General information

We retrospectively identified patients who received atrioventricular pacemaker implantation (DDDR pacemaker) in the Cardiovascular Division of our hospital from February 2018 to September 2019. According to the inclusion and exclusion criteria, patients meeting the requirements were screened periluminally, and arrangements were made for echocardiography at our hospital 1 year after implantation.

Inclusion criteria: Pacemaker implantation in patients with III° AVB. Before pacemaker implantation, LVEF was within the normal range (55% < LVEF < 80%). Exclusion criteria: 1. Complicated arrhythmia; 2. LVEF decreased (LVEF < 55%); 3. Aortic stenosis or moderate or above reflux; and 4. Complicated hypertension, kidney disease, and cardiomyopathy. Additionally, the pacemaker programming method of patients enrolled in the case group should meet the following criteria. (1) Subjects with continuous ventricular pacing dependence after implantation were excluded. Double-chamber permanent pacemaker implantation patients with a preoperative diagnosis of III° AVB were included, and the proportion of ventricular pacing (VP) was confirmed to be greater than 95% between the last follow-up and the date of test by the programmed pacemaker. (2) To ensure that the subject’s ventricular excitement does not bypass its own atrial-ventricular transmission fusion, the programmed pacemaker was set to 350 ms without its own atrial-ventricular transmission after PAV and SAV (the pacemaker was in the state of VP). (3) After the aforementioned verification, to unify the subjects’ AV interphase, the AV interphase was adjusted to PAV/SAV 160/120 (MS). (4) The pacing QRS width of the subjects in ventricular pacing state was measured and recorded manually. The measurement method employed was the lead with the widest QRS wave in the subject’s standard 12-lead electrocardiogram. Before inclusion in the HPSAP group, the pacing position was verified by TTE (Figure 1).

Echocardiography to position the HPSAP electrode. The red arrow indicates that the end of the pacemaker electrode is located below the endocardium of the left ventricle.

According to the criteria, a total of 43 patients were collected and divided into the following categories according to the method of pacemaker implantation. A total of 20 patients were included in the VSP group, comprising 15 men and 5 women ranging from 52 to 80 years old (mean ± s.d., 68.7 ± 12.3). In the HPSAP group, there were 23 patients, comprising 20 men and 3 women, aged from 55 to 78 years (72.4 ± 4.0). As control group subjects, 40 volunteers with no abnormalities in biochemistry, ECG, and or cardiac ultrasound examination were selected, including 30 men and 10 women, aged from 54 to 77 years (64.3 ± 10.5).