Alterations in calcium levels of coronary sinus blood during coronary arteriography in the dog.

Intracoronary administration of contrast materials causes myocardial depression which is related to serveral physiochemical properties of the contrast solution. The role of variations in ambient calcium ions (Ca++) in mediating this effect was evaluated in 19 anesthetized dogs. Sodium meglumine diatrizoate caused decreases in left ventricular peak systolic pressure (LVPSP),-12.6 +/- 3.2%, and dp/dt at a left ventricular pressure (LVP) of 40 mm Hg, -14.3 +/- 4.1%. The total calcium (Cat) decreased from 10.2 +/- 0.2 to 6.5 +/- 0.2 mg%, while Ca++ decreased from 4.6 +/- 0.1 mg% to 2.3 +/- 0.7 mg%. In the presence of systemic hypocalcemia the myocardial depressant actions of this contrast materials were accentuated. Intracoronary administration of contrast material with added Ca++, calcium sodium meglumine metrizoate, caused no myocardial depression. Total calcium decreased only slightly (10.2 +/- 0.2 to 9.1 +/- 0.2 mg%), while Ca++ increased (4.8 +/- 0.1 to 5.1 +/- 0.2 mg%. During systemic hypocalcemia, the calcium metrizoate compound induced increases in LVPSP and dp/dt/LBP40. Thus, contrast materials caused myocardial depression which, at least in part, was related to reduction of ambient calcium through a dilutional and binding action. The addition of Ca++ to monomeric contrast materials reversed the myocardial depressant action and produced a transient rise in ambient Ca++.