OBJECTIVETo investigate the impact of high-dose microbubbles induced by high mechanical index myocardial contrast echocardiography (MCE) on vascular permeability and its recovery time in rats.

METHODSThirty male Wistar rats were randomized into 4 MCE groups (groups A-D) and a control group. In the MCE groups, Evans blue was injected at 10 s before MCE (A), immediately after the end of MCE (B), and at 5 min (C) and 20 min after the end of MCE (D). In the control group, the microbubbles and Evans blue were injected at the end of a 5-min ultrasound exposure. All the rats were sacrificed 5 min after Evans blue injection, and the content of Evans blue in the myocardium and the percentage of Evans blue leakage area were determined.

RESULTSThe percentage of Evans blue leakage area in groups A, B and C were significantly higher than that in the control group (P<0.05), while the percentage was similar between group D and the control group (P>0.05). Evans blue contents in groups A and B were significantly higher than that in the control group (P<0.05), but groups C and D showed comparable contents with the control group E (P>0.05). No significant changes of the heart rates and premature beat number were observed during and after MCE in these groups (P>0.05).

CONCLUSIONHigh mechanical index MCE and a high contrast dose may induce increased microvascular leakage in rats, and the vascular permeability can recover in 20 min after MCE.