| Part 1. Quantitative evaluation of myocaridal perfusion in rabbit by real-time myocardial contrast echocardiographyIn this part, we performed real-time myocardial contrast echocardiography and a continous infusion of SonoVue into the vein to detect the myocardial perfusion of normal rabbits, aiming to evaluate the feasibility of real-time myocardial contrast echocardiography in quantitative evaluation of myocardial perfusion in rabbit and ravel myocardial perfusion status in normal rabbit.Results:①The experiments were finished in all 10 rabbits and high quality images were obtained for every experiment. Afer FLASH, microbubbles in the myocardium were destructed completely.The refilling curve could be fitted in every segment .②Infusing SonoVue in vein, the myocardium got brighter and brighter with the the infusion rate arising from 10ml/h to 30ml/h.Up to 40ml/h, attenuation was seen obviously.The best infusion rate in vein continuously for SonoVue was 30 ml/h.③The contrast appeared in right heart , left heart and myocardium at 7.5±2.2s, 9.1±2.4s and 12.2±1.6s separately. After 16.6±2.3s, contrast produced steadily in myocardium.④The mean A,βand A×βvalue of 6 segments in the short axis view at the papillary muscle level were 9.8±3.0 dB, 1.4±0.5s-1 and 13.5±3.6 dB×s-1 separately. There were no significant difference for A,βand A×βvalue among 6 segments, suggesting the myocardial perfusion was homogeneous in normal rabbit.Part 2. Quantitative evaluation of myocardial perfusion and the relation with histology in rabbit model with coronary artery atherosclerosis by real-time myocardial contrast echocardiographyIn this part, we performed real-time myocardial contrast echocardiography in normal rabbit and rabbit model with coronary artery atherosclerosis, aiming to evaluate the value of real-time myocardial contrast echocardiography in quantitative evaluation of myocardial perfusion in rabbit model of coronary atherosclerosis, to analyse the relation of myocardial perfusion detecting by real-time myocardial contrast echocardiography and narrow degree of the according coronary artery and the desity of myocardial microvassel by comparing with the results of histology.Results:①Rabbits in atherosclerosis group(AS group) were modeled for atherosclerosis successfully. Blood lipid rised significantly comparing with that before modeling and with that of rabbits in normal group(TG 3.89±0.85vs0.82±0.19 & 0.81±0.22mmol/l; TC 28.91±4.52vs1.57±0.13 & 1.58±0.32mmol/l). Marked atherosclerosis was seen in aortic arch in all 10 rabbits.②Marked atherosclerosis was seen in left anterior descending coronary artery in all 10 rabbits. The narrow degree was 71%～99%, mean 81.7±9.3%.③Results of real-time myocardial contrast echocardiography showed that myocardial perfusion decreased in anterior segment and anterorseptal segment in AS group.β(mean 0.9±0.3 vs 1.6±0.5 s-1)and A×β(mean 8.2±2.7 vs 15.1±3.7 dB×s-1)decreased significantly in AS group, but A(mean 8.9±2.0dB vs 10.0±2.9dB) was not differrent significantly between two groups.⑤Density of myocardial microvessel was not differrent significantly between two groups(604±128n/mm2 vs 621±103n/mm2).⑤βand A×βwere related with the narrow degree of left anterior descending coronary artery(r=-0.64(P=0.048), r=-0.77(P=0.01)) , but there was no relation between A and the narrow degree of left anterior descending coronary artery(r=-0.42(P=0.22)). Part 3. Quantitative evaluation of myocardial perfusion and functional change in rabbit model with coronary artery atherosclerosis by real-time myocardial contrast echocardiographyIn this part, we evaluated myocardial perfusion in rabbit model of coronary atherosclerosis with real-time myocardial contrast echocardiography, evaluated myocardial function with tissue Doppler imaging, in order to analysis the relation of myocardial perfusion abnormality and myocardial function abnormality, and to evaluate the value of real-time myocardial contrast echocardiography and tissue Doppler imaging in identifying myocardial ischemia in the early stage in atherosclerosis.Results:①EF(66.6±4.5%vs68.2±5.7%), FS(33.6±3.2%vs34.9±4.3%) and E (0.9±0.1vs0.9±0.1 m/s) was not significantly different between two groups.②The whole myocardial perfusion decreased in AS group withβ(0.9±0.3 vs1.4±0.5s-1)and A×β(8.4±3.1 vs13.5±3.6dB×s-1)decreased.③The regional myocardial perfusion decrease in AS group withβand A×βdecreased in inferoseptal (β0.9±0.3vs1.6±0.5 s-1, A×β8.5±2.7vs15.8±6.3 dB×s-1), anterior (β0.8±0.4vs1.4±0.9 s-1;A×β7.3±3.8vs12.8±6.9 dB×s-1) and inferior segments(β0.8±0.3vs1.3±0.8 s-1;A×β8.0±3.2vs12.3±6.6 dB×s-1).④With QTVI, the whole myocardial function decreased in AS group with Sa(4.3±1.0vs6.1±0.6 cm/s), Ea(3.8±1.4vs6.8±0.7 cm/s)decreased and E/Ea (0.17±0.08vs0.09±0.02)increased.⑤With QTVI, the regional myocardial function decreased in AS group with Em decreased in middle segments of left ventricular anterior wall (2.3±1.7vs4.9±2.1 cm/s) and inferior wall (3.7±1.6vs5.5±1.1 cm/s), Sm decreased in the middle segment of inferior wall (3.0±0.6vs4.3±0.5 cm/s). ConclusionsUnder the conditions of the present experimental study, our conclusions were as follows:①Real-time myocardial contrast echocardiography is feasible in quantitative evaluation of myocardial perfusion in normal rabbit and rabbit model of atherosclerosis. RTMCE might be an effective method to evaluate myocardial perfusion in coronary artery disease in clinic.②Myocardial perfusion is homogeneous in normal rabbits with RTMCE.③Myocardial perfusion in rabbit model of atherosclerosis was abnormal with decreasedβand A×βvalue in RTMCE.④βand A×βwere related with the narrow degree of according coronary artery, suggesting that RTMCE could reflect the narrow degree of coronary artery in rest.⑤Spacial extent of myocardial pefusion abnormality was greater than that of function abnormality, then myocardial perfusion abnormality was earlier than functional abnormality, especially than systolic functional abnormality in rabbit model of coronary artery atherosclerosis. RTMCE is sensitive in identifying myocardial ischemia.⑥QTVI is more sensitive in identifying myocardial ischemia than routine echocardiography.
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