ABSTRACT
Objective: To observe the automatic ventricular capture management (VCM) conifrmed by paced depolarization integral (PDI) evoked response detection via the follow-up study in patients with Zephyr5826 pacemaker implantation. Methods: A total of 102 relevant patients were enrolled. In order to conduct PDI calculation, pacemakers were set by bipolar sensing and bipolar pacing at immediately after implantation. VCM functions were observed at 1 day, 7 days and 1 month, 3, 6, 12 months after implantation, the ventricular threshold by VCM test and manual test were compared. The symptoms of pectoralis major stimulus, diaphragm stimulus and palpitation were observed in all follow-up patients. Results: There was 1 patient died by MI at 1 month after Zephyr5826 pacemaker implantation, the rest 101 patients were followed-up for 12 months. VCM function was successfully turned-on at immediately after implantation in all patients, no pectoralis major stimulus and diaphragm stimulus occurred. VCM function was turned-off in 6/101 (5.9%) patients at 7 days after implantation due to intolerable palpitation caused by daily automatic VCM, instead they received manual test at follow-up visit. The coincidence rate of ventricular thresholds between VCM test and manual test were 100%. Ventricular pacing output voltage by VCM was (0.99 ± 0.48) V,n=608. Compared with regular pacing output voltage (2.5V, 0.4ms), VCM function may save 84% of energy consumption; compared to high pacing output voltage (3.5V, 0.4ms), VCM may save 92%. Loss of ventricular capture and poor sensation were not found by ECG and 24 h dynamic monitoring. Conclusion: Zephyr5826 pacemaker may conduct bipolar pacing and scanning with VCM function, it can be effectively and safely operated by low energy output. A few patients may not use VCM function due to intolerable palpitation.
ABSTRACT
Objective Right ventricular outflow tract septum has become widely used us an electrode placement site. However, data concerning lead performances and complications for lead repositioning with this technique were scant. The purpose of this study was to observe long-term lead performances and complications of right ventricular outflow tract septal pacing and provide evidences for choosing an optimal electrode implantation site. Methods Thirty-six patients with septal active electrode implantation and 39 with apical passive electrode implantation were enrolled in this study. Pacing threshold, R-wave sensing, lead impedance, pacing QRS width and pacing-related compli-cations for two groups at implantation and follow-up were compared. Results There were higher pacing threshold and shorter pacing QRS width at implantation in the septal group compared with the apical group. There were no differences between the septal and the apical groups in pacing threshold, R-wave sensitivity, lead impedance and pace-related complication during a follow-up. Conclusions Right ventricular outflow tract septum could be used as a first choice for implantation site because it had long-term stable lead performances and no serious complications compared with the traditional apical site.
ABSTRACT
Serial meanurements of the pacing threshold have been considered as essential for follow-up of the patients in whom the pacemaker had been implanted because pacing threshold is directly related to the success of long-term pacemaker therapy and reflects the alterations in electrobiologic factors influencing it. The development of the noninvasive technique of measuring pacing threshold such as Vario system made the noninvasive follow-up of it feasible and therefore has contributed to understanding of long-term threshold behavior. This study was performed to get the knowledge of acute and chronic pacing threshold behavior by measuring it serially in 46 patients after pacemaker implantation using a non invasive technique of Vario system. Patients subjected to the present study were 46(18 males, 28 females) comprising 21 sick sinus syndromes, 24 A-V blocks, and 1 combined disorder. All were received a multiprogrammable pacemaker of VVI mode (OPTIMA-MP, Telectronics). Pacing threshold was increased significantly from initial threshold(0.65+/-0.22) 2 days after implantation and reached to peak(1.65+/-0.75 volts) in the fourth week, thereafter it was maintained around twice the initial value. In the 30 patients followed more than 3 months, the maximum increase and difference in pacing thresholds were 0.86+/-0.62 volts and 0.93+/-0.56 volts respectively and the ratios of peak threshold and threshold at the end of follow-up to initial threshold were 2.56+/-1.23 and 2.30+/-1.30 respectively. Pacing threshold exceeded 2.0 volts in 7 patients(15.2%), but transiently in 3 of 5 patients in whom it happened within 6 weeks after implantation. Safety margins of long-term thresholds were acceptable(more than 3) in all patients at 5.0 volts and 19(63.3%) at 2.5 volts of programmed output.