Temporary pacing is indicated in patients with acute hemodynamically significant bradycardia or asystole. Reversible causes such as digitalis toxicity, antiarrhythmic agents, and electrolyte disturbances such as hyperkalemia should be determined and reversed.

Temporary pacing is indicated for overdrive pacing and termination of atrial flutter (type I with long excitable gap) or supraventricular tachycardia due to a reentrant mechanism.

Temporary pacing may be used as a bridge to permanent pacing in patients with complete heart block, high-grade second-degree block, severe sinus node dysfunction, and asystole. Generally, temporary pacing in this setting is for patients with an acute illness (endocarditis and systemic infection elsewhere) that delays permanent pacemaker placement.

Temporary pacing is indicated in patients with bradycardia-dependent ventricular tachycardia and recurrent tachyarrhythmias secondary to long QT syndrome or pause-dependent ventricular tachycardia. Monomorphic ventricular tachycardia can be terminated with antitachycardia pacing through a ventricular temporary wire by pacing at a rate faster than the tachycardia. This involves pacing the chamber in which the reentrant circuit exists. Overdrive pacing is initiated at 10 to 15 beats per minute (bpm) faster than the tachycardia. Pacing is done for several captured beats (up to 10 to 15 seconds) and then abruptly stopped. If tachycardia persists, the pacing rate is sequentially increased by 10 bpm and pacing repeated. The major potential complication of this technique is conversion to a faster or unstable rhythm. The advantage is that post-tachycardia pauses can be managed with pacing if necessary, and direct current cardioversion may be avoided.

Indications for temporary pacing in this setting include development of a new bifascicular block (right bundle branch block [RBBB] with either left-axis [left anterior hemiblock] or right-axis deviation [left posterior hemiblock]), new left bundle branch block (LBBB) with first-degree atrioventricular (AV) block, alternating LBBB and RBBB, Mobitz type II block, and complete heart block. Patients with right ventricular infarction and loss of AV synchrony may benefit from AV sequential pacing.

In certain forms of myocarditis with heart block, such as Lyme disease, or post cardiac surgery, temporary pacing can be used because there is a significant chance of recovery of conduction.

Pacing to increase heart rate in patients with acute aortic regurgitation who have bradycardia and elevated left ventricular end-diastolic pressure can reduce diastolic filling time and improve hemodynamics.

Prophylactic temporary pacing is considered in the following settings: (a) in patients undergoing right heart catheterization and/or myocardial biopsy in the
setting of an LBBB, (b) with complex intervention to the right coronary artery as this supplies the AV node in 90% of individuals, (c) cardioversion in patients with the sick sinus syndrome, although generally the use of transcutaneous pacing back up is used instead, (d) or new 1st degree AV block with acute endocarditis (especially of the aortic valve). Patients who are undergoing alcohol septal ablation for hypertrophic cardiomyopathy receive prophylactic transvenous pacers, given the significant risk of complete heart block during the procedure. Patients who are undergoing balloon aortic valvuloplasty and percutaneous aortic valve replacement have a temporary pacemaker placed for overdrive pacing during balloon inflation and valve implantation.

Temporary atrial, coronary sinus, and ventricular pacemakers are frequently used for electrophysiologic studies.

Ischemic evaluation is occasionally performed via rapid atrial pacing.

Transcutaneous ventricular pacing involves placement of large-surface-area, high-impedance electrodes (Zoll pads) on the anterior (over lead V₃ or the palpable cardiac apex) and posterior chest walls (inferior aspect of the scapula, to the left or right of the spine). It usually requires long pulse widths (20 to 40 milliseconds) and high outputs of up to 100 to 200 mA. Transcutaneous pacing may be useful when transvenous pacing is contraindicated and in code situations. It avoids the complications associated with transvenous pacers such as pneumothorax, right ventricular perforation, infection, bleeding, and venous thrombosis. Failure to capture and severe patient discomfort are common.