Delivery System Support Prevents Endocardial Entanglement and Delamination During Left Bundle Branch Area Pacing

BACKGROUND: The mechanisms behind endocardial entanglement and resultant delamination during left bundle branch area pacing, as well as potential solutions, have not been fully demonstrated in the human heart. METHODS: Active fixation of a lumenless screw-in lead into the right ventricular septum was attempted with or without delivery system support using donor human hearts rejected for transplant. Delivery sheath support was ensured through firm catheter support maintained by a fixed clip. Endocardial entanglement, endocardial delamination after unscrewing, and lead penetration were evaluated using both macroscopic and microscopic analyses. RESULTS: <0.001). In the regions with endocardial entanglement, histological analysis confirmed extensive endocardial delamination with minimal myocardial injury. On the other hand, localized endocardial delamination and deep intramural penetration were observed in the regions without entanglement. Screw-in procedures reattempted into the regions with extensive endocardial delamination following entanglement achieved deep penetration even without delivery system support. CONCLUSIONS: Endocardial entanglement and delamination were confirmed in donor human hearts. Adequate delivery system support, particularly its coaxiality and counterforce effect, is likely to prevent endocardial entanglement and facilitate effective penetration of a lumenless screw-in lead into the human ventricular septum.