Case presentation
We present the case of a 44-year old male who presented with a syncope and documented symptomatic sinus arrests on an insertable cardiac monitor (Reveal LINQTM, Medtronic Inc, Minneapolis, MN). Given his young age of the patient and the presence of a first degree atrioventricular block on his twelve lead electrocardiogram, the patient was planned for HBP. HBP was performed by delivering the SelectSecure 3830 pacing lead (Medtronic) through a long preshaped delivery sheat (C315HIS, Medtronic) towards the His region. After localizing a clear His signal with the tip of the pacing lead, the lead was screwed in by 4 to 5 clockwise rotations. At this first HBP implant site (Figure 1, upper panel), HBP resulted in selective HBP (S-HBP) at both high and low output with pacing threshold of 0.5V at 1.0ms pulse width. This first HBP implant site was accepted as final position. The day after implant, pacing thresholds were stable and the chest X-ray showed correct positioning of the HBP lead after which the patient was dismissed.
At three weeks after implant, the patient presented with exit block on the HBP lead. Interrogation of the pacemaker confirmed the absence of HB capture in unipolar pacing configuration and increased pacing thresholds up to 6V at 1.0ms in bipolar configuration. During lead revision, no macro-dislocation of the HBP lead was observed on fluoroscopy (Figure 1, middle panel) A new HBP lead was guided towards the His bundle region, keeping the first HBP lead in position to serve as anatomical reference (dual lead technique). The first screw attempt of this second HBP lead resulted in non-selective HBP (NS-HBP) at high pacing thresholds and transition towards S-HBP at 1.5V at 1.0ms (loss of capture at 0.75V at 1.0ms). Before slitting the guide sheat of this second HBP-lead, the first HBP lead was removed by 5 counter-clockwise rotations after which the lead came loose and could be completely removed without any resistance. No additional extraction tools were needed. No significant tissue was seen at the tip of the explanted lead. Pacing thresholds for the new HBP lead were stable the day after, but a systolic cardiac murmur was heard upon auscultation. Transthoracic echocardiography revealed the presence of a small perimembranous ventricular septal defect (VSD), located basal to the insertion of the new HBP lead (Figure 1, lower panel). The VSD presented with a restrictive left to right shunt on color Doppler with maximum flow velocitiy of 4,5 m/s; no aortic regurgitation, right ventricular dilatation or pulmonary hypertension were present. The peri-membranous VSD persisted with stable flow velocities over the left to right shunt during 6 months follow up. As the patient remained asymptomatic without developing hemodynamic sings of pulmonary arterial hypertension, VSD closure was not considered and regular follow-up was proposed. 7