Significant sex differences in the correlation of electrocardiographic exercise testing and coronary arteriograms. Am J Cardiol 36: 169, 1975 40. Cumming GR, Dufresne C, Kich L, Samm J: Exercise electrocardiographic patterns in normal women. Br Heart J 35: 1055Heart J 35: , 1973 41. Linhart JW, Laws In the presence of systemic hypocalcemia the myocardial depressant actions of this contrast material 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-t 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/LVP40. Thus, contrast materials caused myocardial depression which, at least in part, was related to reductions 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-. ACUTE LEFT VENTRICULAR power failure and electromechanical dissociation are rare but disastrous complications of coronary arteriography. Currentlyutilized ionic contrast materials have a direct depressing action on the ventricular myocardium which is related at least in part to the hyperosmolarity1 and high sodium ion content4 I of the solution. This solution, which displaces blood during coronary arteriography, is also deficient in calcium ions (Ca++), which have a critical role in contraction of the sarcomere.6-10 Moreover, it has been suggested that the material most frequently used for coronary arteriography contains chelating properties which might further reduce ambient Ca++ in the myocardium.1' It is wellestablished from early investigations6 9 that excitation-contraction coupling depends on the presence of free Ca++, and electromechanical dissociation ensues upon lowering ambient Ca+-in perfusate of isolated heart preparations. Recently, contrast material has been implicated as a causative factor in electromechanical dissociation occurring during coronary arteriography." The purpose of this study was: 1) to determine the extent of and the mechanism by which calcium is lowered in the coronary circulation during coronary arteriography; 2) to compare the severity and time sequence of depression in calcium levels in a "control state" and an induced acute heart failure state; 3) to assess the influence of preexisting systemic hypocalcemia on the myocardial depression induced by contrast materials; and 4) to compare the effects on calcium levels and myocardial contractility of a contrast material containing calcium ions with currently used non-calcium-containing contrast materials.
Methods