A Rare Case of RNRVAS Termination and Re‐Initiation Visualized on a 12‐Lead ECG

Figures

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  FIGURE 1. (A) A standard 12‐lead electrocardiogram showing abrupt cessation (red box) and re‐initiation (blue box) of ventricular pacing (VP), accompanied by a series of atypical rhythm changes. (B) A standard 12‐lead electrocardiogram is shown. Within the blue box, a characteristic pattern of RNRVAS is visualized: ① VP → ② retrograde P wave → ③ non‐captured AP due to atrial refractoriness, forming a repetitive loop. AP, atrial pacing; RNRVAS, repetitive non‐reentrant ventriculoatrial synchrony; VP, ventricular pacing.

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  FIGURE 2. Atrial IEGM, leadless ECG, ventricular IEGM, and event marker channels are displayed. Immediately after an APC (red circle), AP (blue circle) was delivered during the atrial refractory period, followed by VP after the programmed AVD. Retrograde atrial activation was observed after VP, confirming the presence of VA conduction. This VA conduction triggered PMT, as indicated by the blue arrow. PMT was subsequently terminated by the device's PMT termination algorithm (red arrow). AP, atrial pacing; APC, atrial premature contraction; AR, atrial refractory; AS, atrial sensing; AVD, atrioventricular delay; ECG, electrocardiogram; IEGM, intracardiac electrogram; PMT, pacemaker‐mediated tachycardia; VA, ventriculoatrial; VP, ventricular pacing.

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  FIGURE 3. Limb leads extracted from the standard 12‐lead electrocardiogram are shown. Three consecutive VP events occurred during the extended AVD of 450 ms, resulting in VIP OFF (purple line). After VIP OFF, the AVD returned to its baseline value of 250 ms, and the VA interval was prolonged to 607 ms (857–250 = 607). In the previous beat, when VIP was ON, the VA interval was 407 ms (857–450 = 407). This prolonged VA interval allowed the AP stimulus to effectively capture the atrium (highlighted in yellow) beyond the physiologic refractory period caused by the preceding retrograde conduction, leading to the termination of RNRVAS (red line). Subsequently, VIP was reactivated (VIP ON) after three consecutive VS detections within the normal AVD (gray area). Abbreviations such as RNRVAS are defined in Figures 1A,B and 2. AA, atrial–atrial; PVARP, post‐ventricular atrial refractory period; VIP, ventricular intrinsic preference.

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  FIGURE 4. (A) Limb leads extracted from the standard 12‐lead electrocardiogram are shown. This figure illustrates the PVARP during PVC response, the normal PVARP, the PVAB, and the VA interval. Following a PVC, the PVC response algorithm was activated, resulting in an extended post‐ventricular atrial refractory period (PVARP, orange area). A retrograde P wave was sensed within this extended PVARP, and atrial pacing was delivered during the atrial refractory period (non‐capture). Consequently, RNRVAS was re‐initiated, as indicated by the blue line. (B) Limb leads extracted from the standard 12‐lead electrocardiogram illustrating the initiation of RNRVAS following a PVC (⑦, green box). The PVC is followed by a retrograde P wave (⑧, red circles), which is sensed during the PVARP. This triggers the device's PVC response algorithm, delivering AP 330 ms after AR sensing (⑨, magenta arrows). However, the atrium remains refractory at the time of pacing, resulting in non‐capture of AP stimuli (⑩, blue squares). This sequence repeats, initiating the RNRVAS cycle. The blue arrow highlights the continuous RNRVAS loop generated by this paradoxical algorithmic response. Abbreviations such as RNRVAS are…