Intracoronary echo-contrast agents: abnormalities in myocardial function in a normal and reduced coronary perfusion model in dogs.

Abstract

Two-dimensional echocardiography using echo-contrast enhancing agents is a promising technique for evaluating myocardial perfusion. However, the potential deleterious effects of injection of echo-enhancing agents into the coronary circulation have not been well evaluated. We utilized two experimental canine models in which the left anterior descending coronary artery was cannulated and perfused continuously by the left common carotid at normal and reduced coronary flows. Analysis of myocardial function included regional left ventricular systolic function by ultrasonic crystals, subendocardial ST segment shifts, left ventricular dP/dr analysis and measurements of coronary blood flow. One ml of each echo-contrast agent was injected into the left anterior descending coronary artery during normal coronary flow. Echo-enhancing agents included: sonicated 70% sorbitol, 50% dextrose, and 6% dextran, hand-agitated Renografin-saline, and unagitated 0.15% hydrogen peroxide, 20% fat emulsion and oxygenated Oxypherol, a perfluorocarbon compound. Two-dimensional echocardiography determined that all echo-enhancing agents except for 20% fat emulsion and Oxypherol produced good myocardial enhancement. All echo-enhancing agents which produced a good contrast effect did so at the expense of significant reversible contractile abnormalities. Each produced more than a 50% reduction in percent segment shortening. Sorbitol and hydrogen peroxide produced the most severe contractile disturbances. In the normal flow model, sorbitol produced systolic bulging and hydrogen peroxide an 83% reduction in percent segment shortening. Hydrogen peroxide induced systolic bulging in the reduced coronary flow model. Other abnormalities induced by echo-enhancing agents included ST segment shifts and malignant ventricular arrhythmias. Six percent dextran produced a good contrast effect with the least harmful myocardial consequences.