Contrast media used during angiography are known to produce transient alterations in cardiovascular physiology. However, little information is available concerning what alterations, if any, occur in myocardial metabolism after contrast angiography. Sixteen patients with symptoms of ischemic heart disease undergoing elective left ventriculography were studied. Coronary sinus and arterial blood samples were obtained for free fatty acids, glucose and lactate before and after performing left ventriculography with Renografin-76. Coronary blood flow was determined by the thermodilution technique. Five minutes after ventriculography, the arterial level of free fatty acids had decreased by 18.0 +/- 4.9 percent (mean +/- standard deviation) from the baseline (before angiography) samples (probability [p] less than 0.001). Associated with this decrease in arterial free fatty acids was an increase in the myocardial uptake of this substrate. At 5 minutes after left ventriculography, the free fatty acid uptake had increased 48.5 +/- 33.0 percent compared with the baseline value (p less than 0.001). After the injection of contrast medium, there was no significant change in the arterial levels of glucose or lactate. However, significant decreases in the myocardial uptake of glucose and lactate were demonstrated (-72.5 +/- 44.5 percent [p less than 0.001] and -43.2 +/- 22.9 percent [p less than 0.001], respectively) at 5 minutes. The changes in arterial free fatty acids and in the myocardial uptake of the various substrates persisted throughout the sampling period of 20 minutes after ventriculography. These results demonstrate that contrast medium significantly alters myocardial metabolism. These metabolic alterations persist longer than the hemodynamic changes induced by contrast angiography.