Implantation site
During implantation, the implanter intended to deploy MicraTM pacemaker in the mid-septum based on the fluoroscopic RAO 30 image. Postoperative 3D reconstructive CT image of the heart was completed in all patients in both groups and the position of the MicraTM pacemaker in the ventricular septum was determined. Figure 2A-C show an example of MicraTMpacemaker deployment in the mid-septum in zone 2 at implantation and confirmed in the post-implantation CT scan. Post-operative CT reconstructed image confirmed the MicraTM pacemaker location in septal zone 2 (mid-septum) in 13 cases in the non-radiography group (48.1%, 13/27) and 76 cases in the radiography group (93.8%, 76/81, Figure 2D). The difference in the accuracy of intended deployment sites between two groups was significant (P < 0.0001). Other locations confirmed by CT-scan image included the superior and inferior septum as shown in Figure 3. In the non-radiography group, MicraTM pacemaker was deployed in the inferior septum in 6 patients (22.2%) and the superior septum in 8 patients (29.6%) while in the radiography group, MicraTM pacemaker was deployed in the inferior septum in 2 patients (2.5%) and the superior septum in 3 patients (3.7%). In comparison with fluoroscopic image, the site in the superior septum identified in the CT image was found in zone 1 of the fluoroscopic nine-partition image while the site in the inferior septum in CT image was found in zone 3 that was close to the right ventricular apex.