| ObjectiveSome previous studies demonstrated myocardial ischemia may result in changes of left ventricular (LV) torsion. However, none of these approaches provided information regarding the alternations of LV torsion after ischemia-reperfusion. Speckle Tracking Imaging (STI) is a recent ultrasound technique that enables quantification of LV torsion. This study attempted to evaluate the alternations of LV torsion after reflow induced by various durations of ischemia using STI.MethodsFourteen open-chest pigs underwent randomizedly 1 minute (group A) or 15 minutes (group B) of left anterior descending (LAD) ligation and followed up for 1 week. Rotation and torsion of LV in both groups were quantified by STI (Qlab 7.0, Philips iE33) before LAD occlusion, LAD occlusion immediately, and 1-,5-,30-,60-, 90-minute and 1-week after reperfusion. LV ejection fraction (LVEF) and wall motion score index (WMSI) were assessed at the same time points.ResultsThoracotomy and pericardiotomy caused no change in peak apical or basal rotation or peak LV torsion.Except for apical peak subepicardial rotation (Prot-epi) and LV peak subepicardial torsion (Ptw-epi) in group A, LAD occlusion resulted in a severe impairment of rotation and torsion in both groups, especially in group B.One minute after reflow, all decreased rotation and torsion in group A fully recovered. Apical Prot-epi and LV Ptw-epi in group B tended to increase like "U" type and there was significant difference at 90min and 60min after reperfusion relative to ischemia, respectively(all P<0.05). In contrast, hyperemic response resulted in the brief resumption of peak apical rotation and peak LV torsion in the inner layer during 30min after reflow from 3.4±1.2°to 6.5±0.8°(P＜0.05) and from 6.1±1.1°to 7.8±1.0°(P＜0.05), respectively. Consistent with subendo-cardial rotation or torsion, peak apical transmural rotation and peak LV transmural torsion changed after reperfusion. Thus, all of these rotation and torsion versus time profiles appeared like "W" type. There was no significant difference in basal rotation before and after reperfusion.Conclusions(1) As a result of various durations of ischemia, peak rotation and torsion in subendocardium and subepicardium change differently before and after reperfusion.(2) STI may be suitable for evaluation of the extent of ischemia by noninvasive quantification of rotation and torsion in subendocardium and subepicardium. Therefore, duration of assessment of ischemia can be prolonged.(3) There was no significant difference in rotation or torsion before and after thoracotomy and pericardiotomy. ObjectiveInfarct size and transmural extent (TME) are associated strongly with prognosis of acute myocardial infarction (AMI). Previous studies have demonstrated that there exists the relationship between left ventricular (LV) torsion and infarct size, but there are many markers about LV torsion, and it is unknown which are the most sensitive to evaluate infarct size. In addition, few of previous studies provided information about TME assessed by LV torsion. Therefore, the objective of this study, performed in the open-chest swine model of AMI, were (1) to analyze the variations of LV torsion induced by AMI and reperfusion using Speckle Tracking Imaging (STI), (2) to assess the relationship between routine markers of LV torsion and infarct size and TME, (3) to investigate the most sensitive markers of LV torsion reflecting infarct size and TME.MethodsFifteen anesthetized open-chest pigs (weight 20-25 kg), underwent 120 minutes of left anterior descending coronary artery (LAD) ligation followed by 12 hours of reperfusion. Rotation and torsion of LV were obtained by STI before LAD occlusion, LAD occlusion immediately, and 30,60,90 minutes and 12 hours after reperfusion. LV ejection fraction (LVEF) and wall motion score index (WMSI) were quantified at the same time points. TME was measured by Nitrotetrazolium blue chloride (NBT) staining. Total weights of the necrosis myocardium were calculated and expressed as percentages of total LV weight.ResultsOne swine died of persistent ventricular fibrillation before completion of the experiment. Data were presented for the remaining 14 pigs suffered from AMI proved by HE staining finally. LAD ligation resulted in a dramatic decrease in both subepicardial and subendocardial peak apical rotation or peak LV torsion in spite of different regions. Twelve hours after reperfusion, all of the peak rotation and torsion remained significantly reduced (P＜0.01 versus AMI). Peak subepicardial and subendocardial basal rotation did not significantly changed before and after reflow.At AMI and 12-hour follow-up after reperfusion, apical peak bulk rotation (Prot) and LV peak bulk torsion (Ptw) inversely correlated with infarct size (r=-0.69, P＜0.01; r=-0.81, P＜0.01). Additionally, there was a positive correlation between apical Prot as well as LV Ptw and LVEF.Before and after revascularization, there was no or a slight correlation between peak rotation or torsion in both layers and TME.Conclusions(1) Apical peak rotation or LV peak torsion in both layers are severely decreased at AMI, and they do not recover significantly after 12-hour reperfusion.(2) Infarct size well and inversely correlates with apical Prot and LV Ptw at AMI and 12-hour follow-up after reflow, furthermore, the relationship is superior to other peak rotation or LV torsion.(3) During the same time, good relationship between TME and peak rotation or LV torsion could not be found. ObjectiveThe aim of this study were (1) to compare subendocardial and subepicardial torsion between ST-segment elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) by Speckle Tracking Imaging (STI), (2) to identify transmural extent (TME) of the two kinds of myocardial infarction (MI), (3) to investigate whether there are some sensitive markers can reflect TME after MI.MethodsBasal and apical LV short-axis images were acquired in 30 controls (group A) and 65 patients with anterior wall AMI Patients, who underwent successful percutaneous coronary intervention (PCI) within 2-week of AMI onset. The patients were divided into 2 groups according to ST segments (STEMI group [group B, n=34] and NSTEMI group [group C, n=31]). Conventional echocardiography and STI were done in 3 groups before and 1-week,1- and 3-month after PCI.ResultsBefore PCI, AMI caused a severe reduction in peak apical rotation and peak LV torsion of both subendocardium and subepicardium in group B and C relative to those of group A (all P＜0.01). However, peak basal rotation decreased slightly (P>0.05).Three months after PCI, all peak apical rotation and peak torsion in both layers failed to increase significantly in group B, except apical peak bulk rotation (Prot) and LV peak bulk torsion (Ptw) improved.In contrast to pre-PCI, there were obvious changes in apical peak subepicardial rotation (Prot-epi) and LV peak subepicardial torsion (Ptw-epi) from 1.3±0.7°to 2.0±0.5°(P<0.01) and from 2.3±0.6°to 3.1±0.8°(P＜0.01) in group C after 1 month reperfusion, respectively. The both markers after 3 months returned baseline (P>0.05, versus group A). There was significant difference of them between group C and B at the same time points. Apical and LV peak subendocardial and transmural rotation/torsion improved but not significantly after revascularization. At 3-month follow-up after reperfusion, apical Prot and LV Ptw in group C markedly recovered.Conclusions(1) There is significant difference of TME between STEMI and NSTEMI using STI. TME of STEMI is higher than of NSTEMI, and recovery of subepicardial rotation or torsion of the latter is superior to of the former.(2) The TME of MI can be reflexed by follow-up and comparison of changes of both subendocardial and subepicardial peak rotation or torsion using STI.
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