Intravenous magnesium acutely shortened ventricular effective refractory period (247 vs 241 ms; p<0.05) and monophasic action potential duration.
Does intravenous magnesium alter ventricular refractoriness and monophasic action potential duration in humans?
Intravenous magnesium acutely shortens ventricular monophasic action potential duration and refractoriness, which may provide salutary effects in arrhythmias evoked by prolonged repolarization.
Absolute Event Rate: 241% vs 247%
p-value: p=<0.05
The objective of this study was to examine the antiarrhythmic mechanisms of magnesium (Mg). The 12 patients who were selected for the study were given 12 mmol Mg sulphate followed by an infusion of 8 mmol/h. Ventricular effective refractory period (VERP). monophasic action potential duration at 50% and 90% repolarization during spontaneous rhythm (MAPD50, MAPD90) and atrial pacing at a cycle length of 600 ms (MAPD(50)600, MAPD(90)600) were measured before and after the intervention. Plasma magnesium concentration rose from 0.83 +/- 0.05 to 1.85 +/- 0.24 mmol/l (p < 0.001). Shortening of MAPD(50) (250 +/- 45 vs 240 +/- 46 ms; p < 0.05), MAPD(90) (294 +/- 42 vs 283 +/- 41 ms; p < 0.05) and shortening of sinus cycle length (SCL) (783 +/- 153 vs 742 +/- 160 ms; p < 0.01) were detected. During controlled cycle length, magnesium decreased MAPD(50)600 (230 +/- 28 vs 221 +/- 28 ms; p < 0.01), MAPD(90)600 (274 +/- 25 vs 261 +/- 29 ms; p < 0.01) and VERP (247 +/- 25 vs 241 +/- 21 ms: p < 0.05). QRS duration, QT interval and blood pressure remained unchanged. The change in SCL correlated with the change in MAPD(50) (r = 0.58; p < 0.05) and MAPD(90) (r = 0.55; p = 0.06 ) but not with MAPD(50)600, MAPD(90)600 or VERP. Magnesium acutely shortens ventricular monophasic action potential duration and refractoriness. This effect is partly mediated by mechanisms that increase heart rate. The reductions might bring salutary effects in arrhythmias evoked by prolonged repolarization.
Lauri K. Toivonen Hannu J. Parikka (Fri,) reported a other. Intravenous Magnesium vs. Baseline (before intervention) was evaluated on Ventricular effective refractory period (VERP) during controlled cycle length (p=<0.05). Intravenous magnesium acutely shortened ventricular effective refractory period (247 vs 241 ms; p<0.05) and monophasic action potential duration.