Magnesium reduces free radical concentration and preserves left ventricular function after direct current shocks

Area of Science:

• Cardiology
• Biochemistry
• Medical Devices

Background:

• Previous research indicated magnesium's ability to mitigate free radicals in a coronary occlusion-reperfusion model.
• This study investigated magnesium's potential to reduce free radical generation specifically from direct current (DC) shocks.

Purpose of the Study:

• To ascertain if magnesium administration can decrease free radicals produced by DC countershock.
• To evaluate the impact of magnesium on preserving left ventricular contractile function following DC shock.

Main Methods:

• Eight swine underwent electron paramagnetic resonance to monitor coronary sinus ascorbate free radical concentration, a marker for total oxidative flux.
• Epicardial shocks (30 J, biphasic waveform) were delivered with and without magnesium (80 mg/min IV).
• Left ventricular fractional area shortening was assessed via 2-dimensional echocardiography to measure contractile function.

Main Results:

• Magnesium administration significantly reduced the post-shock increase in ascorbate free radical concentration (0.6% vs. 16%, P<0.05).
• Total radical flux was decreased by 72% (P<0.05) with magnesium treatment.
• Left ventricular fractional area shortening was preserved with magnesium (61%) compared to no-magnesium shocks (41%, P<0.05 vs. baseline).

Conclusions:

• Magnesium pre-treatment effectively reduced oxygen free radicals generated by DC shocks.
• Post-shock left ventricular contractile function remained unimpaired in the presence of magnesium.
• Magnesium demonstrates potential cardioprotective effects during epicardial (surgical) defibrillation.