Courtesy ACEP Cardiac pacing capture is depicted above: A, intrinsic bradycardic rhythm; B, pacer spikes are evident without capture; C, effect capture with each pacer spike.

Cardiac pacing is a potentially life-saving skill to which emergency physicians often have a limited exposure during their careers. Although many modalities of cardiac pacing have been described in the literature, trans­cutaneous and transvenous pacing have emerged as the preferred methods for use in the emergency department. This article will review the indications, contraindications, benefits, use, and possible complications of these pacing modalities.

Transcutaneous Pacing: Indications

Since it was originally described in 1952 by Zoll for the treatment of asystole as well as of brady­­dysrhythmias, transcutaneous pacing has continued to be used in the emergency setting. This noninvasive method of cardiac pacing allows for expedient placement and initiation of therapy without the risks of an invasive procedure.

Symptomatic bradydysrhythmias represent the primary indication for the use of transcutaneous pacing. The pathophysiology that results in a slowed ventricular rate may be subdivided into two main etiologic classifications: disorders of impulse formation (such as sinus arrest or sinus bradycardia) and disorders of impulse conduction (such as second- or third-degree AV blocks).

Etiologies that are not responsive to medical treatment may require the initiation of cardiac pacing to ensure adequate cardiac output. Transcutaneous pacing may serve as a needed bridge until transvenous or permanent pacemaker placement can occur.

Transcutaneous Pacing: Contraindications

In the past, cardiac pacing has been used for the treatment of asystolic cardiac arrest. However, randomized controlled trials have failed to demonstrate that it improves mortality. As a result, the 2010 AHA ECC guidelines recommend against the routine use of cardiac pacing for the treatment of asystolic cardiac arrest.

In patients with significant hypothermia, bradydysrhythmias are frequently present; however, it is hypothesized that electrical derangements are a direct result of low temperature on the myocardial cells and not of a primary conduction abnormality.

The evidence on the effect of cardiac pacing in these patients is mixed, and no recommendations exist regarding the use of pacing in the hypothermic patient.