Epicardial Pacing Wires: The Cardiac Surgeon's Insurance Policy

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Updated July 2026  |  More ICU clinical guides →

Almost every patient who comes out of open-heart surgery arrives in the ICU with a few thin wires taped to their chest wall — temporary epicardial pacing wires the surgeon sewed directly onto the surface of the heart before closing. They are cheap insurance against the conduction problems and rhythm disturbances that are common in the first days after cardiac surgery, when the heart is swollen, irritable, and sometimes stunned near the conduction system. This guide covers what atrial and ventricular wires do, the pacing modes you will actually use, overdrive pacing, and the two safety issues that make epicardial wires distinctly a nursing responsibility: microshock protection and safe removal.

Atrial vs. ventricular wires — and why the atrial kick matters

The atrial wires pace the atria; the ventricular wires pace the ventricles. The convention that atrial wires exit on the patient's right and ventricular on the left lets you grab the right pair in a hurry — but confirm against the operative note, because conventions get broken. After cardiac surgery the ability to pace the atrium is prized: the coordinated atrial contraction just before the ventricle beats (the "atrial kick") can contribute a meaningful share of cardiac output in a stiff, freshly operated heart. A patient who is only ventricularly paced loses that synchrony; if they have intact AV conduction, atrial pacing (AAI) or AV-sequential pacing (DDD) often gives a better pressure than ventricular pacing alone.

The modes you'll use

Overdrive pacing for atrial arrhythmias

One trick unique to having atrial wires: certain re-entrant atrial arrhythmias, classically atrial flutter, can sometimes be broken by pacing the atrium faster than the flutter circuit for a short burst, then abruptly stopping — the rapid pacing captures the circuit and, on release, the atrium may resume sinus rhythm. This is a provider-directed maneuver with real risk (it can accelerate the rhythm or degenerate it), done under continuous monitoring with the defibrillator at hand. The nurse's role is setup, monitoring, and documentation — not freelancing the burst.

Reading and troubleshooting

The same three failure modes from any temporary pacemaker apply — failure to pace, failure to capture, and failure to sense — and the same logic (check connections and battery, adjust output for capture problems, adjust sensitivity for sensing problems, all per protocol and order). Epicardial wires do have a particular tendency for capture thresholds to rise over the postoperative days as the wire-to-tissue interface inflames; a wire that captured easily on postoperative day one may need much more output — or may be abandoned — by day three or four. Document the underlying rhythm and whether the patient is pacer-dependent, exactly as with a transvenous wire.

Removal: the reason this is a written order and a monitored event

Epicardial wires are removed by gentle traction when they are no longer needed — but because the wire's other end was sewn to the heart, removal carries a small risk of bleeding into the pericardium and tamponade. Removal follows your facility's protocol: typically a check of coagulation status and platelet count, holding anticoagulation appropriately, gentle steady traction (never forcing a wire that resists — a stuck wire may be cut at the skin and left, per surgeon), and then a period of monitoring for signs of tamponade — hypotension, tachycardia, rising filling pressures, muffled heart sounds, and a narrowing pulse pressure. The patient does not go for a walk immediately after pull; they are watched.

The nurse's role

Identify which wires are atrial and which are ventricular against the op note, know the mode and why it was chosen (chasing the atrial kick, not just a rate), insulate and glove every exposed tip against microshock, recognize the three failure patterns and rising thresholds, set up overdrive attempts without improvising them, and treat wire removal as a monitored procedure with a tamponade watch attached. These wires are quiet until the moment they are not.

Where to go from here

Pair this with the transvenous pacing guide for the three failure modes in depth, the unstable bradycardia guide for the algorithm behind the pacing decision, and the transcutaneous pacing guide for the emergency bridge when no wires are present.