Yasu T, Schmid-Schönbein G W, Cotter B, DeMaria A N
Department of Medicine, University of California at San Diego, La Jolla 92093-0412, USA.
J Am Coll Cardiol. 1999 Aug;34(2):578-86. doi: 10.1016/s0735-1097(99)00209-0.
The purpose of this study was to test the hypothesis that a subgroup of QW7437 microbubbles, dodecafluoropentane-based ultrasound contrast microspheres, resides for prolonged periods in the microvasculature.
QW7437 produces echo enhancement in myocardium which may persist relatively longer than opacification in the left ventricular cavity. The mechanism for this persistent enhancement remains unknown.
The transit of fluorescently labeled erythrocytes was examined by fluorescence intravital microscopy in the microvessels in five rat mesenteries. Ten rats were used to observe the behavior of fluorescently labeled QW7437 microbubbles in the mesenteric microcirculation.
There was no significant change in erythrocyte velocity in the arterioles and venules after the administration of QW7437 microbubbles (0.05 ml/kg) preactivated by negative hydrodynamic pressure. Of 552 microbubbles observed in four arterioles and five capillaries, 549 (99.5%) passed without stoppage (> or = 0.1 s stoppage); only one stopped transiently in arteriole and two in capillaries, each for <0.5 s. Sixty-five of 478 microbubbles (13.6%) observed in six postcapillary venules 11 to 30 microm in diameter and 24 of 408 microbubbles (5.9%) in four venules 31 to 50 microm in diameter stopped transiently (0.1 to 180 s) with an attachment to venular endothelium; the remaining microbubbles passed through the venules without stoppage.
Prolonged survival as microbubbles in the circulation and transient stoppage of a subgroup of microbubbles in the microvasculature, particularly in venules, are potential mechanisms for the persistent tissue echo enhancement by QW7437 microbubbles during contrast echocardiography.
本研究旨在验证以下假设，即QW7437微泡（一种基于十二氟戊烷的超声造影微球）的一个亚组会在微血管中长期留存。
QW7437可使心肌回声增强，这种增强可能比左心室腔的显影持续时间相对更长。这种持续增强的机制尚不清楚。
通过荧光活体显微镜检查五只大鼠肠系膜微血管中荧光标记红细胞的通过情况。使用十只大鼠观察荧光标记的QW7437微泡在肠系膜微循环中的行为。
在给予经负流体动力压力预激活的QW7437微泡（0.05 ml/kg）后，小动脉和小静脉中的红细胞速度没有显著变化。在四条小动脉和五条毛细血管中观察到的552个微泡中，549个（99.5%）无阻碍通过（停滞时间≥0.1秒）；只有一个在小动脉中短暂停滞，两个在毛细血管中短暂停滞，每次停滞时间均小于０.5秒。在直径为11至30微米的六条毛细血管后微静脉中观察到的478个微泡中有65个（13.6%），在直径为31至50微米的四条微静脉中观察到的408个微泡中有24个（5.9%）短暂停滞（0.1至180秒）并附着于微静脉内皮；其余微泡无阻碍地通过微静脉。
作为微泡在循环中长时间留存以及微泡亚组在微血管（尤其是微静脉）中短暂停滞，是QW7437微泡在超声心动图造影期间使组织回声持续增强的潜在机制。
