A review of the atrial upper rate algorithms of St. Jude Medical (Abbott) cardiac implantable electronic devices

Abstract

This review focuses on the manifestations of the three triggered atrial upper rate functions of St Jude Medical cardiac implantable electronic devices. The occurrence of repetitive nonreentrant ventriculoatrial synchrony (RNRVAS) is also evaluated as a basis for the development of automatic mode switching (AMS) and as a trigger for atrial tachycardia/atrial fibrillation (AT/AF) event recordings. RNRVAS is a common trigger for AMS because all the atrial events or intervals are used to calculate the filtered atrial rate interval (FARI). Once AMS is initiated, it will also effectively stop RNRVAS because entry into AMS also shortens the postventricular atrial refractory period (PVARP). Recent design developments to eliminate or minimize unusual upper rare responses include the following: (1) P waves in the PVARP are no longer counted towards the FARI if they are followed by an atrial paced event. (2) In new devices the AT/AF detection algorithm substitutes the Moving Average Interval (a relatively complex calculation) with the new FARI average. (3) Improved design of the rate-responsive PVARP with a far more aggressive response than in the past (enhanced atrial protection interval).

A sudden change in pacing rate: Normal or malfunction?

“…Every episode started with an intrinsic P wave, which is consistent with the startup characteristics of AMS in the SJM (Barold, 2017). However, no atrial tachycardia was observed before any episode.…”

Potential triggering of repetitive nonreentrant ventriculoatrial synchrony by loss of atrial capture

“…RNRVAS was first described by Barold (1991). Several studies showed that in two‐chamber devices, long AV delay, long PVARP, short lower rate interval, presence of VA conduction and long VA conduction periods were predisposing factors of RNRVAS (Barold, 1991, 2017; Barold & Levine, 2001). A few studies described ventricular ectopic beats and retrograde atrial conduction after ventricular pacing as a trigger mechanism for RNRVAS (Barold, 1991; Sharma et al, 2016).…”

“…These data prove RNRVAS is underreported and in fact more frequently encountered than currently estimated. In the ASSERT study, all the pacemakers were of St Jude Medical and atrial arrhythmia recognition algorithms of St Jude Medical devices are thought to be more sensitive in recognizing RNRVAS (Barold, 2017; Barold & Stroobandt, 2012; Kaufman et al, 2012). In St Jude Medical devices, AHRE algorithms use both sensed and paced atrial signal for recognition, therefore RNRVAS attacks are recorded as AHRE (Barold, 2017).…”

“…In the ASSERT study, all the pacemakers were of St Jude Medical and atrial arrhythmia recognition algorithms of St Jude Medical devices are thought to be more sensitive in recognizing RNRVAS (Barold, 2017; Barold & Stroobandt, 2012; Kaufman et al, 2012). In St Jude Medical devices, AHRE algorithms use both sensed and paced atrial signal for recognition, therefore RNRVAS attacks are recorded as AHRE (Barold, 2017). The actual incidence of RNRVAS is unknown due to the absence of specific algorithms for recognizing RNRVAS in CIEDs.…”

“…To the best of our knowledge, there are no algorithms specifically for detection or termination of RNRVAS in the devices available today. Certain adjustments in device programs may prevent or terminate RNRVAS (Barold, 1991(Barold, , 2017Barold & Levine, 2001;Sharma et al, 2016) and we recommend that as many of these modifications as possible be included in the upcoming device algorithms. devices have noncompetitive atrial pacing algorithm which is programmable and may eliminate RNRVAS (Bertaglia et al, 2019).…”