Figure 2.

The 12-Lead Electrocardiogram Before and After Leadless Pacemaker Infection, Suggesting Right Bundle Branch Injury

Although the change is minor, the appearance of a positive notch within the QRS complex of V₁, indicative of a delay in right ventricular depolarization, may be caused by an infectious involvement of the right bundle branch in the setting of right ventricular septal pacing near the base of the moderator band. An alternative explanation for the notch would be that it represents a myocardial scar or anisotropic conduction in the setting of chronic or acute hemodynamic shifts, given that the V₁ voltage dropped from 14 mV to 10 mV and the P-wave developed a deeper negative deflection suggestive of a P-mitrale pattern. The electrocardiograms were recorded 9 months apart and, for the low- and high-pass filters, were set at 150 Hz and 0.05 Hz, respectively. Of note, the shift in precordial transition (V₅ preinfection vs V₄ during infection) seems to reflect only changes in the position of the leads, as this shift was not consistent across serial electrocardiograms.