Viable myocardium evaluation by two dimensional speckle tracking imaging combined with adenosine stress echocardiography / 中华心血管病杂志

<p><b>OBJECTIVE</b>Regional left ventricular (LV) function could be detected by measuring peak-systolic strain by speckle tracking imaging (STI). We evaluated the value of STI combined with adenosine stress echocardiography on assessing myocardial viability in patients with myocardial infarction (MI).</p><p><b>METHODS</b>Two dimensional echocardiography was performed at rest and after adenosine stress echocardiography (infused at 140 µg×kg(-1)×min(-1) over a period of 6 min) in 39 stable patients with previous MI. Peak-systolic (Speak-sys) circumferential strain, radial strain and longitudinal strain were assessed by STI. Radionuclide myocardial perfusion/metabolic imaging served as the "gold standard" to detection of myocardial viability.</p><p><b>RESULTS</b>(1) There were 215 viable and 153 non-viable regions among 368 abnormal motion segments out of 624 segments in 39 MI patients according to radionuclide imaging results. (2) Speak-sys was similar between viable and nonviable myocardium at rest (all P > 0.05). After adenosine infusion, radial Speak-sys [(37.98 ± 5.45)% vs. (30.22 ± 5.47)%], longitudinal Speak-sys [(-23.71 ± 4.53)% vs. (-17.52 ± 4.34)%] increased significantly (P < 0.05)in viable segments compared to baseline levels and were significantly higher than in nonviable segments radial Speak-sys [(37.98 ± 5.45)% vs. (30.12 ± 5.37)%] and longitudinal Speak-sys [(-23.71 ± 4.53)% vs. (-16.95 ± 4.62)%] (P < 0.05), while remained unchanged in nonviable segments before and after adenosine infusion. Circumferential Speak-sys was similar before and after adenosine infusion in both viable and nonviable segments (all P > 0.05). (3) Delta radial strain change > 9.8% has a sensitivity of 82.3% and a specificity of 81.1% whereas a delta change of longitudinal strain > 16.5% has a sensitivity of 83.5% and a specificity of 92.3% for detecting viable segments.</p><p><b>CONCLUSIONS</b>Speckle tracking imaging combined with adenosine stress echocardiography could serve as a new and reliable method of assessing myocardial viability.</p>

Evaluation of viable myocardium by two-dimensional strain imaging combined with adenosine stress echocardiography in dogs underwent experimental ischemia/reperfusion injury / 中华心血管病杂志

<p><b>OBJECTIVE</b>to explore the feasibility of evaluating viable myocardium with two-dimensional strain imaging combined with adenosine stress echocardiography.</p><p><b>METHODS</b>acute myocardial infarction and reperfusion model was made by ligating anterior descending coronary artery for 90 minutes followed by 120-minute reperfusion in 15 healthy mongrel dogs. Images were acquired at baseline and after reperfusion. Adenosine was then infused and image acquisition repeated. Regional peak-systolic strain in radial, circumferential and longitudinal motion on anterior wall and anterior septum were measured. TTC staining served as a "gold standard" to define viable and nonviable myocardium. The ratio of infarct area (S(N)) to total area (S) was calculated and viable myocardium was defined with S(N)/S ≤ 50%.</p><p><b>RESULTS</b>at baseline, RS(peak sys), CS(peak sys) and LS(peak sys) were similar between viable (n = 37) and nonviable myocardial segments (n = 53) and significantly decreased after reperfusion in both viable and nonviable myocardial segments. Compared with values obtained after reperfusion, LS(peak sys) and RS(peak sys) remained unchanged in nonviable myocardial segments and significantly increased in viable myocardial segments after adenosine (P < 0.05). Post adenosine RS(peak sys) was negatively correlated with S(N)/S and CS(peak sys) and LS(peak sys) were positively correlated with S(N)/S. With ΔRS(peak-sys) (before and after adenosine) ≥ 13.5%, the sensitivity was 83.8% and specificity was 83.0% for distinguishing viable from nonviable myocardial segment. With ΔLS(peak sys) ≥ 11% as cutoff value, the sensitivity was 78.4% and specificity was 88.7% for distinguishing viable from nonviable myocardial segment. Combining ΔRS(peak sys) and ΔLS(peak sys), the sensitivity and specificity for distinguishing viable from nonviable myocardial segment were 91.9% and 79.2%, respectively.</p><p><b>CONCLUSIONS</b>two-dimensional strain imaging combined with adenosine stress echocardiography could quantitatively identify viable and nonviable myocardium.</p>

Effects of simulated microgravity on L-ARG-NO-CGMP pathway of abdominal aorta in rats / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of simulated microgravity on dilatory responsiveness and NOS expression of abdominal aorta in rats.</p><p><b>METHODS</b>Twenty male healthy SD rats, which body weight ranged from 300 g to 330 g, were divided into control group and simulated microgravity group randomly. After 4 weeks, using isolated arterial rings from rats, arterial dilatory responsiveness of abdominal aorta were examined in vitro. And the expression of nitric oxide synthase (NOS), including endothelial NOS (eNOS) and inducible NOS (iNOS), were observed by Western blot.</p><p><b>RESULTS</b>Dilatory responses of arterial rings to L-Arginine (10(-8)-10(-3) mol/L), and Acetylcholine mol/L) were decreased in simulated microgravity rats compared with that of controls; but dilatory responses of isolated aortic rings to sodium nitroprusside (mol/L) and 8-bromo-cGMP(mol/L) were similar in both simulated microgravity rats and control rats. The expression of both eNOS and iNOS had not showed significant differences between two groups.</p><p><b>CONCLUSION</b>The data indicate that endothelium dependent vasorelaxation in abdominal aortic rings are decreased by 4-week simulated microgravity, and this change may be result from altered NOS activity in endothelium.</p>