Syncope after successful implantation of atrioventricular synchronous leadless pacemaker caused by polymorphic ventricular tachycardia

Figure 1. Thoracic fluoroscopy view depicting the Micra delivery system after deployment of the Micra device (Medtronic, Minneapolis, MN). View is confirming proper placement at the septal aspect of the right ventricle on a: standard left anterior oblique view and b: right anterior oblique view.

Figure 2. Telemetry strip showing initiation of polymorphic ventricular tachycardia following a paced beat (blue arrows) after premature ventricular contraction (orange arrows). Dissociated atrial activity is marked with green arrows. Accelerometer sensor failed to detect the mechanical atrial activity and led to premature pacing at the lower programmed rate. Figure shows the short-long-short setup for polymorphic arrhythmia in this patient.

Figure 3. A: The correlation between recorded surface electrocardiogram and accelerometer sensing of ventricular mechanical changes during different phases: A3: passive ventricular filling, A4: active atrium contraction. Shown is a successful electromechanical correlation after adjusting A4 sensing and treatment with beta blockers. PVAB = postventricular atrial blanking period. B: Changes in accelerometer sensing threshold over time in this patient. Improper sensing after implantation is noted (threshold > 1.6 m/s2). It also shows improvement in the A4 acceleration sensing after adjustments made to sensing parameters and titrating up beta blocker dose over time.