Is blood squeezed out from the microcirculation soon after coronary occlusion?: real time myocardial contrast echocardiographic study

摘要

BACKGROUND AND OBJECTIVES: The fate of blood trapped inside the myocardial microvessels after complete occlusion of the coronary artery has not been elucidated. Blood may be squeezed out by residual contraction even after coronary occlusion. The microcirculation was examined soon after coronary occlusion by real-time contrast echocardiography. METHODS: Myocardial opacification in the short-axis view was examined during infusion of FS69 (Optison) using the Coherent Contrast Imaging method(SIEMENS Sequoia 512) in 17 open chest dogs. The left circumflex coronary artery was completely ligated for 15 sec and the video intensity (256 gray level) of the risk area was measured at end-systole of every 3 beats before and after ligation. Temporal deterioration of the wall motion was evaluated, defined as normokinesis, mild hypokinesis and severe hypokinesis, and akinesis. Changes in the video intensity during each stage of wall motion abnormalities were examined. RESULTS: The video intensity of the risk area decreased significantly after coronary occlusion. Wall motion of the risk area deteriorated gradually after ligation, in which mild hypokinesis, severe hypokinesis and akinesis developed consecutively at 2.8 +/- 0.5, 5.4 +/- 0.5 and 7.8 +/- 0.8 sec after coronary ligation, respectively. The changes in video intensity during each stage of the wall motion abnormalities were small and not statistically significant, irrespective of severity of wall motion abnormalities. CONCLUSIONS: These findings suggest that the blood remains in the vascular bed immediately after the coronary occlusion and is not squeezed out even if wall motion of the risk area continues.