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[Frequency-dependent rise in absolute threshold during DDD-R stimulation--clinical consequences].
B Bienstein1, W Grosse-Heitmeyer
1Medizinische Klinik, Kardiologie, St. Bonifatius-Hospital Lingen/Ems.
Deutsche Medizinische Wochenschrift (1946)
|February 24, 2001
Summary
A rate-adaptive pacemaker showed increased stimulation thresholds at higher pacing rates in a patient with sick sinus syndrome. This rate-dependent threshold rise necessitates further investigation and potential use of advanced pacemaker technology.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- A 65-year-old female with sick sinus syndrome and a history of pacemaker implantation presented with dizziness and dyspnea.
- The patient had a rate-adaptive DDD-R pacemaker system implanted one year prior, with a previous DDD system in place for 14 years.
Observation:
- Pacemaker analysis revealed a significant rate-dependent increase in stimulation threshold, particularly at higher pacing rates (70-160 bpm).
- This threshold increase was observed consistently with both the original and newly implanted ventricular leads.
- Repeated pacemaker controls over six months post-new lead implantation confirmed a persistent rise in pacing threshold.
Findings:
- A further ventricular lead implantation was required due to the rate-dependent threshold increase.
- Despite the threshold increase, pacemaker programming allowed for a sufficient safety margin due to a generally low baseline stimulation threshold.
- The study highlights marked individual variations in the rate-dependent threshold phenomenon, with no clear correlation to cycle length or time since implantation.
Implications:
- This case underscores the challenge of rate-dependent threshold increases in DDD-R pacemaker stimulation.
- Further research involving varied stimulation cycle lengths is recommended for high-risk patients.
- Modern pacemaker systems with autocapture functionality may offer a solution to mitigate this issue.