太田 剛弘², 別府 慎太郎¹, 中谷 敏¹, 宮武 邦夫¹

Takahiro OHTA², Shintaro BEPPU¹, Satoshi NAKATANI¹, Kunio MIYATAKE¹

¹国立循環器病センター研究所, ²（現）横浜南共済病院第一内科

¹National Cardiovascular Center, Research Institute and Hospital, ²The 1st Department of Internal Medicine, Yokohama Minami kyosai Hospital

キーワード : Echocardiography, Myocardial perfusion, Microbubble, Microcirculation, Contrast

Recently, it has been reported that myocardial contrast echocardiograhpy is useful in assessing coronary perfusion. Since the source of contrast echo is microbubble, its number and size are important factors for evaluating microcirculation. Theoretically, a contrast medium with numerous microbubbles as small as red blood cells is preferable. We examined the size, number and stability of microbubbles in various contrast agents. The contrast agents examined were 76% Urografin, Iopamiron 370, Haemacell, 5% human albumin and 0.9% saline. Agitation was performed both by hand and by sonication. The number and size of microbubbles were analyzed by the Coulter counter, and the shape and size were observed directly through polarized light microscopy. The size distribution of the microbubbles was not standard, but deviated to the direction of the small size for any agent agitated by any method. The mean size of the microbubbles was the smallest in the sonicated albumin and the largest in hand-agitated Urografin. In the sonicated albumin, the total number of microbubbles was approximately 400,000 p/ml and their median size in diameter was 5 microns. In general, large microbubbles diminished within a few minutes after agitation, while remaining in the Urografin solution for several minutes. The smaller microbubbles with a diameter of less than 3 microns were stable in all agents except saline. In addition, the translucency of the contrast solution, which was examined by thin layered light, was maintained over a long period. However, the agents were not echogenic more than 10 minutes after agitation in vitro. Therefore, smaller microbubbles less than 2 to 3 microns in diameter might not be echogenic. In any case, the number of the microbubbles ranging from 5 to 10 microns in diameter were prominent in sonicated albumin. We, therefore, concluded that the sonicated albumin was the best agent for myocardial contrast echocardiography.