Effect of lntracoronaryInjectionsof Sonicated Microbubbles on Left VentricularContractility ROBERTO M. LANG, MD, KENNETH M. BOROW, MD, ALEX NEUMANN, BS, JAFAR AL-SADIR, MD, and STEVEN B. FEINSTEIN, MD Despite the recent interest in contrast-enhanced echocardiography as a means of defining myocardi- al perfusion, the effects of echo contrast agents on left ventricular (LV) contractility in humans remains poorly defined. This is particularly relevant because intracoronary injection of contrast agents used for angiographic visualization of coronary arteries pro- duces significant alterations in LV hemodynamics. The relation of LV end-systolic wall stress (ueS) to rate-corrected velocity of fiber shortening (Vcfc), a load-independent index of contractility, was studied in 7 patients undergoing elective coronary arteriog- raphy. Two-dimensional and targeted M-mode echocardiographic and central aortic pressure trac- ings were recorded during injections of standard vol- umes of angiographic (7 to 9 ml of nonsonicated Renografin-76) and echocardiographic (1.5 to 2.0 ml of sonicated Renografin-76) contrast agents into the left main coronary artery. The order in which agents were injected was randomly determined. Myocardial contractility was assessed under control conditions and 5 and 15 seconds after injection. Al- terations in contractility relative to control were measured as the change in Vcfc after elimination of afterload (a,,) as a confounding variable. An injec- tion of Renografin-76 adequate for angiographic im- aging of coronary artery anatomy resulted in a sig- nificant depression of LV contractility (p <O.OOl) in conjunction with a tendency toward increased after- load (p = 0.12); recovery occurred by 15 seconds after injection. The smaller amounts of sonicated Renografin-76 required to give adequate contrast enhancement of the myocardium did not alter LV contractile state or afterload. Thus, sonicated Reno- grafin-76 is a safe echocardiographic contrast agent without adverse effects on LV contractility and the volume of contrast material injected rather than the presence of microbubbles appears to be the major determinant of altered myocardial mechanics. (Am J Cardiol 1987;80:166-171) R ecently, contrast-enhanced echocardiography has been proposed as an accurate means of defining myo- cardial perfusion. 1-5 However, limited data are avail- able regarding the toxicity and safety of echocardio- graphic contrast agents. In humans, the most widely used angiographic and echocardiographic contrast agent is meglumine diatrizoate (Renografin-76). When injected in the usual volumes, this iodinated contrast material acutely alters systemic blood pressure, heart rate and ventricular filling volumes.6-g Because tradi- From the Section of Cardiology, Department of Medicine, The University of Chicago Medical Center, Chicago, Illinois. This work was supported in part by grants from the Goldblatt Re- search Foundation and the Amoco Foundation, Chicago, Illi- nois. Manuscript received December 1, 1986; revised manu- script received March 9,1987, accepted March 11, 1987. Address for reprints: Roberto M. Lang, MD, University of Chicago Medical Center, Section of Cardiology, 5841 South Maryland Avenue, Box 44, Chicago, Illinois 60637. 166 tional ejection phase indexes of left ventricular (LVJ performance are dependent on all of these variables, they cannot separate derangements in contractility from alterations in LV loading conditions. we avoided this limitation by using the load- and heart rate-inde- pendent relation between end-systolic wall stress (a,,) and rate-corrected velocity of fiber shortening (Vcfc)10m14 to assess the effects of intracoronary injec- tions of sonicated and nonsonicated Renografin-76 on LV contractile state in humans. Methods Patients: Seven patients participated in the proto- col, which was approved by the University of Chica- go’s Clinical Investigation Committee. The study pop- ulation consisted of 6 men and 1 woman undergoing routine coronary angiography. The age range was 36 to 70 years (mean 51 f 12). No patients had segmental wall motion abnormalities as assessed by %dimen- sional (Z-D] echocardiography and biplane left ven-