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Circadian modulation of ventricular tachycardia cycle length variability in ICD patients with dilated cardiomyopathy

A G Manolis1, A Katsivas, E Lazaris

  • 1Hellenic Red Cross Hospital, Athens, Greece.

Pacing and Clinical Electrophysiology : PACE
|January 1, 1997
PubMed

Insights

Ventricular tachycardia (VT) cycle length variability differs between day and night in dilated cardiomyopathy patients. This study found less VT variability during the day, suggesting circadian rhythm influences arrhythmia characteristics.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Devices

Background:

  • Ventricular tachycardia (VT) typically shows stable RR intervals after onset.
  • Dilated cardiomyopathy (DCM) is a significant risk factor for VT.
  • Third-generation implantable cardioverter-defibrillators (ICDs) are used for VT management.

Purpose of the Study:

  • To evaluate ventricular tachycardia cycle length (VTCL) variability in DCM patients.
  • To assess circadian modulation of VTCL variability.
  • To correlate VTCL variability with time of day (day vs. night).

Main Methods:

  • Analysis of 83 VT episodes in 10 DCM patients with implanted ICDs.
  • Calculation of VTCL variability using the coefficient of variance of RR intervals (CVRR).
  • Comparison of CVRR and mean RR intervals between daytime and nighttime VT episodes.

Main Results:

  • No significant difference in mean RR intervals between day (335 +/- 29 ms) and night (350 +/- 22 ms).
  • Significantly lower CVRR (VTCL variability) during daytime (2.83 +/- 0.52) compared to nighttime (3.36 +/- 0.48) (P = 0.017).
  • 55 VT episodes occurred during the day, 28 during the night.

Conclusions:

  • Circadian modulation of VTCL variability is present in DCM patients.
  • VTCL variability is reduced during daytime compared to nighttime.
  • Sympathovagal balance alterations may explain circadian modulation of VTCL variability in DCM.

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