Unstable patients may be treated with atropine, although this will be ineffective in patients with wide complex escape rhythms. Unstable patients for whom timely cardiology consultation is unavailable should undergo temporary transvenous pacemaker insertion in the ED by the ED physician. Obtain a chest radiograph to confirm placement and exclude complications of the procedure, including pneumothorax and hemothorax. Cardiology consultation is indicated for all patients with third-degree heart block. The consultation is urgent in patients with concomitant acute MI, wide complex escape rhythms, or symptoms of hypoperfusion.
Catecholamines have only a limited role.
Vagolytics - The goal is to improve conduction through the AV node by reducing vagal tone via muscarinic receptor blockade. This only is effective if the site of block is within the AV node. For patients with infranodal block, this therapy is ineffective. Insufficient doses may cause paradoxical effects slowing further the heart rate. The admitting cardiologist will determine the timing of permanent pacemaker implantation.