Cellular Basis for the Brugada Syndrome and Other Mechanisms of Arrhythmogenesis Associated With ST-Segment Elevation
Key result
Right ventricular epicardial action potential dome loss drives transmural voltage gradients, ST elevation, and VT/VF.
Why the study?
The cellular basis for the Brugada syndrome and mechanisms of arrhythmogenesis associated with ST-segment elevation were not fully understood.
Does the loss of the action potential dome in the right ventricular epicardium cause ST-segment elevation and arrhythmogenesis in Brugada syndrome?
Population
Arterially perfused wedges of canine right ventricle
Comparison
Pharmacological manipulation with pinacidil, flecainide plus acetylcholine, isoproterenol, 4-aminopyridine, or quinidine
Design
Preclinical experimental study
Authors
Discussion
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Implication
Supports Ito blockade rationale in Brugada syndrome; leaves open human translation from this animal model.
Key Points
- The study investigates the cellular mechanisms underlying Brugada syndrome and associated arrhythmias.
- Used arterially perfused wedges of canine right ventricle to record transmembrane action potentials and electrograms.
- Examined effects of pinacidil, flecainide, acetylcholine, and isoproterenol on action potential and ST-segment elevation.
- Assessed the role of transient outward current block in stabilizing the action potential dome.
- Loss of the action potential dome caused ST-segment elevation, linked to abnormal repolarization.
- Action potential dome restoration with isoproterenol reduced ST-segment elevation, lowering arrhythmia risk.
- Blockade of I(to) with 4-aminopyridine or quinidine normalized activity and prevented ventricular tachycardia and fibrillation.
Structured PICO
Does the loss of the action potential dome in the right ventricular epicardium cause ST-segment elevation and arrhythmogenesis in Brugada syndrome?
P
Population
Arterially perfused wedges of canine right ventricle (RV)
I
Intervention
Pharmacological manipulation with pinacidil (2 to 5 micromol/L), flecainide (7 micromol/L) + acetylcholine (2 to 3 micromol/L), isoproterenol (0.1 to 1 micromol/L), 4-aminopyridine (1 to 2 mmol/L), or quinidine (5 micromol/L)
O
Outcome
Transmembrane action potentials, unipolar electrograms, and transmural ECG (ST-segment elevation, loss of action potential dome, dispersion of repolarization, and VT/VF)surrogate
Depression or loss of the action potential dome in RV epicardium creates a transmural voltage gradient responsible for ST-segment elevation and triggers VT/VF via phase 2 reentry, suggesting I(to) blockers like quinidine as effective pharmacological treatment.
Cite This Study
Yan et al. (1999) studied Brugada syndrome. Pharmacological agents (pinacidil, flecainide, acetylcholine, isoproterenol, 4-aminopyridine, quinidine) was evaluated on Transmembrane action potentials, unipolar electrograms, and transmural ECG changes. Loss of the action potential dome in the right ventricular epicardium creates a transmural voltage gradient responsible for ST-segment elevation and phase 2 reentry triggering VT/VF.