Myocardial ischaemia and post-systolic shortening

The assessment of regional wall motion is useful to identify myocardial ischaemia because wall motion abnormalities occur relatively upstream in the ischaemic cascade. Echocardiography is widely used for this, but the subjectivity of visual observation may hamper accurate evaluation. The analysis of myocardial velocity and strain by tissue Doppler and speckle tracking echocardiography has allowed the quantitative assessment of regional wall motion and facilitated the detection of subtle myocardial deformation that is diffi cult to identify by conventional methods, such as post-systolic shortening (PSS). PSS is de fined as myocardial shortening that occurs after end-systole (or aortic valve closure), and it is observed in the myocardium with regional contractile dysfunction. In experimental and clinical studies, it has been reported that the assessment of PSS is superior to that of conventional parameters such as wall thickening or peak systolic strain in detecting acute ischaemia and diagnosing coronary artery disease. Moreover, it has recently been found that PSS remains after recovery from brief ischaemia despite the rapid recovery of peak systolic strain. The assessment of PSS allows after-thefact recognition of myocardial ischaemic insults and is expected to be used for ischaemic memory imaging. In this review, the usefulness of the assessment of PSS for the diagnosis of acute ischaemia and ischaemic memory is demonstrated, and issues that need to be resolved for the widespread use of this assessment in the echocardiographic laboratory are discussed.This article has been accepted for publication in Heart, 2015 following peer review, and the Version of Record can be accessed online at http://dx.doi.org/10.1136/heartjnl-2013-305403

Novel Estimation of Left Ventricular Filling Pressure Using 3-D Speckle-Tracking Echocardiography: Assessment in a Decompensated Systolic Heart Failure Model

E/e′ allows for the non-invasive estimation of left ventricular (LV) filling pressure; however, Doppler malalignment can make the estimation unreliable, especially in dilated systolic failing hearts. The ratio of peak early diastolic filling rate to peak early diastolic global strain rate (FRe/SRe), which is a parameter derived from 3-D speckle-tracking echocardiography to estimate filling pressure, may be better applied in dilated systolic failing hearts because it can be obtained without the Doppler method. We investigated whether FRe/SRe could provide a better estimation of filling pressure than E/e′ in 23 dogs with decompensated systolic heart failure induced by microembolization. FRe/SRe had better correlation coefficients with LV end-diastolic pressure (0.75–0.90) than did E/e′ (0.40). The diagnostic accuracy of FRe/SRe in distinguishing elevated filling pressure was significantly higher than that of E/e′. This study indicates that FRe/SRe may provide a better estimation of LV filling pressure than E/e′ in dilated systolic failing hearts.Takeda S., Asanuma T., Masuda K., et al. Novel Estimation of Left Ventricular Filling Pressure Using 3-D Speckle-Tracking Echocardiography: Assessment in a Decompensated Systolic Heart Failure Model. Ultrasound in Medicine and Biology 47, 1536 (2021); https://doi.org/10.1016/j.ultrasmedbio.2021.02.008

Deterioration of longitudinal, circumferential, and radial myocardial strains during acute coronary flow reduction: which direction of strain should be analyzed for early detection?

Longitudinal myocardial strain is considered to deteriorate in the early ischemic stage compared to circumferential and radial strains because the subendocardial inner oblique fibers are generally directed along the longitudinal axis. However, it is unclear whether the decrease in longitudinal strain precedes a decrease in circumferential and radial strains during acute coronary flow reduction. The left anterior descending artery was gradually narrowed in 13 open-chest dogs. Whole-wall and subendocardial longitudinal, circumferential, and radial strains were analyzed at baseline and during flow reduction. Peak systolic and end-systolic strains, the postsystolic strain index (PSI), and the early systolic strain index (ESI) were measured in the risk area; the decreasing rate in each parameter and the diagnostic accuracy to detect flow reduction were evaluated. Absolute values of peak systolic and end-systolic strains gradually decreased with flow reduction. The decreasing rate and diagnostic accuracy of longitudinal systolic strain were not significantly different from those in other strains, although the diagnostic accuracy of radial systolic strain tended to be lower. PSI and ESI gradually increased with flow reduction. In these parameters, a lower diagnostic accuracy with respect to radial strain was not demonstrated. During acute coronary flow reduction, the decrease in longitudinal systolic strain did not precede that in circumferential systolic strain; however, the decrease in radial systolic strain may be smaller than that of other systolic strains. In contrast, there appeared to be no differences in the PSI and ESI values among the three strains.This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1007/S10554-020-01888-

Myocardial layer-specific analysis of ischemic memory using speckle tracking echocardiography

The assessment of post-systolic shortening (PSS) by speckle tracking echocardiography allows myocardial ischemic memory imaging. Because the endocardial layer is more vulnerable to ischemia, the assessment of this layer might be useful for detecting ischemic memory. Serial echocardiographic data were acquired from nine dogs with 2 min of coronary occlusion followed by reperfusion. Regional deformation parameters were measured in the risk and normal areas. Using speckle tracking echocardiography, circumferential strain was analyzed in the endocardial, mid-wall, and epicardial layers; and radial strain was analyzed in the inner half, outer half and entire (transmural) layers. In the risk area, peak systolic and end-systolic strain in the circumferential and radial directions significantly decreased during occlusion, but recovered to the baseline levels immediately after reperfusion in all layers. However, circumferential post-systolic strain index (PSI), a parameter of PSS, significantly increased during occlusion, and the significant increases persisted until 20 min after reperfusion in the endocardial and mid-wall layers. Radial PSI tended to increase after reperfusion in the inner half and entire layers but these increases were not significant compared with baseline. In the normal area, systolic strains and PSI in the radial and circumferential directions hardly changed before and after occlusion/reperfusion in all layers. In layer-specific analysis with speckle tracking echocardiography, circumferential PSS in the endocardial and mid-wall layers may be useful for detecting ischemic memory. © 2014 Springer Science+Business Media.This is a post-peer-review, pre-copyedit version of an article published in International Journal of Cardiovascular Imaging. The final authenticated version is available online at: https://doi.org/10.1007/s10554-014-0388-x

Regional heterogeneity of afterload sensitivity in myocardial strain

Purpose: The peak systolic strain decreases due to afterload augmentation. However, its deterioration (i.e., afterload sensitivity) may be different within the left ventricular (LV) segments. We investigated how afterload influences regional strain and whether there is regional heterogeneity of afterload sensitivity. Methods: Afterload was increased by aortic banding in 20 open-chest dogs. Short-axis images were acquired at baseline and during banding. Circumferential strain was analyzed in six segments, and the absolute decrease in the peak systolic strain during banding (Δε) was calculated for each segment. To assess the effect of the compensatory preload recruitment during banding, the endocardial lengths of the septum and free wall were measured at end-diastole, and the rate of increase due to banding was calculated. Results: LV systolic pressure was significantly increased during banding (100 ± 14 vs. 143 ± 18 mmHg, P < 0.001). The peak systolic strain in all segments was significantly decreased during banding. Δɛ in the anterior segment, which is a part of the free wall, was significantly lower than that in the inferoseptal segment (2.6 ± 4.7 vs. 6.5 ± 3.5%, P = 0.035). The rate of increase in endocardial length in the free wall was significantly larger than that in the septum (15.6 ± 10.4 vs. 8.1 ± 7.4%, P = 0.014). Conclusion: The decrease in septal strain during afterload augmentation was larger than that in free wall strain, indicating that there was regional heterogeneity of afterload sensitivity in circumferential strain. The larger compensatory preload recruitment in the free wall than in the septum is implicated as a cause of the heterogeneity.This is a post-peer-review, pre-copyedit version of an article published in Journal of Medical Ultrasonics. The final authenticated version is available online at: https://doi.org/10.1007/s10396-020-01045-3

Detection of abnormal myocardial deformation during acute myocardial ischemia using three-dimensional speckle tracking echocardiography

Background: Three-dimensional (3D) speckle tracking echocardiography can simultaneously evaluate circumferential, longitudinal, and radial strain without being affected by through-plane motion. Moreover, the assessment of area change ratio may allow measuring regional myocardial deformation more accurately. We investigated the changes in each deformation parameter during acute coronary flow reduction, and evaluated whether the spatial extent of the abnormal values in each deformation parameter corresponded to that of the perfusion abnormality. Methods: In 10 dogs, myocardial strains of three directions and area change ratio were analyzed at baseline and during three different ischemic conditions. The peak systolic value and the post-systolic index (PSI) were measured in both the ischemic and normal segments. The function abnormality, derived from the deformation parameter, and the perfusion abnormality, derived from Evans blue staining, were evaluated in each segment during complete occlusion and the concordance rate between both abnormalities was calculated. Results: In all deformation parameters, the peak systolic value tended to gradually decrease and the PSI tended to gradually increase with the severity of flow reduction in the ischemic segment. Especially in area change ratio, significant changes were observed in both the peak systolic value and the PSI during occlusion compared to baseline. The concordance rate was the highest in the PSI assessed by area change ratio. Conclusions: Among 3D myocardial deformation parameters, area change ratio demonstrated better detectability of acute coronary flow reduction than conventional strain components. Area change ratio may be a useful parameter for detecting acute ischemia by 3D speckle tracking echocardiography.This is a post-peer-review, pre-copyedit version of an article published in Journal of Echocardiography. The final authenticated version is available online at: http://dx.doi.org/10.1007/s12574-019-00449-6.https://doi.org/10.1007/s12574-019-00449-

Ultrasound inflammation imaging in rats with myocardial ischemia-reperfusion: Evaluation by non-specific targeted contrast microbubbles

Background: Reports on ultrasound inflammation imaging with non-specific targeted microbubbles in the heart have been scarce. We investigated whether inflammation induced by myocardial ischemia-reperfusion in rats could be evaluated by ultrasound inflammation imaging with non-specific targeted microbubbles. Methods: Six rats subjected to 30 min of occlusion of the left anterior descending artery (LAD) followed by 4 h of reperfusion (ischemia group) and 4 rats subjected to the sham operation (sham group) were used. Ultrasound inflammation imaging was performed 4 h after reperfusion, and non-circulating signal intensity (SI), which reflects the signal derived from microbubbles phagocytosed by neutrophils in inflamed tissue, was calculated by the SI difference between the initial and subsequent imaging both in the LAD and non-LAD areas. The accumulation of neutrophils was confirmed by myeloperoxidase (MPO) staining. Results: Non-circulating SI in the LAD area was significantly greater for the ischemia group than the sham group [5.19 ± 2.19 (ischemia) vs. 0.31 ± 0.13 (sham) dB, p < 0.01]. Non-circulating SI in the LAD area was significantly higher than that in the non-LAD area when compared in the same rat of the ischemia group [5.19 ± 2.19 (LAD) vs. 0.18 ± 0.64 (non-LAD) dB, p < 0.01]. MPO-positive cells were confirmed in the LAD area of the ischemia group. Conclusion: Inflammation induced by myocardial ischemia-reperfusion in rats could be quantitatively assessed by ultrasound inflammation imaging with non-specific targeted microbubbles.This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1007/s12574-010-0051-z

Cerebellar Blood Flow and Gene Expression in Crossed Cerebellar Diaschisis after Transient Middle Cerebral Artery Occlusion in Rats

Crossed cerebellar diaschisis (CCD) is a state of hypoperfusion and hypometabolism in the contralesional cerebellar hemisphere caused by a supratentorial lesion, but its pathophysiology is not fully understood. We evaluated chronological changes in cerebellar blood flow (CbBF) and gene expressions in the cerebellum using a rat model of transient middle cerebral artery occlusion (MCAO). CbBF was analyzed at two and seven days after MCAO using single photon emission computed tomography (SPECT). DNA microarray analysis and western blotting of the cerebellar cortex were performed and apoptotic cells in the cerebellar cortex were stained. CbBF in the contralesional hemisphere was significantly decreased and this lateral imbalance recovered over one week. Gene set enrichment analysis revealed that a gene set for "oxidative phosphorylation" was significantly upregulated while fourteen other gene sets including "apoptosis", "hypoxia" and "reactive oxygen species" showed a tendency toward upregulation in the contralesional cerebellum. MCAO upregulated the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in the contralesional cerebellar cortex. The number of apoptotic cells increased in the molecular layer of the contralesional cerebellum. Focal cerebral ischemia in our rat MCAO model caused CCD along with enhanced expression of genes related to oxidative stress and apoptosis