Document Detail

Acute effects of a class IA antiarrhythmic drug on the ventricular evoked response amplitude in patients with cardiac pacemakers.
MedLine Citation:
PMID:  11173781     Owner:  NLM     Status:  MEDLINE    
Some newer cardiac pacemakers are able to control the efficacy of the ventricular pacing pulse beat by beat and to adjust the ventricular output to the actual pacing threshold. This capture verification is based on the detection of the ventricular evoked response amplitude, which has to be detected immediately after the pacing pulse. The sensitivity of the pacemaker to detect the evoked response amplitude must be adjusted individually to avoid the simultaneous detection of lead polarization. The aim of the present study was to evaluate the acute effects of a class IA antiarrhythmic drug on the evoked response amplitude and polarization in 13 pacemaker patients. The implanted pacemaker was the VVIR pacemaker Regency (St. Jude Medical), which provides the automatic capture verification algorithm Autocapture. The patients received 50 mg of ajmaline intravenously within 1 min. The evoked response amplitude and polarization were measured before and 2, 4, 6 and 8 min after ajmaline injection. The evoked response amplitude significantly decreased from 8.0 +/- 4.0 mV to a minimum value of 6.4 +/- 3.1 mV 2 min after drug administration. The decrease remained significant from the end of the application up to 6 min. The recommended sensitivity setting for the evoked response significantly (p < 0.05) decreased from 4.0 +/- 2.3 mV before to 3.1 +/- 1.3 mV 2 min after administration. No significant changes were observed for polarization. After the ajmaline application in 2 patients, the pacemaker recommended the deactivation of Autocapture for 9 min in 1 patient and 12 min in the other. The reasons were a decrease in the evoked response amplitude from 3.1 to 1.9 mV and from 9.0 to 5.7 mV, respectively, with a polarization ranging to about 3.0 mV. In conclusion, the ajmaline injection decreased the evoked response amplitude for some minutes. These findings indicate that antiarrhythmic drugs can alter the automatic capture verification function.
A Schuchert; T Meinertz
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Cardiology     Volume:  94     ISSN:  0008-6312     ISO Abbreviation:  Cardiology     Publication Date:  2000  
Date Detail:
Created Date:  2001-02-22     Completed Date:  2001-04-12     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  1266406     Medline TA:  Cardiology     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  103-5     Citation Subset:  IM    
Copyright Information:
Copyright 2001 S. Karger AG, Basel
Medical Clinic, Department of Cardiology, University Hospital Eppendorf, Hamburg, Germany.
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MeSH Terms
Ajmaline / pharmacology*
Anti-Arrhythmia Agents / pharmacology*
Arrhythmias, Cardiac / therapy*
Cardiac Pacing, Artificial*
Evoked Potentials / drug effects*
Middle Aged
Pacemaker, Artificial
Sensitivity and Specificity
Reg. No./Substance:
0/Anti-Arrhythmia Agents; 4360-12-7/Ajmaline

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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