As with transcutaneous pacing, symptomatic bradycardia is the primary indication for transvenous pacemaker placement. Transvenous pacing should also be considered for patients who are unable to tolerate transcutaneous pacing or the hemodynamic effects of sedation, or in whom transcutaneous pacing fails to obtain or maintain electrical capture.

In addition, prophylactic placement has been described for conditions that pose a high risk for progressing to symptomatic bradydysrhythmias. These conditions include asymptomatic bradydysrhythmias, new bundle branch/bifascicular block, or following an acute MI. Occlusion resulting in anterior or inferior infarct may involve the conduction system and predispose a patient to dysrhythmias, with a subsequent increase in mortality.

Transvenous Pacing: Contraindications

Contraindications to transvenous pacing are similar to those mentioned above for transcutaneous pacing. Because of the need to introduce the pacing lead into the central venous system, distortions of anatomy or bleeding dyscrasias remain relative contraindications and must be assessed prior to placement.

Cardiac glycoside toxicity, as well as other drug ingestions, can cause myo­cardial irritability and increase the risk of ventricular fibrillation as the pacing lead is introduced. Therefore, possible drug ingestion should be assessed prior to transvenous placement.

Transvenous Pacing: Procedure

Transvenous pacing begins with cannulation of the central venous system followed by the introduction of the pacing catheter. The equipment that is necessary for successful transvenous pacing includes:

• ECG monitoring equipment with monitor and cables.
• ECG patches.
• Sterile gown, gloves, drapes.
• Sheathed, single-lumen central venous catheter.
• Pulse generator unit.
• Pacer cables.

Several anatomic sites may be used to gain access to the central venous system. The right internal jugular vein and the left subclavian vein are the preferred sites of entry.

Once the patient is monitored with routine ECG readings, sterile technique is used to prepare the site for central venous access.

A single-lumen catheter may be placed and secured using standard technique. The pacing catheter contains a small balloon at the distal tip that must be checked for leaks prior to insertion. This can be accomplished by filling the balloon with 1.5 mL of air while the balloon rests in a container of saline.

The presence of bubbles in the saline indicates a leak in the balloon, and a new catheter will be needed. Once the balloon has been confirmed to be intact, connect the positive and negative electrodes to the external pacemaker unit and advance the catheter through the introducer sheath to roughly 20 cm.