Rationale and objectives: The objective of the present study was to compare the data regarding the ability of real-time myocardial contrast echocardiography (MCE) to assess altered myocardial blood flow produced by graded coronary stenoses between open- and closed-chest canine models.
Materials and methods: Three grades of left anterior descending coronary artery stenosis and occlusion were created in 6 open- and 6 closed-chest canine models. MCE used FS-069 infusion and real-time imaging. Myocardial signal intensity versus time plots were fitted to a 1-exponential function to obtain the peak signal intensity (A) and rate of signal intensity rise (b) for quantification of myocardial blood flow.
Results: The value of b obtained from closed-chest canine models (without stenosis = 0.995 +/- 0.087, mild stenosis = 0.968 +/- 0.076, moderate stenosis = 0.569 +/- 0.077, severe stenosis = 0.288 +/- 0.032, occlusion = 0.085 +/- 0.031) was not significantly different from that obtained from open-chest canine models (without stenosis = 1.028 +/- 0.107, mild stenosis = 0.998 +/- 0.098, moderate stenosis = 0.601 +/- 0.055, severe stenosis = 0.321 +/- 0.029, occlusion = 0.079 +/- 0.028) at any grade of stenosis (P = 0.09, 0.08, 0.44, 0.11, 0.74, respectively).
Conclusions: In myocardial regions where attenuation of the ultrasound beam and artifacts produced by the chest wall are minimal, the data from transthoracic MCE in the closed-chest model may show values similar to those from MCE in the open-chest model.