The importance of avoiding unnecessary right ventricular pacing in clinical practice

Table 2 Pacemaker algorithms that reduce right ventricular pacing

Reverse Mode Switch/RYTHMIQ™ (Boston Scientific, St. Paul, MN, United States)

Atrial based pacing in AAI(R) with VVI backup (LRL minus 15/min) with the two modes operate independently from one another. If complete AVB occurs, ventricular paces will be delivered at backup VVI rate, asynchronous to the AAI rate. If 3 slow ventricular beats are detected in a window of 11 beats, AV conduction is considered blocked and switch to DDD (R) takes place. The algorithm will switch back to AAI if intact AV conduction is recuperated

Managed Ventricular Pacing™ (Medtronic, Minneapolis, MN, United States)

Atrial based pacing (labeled as AAI(R)+) with switch to DDD(R) if AV block is detected, defined as 2/4 absent ventricular event. The algorithm checks for AV conduction at regular intervals and if present it will switch back to AAI(R)+

Ventricular Intrinsic Preference™ (St. Jude Medical, Sylmar, CA, United States)

Intrinsic AV conduction is assessed by increasing AV delay at regular intervals (programmable AV extension of up to 200 ms; maximum AV delay 350 ms). If present, the longer AV delay will be maintained until a programmable number of cycles of absent ventricular sensed events (i.e., continuous need for ventricular pacing), thus deactivating the algorithm

AV hysteresis (Biotronik, Berlin, Germany)

Similar to Ventricular Intrinsic Preference™ (St. Jude)

AAISafeR™ and AAISafeR2™ (Sorin Group, Mirandola, Italy)

Atrial based pacing in AAI (R). Abnormal AV intervals (> 350 ms if atrial sensed; > 450 ms if atrial paced) are monitored. Switch to DDD in response to any of the following:

> 6 abnormal AV intervals (“first degree AVB”)

> 3/12 nonconducted atrial events (“second degree AVB”)

> 2 consecutive nonconducted atrial event (“advanced AVB”)

Ventricular pauses of 2–4 s (programmable)

AV: Atrioventricular; AVB: Atrioventricular block; LRL: Lower rate limit; VVI: Ventricular.