Changes in left ventricular function produced by the injection of contrast media

The effect of radiopaque contrast media on left ventricular volume and function was analyzed during and after selective left ventricular injection of 1 c.c. per kilogram of contrast medium (76 per cent meglumine diatrizoate) or physiological saline. Radiopaque markers were implanted near the endocardium of the left ventricle in open-chest dog preparations. Biplane cinefluorography films were taken while monitoring left ventricular pressure and its derivative ( dp dt), aortic pressure, and the ECG. End-systolic and diastolic volumes were calculated from the biplane cine films and matched with the simultaneous pressures. Systolic and diastolic volumes, stroke volume, peak left ventricular pressure, left ventricular end-diastolic pressure, and maximal rate of left ventricular pressure rise (max. dp dt) were compared for 16 beats and for 15 minutes after injection of physiological saline or contrast medium. In 7 paired studies the injection of either contrast medium or saline produced an immediate increase in left ventricular end-diastolic pressure and volume, stroke volume, ejection fraction, max. dp dt, and peak left ventricular pressure, indicating a Frank-Starling effect. Thirteen to 16 beats after the injection of saline, all values returned toward control levels; whereas, after contrast medium injection, left ventricular end-diastolic pressure and volume increased further with a fall in max. dp dt, indicating a decrease in contractility. Subsequently, at 1 minute after the injection of contrast media, left ventricular contractility increased, as evidenced by a rise in max. dp dt and a fall in left ventricular end-diastolic volume. All values returned to control values after 15 minutes. Thus, the injection of either saline or contrast medium results in an immediate alteration in left ventricular function secondary to an increased volume load (the Frank-Starling mechanism). Left ventricular function returns rapidly to control level after the saline injection. After the contrast medium injection, however, the volume effect is followed first by a transient deterioration in function and subsequently bya transient increase in left ventricular function, an effect possibly resulting from changes in osmolality.