A Prospective Multicenter Study on the Safety of a Pacemaker with Automatic Energy Control: Influence of the Electrical Factor on Chronic Stimulation Threshold.

Abstract

The effectiveness and safety of a pacemaker with automatic control of capture was evaluated in 162 patients followed at 27 Spanish centers. The aim of our prospective, multicenter, and randomized trial was to determine the relationship between the voltage output of the pulse generator and the stimulation threshold. We randomized 162 patients (107 men, mean age 75 +/- 12 years). We implanted a ventricular pacemaker model Regency SR+ or SC+ with Pacesetter's low polarization bipolar leads Membrane E 1450. The patients were randomized to receive Autocapture or not; group I (81 patients) Autocapture On, pulse output automatically adjusted and group II (81 patients) Autocapture Off, fixed output parameters (3.9 V, 0.37 ms). We performed a 6-month follow-up measuring stimulation threshold by means of the VARIO test and Autocapture test, evoked response signal, and R wave signal. The mean R wave was 15.77 +/- 3.5 mV at the end of the follow-up for group I, and 14.91 +/- 6.8 mV for group II (P = NS). The measured evoked response at the end of the follow-up was 9.25 mV in Group I and 8.48 mV in Group II (P = NS). The stimulation threshold was not different between groups. The current density created with the voltage and pulse width used in this study (< or = 3.9 V and 0.37 ms) at the tip of this electrode during the maturation process had no influence on the development of the chronic detection and stimulation thresholds.

Automated Left Ventricular Capture Management

“…Importantly, we did not observe the erroneously high thresholds that are sometimes seen in the evoked potential methods. These could be very bothersome in CRT devices by causing both diminished longevity and the possibility of phrenic nerve stimulation 6 . The data on the variability of the LV threshold supports the need for capture management and in that there are a significant number of patients with a high degree of threshold variation.…”

“…These could be very bothersome in CRT devices by causing both diminished longevity and the possibility of phrenic nerve stimulation. 6 The data on the variability of the LV threshold supports the need for capture management and in that there are a significant number of patients with a high degree of threshold variation. New CRT-D systems include this ability to automatically measure the LV capture threshold.…”

“…These methods have been shown to be fairly accurate but are significantly limited by the presence of premature ventricular contractions. 6 These capture management methods have generally resulted in an increase in predicted longevity. 7 However, this impact may be greater with a more reliable measure of the stimulation threshold.…”

Underestimation of Pacing Threshold as Determined by an Automatic Ventricular Threshold Testing Algorithm

“…Automatic pacing threshold algorithms have been demonstrated to be safe and useful for prolonging device longevity. [7][8][9] It should be noted that an automatic capture algorithm that examines an evoked response on a beat-to-beat basis would have prevented the adverse clinical outcome described in this case report. However, examples have been reported where these algorithms led to adverse clinical outcomes.…”

Clinical Evaluation of Two Different Evoked Response Sensing Methods for Automatic Capture Detection in the Left Ventricle

“…Alternative methods shown to be effective in reducing polarization include coating of the lead with titanium nitride or iridium oxide, thereby increasing the lead/tissue interface surface area and reducing polarization, 14 and separation of the pacing and sensing vectors. 18 Both of these methods restrict the leads compatible with the feature to low polarization leads, [23][24][25] or bipolar leads, respectively. The LV Ring →Can vector investigated in this study demonstrated the feasibility of a modification to the methodology published by Butter et al 18 In contrast to the methodology published by Butter et al, the LV Ring →Can sensing vector shared the Can electrode between the pacing and sensing vectors during LV unipolar pacing in this study.…”