CTSNet Step-by-Step Series: Pacing Wires
In the acute postoperative period after cardiac surgery,
pacing wires can be inserted into the atria or ventricles to form an external
artificial cardiac conductive system controlled by an external pulse generator.
While the majority of patients do not require pacing, postoperative pacing
wires are almost always positioned because of the risk of conductive
abnormalities such as postoperative block or atrial fibrillation, which is
extremely common in the period immediately following cardiac surgery. Risks
associated with the insertion of epicardial pacing wires include infection,
perforation, and tamponade.
Temporary epicardial wires can be either unipolar or bipolar. Ventricular pacing wires are important due to the risk of heart block and arrhythmia in the postoperative period. Atrial wires may also be important as they allow coordinated pacing of the heart.
The epicardial wires are positioned on the anterior cardiac surface. The atrial leads are normally inserted on the right atrial appendage, and the ventricular leads are inserted on the diaphragmatic surface of the right ventricle. Small needles at one end are used to embed the wire partially through the wall of myocardium. The insertion location must be selected carefully to avoid arterioles and venules, and to avoid straddling a bypass graft. If the right atrial appendage is used, ensure the bare wire does not also come into contact with the right ventricle in order to avoid simultaneous atrial and ventricular contraction. Part of the uninsulated wire is pulled through the myocardium and the needle is then cut off. Leads should be positioned so as not to become dislodged after they are placed, but they should not be so well anchored that they cannot easily be removed later.
A large needle on the other end of the wire is used to penetrate the body wall, bringing the wire to the surface. When selecting the exit site, ensure that the exit direction of the pacing wire from the epicardium is in as straight a line as possible to the exit site, to avoid tearing upon removal. The exit site should be located at the inferior end of the pericardium, below the sternotomy, to reduce the risk of tamponade on removal. By convention, wires placed on the right atrium are brought out through the skin on the right of the patient’s midline, and those on the right ventricle are brought out on the left of the midline. Some wires are coiled to assist fixation; the coil gives room for error when the patient is repositioned. This way, even if the patient makes sudden erratic movements, there will be plenty of give and the wires will not come out of the epicardium.
Postoperative care should take place in a cardiac-protected electrical environment. For example, electrical equipment should be adequately isolated and large metal objects such as the patient bed should be electrically discharged. Although both atrial and ventricular temporary epicardial leads are reliable for short-term use, their function deteriorates on a daily basis. The wires should be checked daily for underlying rhythm, sensitivity, capture threshold, and rate. When indicated, the pacing wires can be removed by gentle traction allowing motion of heart to assist dislodgement from the epicardial surface.
Observe the patient for a few hours after removing the pacing wires, as there is a small risk of tamponade at this point. Other complications noted with removal of epicardial pacing wires include ventricular arrhythmia and damage to coronary anastomoses.
Reade MC. Temporary epicardial pacing after cardiac surgery:
a practical review: part 1: general considerations in the management of
epicardial pacing. Anaesthesia. 2007;62(3):264-271.
Reade MC. Temporary epicardial pacing after cardiac surgery: a practical review. Part 2: Selection of epicardial pacing modes and troubleshooting. Anaesthesia. 2007;62(4):364-373.