Pacing the heart: Where are we at?

Introduction
The surgeon is often directly or indirectly involved in cardiac pacing. The involvement may be as minimal as supporting the cardiologist in gaining vascular access or as involved as to implanting an epicardial pacemaker. There are several things a surgeon should know for proper management of these cases.

Cardiac conditions requiring pacing
Permanent pacemakers are often implanted for 3rd degree atrioventricular (AV) block or sick sinus syndrome, less commonly they are used for patients with advanced 2nd degree AV block, atrial standstill, and sinus bradycardia. Presence of clinical signs associated with bradyarrhythmias is definitely an indication to intervene, however, a pacemaker can be also be considered for asymptomatic patients when circumstances require it. Rate of escape of subsidiary pacemaker sites is an important consideration. Feline junctional and ventricular escapes are usually > 100 bpm and do not cause symptoms. Rates < 90 bpm often cause symptoms. Canine ventricular escape rhythms are generally between 30 – 60 bpm. Rate < 40 bpm will likely cause lethargy, syncope or CHF. Experimentally, pacemakers have also been used for other conditions like hypertrophic cardiomyopathy and dilated cardiomyopathy. Additionally, pacemakers can be implanted in patients requiring nodal ablation often done in patients with refractory supraventricular tachycardia.

Temporary pacing can be a necessary temporary solution for surgical interventions in patients with anticholinergic unresponsive bradyarrhythmias.  [...]