Leonor Garcia Rincon

Automatic adjustment of pacing output in the clinical setting

BACKGROUND AutoCapture (AC) is a programmable feature that enables the pacemaker to both track the capture threshold and automatically adjust the output on a beat-by-beat basis. Although AC safely and significantly reduces the current drainage, some authors have argued that the longevity benefit of such a system is overstated. This study aims to estimate the longevity extension that can be obtained, in the clinical routine, by turning the AC on in comparison to pacemakers programmed to operate at the shipped and manually optimized output. METHODS We selected 83 consecutive patients who received implanted St Judes Affinity pacemakers >6 months earlier. Eight patients died or were lost to follow-up and in 9 subjects the AC could not be turned on. In the remaining 66 patients, current drain and estimated longevity were compared in 3 situations: (1) AC on; (2) AC off, optimized programming (100%-150% voltage threshold); (3) AC off, shipped output (3.5 V). RESULTS Five patients had large variations (>1 V) of the AC threshold. Current drainage was 8.0 +/- 0.9 mA in the AC group, 8.7 +/- 1.8 mA with AC off and optimized programming, and 11.3 +/- 2.3 mA at shipped output (P <.01). Estimated longevity was significantly extended (P <.01) by AC (12.1 +/- 1.0 years) when compared to shipped (8.9 +/- 1.7 years) and optimized programming (11.3 +/- 1.4 years). CONCLUSION Reprogramming the pacemaker output significantly enhanced its estimated longevity; AC added a moderate but significant extension over manual reprogramming and was associated with increased safety in patients with large ventricular threshold variations.

Health-Related Quality of Life in Brazilian Pacemaker Patients

Background: Most quality of life (QoL) studies of pacemaker patients have been conducted in either North America or Europe and their applicability to Latin American populations is largely unknown. Our aim is to study health‐related QoL indices in Brazilian pacemaker patients and their determinants using both a generic (SF‐36) and a disease‐specific questionnaire (AQUAREL).

The portuguese version, cross-cultural adaptation and validation of specific quality-of-life questionnaire - AQUAREL - for pacemaker patients

OBJECTIVE To translate, to make the cultural adaptation and to evaluate reproducibility and validity of the Portuguese version of the AQUAREL (Assessment of QUAlity of life and RELated events) questionnaire, which is a specific tool to assess quality of life in pacemaker patients. METHODS We evaluated 202 pacemaker patients: 63 patients during the cross-cultural adaptation stage and 139 during the reproducibility and validity evaluation stages. The questionnaire translation was reviewed repeatedly until > or = 85% of patients correctly understood the questions. Reproducibility of the final version was tested in 69 patients in whom the interview was performed twice by the same researcher. Validity was checked by the correlation between scores obtained in AQUAREL domains and those obtained in SF36 domains, in the functional class and the distance walked in the six-minute test. RESULTS The internal consistency of AQUAREL was adequate, with Cronbachs alpha coefficient varying between 0.59 and 0.85. Reproducibility was good, with high correlation coefficients (0.68-0.89) and random distribution of data in Bland and Altman plots, without systematic bias. A significant association was observed among AQUAREL domains and those obtained in SF36 domains and the functional class (p<0.01), although significant correlations with the distance walked in the six-minute test were not found. CONCLUSION The Portuguese version of the AQUAREL questionnaire is easy and rapid to apply, and could be used as a specific questionnaire to assess quality of life in pacemaker patients.

Enhancing longevity of pacemakers through reprogramming. Underutilization and cost-effectiveness

OBJECTIVE This study was performed to observe the number of pacemakers that had never been reprogrammed after implantation, and the effect of optimised output programming on estimated longevity of pulse generators in patients with pacemaker METHODS Sixty patients with Teletronics Reflex pacemakers were evaluated in a pacemaker clinic, from the time of the beginning of its activities, in June 1998, until March 1999. Telemetry was performed during the first clinic visit, and we observed how many pulse generators retained nominal output settings of the manufactures indicating the absence of reprogramming until that date. After evaluation of the capture threshold, reprogramming of pacemakers was performed with a safety margin of 2 to 2.5:1, and we compared the estimated longevity based on battery current at the manufacturers settings with that based on settings achieved after reprogramming. RESULTS In 95% of the cases, the original programmed setting was never reprogrammed before the patients attended the pacemaker clinic. Reprogramming the pacemaker prolonged estimated pulse generator life by 19.7+/-15.6 months (35.5%). CONCLUSION The majority of the pacemakers evaluated had never been reprogrammed. Estimated pulse generator longevity can be prolonged significantly, using this simple, safe, efficacious, and cost-effective procedure.

Effect of activating intrinsic conduction search on left ventricular dyssynchrony in patients with conventional pacemaker

Rightventricular(RV)apicalpacingcreatesanabnormalventricularactivation pattern inducing cardiac dyssynchrony, ventricular dysfunc-tion,andanincreasedmortalityrisk[1–3].Atrial-basedpacingtomain-tainatrioventricular(AV)synchronycandecreasetheincidenceofatrialfibrillation (AF), heart failure and overall mortality rates [1]. However,evenwhenAV-nodefunctionispreserved,dual-chamber(DDD)pacingoften results in frequent ventricular pacing [3]. Previous analyses linkthefrequencyofRVpacedbeatstoincreasedrisksofAFandheartfailurein patients with sinus-node disease [4].To overcome the limitations of pacing-induced asynchronouselectricalactivation,devicealgorithmshavebeendevelopedtopromotenormal AV synchrony by preserving the physiologic ventricular activa-tion sequence [2].Specifically, intrinsic conduction search (ICS) hasbeen shown to lead to a decrease in unnecessary RV pacing and itsadverse consequences on left ventricular function [5,6].Moreover,pulsegeneratorlongevityisanimportant issueinthecareof pacemaker patients [7]. One of the determinants of pacemaker lon-gevityisthe energy consumption ofthepulsegenerator,whichdependson programmable variables, including output parameters of the system(voltage and pulse width), and the frequency and percentage of pacing.A previous study using an algorithm to preserve normal AV synchrony

Comparative study of relative bioavailability between two formulations containing Clozapine 100 mg in patients with schizophrenia

This study aimed to evaluate the bioequivalence between two products containing Clozapine 100 mg (testing product: LifalClozapina® from Lifal – Industrial Pharmaceutical Laboratory of Alagoas S/A and the reference product: Leponex® from the Novartis Biociencias S/A. Laboratories) in 40 volunteers. The study was open, randomized, cross-over type, in a state of equilibrium, with two periods (two sequences) in which volunteers were given, in each period, the testing formulation or the reference formulation. The relative bioavailability of the formulations following oral administration was evaluated based on statistical comparisons of relevant pharmacokinetic parameters obtained from blood samples in a 24 hours period. The concentration of Clozapine was measured using an appropriate and valid analytical method. The pharmacokinetic measures used were: Cmin and Cmax, and ASCt. The mean differences (± SD) between reference and testing were: 0.1615 ± 0.3404 (ng/mL); -0.0969 ± 0.4131 (ng/mL); and 0.9143 ± 3.9941 (ng*h/mL). The confidence intervals for medium bioequivalence met the limits determined by the National Agency of Sanitary Surveillance (ANVISA) of 80 to 125%, and both medications were considered bioequivalent. Thus, the testing and reference products are considered interchangeable.