Cardiac Pacing

Hemodynamic instability (presyncope, angina, altered mentation, pulmonary edema) secondary to:

Bradydysrhythmias:

Sinus bradycardia

Sinus node dysfunction

Atrioventricular (AV) node conduction blocks (second and third degree)

Acute myocardial infarction with bifascicular block, alternating bundle branch block, new left bundle branch block (LBBB), escape rhythm <40 bpm

Malfunctioning permanent pacemaker

Electrolyte/metabolic disturbances (i.e., hyperkalemia) if medical therapies fail or are unavailable

Post–cardiac surgery (i.e., valve replacement)

Thoracic trauma (i.e., cardiac contusion)

Other (i.e., lyme carditis, endocarditis)

Tachydysrhythmias (overdrive pacing, typically transvenous only):

Supraventricular tachycardia (SVT)

Ventricular tachycardia (VT)

Transvenous Pacing—same as above, but also including:

Failure or nontolerance of transcutaneous pacing

Bridge to permanent pacemaker placement

High risk of progression to complete heart block

Overdrive pacing

CONTRAINDICATIONS

Absolute

Asymptomatic, stable rhythms (i.e., first-degree AV block)

Prosthetic tricuspid valve (transvenous only)

Relative

Severe hypothermia (may be physiologic bradycardia; can induce fibrillation)

Brady-asystolic arrest >20 minutes

Drug-induced dysrhythmias (although can be utilized as last resort if antidote fails)

TRANSCUTANEOUS PACING PROCEDURE

Landmarks

Pacer pads should preferentially be placed over the precordium anteriorly and in the interscapular paraspinous region posteriorly. Anterolateral pad placement is also acceptable.

Supplies

Cardiac monitor with pacemaker capabilities (if electrocardiogram [ECG] monitor is not part of the pacer unit, a separate monitor and adaptor will be required)

Adhesive pacing pads

ECG electrodes

Safety razor

Technique

Preparation

In conscious patients, reassurance and explanation of the procedure, including expectations for discomfort, are extremely important

Remove excess hair if time permits

Continuous cardiac and pulse oximetry monitoring, intravenous access, and bedside capability for resuscitation, including airway management, defibrillation, and arrhythmia treatment, should be at the bedside before initiation

Pacer/Electrode Placement

Pads are placed as shown in FIGURE 9.1

Anterior chest pacing pad (negative charge electrode) is placed over the point of maximal impulse

If access to the posterior chest wall is limited or difficult, posterior pacer pad may also be placed in cardiac apex/base position (identical to electrical cardioversion placement)

ECG electrodes should be placed in limb lead positions for monitoring

Pacing

Identify pacemaker mode on equipment and turn to “on”

Set heart rate to 70 bpm

Place and maintain one hand in pulse-check position (radial, femoral, or carotid) or observe noninvasive or invasive blood pressure response

In bradyasystole and unconscious patients, set current to 150 to 200 mA and lower in 10-mA decrements; set current at the lowest level that will consistently achieve mechanical capture

In stable and conscious patients, set current to 10 mA and raise in 10-mA increments until mechanical capture is achieved

Observe cardiac monitor for pacemaker spikes and electrical capture—“electrical capture” refers to narrow pacemaker spikes followed by typically wide ventricular complexes

Monitor constantly for “mechanical capture”—a palpable arterial pulse induced by pacemaker discharges or perfusing blood pressure by noninvasive or invasive blood pressure monitoring

Titrate sedation/analgesia/anxiolysis to allow for tolerance of ongoing pacing

Failure to achieve mechanical capture should prompt immediate preparation for transvenous pacer placement

Complications

Unrecognized ventricular fibrillation

Local discomfort

Cutaneous injury

FIGURE 9.1 Proper placement of transcutaneous pacing electrodes. (From Morton PG, Fontaine DK. Critical Care Nursing. 10th ed. Philadelphia, PA: Wolters Kluwer Health; 2012.)

SAFETY/QUALITY TIPS

Procedural

The most common causes of failure to capture in transcutaneous pacing are improper electrode placement or large patient size

For many patients, adequate amperage will not be possible without aggressive sedation/analgesia

Cognitive

Compared to transvenous pacing, transcutaneous pacing is painful and ineffective. Transcutaneous pacing should be thought of as a brief bridge to transvenous pacing or correction of the underlying disorder.

Electrical capture is not mechanical capture, and mechanical capture is what counts. Once electrical capture occurs, mechanical capture must be immediately verified using pulses, invasive arterial pressure monitoring, ultrasound, or (most conveniently) pulse oximetry.