Perioperative and post-operative bradycardia is relatively common during and after heart transplant. Possible etiologies including sympathetic denervation, ischemic injury to the sinus node, and graft ischemia. In the post-operative setting progressive conduction system disease associated with coronary artery disease, chronic rejection, and injury from routine endomyocardial biopsies can all result in AV dysfunction and subsequent heart block and junctional bradycardia. Management in the perioperative period can be done via external pacing wires – because these are inserted directly into the myocardium, they are unaffected by sinus node function. Alternatively, bradycardia can be treated with direct sympathomimetics such as isoproterenol and epinephrine/norepinephrine. It has been historically understood that indirect agents such as ephedrine or those that work via a vagolytic mechanism (glycopyrrolate, atropine) will not be effective in increasing heart rate, due to total autonomic denervation. In the post-operative setting, pacemakers are indicated for bradycardia that does not resolve.
Heart transplant: Autonomic effect