Noninvasive quantification of regional ventricular function in rats: assessment of serial change and spatial distribution using ultrasound strain analysis.

BACKGROUND: The optimal method for quantitative assessment of regional ventricular function in rats remains unclear. The goal of this study was to investigate the use of ultrasonic strain rate (SR) and strain analysis in evaluating the serial change and spatial distribution of regional contractile function in rats. METHODS: In all, 22 anesthetized rats underwent incremental dobutamine infusion (protocol 1) for assessment of serial change or underwent coronary ligation (protocol 2) for assessment of spatial distribution. For protocol 1, the serial change of systolic SR and strain during dobutamine was measured in the posterior myocardium on the short-axis view, and the systolic strain was compared with the percent change in wall thickening. For protocol 2, the spatial distribution of strain profile was analyzed in normal, peripheral ischemic, and central ischemic regions that were identified by myocardial contrast echocardiography. RESULTS: In protocol 1, the incremental dobutamine infusion resulted in a gradual increase in peak systolic SR. In contrast, peak systolic strain increased with low-dose dobutamine but tended to decrease for higher doses of dobutamine. Further, the serial change of peak systolic strain corresponded to changes in percent change in wall thickening, but the strain values were always lower than percent change in wall thickening. In protocol 2, the strain profile indicated postsystolic thickening in the peripheral ischemic region and indicated systolic wall thinning in the central ischemic region. CONCLUSIONS: Ultrasonic determination of SR and strain is an accurate and noninvasive method of quantitation of the serial change and spatial distribution of regional contractile function in rats.

[Efficacy of intravenous myocardial contrast echocardiography for assessment of perfusion area of the heart in mice].

BACKGROUND AND OBJECTIVES: Intravenous myocardial contrast echocardiography is used clinically, but use in small animals has not been evaluated. The conditions for myocardial opacification and the feasibility of myocardial contrast echocardiography were examined in mice. METHODS: Closed chest mice were examined. The left ventricular short-axis view at the mid papillary muscle level was recorded before and after NC100100 injection using a SONOS 5500 (PHILIPS). Real time and intermittent triggering (every 5 beats) myocardial contrast echocardiography was performed with a mechanical index of low (0.3), middle (0.7), and high (1.5). Open chest mice were examined after left anterior descending coronary artery ligation. Myocardial contrast echocardiography was performed using intermittent triggering imaging (every 5 beats) with high mechanical index (1.5). The ratio of the non-perfused area to the whole left ventricular wall area was compared with that of the non-stained area by Evans Blue. RESULTS: The left ventricular myocardium was opacified in any setting. Good opacification was acquired at middle mechanical index (0.7) in real time myocardial contrast echocardiography and at high mechanical index (1.5) in intermittent myocardial contrast echocardiography. The opacified and non-opacified myocardium were clearly identified in all mice with coronary ligation. The non-opacified area ratio showed a good correlation with the non-stained area ratio (y = 0.93x + 0.51, r = 0.94, p < 0.05). CONCLUSIONS: Myocardial contrast echocardiography can be used to assess myocardial perfusion and determine the ischemic area accurately in situ in the mouse.