Microbubble formation: in vitro and in vivo observation

Injection of liquid through a catheter into the circulation is known to produce clouds of signals detected by sonography. Blood forced through a stenotic conduit produced sonographic clouding, and bubbles of 10-100 microns were observed were observed by light microscopy. The microbubbles persisted up to three and a half minutes. Microbubbles were observed in the microcirculation of the rat by placing the catheter tip into the descending aorta of 15 animals, viewing the mesentery at 400X magnification, and recording the results on videotape. Following injection of the rats' own blood, numerous microbubbles lodged promptly at the arteriolar level and obstructed blood flow for up to 200 sec before shrinking sufficiently to pass downstream and allow restitution of flow.