The Effects of Infusion of Calcium and Magnesium Ions on the Cardiovascular System in Man

Abstract

The effects of Ca2+ and Mg2+ infusion on the cardiovascular system were studied in 96 normotensive subjects and 85 hypertensive patients. The effects of Ca2+ infusion on the systolic time intervals were characterized by the shortening of the QS2I, PEPI, and ICT intervals, and increase in ET/PEP. The responses of the systemic hemodynamics were elevation of mean blood pressure and increase in cardiac index and stroke index. The heart rate was not altered. Ca2+ apparently has a positive inotropic action and increases the left ventricular performance. The effects of Mg2+ infusion on the systolic time intervals were characterized by the prolongation of the QS2I, PEPI, and ICT. The responses of systemic hemodynamics were elevation of mean blood pressure and increase in heart rate. The ET/PEP and cardiac index tended to decrease, but these changes were not significant. Mg2+ apparently depresses myocardial contractility and has a positive chronotropic action. There were no significant differences in the systolic time intervals and hemodynamic responses to the infusion of Ca2+ and Mg2+ between normotensives and hypertensives.