Flow dynamics of QW7437, a new dodecafluoropentane ultrasound contrast agent, in the microcirculation
Microvascular mechanisms for persistent tissue echo enhancement
Takanori Yasu, MD, PhD*,
Geert W. Schmid-Schönbein, PhD ,
Bruno Cotter, MD* and
Anthony N. DeMaria, MD, FACC*
* Cardiology Division, Department of Medicine, University of California at San Diego, La Jolla, California, USA
Department of Bioengineering, University of California at San Diego, La Jolla, California, USA
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Figure 1 Two QW7437 microbubbles labeled by PKH-26 under transillumination (left panel) and their fluorescent image (right panel).
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Figure 2 The time course of individual QW7437 microbubble velocities in four arterioles (a), vessel diameter between 13 µm and 29 µm) and in five capillaries (b), vessel diameter between 5 µm and 8 µm). Open squares show microbubbles with a transient stoppage ( 0.1 s stoppage at one site), and small closed squares show microbubbles without it. In a, only one microbubble showed a stoppage for 0.27 s to a terminal arteriole at 465 s after the administration. In b, two microbubbles showed a transient stoppage in capillaries for 0.37 s and 0.40 s, respectively.
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Figure 3 A fluorescently labeled QW7437 microbubble moving along an arteriole and capillary. An arteriole with a diameter of 19 µm, branching into an 18-µm arteriole and a 10-µm arteriole turning into a 7-µm capillary, was imaged under transillumination in A. The flow in the arteriole is from right to left. In B, a PKH-26–labeled QW7437 microbubble was moving through the arteriole at 60 s after the bolus injection. C shows the image of the bubble entering into the capillary at 0.07 s after B. In D, the bubble was moving along the capillary without stoppage at 0.13 s after B.
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Figure 4 The time course of individual QW7437 microbubble velocities in six venules with a vessel diameter between 11 µm and 30 µm (a) and in four venules with a vessel diameter between 31 µm and 50 µm (b). Open squares show microbubbles with transient stoppage (0.1 s stoppage at one site), and small closed squares show microbubbles without transient stoppage.
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Figure 5 Sequence of micrographs showing the process of attachment of fluorescently labeled QW7437 microbubbles to the postcapillary venules. The flow is from top to bottom right. A: A 12-µm postcapillary venule indicated by an arrow running on the right side of a 48-µm collecting venule under transillumination. B: Two microbubbles showed transient stoppage to a 12-µm postcapillary venule 150 s after the labeled QW7437 bolus injection. C: 1.0 s after B. The right microbubble (small arrow) moved as slowly as 15 µm in 1.0 s; however, the left microbubble (large arrow) remained at the same site. D: 5.0 s after B. The right microbubble (small arrow) moved away after stopping for 4.0 s at the same locale shown in C. The left microbubble (large arrow) stayed at the same site as shown in B. E: 5.07 s after B. The microbubble. (large arrow) has started to move again after stopping for 5.1 s.
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