Bibliothek

Notizen: CABRERA, M.E., et al.: Can Current Minute Ventilation Rate Adaptive Pacemakers Provide Appropriate Chronotropic Response in Pediatric Patients? Since children have different activity patterns and exercise responses, uncertainty exists as to whether minute ventilation (MV) sensors designed for adults provide adequate chronotropic response in pediatrics. In particular, high respiratory rates (RR 〉 48 breaths/min), which are characteristic of the ventilatory response to exercise in children, cannot be sensed by MV rate responsive pacemakers. The purpose of this study was to evaluate the MV sensor rate response of the Medtronic Kappa 400 using exercise data from healthy children in a computer simulation of its rate response algorithm. Thirty-eight healthy children, ages 6–14, underwent a treadmill maximal exercise test. Subjects were divided based on body surface area (BSA) and MV rate response parameters were selected. Respiratory rates and tidal volumes were entered into the Kappa 400 rate response algorithm to calculate sensor-driven rates. Intrinsic heart rate (HR), oxygen uptake, and sensor-driven rates were normalized to HR reserve (HRR), metabolic reserve (MR), and sensor-driven reserve to compare across groups. Linear regression analysis among sensor-driven rate reserve, HRR, and MR was performed as described by Wilkoff. The mean slopes (± SD) of the relationships between the sensor-driven rate reserve and HRR were 1.06 ± 0.34, 1.07 ± 0.28, and 1.01 ± 0.19 for children with BSA 〈 1.10 m2, 1.10 〈 BSA 〈 1.40 m2, and BSA 〉 1.40 m2, respectively. High correlations were found between sensor-drive rates and HR responses and between sensor-drive rates and MV throughout exercise. No significant differences were noted between sensor-drive rates and HR using the Wilkoff model. From this study the authors conclude that: (1) MV is a good physiological parameter to control heart rate and (2) simulated sensor-driven rates closely match intrinsic HRs during exercise in healthy children, which supports the appropriateness of clinical validation in pediatric pacemaker patients.

Notizen: Abstract Background: The Ablate and Pace Trial (APT) prospectively assessed the effects of catheter ablation of the AV conduction system and permanent pacemaker implantation on health-related quality of life, survival, exercise capacity, and ventricular function in 156 patients with symptomatic atrial fibrillation. Methods: All patients referred for catheter ablation and permanent pacemaker implantation because of medically-refractory atrial fibrillation at 16 centers were screened for enrollment in a prospective registry. Baseline assessment prior to ablation included measurement of quality of life, including the Health Status Questionnaire, the Quality of Life Index and the Symptom Checklist: Frequency and Severity. Exercise capacity was assessed with metabolic treadmill exercise testing and ventricular function was quantitated with echocardiography. The quality of life instruments, exercise capacity, and echocardiography were repeated at 3 and 12 months after catheter ablation. Results: The APT population included 90 men and 66 women (66.1 ± 11.5 years of age) with either chronic (n = 70), recurrent (n = 31), or paroxysmal atrial fibrillation (n = 55). Structural heart disease was present in 78.2% of patients. Successful ablation of AV conduction was achieved in 155 of 156 patients (99.4%). Survival at 1 year was 85.3%, with 5 of 23 deaths being sudden cardiac deaths. Survival over the first year of follow-up was significantly lower for patients with a baseline left ventricular ejection fraction (LVEF) 〈0.45 (0.73) than for patients with a LVEF ≤0.45 (0.88, p = 0.03). The NYHA functional class improved from 2.1 at baseline to 1.8 at 3 months and 1.9 at 12 months of followup (p = 0.0001). Significant improvement in quality of life scores were noted for all 8 subscales of the Health Status Questionnaire, for the overall rating of the Quality of Life Index, the Health and Function subscales; Arrhythmia-related symptoms were markedly reduced as measured by the Symptom Checklist: Frequency and Severity scale. The mean LVEF improved from 0.50 ± 0.20 at baseline to 0.54 ± 0.20 at 3 months (p = 0.03). The LVEF 12 months after ablation was 0.52 ± 0.20, not statistically different from baseline. Individuals with reduced systolic function at baseline had the greatest improvement, from LVEF 0.31 ± 0.20 at baseline to 0.41 ± 0.20 at 3 months and 0.41 ± 0.30 at 12 months (p = 0.0001). There were no significant changes in treadmill exercise duration (10.0 ± 4.3 min at baseline and 11.6 ± 3.6 min at 12 months) or VO2max (1467 ± 681 ml O2 min baseline and 1629 ± 739 ml O2 min at 12 months). Conclusions: Catheter ablation of the AV conduction system and permanent pacemaker implantation were associated with improved quality of life and left ventricular function in this population of highly symptomatic patients with atrial fibrillation refractory to medical therapy.