Therapeutic Hypothermia (30.DEG.C) Enhances Arrhythmogenic Substrates, Including Spatially Discordant Alternans, and Facilitates Pacing-Induced Ventricular Fibrillation in Isolated Rabbit Hearts
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Key result
Therapeutic hypothermia increases pacing-induced VF vulnerability by facilitating wavebreaks and earlier spatially discordant alternans.
- P<0.05
- n=7
Why the study?
Does therapeutic hypothermia (30 degrees C) increase the vulnerability to pacing-induced ventricular fibrillation in isolated rabbit hearts?
Population
Langendorff-perfused isolated rabbit hearts
Comparison
Therapeutic hypothermia (30 degrees C) vs Baseline and rewarming
Design
Preclinical
Authors
Discussion
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Implication
May warrant caution with therapeutic hypothermia; leaves open translation of proarrhythmic effects from rabbit models to clinical VF risk.
Structured PICO
Does therapeutic hypothermia (30 degrees C) increase the vulnerability to pacing-induced ventricular fibrillation in isolated rabbit hearts?
P
Population
7 isolated rabbit hearts studied to evaluate the arrhythmogenic effects of therapeutic hypothermia at 30°C.
I
Intervention
Therapeutic hypothermia (30 degrees C)
C
Comparator
Baseline (37 degrees C) and rewarming (37 degrees C)
O
Outcome
Epicardial activations of VF, wavebreaks, APD/CV restitution, APD alternans, and pacing-induced VF vulnerabilitysurrogate
Main Result
Absolute Event Rate: 7.9% vs 6.2%
p-value: p=<0.05
Therapeutic hypothermia at 30°C increases vulnerability to pacing-induced ventricular fibrillation in isolated rabbit hearts by enhancing proarrhythmic electrophysiological parameters.
Limitations
- Mapping data at the exact initiation of VF were not available in most episodes.
- Transmural temperature distribution throughout the heart was not directly measured.
- Cytochalasin-D was only used in Protocol II, not Protocol I.
- Optical mapping data were recorded only from the epicardial surface, leaving intramural activations unknown.
Cite This Study
Hsieh et al. (2009) studied Ventricular fibrillation (n=7). Therapeutic hypothermia vs. Baseline (37°C) was evaluated on Number of phase singularities (wavebreaks) during VF (p=<0.05). Therapeutic hypothermia (30°C) increased the vulnerability to pacing-induced ventricular fibrillation by facilitating wavebreaks and promoting earlier onset of spatially discordant alternans.
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