title: Quantification of transmural gradient of blood flow in myocardial ischemia with real-time myocardial contrast echocardiography and dipyridamole stress test.
abstract: Transmural redistribution of myocardial blood flow (MBF) is the earliest sign of myocardial ischemia. We aimed to evaluate the ability of real-time myocardial contrast echocardiography (MCE) combined with dipyridamole stress to quantify the transmural gradient of MBF during graded coronary stenosis. Real-time MCE was performed in 14 open-chest dogs at seven experimental stages: baseline; hyperemia induced by 6-min infusion of dipyridamole; 50%, 75% and 90% reduction of hyperemic flow after constriction in each stage for 10 min; reperfusion for 10 min; and subtotal occlusion of the left anterior descending coronary artery (LAD) for 90 min. We obtained MCE perfusion parameters from subendocardial (A-endo, beta-endo and A x beta-endo) and subepicardial (A-epi, beta-epi and A x beta-epi) layers of the ventricular septum and calculated their transmural gradients (A-EER, beta-EER and A x beta-EER) and systolic wall thickening (SWT). The sensitivity and specificity of each parameter for predicting 75% reduction of hyperemic flow, which was defined as mild myocardial ischemia, were derived by receiver operating characteristic (ROC) curve analysis. No transmural gradients were found at baseline; during maximal hyperemia and 50% reduction of hyperemic flow. beta-endo, A x beta-endo, beta-EER and A x beta-EER decreased significantly when the hyperemic flow was reduced by 75% or more. In contrast, SWT remained unchanged until the hyperemic flow was reduced by 90%. Among all parameters measured, beta-EER and A x beta-EER had the highest and SWT the lowest sensitivity and specificity in predicting mild myocardial ischemia. In conclusion, real-time MCE combined with dipyridamole stress allows for quantification of the transmural gradient of MBF. beta-EER and A x beta-EER are more sensitive than SWT and other MCE parameters in detecting mild myocardial ischemia.
authors.affiliation: The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, Jinan, Shandong, China.
authors.forename: Gui-Hua
authors.initials: GH
authors.lastname: Yao
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.forename: Feng-Rong
authors.initials: FR
authors.lastname: Sun
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: Yu-Xia
authors.initials: YX
authors.lastname: Zhao
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Zhong
authors.forename: Shi-Fang
authors.initials: SF
authors.lastname: Ding
authors.forename: Wen-Qiang
authors.initials: WQ
authors.lastname: Chen
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Li
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D003287:Contrast Media; D003326:Coronary Circulation; D004176:Dipyridamole; D004285:Dogs; D005240:Feasibility Studies; D005260:Female; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D015588:Observer Variation; D010743:Phospholipids; D015203:Reproducibility of Results; D013459:Sulfur Hexafluoride; D013599:Systole; D014463:Ultrasonography; D014665:Vasodilator Agents
chemical_list: D003287:Contrast Media; D010743:Phospholipids; D014665:Vasodilator Agents; C420843:contrast agent BR1; D004176:Dipyridamole; D013459:Sulfur Hexafluoride