Effect of pressure on intracardiac backscatter from microbubbles

Abstract

The backscatter from sonicated albumin microbubbles (Albunex) was analyzed using acoustic densitometry in anin vitro pulsatile heart model to evaluate the effects of pressure on the backscatter from Albunex, and the cardiac cyclic changes of intracardiac backscatter from sonicated albumin microbubbles in 16 healthy persons were analyzed. It was found that the Albunex microbubbles were compressed in systole and decompressed in diastole, causing corresponding changes of backscatter in cardiac cycle. Although the intensities of backscatter in diastole and systole were related to the concentration of microbubbles, the concentration of microbubbles had no effect on the difference of end-diastolic and end-systolic backscatter. The difference of the backscatter was highly correlated with end-systolic pressure (r=0.96,P = 0.001). In human studies, we also observed same intracardiac cyclic changes of backscatter from sonicated albumin microbubbles. Our study indicates that it is possible to evaluate the intracardiac pressure non-invasively by analyzing the intracardiac backscatter from the microbubbles with acoustic densitometry.

Keywords

ultrasound backscatter / microbubbles / intracardiac pressure

References

[1] ShapiroJ R, RrisnerS A, LichtenbergG S, et al. . Intravenous contrast echocardiography with use of sonicated albumin in humans: systolic disappearance of left ventricular contrast after transpulmonary transmission. J Am Coll Cardiol, 1990, 161603-1603

[2] BraymanA A, AzadnivM, MillerM W, et al. . Effect of static pressure on acoustic transmittance of Albunex microbubbles suspensions. J Am Soc Echocardiogr, 1996, 992403-2403

[3] GottliebS, ErnstA, MeltzerR S. Effect of pressure on echocardiographic videodensity from sonicated albumin: Anin vitro model. J Ultrasound Med, 1995, 14109-109

[4] VuilleC, NidorfM, MorriseyRL, et al. . Effect of static pressure on the disappearance rate of specific echocardiographic contrast agents. J Am Soc Echocardiogr, 1994, 7347-347

[5] Mor-AviV, ShorffS G, RobinsonK A, et al. . Effect of left ventricular pressure on sonicated albumin microbubbles: Evaluation using an isolated rabbit heart model. J Am Coll Cardiol, 1994, 241779-1779

[6] IsmailS, AndersonT A. Integrated backscatter and digital acquisition during myocardial contrast echocardiography: Is there an advantage over conventional echocardiography for intracoronary injections?. J Am Soc Echocardiogr, 1995, 8453-453

[7] WaltmanT, UndesserK, KwanO L, et al. . Variables capable of influencing videointensity measurements from left ventricular contrast opacification. Circulation, 1993, 88(4): 1-162

[8] MorseP M, IngardK U. Theoretical Acoustics, 1968, Wuhan, McGrawHill: 400-400

[9] PowsnerS M, MarcusR S. Quantitation of echo contrast effects. Am J Physiol Imaging, 1986, 1124-124