Unlabelled: In single-lead VDD pacing the atrial sensitivity frequently is programmed to sensitive values. Atrial sensing of ventricular far-field signals should be reduced by differential atrial sensing. The aim of the study was to evaluate the effectiveness of this approach.
Methods: The study included 10 patients with a single-lead VDD pacemaker (Thera 8948, Lead 5032). The atrial sensitivity was set to its most sensitive value of 0.18 mV and the telemetered intraatrial EGM was continuously recorded. After atrial tracked ventricular pacing, VVI pacing was performed with pacing rates from 100 to 160 beats/min in steps of 10 beats/min and up to 165 beats/min. The peak-to-peak amplitudes of P waves (P) and ventricular far-field signals (VFFS) were measured from the recordings. The ratio P/VFFS that defines the atrial signal-to-noise ratio was calculated, and the time from stimulus to maximum of the far-field signals amplitude (Tmax) was measured.
Results: P measured 0.98 +/- 0.76 mV. A VFFS was visible in the atrial channel in all patients with an amplitude of 0.45 +/- 0.25 mV (range 0.01-1.0 mV), independent of the pacing rate. The ratio P/VFFS was 3.9 +/- 4.2 (range 0.9-21.0). Tmax measured 99.4 +/- 15.2 ms during sinus rhythm. A rate dependent shortening of Tmax to 92.7 +/- 11.2 ms at 140 beats/min was observed (P = 0.001). At rates above 140 beats/min no further shortening occurred.
Conclusion: Ventricular far-field signals are measurable in the atrial channel of VDD systems and may reach considerable amplitudes, which are not rate dependent. Although differential sensing provides favorable P waves to ventricular far-field signal ratios, refractory periods are needed to avoid far-field sensing. The rate dependent shortening of the ventricular signal can be detected in the atrial channel in VDD pacing.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1111/j.1540-8159.1998.tb01159.x | DOI Listing |
J Arrhythm
February 2025
Current guidelines recommend cardioverter-defibrillator (ICD) programming, including faster detection rates, longer detection durations, and strict discrimination for supraventricular tachycardia (SVT) to prevent unnecessary ICD treatment. This delayed-style ICD programming could lead to a rise in the possibility of VF undersensing. To avoid this risk, an innovative algorithm known as VF Therapy Assurance (VFTA; Abbott, Sylmar, CA) has been developed.
View Article and Find Full Text PDFEuropace
October 2024
Department of Cardiology, University Hospital Coventry and Warwickshire NHS Trust, CV2 2DX Coventry, UK.
Europace
July 2024
Institute for Cardiovascular Science, University College London, 5 University Street, London, WC1E 6JF, UK.
Aims: Successful ventricular arrhythmia (VA) ablation requires identification of functionally critical sites during contact mapping. Estimation of the peak frequency (PF) component of the electrogram (EGM) may improve correct near-field (NF) annotation to identify circuit segments on the mapped surface. In turn, assessment of NF and far-field (FF) EGMs may delineate the three-dimensional path of a ventricular tachycardia (VT) circuit.
View Article and Find Full Text PDFJACC Clin Electrophysiol
July 2024
Institut Clínic Cardiovascular, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain. Electronic address:
Background: A partial delineation of targets for ablation of ventricular tachycardia (VT) during a stable rhythm is likely responsible for a suboptimal success rate. The abnormal low-voltage near-field functional components may be hidden within the high-amplitude far-field signal.
Objectives: The aim of this study was to evaluate the benefit and feasibility of functional substrate mapping using a full-ventricle S3 protocol and to assess its colocalization with arrhythmogenic conducting channels (CCs) on late gadolinium enhancement cardiac magnetic resonance.
Front Physiol
May 2024
Arrhythmia Unit, Department of Cardiology at Virgen Del Rocío University Hospital, Sevilla, Spain.
Cardiac arrhythmias cause depolarization waves to conduct unevenly on the myocardial surface, potentially delaying local components with respect to a previous beat when stimulated at faster frequencies. Despite the diagnostic value of localizing the distinct local electrocardiogram (EGM) components for identifying regions with decrement-evoked potentials (DEEPs), current software solutions do not perform automatic signal quantification. Electrophysiologists must manually measure distances on the EGM signals to assess the existence of DEEPs during pacing or extra-stimuli protocols.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!