Worsening Heart Failure From Decreased Atrioventricular Synchronization Rate of a Leadless Pacemaker

Figures

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  Figure 1. 12-Lead Electrocardiograms Before Micra AV Implantation, With and Without Atrioventricular Synchrony After Micra AV (Medtronic) Implantation (A) Complete atrioventricular block before the implantation of a leadless pacemaker (Micra AV). (B) Atrial mechanically synchronized ventricular pacing after implantation of a leadless pacemaker (Micra AV) (2 years before the current admission). (C) Atrioventricular dyssynchronous pacing on admission for congestive heart failure (current hospitalization).

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  Figure 2. Fluoroscopic Images of a Leadless Pacemaker A leadless Micra AV pacemaker (Medtronic) was located in the right ventricular apical septum in (A) the right anterior oblique view and (B) the left anterior oblique view.

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  Figure 3. Time Course of the Echocardiographic Parameters of the LVOT VTI and the LVEF The left ventricular outflow tract velocity-time integral (LVOT-VTI) and the left ventricular ejection fraction (LVEF) had decreased after implantation of a leadless pacemaker. Both parameters were worse on admission for heart failure. Reprogramming the pacemaker settings improved both parameters. After 1 year, the left ventricular ejection fraction increased to more than 50%.

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  Figure 4. Atrial Mechanical Synchronized Ventricular Pacing Reprogramming of pacemaker parameters by prolonging the A3 window end (from 600 ms to 675 ms) and increasing the A4 threshold (from 1.0 m/s2 to 1.8 m/s2); atrial mechanical synchronized ventricular pacing is almost obtained. PVAB = post ventricular atrial blanking.

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  Figure 5. Electrocardiographic Change After Reprogramming the Pacemaker Parameters The manual atrial mechanical test reveals that atrial mechanical oversensing causes atrioventricular dyssynchronous ventricular pacing. After reprogramming the parameters, (P-wave, lower triangle; PQ interval <300 ms, arrow; PQ interval ≧300 ms) synchronized ventricular pacing was obtained with heart rate (HR) reduction. bpm = beats/min.