Case Report
A 78-year-old man with a body mass index of 26.5 kg/m2had paroxysmal atrial fibrillation (AF). He was taking rivaroxaban 30 mg daily. He underwent two catheter ablation procedures to treat the AF, but the AF recurred. Because he experienced cryptogenic syncope, an implantable cardiac monitor (ICM) (Jot Dx TM Abbott) was implanted. A month after the ICM implantation, sinus node arrest was detected on the ICM when the AF terminated. Based on that finding, we decided to implant an Aveir LP. Figure 1A-1B shows the contrast imaging taken just prior to the fixation of the Aveir LP delivery catheter. At the end of the procedure, the pacing thresholds were 0.75V/0.2 msec and 0.5V/0.4 msec and there were no abnormalities in the position of the Aveir LP (Figure 1C ). One month after the implantation, the pacing thresholds increased to 1.25V/0.2msec and 2.5V/0.4msec, and a chest x-ray showed that the docking button side of the Aveir LP had dropped (Figure 1D) . Four months after the implantation, the pacing thresholds continued to deteriorate to 5.0V/0.2 msec and 3.5V/0.4 msec, and on chest x-ray, the docking button side of the Aveir LP had dropped further toward the inferior wall of the RV (Figure 1E) . The helix of the Aveir LP was found to be attached to a trabeculation within the RV endocardium on the cardiac CT scan (Figure 1F) , which was thought to cause instability of the position of the Aveir LP. In addition, on the 3D CT images, the docking button of the Aveir LP was fixed to the inferior wall of the RV (Figure 1G-1H ). This patient experienced pre-syncope due to pacing failure. Thus, 6 months after the implantation, we decided to perform a retrieval of the Aveir LP and a replacement with a Micra LP (Medtronic Inc., Minneapolis, MN). During the procedure the patient was sedated with dexmedetomidine and propofol while monitoring the bi-spectral index. We performed RV angiography and confirmed the position of the Aveir LP from the right anterior oblique (RAO) and left anterior oblique (LAO) views (Figure 2A-2B ). As observed in the preoperative cardiac CT, the docking button side of Aveir LP had dropped to the inferior wall of the RV. The Aveir LP introducer was placed through the right femoral vein while the AgilisTM sheath was positioned through the left femoral vein. An initial attempt was made to capture the docking button with the Aveir LP retrieval catheter (Figure 2C ). The docking button was wedged into the inferior wall of the RV, so we could not capture it with the tri-loop snare of the Aveir LP retrieval catheter. An attempt was then made to release the wedged docking button using an electrode catheter inserted through the AgilisTM sheath via the left femoral vein. However, the electrode catheter could not be maneuvered under the Aveir LP body and the position of the Aveir LP body could not be adjusted (Figure 2D-2E) . The AgilisTM sheath for use with a pigtail catheter was then inserted through the right internal jugular vein. The pigtail catheter was advanced from the RV septum toward the free wall of the RV, and then a RadifocusTMguidewire was advanced to the caudal side of the Aveir LP body (Figure 2F) . After the pigtail catheter was advanced over the RadifocusTM guidewire, we captured the pigtail catheter using a single-loop snare in the right atrium via the left femoral vein (Figure 2G-2H) . By simultaneously pulling the pigtail catheter from the cranial side and the single-loop snare from the caudal side (Figure 2I) , the docking button was released from the inferior wall of the RV, and a swing movement (SM) of the Aveir LP was observed under fluoroscopy (Figure 2J) . Then, we successfully captured the docking button using the tri-loop snare of the retrieval catheter and subsequently docked the retrieval catheter with the Aveir LP (Figure 3A-3C) . We also confirmed that there was no entanglement between the Aveir LP and RV structures using a protective sleeve (Figure 3D) . The Aveir LP was able to be released from its fixation to the trabeculation of the RV endocardium by unscrewing it counterclockwise. The retrieval catheter was removed from the Aveir LP introducer (Figure 3E) . RV angiography did not show any contrast retained in the pericardial sac (Figure 3F-3G) . We inserted the Micra delivery catheter and placed the Micra in the low septum of the RV (Figure 3H-3I) . The Aveir LP body and the retrieval catheter did not have any myocardial tissue or fibrosis (Figure 3J) . No major complications were observed during the extraction procedure or follow-up period.