What is the clinical evidence from this study?

Study design: Other. Population: Ventricular fibrillation (n=6). Intervention: Amiodarone vs. Baseline. Primary outcome: Cycle length of ventricular fibrillation (ms) (p=<0.05).

What does this research mean for the field?

Acute amiodarone infusion increases the cycle length of ventricular fibrillation and reduces spontaneous wave breaks in isolated swine right ventricles, effects associated with flattened action potential duration restitution curves and increased reentrant wave front core size. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

March 1, 2002Open Access

Effects of amiodarone on wave front dynamics during ventricular fibrillation in isolated swine right ventricle

Q: What are the key findings of this study?

Amiodarone infusion increased the cycle length of ventricular fibrillation from 83.3 ms to 118.4 ms and reduced spontaneous wave breaks in isolated swine right ventricles.

Q: What does this research mean for the field?

Acute amiodarone infusion increases the cycle length of ventricular fibrillation and reduces spontaneous wave breaks in isolated swine right ventricles, effects associated with flattened action potential duration restitution curves and increased reentrant wave front core size. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Key Result

Amiodarone infusion increased the cycle length of ventricular fibrillation from 83.3 ms to 118.4 ms and reduced spontaneous wave breaks in isolated swine right ventricles.

Structured PICO

Does amiodarone improve wave front dynamics and flatten APD restitution during ventricular fibrillation in isolated swine right ventricles?

Population

6 isolated swine right ventricles from farm pigs (25-32 kg)

Intervention

Amiodarone 2.5 microg/ml added to perfusate for 30 minutes

Comparator

Baseline (before amiodarone infusion)

Outcome

Wave front dynamics during ventricular fibrillation (cycle length, spontaneous wave breaks, reentrant wave front cycle length, and central core area)surrogate

Amiodarone reduces spontaneous wave breaks and flattens APD restitution curves during ventricular fibrillation in isolated swine right ventricles, providing a potential electrophysiological mechanism for its antifibrillatory efficacy.

Main Result

Absolute Event Rate: 118.4% vs 83.3%

p-value: p=<0.05

Limitations

Acute effects of amiodarone cannot be reversed, preventing washout testing.
Used isolated normal right ventricles, which may not be applicable to diseased human hearts.
Flattening of APD restitution may only partially explain the antifibrillatory effects of amiodarone, as other drugs with this effect are less clinically effective.

Abstract

The effects of acute amiodarone infusion on dynamics of ventricular fibrillation (VF) are unclear. Six isolated swine right ventricles (RVs) were studied in vitro. Activation patterns during VF were mapped optically, whereas action potentials were recorded with a glass microelectrode. At baseline, VF was associated with frequent spontaneous wave breaks. Amiodarone (2.5 microg/ml) reduced spontaneous wave breaks and increased the cycle length (CL) of VF from 83.3 +/- 17.8 ms at baseline to 118.4 +/- 25.8 ms during infusion (P < 0.05). Amiodarone increased the reentrant wave front CL (114.4 +/- 15.5 vs. 78.2 +/- 19.0 ms, P < 0.05) and central core area (4.1 +/- 3.8 vs. 0.9 +/- 0.3 mm2, P < 0.05). Within 30 min of infusion, VF terminated (n = 1), converted to ventricular tachycardia (VT) (n = 1) or continued at a slower rate (n = 4). Amiodarone flattened the APD restitution curves. We conclude that amiodarone reduced spontaneous wave breaks. It might terminate VF or convert VF to VT. These effects were associated with the flattening of APD restitution slope and increased core size of reentrant wave fronts.

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