involves electrical cardiac stimulation to treat a bradyarrhythmia or tachyarrhythmia until it resolves or until long-term therapy can be initiated. The purpose of temporary pacing is to reestablish normal hemodynamics that are acutely compromised by a slow or fast heart rate. Temporary pacing can also be used prophylactically when the need for pacing is anticipated [1-7]. In some situations, temporary pacing can be lifesaving.

This topic will review the indications, contraindications, techniques, and procedural aspects of temporary cardiac pacing. Issues related to permanent cardiac pacing are discussed separately. (See "Modes of cardiac pacing: Nomenclature and selection" and "Permanent cardiac pacing: Overview of devices and indications".)

INDICATIONS — Any symptomatic indication for permanent cardiac pacing is potentially an indication for temporary cardiac pacing. However, temporary cardiac pacing is most commonly used for patients with symptomatic bradyarrhythmias, most frequently due to atrioventricular (AV) nodal block. When it is evident that a permanent pacemaker is ultimately indicated, many implanting clinicians proceed directly with implantation of a permanent pacemaker. (See 'Temporary versus permanent cardiac pacing as the initial therapy' below and "Permanent cardiac pacing: Overview of devices and indications".)

In general, temporary cardiac pacing is indicated when a bradyarrhythmia causes symptoms and/or severe hemodynamic impairment and when permanent cardiac pacing is not immediately indicated, not available, or the risk of inserting a permanent pacemaker exceeds potential benefit. The main reason for temporary cardiac pacing is to treat severe symptoms and/or hemodynamic instability due to a bradycardia, or to prevent potential deterioration resulting in hemodynamic instability.

Reversible conditions — Temporary cardiac pacing is indicated for bradycardia that results from an acute and reversible cause that will likely not require permanent pacing. This includes:

●Acute myocardial infarction (MI). (See 'Acute MI' below.)

●Electrolyte disturbances, toxicities, and drug-induced causes for bradycardia including hyperkalemia, digoxin toxicity, beta blocker sensitivity or overdose, and calcium channel blocker sensitivity or overdose. (See "Causes and evaluation of hyperkalemia in adults" and "Cardiac arrhythmias due to digoxin toxicity" and "Major side effects of beta blockers" and "Major side effects and safety of calcium channel blockers".)

●Injury to the sinus or AV node or His-Purkinje system after heart surgery. Damage to the sinus or AV node from coronary bypass graft surgery usually improves over time [8,9]. In contrast, damage to the AV node or His-Purkinje system after valve surgery may not resolve, and a permanent pacemaker is often required. (See "Early cardiac complications of coronary artery bypass graft surgery", section on 'Bradyarrhythmias'.)

●Lyme disease. (See "Lyme carditis".)

●Chagas disease, found most commonly in Central and South America, is caused by Trypanosoma cruzi. It most commonly results in right bundle branch block, hemiblock (left anterior or left posterior fascicular block), or complete heart block and also leads to a cardiomyopathic state. (See "Chronic Chagas cardiomyopathy: Clinical manifestations and diagnosis", section on 'Arrhythmias'.)

●Heart transplantation, which may be associated with sinus node injury and dysfunction that usually recovers over time. (See "Heart transplantation in adults: Arrhythmias".)

●Cardiac trauma, as occurs after a motor vehicle accident with associated blunt chest trauma. (See "Initial evaluation and management of blunt thoracic trauma in adults", section on 'Cardiac injury'.)

●Subacute bacterial endocarditis with an aortic valve abscess damaging the His-Purkinje system and causing AV block, which may or may not improve following antimicrobial and surgical treatment. (See "Clinical manifestations and evaluation of adults with suspected left-sided native valve endocarditis".)

●Catheter trauma to the right bundle branch in a patient with preexisting left bundle branch block, which may cause complete heart block. This may occur in a patient requiring hemodynamic monitoring with a pulmonary artery catheter placed into the right ventricle, when such a patient has a left bundle branch block or an intraventricular conduction delay. (See "Pulmonary artery catheterization: Indications, contraindications, and complications in adults".)

●Acute heart block may occur during transcatheter aortic valve implantation (TAVI) or alcohol septal ablation procedures and may require pacing support. Other acute pacing techniques related to the left ventricular wire already in place for the TAVI procedure have been successfully employed [1,2].

●Repetitive monomorphic ventricular tachycardia requiring overdrive pacing, which can terminate the arrhythmia until proper drug or ablative therapy can be instituted. This can be accomplished by endocardial or epicardial pacing. One commonly used method is to "burst" pace at progressively more rapid rates. When using overdrive pacing for ventricular tachycardia termination, backup defibrillation must be available since ventricular fibrillation can be provoked.

●Myocarditis of an infectious etiology could result in conduction system abnormalities as a result of the related inflammatory process. There are multiple potential etiologies, but conduction system abnormalities that require temporary pacing are rare [1,2].

Acute MI — Temporary cardiac pacing may be necessary in patients with an acute MI, even when permanent pacing is not ultimately required [1,2]. Revascularization strategies with thrombolysis and angioplasty have significantly reduced the need for temporary and permanent cardiac pacing since there is often less myocardial damage and a greater chance that bradycardia and conduction abnormalities will not occur. There may, however, be a need for temporary cardiac pacing. (See "Conduction abnormalities after myocardial infarction".)

An important consideration in the setting of an acute MI is that a bradycardia, even if asymptomatic or transient, can cause decreased coronary blood flow and reduced myocardial perfusion. Guidelines from the American Heart Association and American College of Cardiology recommend temporary bradycardia pacing in patients with high-grade AV block and/or new bundle branch block (particularly left bundle branch block) or bifascicular block in patients with an anterior/lateral MI [1,2]. Clinical judgment should be used when applying the guidelines to an individual patient's clinical situation and weighing the risk versus benefits of placing a temporary pacing lead.

Weighing the benefits of temporary pacing — A difficult issue is when, and if, a temporary pacemaker is needed for patients with intermittent conduction abnormalities. As an example, a patient admitted to the hospital because of presyncope who has a single, five-second pause documented on continuous monitoring might not need a temporary pacemaker wire, particularly since its insertion might actually cause complications that would offset any potential benefit. Similarly, a patient with complete heart block who has a stable escape rhythm can usually wait for a permanent pacemaker; a temporary pacemaker in such a patient might result in pacemaker-dependence with the risk of asystole if the lead dislodges. In such patients, it is best to place a temporary pacing wire only if there is the imminent risk of asystole before a permanent pacemaker can be placed.

Permanent pacemaker system revisions — Temporary cardiac pacing is required in patients who are pacemaker-dependent when a pacemaker generator change or lead revision/replacement is needed for either of the following:

●Pacemaker system (generator and/or lead) infection

●Ventricular lead malfunction or failure

For the pacemaker-dependent patient whose pulse generator has reached elective replacement indicators, a temporary pacemaker would usually be placed at the onset of the permanent pulse generator replacement. In such situations, consideration must be given to a potential interaction between the permanent and temporary cardiac pacemakers. If, for example, the temporary cardiac pacemaker fails to capture but its output or pacing stimulus is sensed by the permanent cardiac pacemaker, the permanent cardiac pacemaker might be inhibited, resulting in a severe bradycardia or asystole. With a temporary pacemaker in place and programmed asynchronously, there would not be concern about interference from electrocautery, which would likely be used for dissection and/or to cauterize any bleeding within the pocket.

With a functioning temporary pacemaker in place, there is no concern about maintaining an adequate heart rate when the permanent pulse generator is disconnected and a new one placed. There are some experienced implanters who prefer to do a very fast switch between the old and new pulse generator and avoid temporary pacemaker placement. However, this leaves the potential for asystole if there are any problems with the pulse generator switch, and placing a temporary pacemaker for dependent patients is the typical approach.

Pacing to prevent tachyarrhythmias — Rapid temporary cardiac pacing can be used in some situations to prevent a tachyarrhythmia from occurring.

●Post-cardiac surgery — Overdrive pacing has been used after cardiac surgery to prevent atrial fibrillation and atrial flutter, although beta blockers are usually the treatment of choice. The potential efficacy of overdrive pacing was illustrated in a randomized trial of 96 patients undergoing coronary artery bypass graft surgery who were in sinus rhythm without antiarrhythmic drugs on the second postoperative day [10]. Overdrive pacing for 24 hours significantly reduced the incidence of atrial fibrillation (10 versus 27 percent). (See "Atrial fibrillation and flutter after cardiac surgery".)

●Ventricular tachyarrhythmias — Some ventricular tachycardias can be prevented by rapid pacing. An example is torsades de pointes (TdP), a polymorphic ventricular tachycardia associated with a long QT interval. Atrial or ventricular pacing at rates between 90 and 110 beats per minute can prevent initiation of TdP by shortening the QT interval and by preventing PVCs that might trigger the tachycardia. This approach is not commonly used but may be effective for some patients. (See "Congenital long QT syndrome: Treatment".)

CONTRAINDICATIONS — In patients with symptomatic bradyarrhythmias or other indications for temporary cardiac pacing, there are no absolute contraindications, particularly in patients who have life-threatening hemodynamic instability. However, temporary transvenous cardiac pacing should be avoided or used with caution in the following settings:

●In patients with intermittent, mild, or rare symptoms in whom the bradycardia is well tolerated. This includes symptomatic complete heart block with an adequate and "stable" escape rhythm or symptomatic sinus node dysfunction with only rare pauses.

●In patients with a prosthetic tricuspid valve, as the temporary cardiac pacemaker lead could damage the valve or become trapped in the prosthesis.

●In a patient with an MI who has received a thrombolytic agent and is being aggressively treated with anticoagulation or antiplatelet agents. Even insertion of the catheter by a cutdown, thus allowing direct visualization of the vessel and better control of bleeding, may be associated with significant bleeding in such patients.

PACING TECHNIQUES

Temporary versus permanent cardiac pacing as the initial therapy — The main reason for temporary cardiac pacing is to treat severe symptoms and/or hemodynamic instability due to a bradycardia, or to prevent potential deterioration resulting in hemodynamic instability. However, when it is evident that a permanent pacemaker is indicated, many electrophysiologists proceed directly with implantation of a permanent pacemaker to minimize the number of procedures performed and the associated complications related to temporary cardiac pacing. (See 'Indications' above and 'Complications' below.)

Temporary cardiac pacing techniques — Temporary cardiac pacing can be performed in a variety of ways:

●Internally using transvenous endocardial leads

●Externally via transthoracic patches

●Internally using atrial or ventricular epicardial leads placed at the time of surgery

●Internally via an esophageal electrode, which is primarily used for atrial pacing and recording

Transvenous — Temporary cardiac pacing via a transvenous approach is the preferred approach to temporary cardiac pacing for most patients [1-7]. Transvenous pacing requires expertise in both venous and cardiac anatomy in order to effectively access the vasculature and advance the electrode into the heart. (See 'Transvenous lead placement' below.)

Transvenous pacing has the advantages of being more comfortable for the patient (compared with transcutaneous pacing) and more durable (compared with both transcutaneous and epicardial pacing) in patients in whom the anticipated duration of temporary cardiac pacing may be several days to weeks. Limitations to traditional transvenous pacing using a lead specifically designed for temporary pacing include limited patient mobility (most patients will be restricted to bed or chair and cannot ambulate).

There are some situations when a longer duration of temporary pacing will be required. The most common scenario is removal of an infected system in a patient where bacteremia or endocarditis is present and prolonged antibiotics will be required to clear the systemic infection prior to implantation of a new pacing system. In such patients, essentially normal mobility can be restored if a permanent active fixation pacing lead (typically with a peel-away sheath) is placed in the right ventricle via internal jugular venous access and connected to a standard permanent pacemaker that is then secured to the patient.

Centers that do a relatively high volume of pacemaker implants may have a device that cannot be permanently implanted because it is beyond its expiration date or it has been contaminated. There have been several published series using variations of this technique [11,12].

More details regarding the placement of transvenous pacing electrodes are presented below. (See 'Procedural aspects of temporary transvenous pacing' below.)

Transcutaneous — In most situations where urgent temporary cardiac pacing is needed, transcutaneous pacing is the technique that can be initiated most rapidly [13,14]. Adhesive pads are placed directly on the patient's chest, typically in the anterior and left lateral positions or in the anterior and posterior positions (figure 1). The pads are in addition to the standard adhesive electrodes for telemetry monitoring, which may need to be slightly repositioned to accommodate the transcutaneous pacing pads. In some patients with large amounts of body hair, the area will need to be shaved to allow for proper adhesive contact.

Transcutaneous pacing is limited by two significant clinical issues, namely high capture thresholds and patient discomfort:

●Inability to achieve capture and successfully pace the heart – Because of the impedance of the intervening chest wall structures (ie, skin, musculature, and bony and connective tissues) and the difficulty in knowing the exact location of the heart within the thorax, successful capture and pacing are not achieved in all patients. In addition, capture may be interrupted due to patient movement or inadequate adhesion of the pads to the chest wall (eg, in a diaphoretic patient). Another pitfall is difficulty assessing capture as the large stimulus artifact can make the monitor misleading, given the appearance of capture when this is not actually the case.

●Patient discomfort – In order to overcome the higher impedance associated with intervening chest wall structures to successfully stimulate the myocardium, relatively higher energy levels are required when using transcutaneous pacing. This can result in non-myocardial muscle stimulation and discomfort that is not tolerated by the patient.

Because of the limitations associated with transcutaneous pacing, this method should be considered only as a temporizing measure for unconscious patients or those in whom sedation can be administered, until either temporary transvenous pacing can be established or until a permanent cardiac pacemaker can be inserted.

Epicardial — Temporary cardiac pacing with epicardial pacing wires is used exclusively following cardiac surgery and can be used for temporary cardiac pacing if bradycardia occurs, or for overdrive pacing of postoperative tachyarrhythmias [15]. Leads may be attached to the atrium, ventricle, or both chambers at the time of the cardiac surgical procedure, with the wires tunneled and externalized [15].

In most patients, temporary epicardial pacing is utilized only during the initial days following surgery. Temporary epicardial leads are generally only used for a limited period because of problems that can develop. One concern is that, when present for more than one week, the pacing threshold will often rise and there may not be adequate and reliable capture. Once the pacing threshold rises or consistent capture is not possible, the leads should be removed and an alternate means of temporary cardiac pacing, if needed, should be instituted if the clinical requirement persists.

A variety of temporary epicardial leads are available, and the surgeon must be aware of the differences and various fixation mechanisms [15].

Transesophageal — A transesophageal pacemaker lead can be used for atrial pacing and/or recording. It can be inserted through the mouth or the nose, depending upon the type of catheter used. However, the catheter is uncomfortable to place, pacing is unreliable, and pain is common because it requires high current and pulse width for adequate and continual capture. For these reasons, transesophageal pacing is not commonly used, although it may occasionally have a role for diagnostic purposes. It has also been of some use for pace termination of atrial tachycardia or atrial flutter and for establishing the presence of intrinsic sinus activity (P waves) if they are not obvious on the electrocardiogram.

Permanent cardiac pacing techniques — Permanent cardiac pacing is discussed in detail separately. (See "Permanent cardiac pacing: Overview of devices and indications" and "Modes of cardiac pacing: Nomenclature and selection".)

PROCEDURAL ASPECTS OF TEMPORARY TRANSVENOUS PACING — Prior to implantation of a temporary transvenous pacing system, knowledge about normal anatomy and endocardial structures and the ability to distinguish between normal electrograms and artifact are important to guide vascular access, proper lead positioning, and device programming [16].

Vascular access — The preferred access sites for temporary transvenous pacing leads are the left subclavian vein and the right internal jugular vein; this relates primarily to the underlying venous anatomy, curvature of the pacing lead, and ease of advancing the lead into the heart. In addition, the subclavian approach permits more freedom of patient motion and might be useful in a patient who requires a long-term temporary pacemaker. A brachial vein approach is not recommended because of the risk of cardiac puncture and instability. While a femoral vein approach is fairly common, particularly among patients who receive a temporary pacemaker in the cardiac catheterization lab while undergoing percutaneous coronary intervention, this approach is not recommended for longer-term temporary pacing because of the risks of deep vein thrombosis, infection, and right ventricular perforation. When temporary pacing is established via the femoral vein, patients should remain continuously supine with their leg straight.

Ultimately, however, the best approach to minimize complications is the one with which the clinician has the most experience. If there is a high likelihood that a permanent pacemaker will be required, this should be taken into account at the time the venous access site for the temporary pacemaker is chosen. For example, if a patient is left-hand dominant and the permanent pacemaker would be placed in the right prepectoral region, then it would be desirable to use a site other than the right subclavian vein for the temporary lead.

An extensive discussion of the preparation and techniques used for achieving central venous access is presented separately. (See "Central venous access in adults: General principles".)

Transvenous lead placement — Once central venous access has been secured and the introducer sheath is in place, the transvenous lead is inserted and advanced into the heart. The progress of the advancing lead can be monitored in several ways:

●Lead markings – Leads designed as temporary transvenous leads have markings indicating the distance from the tip of the lead; these should be monitored to estimate the location of the lead tip within the vasculature or the heart.

●Continuous electrocardiographic monitoring – Continuous electrocardiographic monitoring is recommended during the insertion of a transvenous pacing lead [16-18]. In nearly all patients, frequent PVCs or brief runs of nonsustained ventricular tachycardia will be seen when the tip of the transvenous pacing lead encounters the right ventricular myocardium.

●Fluoroscopy – Fluoroscopy, either from a portable bedside unit or in a dedicated procedure room, is highly desirable and helpful when available as it allows for direct visualization of the transvenous pacing lead and optimal placement of the lead within the right ventricle. While not always necessary for lead placement via subclavian or internal jugular venous access, fluoroscopy is required for placement via femoral venous access in order to manipulate the catheter into the proper position. If fluoroscopy is not available, a preformed balloon-tipped catheter can be placed from the right internal jugular or left subclavian vein as it will tend to "float" toward the right ventricle. A balloon-tipped catheter cannot generally be placed during cardiac arrest due to inadequate blood flow.

●Echocardiography – Continuous echocardiographic monitoring has also been successfully used for placement of temporary pacing wires [19,20].

When the lead is placed in the right ventricular apex, there should be slight excess lead or "slack" (pressure at the tip, with a bend at the tricuspid ring) to ensure that the lead does not become dislodged. The lead should be tied down. If a technique has been used where the vein is visualized, then a "tie" is placed where the lead exits from the vein, and then another tie is placed between the patient's skin and a loop formed with the lead. The loop should be large enough to prevent tension on the lead, preventing it from becoming dislodged and the pacemaker losing capture. If the lead was placed in a percutaneous fashion, for example, then it is common to only place a tie between the patient's skin and a loop formed with the lead.

When a patient is pacemaker-dependent, it is crucial that the lead be placed in a stable position, and fluoroscopy should be used whenever possible.

Temporary dual-chamber pacing may rarely be useful for patients who require AV sequential pacing for hemodynamic benefit. Included in this group are patients with an acute MI, particularly when associated with right ventricular involvement, and after cardiac surgery, especially when diastolic dysfunction is present.

Temporary BiV pacing with a transvenous pacing catheter placed in a coronary vein via the coronary sinus may provide short-term benefit to selected patients but is not a standard clinical technique at this time. It has been shown to be of value in cardiogenic shock and to improve coronary artery bypass graft flow following surgery [21,22]. (See "Prognosis and treatment of cardiogenic shock complicating acute myocardial infarction".)

Types of transvenous leads — Various types of transvenous leads are available. Transvenous pacing leads are typically stiffer than permanent pacing leads, making manipulation more difficult, but the leads are balloon-tipped for easier insertion. They come with various curves, including a preformed atrial "J" wire, and in 2, 5, 6, and 7 French sizes; they are generally bipolar or quadripolar. As noted, another option is to "exteriorize" permanent pacemaker leads if long-term temporary pacing (ie, weeks) is being considered. These leads can then be removed when temporary pacing is no longer needed. (See 'Transvenous' above.)

Endocardial screw-in temporary leads can be used to help maintain stability. These leads, purposefully flimsy, are thin and deployed through a sheath that is then removed. These leads can maintain excellent pacing and sensing thresholds for many weeks.

In general, atrial leads are not inserted when bradycardia alone is the indication for pacing. However, an atrial lead is inserted for the rare patient who has symptomatic sinus pauses or sinus bradycardia but intact AV nodal conduction, or pace termination of atrial tachyarrhythmias, particularly atrial flutter, and rarely to provide AV synchrony for hemodynamic purposes [23-26]. The benefits of atrial pacing for conditions of sinus bradycardia or junctional rhythm are most prominent after cardiac surgery for patients with ischemia, ventricular hypertrophy, or heart failure.

Connecting the lead and pulse generator — The connector cable linking the transvenous pacing lead to the pacemaker generator is a simple aspect of the system, but it is important for these connectors to be screwed tightly and securely fastened. An improper connection or inadvertent disconnection can result in pacing malfunction or even asystole and possibly death in a patient who is pacemaker-dependent. Even if a patient is not initially pacemaker-dependent but is then paced, abrupt disconnection of the pacing or turning off of the pacemaker could lead to asystole due to newly acquired pacemaker-dependence as a result of overdrive pacing [27].

Several types of pulse generators are available that permit single- and dual-chamber pacing. For the vast majority of patients, single-chamber ventricular temporary pacing is most appropriate. For the patient with symptomatic sinus arrest and completely normal AV nodal conduction, atrial temporary pacing may be utilized. (See 'Pacemaker programming' below and "Modes of cardiac pacing: Nomenclature and selection".)

Pacemaker programming — The temporary pacing rate should be set to whatever rate optimizes the patient's hemodynamics. For a pediatric patient and often for postoperative patients, a faster heart rate (eg, 80 to 100 beats per minute) may be desired. For most other patients, a rate of 60 to 70 beats per minute will likely be adequate. If the patient is pacemaker-dependent, then the temporary pacer can be turned to the least sensitive value (ie, the temporary pacemaker will essentially function in an asynchronous mode). If the patient has an intermittent intrinsic ventricular rhythm, then the sensitivity should be adjusted to allow normal sensing of the intrinsic events.

To ensure proper pacemaker sensing and capture, the pacemaker output should be set at least two to three times the pacing threshold (ie, the minimum output necessary for pacemaker capture). The pacing threshold, especially in the ventricle, should ideally be less than or equal to 1 milliamp, especially for the patient who is pacemaker-dependent.

COMPLICATIONS — Complications are not uncommon in patients treated with temporary cardiac pacing [5-7,27]. Complications may be related to venous access, the transvenous pacing lead, or external electromagnetic interference [5-7,27]. The complications associated with temporary cardiac pacing, particularly temporary transvenous cardiac pacing, have led to many clinicians frequently proceeding directly with implantation of a permanent pacemaker (when the likelihood of conduction system recovery is minimal) or to utilizing a temporary transvenous system with a permanent endocardial screw-in lead. (See 'Temporary cardiac pacing techniques' above and 'Types of transvenous leads' above and "Central venous catheters: Overview of complications and prevention in adults".)

Serious complications of temporary cardiac pacing are rare but are important to recognize and include:

●Lead dislodgement and disconnection, which could lead to asystole

●Bleeding

●Myocardial perforation, which could lead to cardiac tamponade

●Pulmonary embolism

●Catheter knotting

●Air embolism

●Various arrhythmias including ventricular tachycardia and ventricular fibrillation

●Pneumothorax

●Extracardiac stimulation

●Infection

External temporary pacemakers are used mainly in intensive care units, and therefore the risk of electromagnetic interference is limited. External electromagnetic interference with cardiac devices is discussed in detail separately. (See "Cardiac implantable electronic device interactions with electromagnetic fields in the nonhospital environment".)

POSTPROCEDURE MANAGEMENT

Immediate postprocedural management — Immediately following completion of transvenous lead placement, a chest radiograph should be obtained to establish the position of the lead. Additionally, an immediate postprocedure 12-lead electrocardiogram (ECG) should be recorded during pacing to determine the electrocardiographic appearance of the QRS complex. Although a standard transvenous ventricular lead is often positioned at or near the right ventricular apex, if a permanent endocardial lead is used for longer-term temporary pacing, the lead could be placed essentially anywhere in the right ventricle. With the lead positioned in the right ventricle, the QRS should generally have a left bundle branch block morphology and a superior axis (ie, an upright QRS complex in lead I and aVL).

A physical examination should be performed immediately following transvenous lead placement, with subsequent daily assessments, to evaluate for any of the following:

●Pericardial friction rub, which may be indicative of cardiac perforation

●Hypotension with muffled heart sounds and jugular venous distension, suggesting cardiac tamponade

●Asymmetrical or absent breath sounds, suggesting a pneumothorax

Management for the duration of temporary pacing — Continuous ECG monitoring is mandatory during the entire time the patient has a temporary cardiac pacemaker, and a separate intravenous access is recommended should there be a need for drug therapy. Daily chest radiographs are not mandatory, but a chest radiograph should be repeated if there is evidence of failure to capture or failure to sense, or if a ventricular tachyarrhythmia occurs, all of which suggest potential electrode dislodgement. Daily ECGs are also not needed.

Patients with temporary pacemakers require a daily check of pacing thresholds to make certain that there is proper capture. The need to continue temporary cardiac pacing should be reevaluated daily, with device removal if the patient has recovered stable intrinsic electrical activity or consideration of permanent cardiac pacing if indicated. If there are any episodes of failure to sense a premature ventricular complex/contraction (PVC; also referred to a premature ventricular beats or premature ventricular depolarizations) or an intrinsic normally conducted QRS complex, the sensing of the temporary pacemaker should be reevaluated.

In most institutions a special dressing may be applied that is felt to resist infection. Some of the occlusive and transparent dressings that are available can be left in place for up to seven days. Fever and/or local erythema or drainage at the venous access site would suggest an infection and should prompt appropriate evaluation and, if needed, removal of the temporary pacing system. All connections and pacemaker programmed settings should be checked routinely.

If the patient has a permanent endocardial lead placed and attached to an externalized permanent pacemaker when it is assumed that longer duration temporary pacing will be necessary, the patient can have unrestricted movement other than limitation of arm/shoulder restriction on the ipsilateral side of the temporary pacemaker.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Arrhythmias in adults" and "Society guideline links: Cardiac implantable electronic devices".)

SUMMARY AND RECOMMENDATIONS

●Temporary cardiac pacing involves electrical cardiac stimulation to treat bradyarrhythmias and rarely a tachyarrhythmia, until it resolves or until long-term therapy can be initiated. The purpose of temporary pacing is to reestablish circulatory integrity and normal hemodynamics that are acutely compromised by a slow or fast heart rate. (See 'Introduction' above.)

●Temporary cardiac pacing is most commonly utilized for patients with symptomatic bradyarrhythmias, most frequently due to atrioventricular (AV) nodal block. Temporary cardiac pacing for bradycardia that results from an acute and reversible cause (eg, acute myocardial infarction, electrolyte disturbances, drug toxicities, Lyme disease, etc) will often not require permanent pacing. (See 'Indications' above.)

●Temporary cardiac pacing can be performed in a variety of ways, most commonly via transvenous endocardial leads designed for temporary pacing, transvenous endocardial leads designed for permanent cardiac pacing if longer-term temporary pacing will be required, or transcutaneous leads. Temporary transvenous pacing is the preferred approach for most patients, although transcutaneous pacing can be initiated more rapidly in an emergency. (See 'Pacing techniques' above.)

●The preferred access sites for temporary transvenous pacing leads are the left subclavian vein and the right internal jugular vein; this relates primarily to the curvature of the lead and ease of advancing the lead into the heart. A brachial vein approach is not recommended because of the risk of cardiac puncture and instability, while a femoral vein approach is not recommended because of the risks of deep vein thrombosis and infection and the need for the patient to remain continuously supine. (See 'Vascular access' above.)

●Once central venous access has been secured and the introducer sheath is in place, the transvenous lead is inserted and advanced into the heart. The progress of the advancing lead can be monitored using lead marking, continuous electrocardiographic monitoring, and/or fluoroscopy. (See 'Transvenous lead placement' above.)

●The temporary pacing rate should be set to whatever rate optimizes the patient's hemodynamics. For a pediatric patient and often for postoperative patients, a faster heart rate (eg, 80 to 100 beats per minute) may be desired. For most other patients, a rate of 60 to 70 beats per minute will likely be adequate. If the patient is pacemaker-dependent, then the temporary pacer can be turned to the least sensitive value (ie, the temporary pacemaker will essentially function in an asynchronous mode). If the patient has an intermittent intrinsic ventricular rhythm, then the sensitivity should be adjusted to allow normal sensing of the intrinsic events. (See 'Pacemaker programming' above.)

●Immediately following completion of transvenous lead placement, a chest radiograph should be obtained to establish the position of the lead, an immediate postprocedure 12-lead ECG should be recorded during pacing to determine the electrocardiographic appearance of the QRS complex, and a physical examination should be performed to evaluate for any evidence of cardiac tamponade or pneumothorax. (See 'Immediate postprocedural management' above.)

●Continuous ECG monitoring is mandatory during the entire time the patient has a temporary cardiac pacemaker, and a separate intravenous access is recommended should there be a need for drug therapy. Daily chest radiographs and ECGs are not needed; however, patients with temporary pacemakers require a daily check of pacing thresholds to make certain that there is proper capture. (See 'Management for the duration of temporary pacing' above.)

ACKNOWLEDGMENTS — The UpToDate editorial staff acknowledges Brian Olshansky, MD, and David L Hayes, MD, who contributed to an earlier version of this topic review.