To evaluate electrode position and left ventricular ejection fraction in patients undergoing left bundle branch pacing (LBBP) by echocardiography.

Sixty-four patients who underwent LBBP at Hwa Mei Hospital of University of Chinese Academy of Sciences from March 2018 to October 2020 were selected. According to the position of the pacing electrode, they were divided into an anterior ventricular septum group (17 cases) and a posterior ventricular septum group (47 cases). According to the preoperative left ventricular systolic function, the patients were divided into a normal left ventricular systolic function group (44 cases) and an abnormal left ventricular systolic function group (20 cases). All patients underwent echocardiography within 3 days before operation and 3 months after operation to evaluate the positioning of pacing electrodes , and to compare and analyze the left ventricular systolic function before and after LBBP operation.

Echocardiography showed that the electrode screwing depths in the anterior ventricular septum group and the posterior ventricular septum group were (10.6±1.6) mm and (10.3±1.6) mm, respectively, and there was no significant difference between the two groups (P=0.72); the distance between the electrode screwing point and the right coronary valve of the aorta in the anterior ventricular septum group was (23.9±5.5) mm, while the distance between the electrode screw-in point and the root of the tricuspid septum in the posterior ventricular septum group was (24.1±5.3) mm. In patients with normal left ventricular systolic function, the left ventricular diastolic volume (LVEDV), left ventricular systolic volume (LVESV), and left ventricular ejection fraction (LVEF) before surgery were not statistically different from those at 3 months after surgery (P＞0.05 for all). In the abnormal left ventricular systolic function group, the LVEDV and LVESV at 3 months after operation were significantly lower than those before operation, and the LVEF was significantly higher than that before operation (P＜0.05 for all). Among the 64 patients, two had the electrode tip penetrating the left ventricular surface of the ventricular septum and entering the left ventricular cavity, and the other 62 had no complications.

LBBP can improve left ventricular systolic function in patients. Echocardiography can display the depth and position of the LBBP electrode into the ventricular septum, providing valuable information for accurate clinical positioning and pacing, and playing an important role in the follow-up assessment of left ventricular systolic function before and after LBBP surgery.