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Congestive heart failure and VVI pacing mode: dynamic behavior of the dispersion of ventricular repolarization

A G Manolis1, A Katsivas, D Koutsogeorgis

  • 1Hellenic Red Cross Hospital, Athens, Greece.

Pacing and Clinical Electrophysiology : PACE
|November 1, 1996
PubMed

Insights

Congestive heart failure (CHF) patients show circadian variation in ventricular repolarization dispersion, with higher values at night. This nighttime increase in dispersion is linked to vagal activity in abnormal heart muscle areas.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Circadian Biology

Background:

  • Congestive heart failure (CHF) is associated with altered cardiac electrophysiology.
  • Ventricular repolarization dispersion is a marker of arrhythmogenic substrate.
  • Circadian variations in cardiovascular events are well-documented.

Purpose of the Study:

  • To investigate the circadian variation in spatial dispersion of ventricular repolarization.
  • To compare repolarization dispersion in patients with CHF and controls.
  • To explore the relationship between pacing, CHF, and repolarization dynamics.

Main Methods:

  • Utilized 24-hour Holter monitoring with Frank orthogonal leads in 14 CHF patients and 20 controls.
  • Patients were continuously paced (VVI mode, 70 bpm).
  • Measured hourly mean spike-T interval dispersion, assessing spatial and temporal dynamics.

Main Results:

  • CHF patients exhibited significant circadian variation in spike-T interval dispersion (higher at night: 45 ± 7 ms vs. daytime: 39 ± 5 ms, P=0.003).
  • Control group showed no significant day-night difference in dispersion (38 ± 6 ms vs. 40 ± 8 ms, P=NS).
  • Nighttime dispersion was significantly higher in CHF patients compared to controls (P=0.0004).

Conclusions:

  • Paced patients with CHF due to dilated cardiomyopathy display a circadian variation in ventricular repolarization dispersion.
  • Increased nighttime dispersion in CHF patients may be influenced by vagal tone acting on heterogeneous myocardial regions.
  • These findings highlight the temporal aspect of repolarization abnormalities in heart failure.

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