Implant procedure
Electroanatomical mapping was used during the implant in 6 patients: 4 with cc-TGA (1 with additional dextrocardia and 1 with a double switch operation), 1 with D-TGA and atrial switch operation (Senning) and in 1 patient with repaired VSD in order to identify the HB area and to delineate the anatomy (Figure 1).
Overall, acute implant success defined by HBP or LBBAP criteria was 100%. HB pacing was attempted in 14 patients (6 patients with cc-TGA, 3 Tetralogy of Fallot, 2 with a repaired VSD, 1 patient with D-TGA and a Rastelli correction, 1 with Ebstein’s anomaly and 1 with AV canal) and was successfully achieved in 10 (71%). The 4 patients with unsuccessful HBP underwent LBBAP. In the remaining 6 patients LBBAP was used as the primary implant strategy. Strict LBB capture criteria were present in 5 patients and these patients were deemed to have LBBP while the remaining 5 patients were defined as LVSP with a significant reduction in final paced QRS width (figure 2). The time employed for the CSP lead implant widely varied ranging from 4-115 minutes with a mean of 31±28 min. The mean total implant procedure duration was 126±82 min.
A standard C315 His sheath was used first in all patients except one in which a C315S sheath was employed. Additional sheaths (C304 or others) were used in 10 patients (50%) due to difficulties in either localizing or achieving stable positions with the C315 His sheath. However, at the end, a C315 His or C315S sheath was used for definitive lead deployement in 14 patients (74%) and a C304 sheath was used for lead fixation in 4 patients. In 1 patient (D-TGA and large VSD corrected with a Rastelli surgery) a standard active fixation lead (Solia S53, Biotronik) was finally used with a previously preformed stylet to get access to the HB area resulting in a successful implantation. In patient #11 with a cc-TGA and a double switch operation a Attain Command 6250V-3D sheath was used for lead delivery. Table 2 summarizes the principal baseline characteristics and implant details for each patient.