- there is extensive evidence demonstrating the deleterious effect of prolonged right ventricular pacing on left ventricular function; prolonged right ventricular pacing has been shown to induce deleterious ventricular remodeling with increased ventricular volumes and increased risk of atrial arrhythmia
- prevention of unnecessary ventricular pacing allows battery saving, prolongs the life of the device and may reduce the frequency of battery replacement
- high percentage of right ventricular pacing in a patient implanted for sinus node dysfunction with preserved AV conduction should alert the physician at the time of interrogation and elicit a discussion regarding the use of specific algorithms
- evaluation of the burden of ventricular pacing is an important follow-up component in a patient with sinus node dysfunction, with the aim of reducing to minimum any unnecessary ventricular pacing
- different strategies and algorithms have been designed by device manufacturers to mitigate unnecessary ventricular pacing without inducing symptoms or compromising safety, when AV conduction is interrupted
- permanent programming of long AV delays may prevent ventricular pacing but may also sacrifice optimal end-diastolic preload by the atria, increase the risk of PMT and favor the occurrence of 2:1 block during exercise
- the concept of AV hysteresis refers to intermittent prolongation of the AV delay to promote intrinsic activation; this method, introduced before the development of dedicated pacing modes, is still available in the newer platforms of all different manufacturers
- specific pacing modes ensuring transition between DDD to AAI/ADI modes have been developed by the different manufacturers; the modes are easy to set up and program but the general philosophy of each of these modes needs to be perfectly understood
- it is not uncommon to be called by a nurse who considers a tracing with blocked P wave as corresponding to a device dysfunction; it is therefore essential to understand the operating principles of these specific modes so as not to be surprised if intermittent, blocked P waves occur
- these modes should be avoided in patients with high-grade AV block
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