Effects of contrast materials on left ventricular function.

The effects of intracoronary administration of contrast materials were investigated in conscious and anesthetized dogs prepared with pressure gauges or catheters in the left ventricle for measuring aortic pressure (P), LVP, and dP/dt, and dimension crystals on opposing endocardial surfaces of the LV for measuring LV dimensions and its first derivative dD/dt (velocity of contraction). All contrast materials were tested at a concentration of 370 mg I/ml. Biphasic responses were observed with monomeric contrast materials; direct effects occurred within the first 10 seconds after injection, while secondary or indirect effects (reflex?) ensued near the end of the first 10 seconds or in the second 10-second period (Higgins, 1978). The standard sodium-containing monomeric contrast material caused decreases in LV peak systolic pressure (LVSP), peak dP/dt, dP/dt at an LVP of 40 mmHg (dP/dt40), peak -dP/dt, -dP/dt at an LVP of 50 mmHg (-dP/dt50), and dD/dt (Higgins, 1978, Newell, 1979). It caused increases in LV end-systolic and end-diastolic dimension. The decreases in -dP/dt (rate of relaxation) persisted during the second 10 seconds, when the parameter of LV contractile state had increased above control levels. Similar effects were observed in the presence of regional myocardial ischemia. Monomeric ionic material with added calcium ions (Isopaque 370) caused initial and secondary increases in LVSP and indexes of LV contractile state but still produced decreases in LV relaxation rate (-dP/dt50). Standard monomeric materials caused a decline in Ca++ of coronary sinus blood concomitant with the depression in LV contractile state, while the calcium-containing material produced an increase in Ca++ in association with the enhancement in LV contractile state (Higgins, 1978). Several nonionic materials also have been tested in this preparation: metrizamide, P-297, and iopamidol. These materials had similar effects on LV function; each caused a slight increase or no change in indexes of LV contractile state and no change in LV dimensions. A new monacid dimer (P-286) with a lower sodium content than monomeric materials produced effects on LV function which were less deleterious than standard monomeric materials, but more so than the nonionic materials.