Background
The terms “programmed stimulation” and “entrainment,” in the context of this article, refer to specific methods of pacing the heart. Typically, these techniques are used to gather information about the cardiac conduction system, which can then be used to guide the treatment of heart rhythm disorders.
As an example of its utility, these techniques demonstrated that most ventricular tachycardia in the setting of ischemic heart disease is reentrant rather than automatic.
These observations have led to the development of anti-tachycardia pacing as a painless alternative to high-energy implantable cardioverter-defibrillator (ICD) shocks and have been instrumental in guiding the ablative therapy of ventricular and supraventricular arrhythmias.
Programmed stimulation, which is a means of entrainment, is most commonly used during invasive electrophysiologic studies, although it may also be accomplished to some degree through an existing pacemaker or implanted defibrillator. Most of this article focuses on the principles involved, which can be applied in either situation.
This article also discusses some of the historical basis for the techniques and the general electrophysiologic principles involved in programmed stimulation of the heart, although a comprehensive review of the subject is beyond the scope of this article. While these techniques are typically used to guide ablation, the discussion of ablation per se is also beyond the scope of this article.