Computer Modeling of DDD Pacemakers for Use in Prophylaxis of Junctional Reentry Tachycardia

A computer simulation model of cardiac rhythm and heart-pacemaker interactions has been used to examine the response of short AV delay DDD pacing to an atrial premature depolarization in patients with a potential junctional reentry circuit. Special attention was given to the possibility of using the pacemaker to prevent atrioventricular reentry tachycardia mediated by a bidirectional accessory pathway. The computational experiments examined: (a) the differences between pacing modes with constant and quasi-Wenckebach prolongation of AV delay; (b) the effects of imposing therestrictions of a pacemaker atrial refractory period and upper rate limit; and (c) the effects of varying the ventricular refractory period so that it was either the same or longer than that of the atria. The computational results prove that some possible modes of initiation of functional reentry tachycardia are beyond theprophylactic capabilities of current DDD pacemakers. Future possibilities involving theuse of computer modeling to develop more sopbisticated pacemaker modes are briefly discussed.