From bedside to bench: entrainment and other stories

The concepts of transient entrainment of reentrant rhythms started with studies of overdrive pacing of atrial flutter (AFL) in patients in the immediate period after open heart surgery. Initial studies demonstrated the need to achieve a critical pacing rate and a critical duration of pacing at the critical pacing rate to interrupt AFL. Further pacing studies of AFL, ventricular tachycardia, atrioventricular (AV) reentrant tachycardia, AV nodal reentrant tachycardia, and atrial tachycardia refined the understanding of what occurs during overdrive pacing of reentrant tachycardias, and permitted a mechanistic understanding of transient entrainment as continuous resetting of a reentrant tachycardia to a pacing rate that is faster than the rate of the tachycardia, but which fails to interrupt it. The demonstration of transient entrainment of a tachycardia provides a reliable clinical tool to establish the presence of a reentrant rhythm. Moreover, the principles of entrainment have also been applied clinically to assist in effective application of antitachycardia pacing and catheter ablation techniques.