Current-Driven Domain Wall Motion in Curved Ferrimagnetic Strips Above and Below the Angular Momentum Compensation

Current driven domain wall motion in curved Heavy Metal/Ferrimagnetic/Oxide multilayer strips is investigated using systematic micromagnetic simulations which account for spin-orbit coupling phenomena. Domain wall velocity and characteristic relaxation times are studied as functions of the geometry, curvature and width of the strip, at and out of the angular momentum compensation. Results show that domain walls can propagate faster and without a significant distortion in such strips in contrast to their ferromagnetic counterparts. Using an artificial system based on a straight strip with an equivalent current density distribution, we can discern its influence on the wall terminal velocity, as part of a more general geometrical influence due to the curved shape. Curved and narrow ferrimagnetic strips are promising candidates for designing high speed and fast response spintronic circuitry based on current-driven domain wall motion.

691 Distribution of wall motion abnormalities in young patients presenting with acute coronary syndrome

Aims Distribution of wall motion abnormalities (WMA) in young patients presenting with acute coronary syndrome (ACS) is not well described. Methods and results We included 91 consecutive young patients (≤45 years at presentation) with ACS with obstructive or without obstructive coronary artery disease referred from October 2013 until March 2021 to our clinic. Wall motion abnormalities, wall motion score index (WMSI) and left ventricle ejection fraction (LVEF) were evaluated. A wall motion abnormality in at least one segment was present in 78.7% of patients. Mean LVEF was 50.9 ± 8.8% and mean WMSI was 1.38 ± 0.37%. Akinesia of at least one segment was present in 49.4%, dyskinesia and aneurysm were rare (1.1%, respectively). Ventricular thrombus was observed in 4.7%. Distribution of wall motion abnormalities is presented in Figure A. Most frequently WMA affected the apex and the basal inferior wall. The severity of WMA for each segment is presented in Figure B. The mean highest severity of WMA affected the apex, and the inferior and infero-septal wall. In the subgroup of patients presenting without obstructive coronary artery disease, WMA were less prevalent (37.5%), LVEF was higher (57.1% vs. 50.4% P = 0.032), and WMSI was lower (1.16% vs. 1.40% P = 0.07), but similarly affected with higher frequency the apex area. Conclusions In conclusion, WMA are frequent in young patients presenting with ACS, mostly affecting the apex. More severe abnormalities of wall kinesis affect the apex and the inferior and infero-septal wall.

704 Stress echocardiography: myocardial work ‘works’

Stress echocardiography is a widely employed diagnostic technique relying on subjective assessment of left ventricular wall motion and particular expertise. We report a case of a male patient with chronic coronary syndrome, who underwent dipyridamole echocardiography before planned non cardiac surgery. Despite the absence of symptoms and relevant electrocardiographic and wall motion changes, only 2D strain and, especially, Myocardial Work analysis was able to detect abnormalities suggestive of myocardial ischaemia. Thus, coronary angiography was performed, showing critical stenosis of the proximal Circumflex artery, that was treated with angioplasty and drug-eluting stent implantation. Interestingly, the location of strain and myocardial work abnormalities was consistent with the culprit vessel territory. This case highlights the particular usefulness of advanced echocardiographic techniques, especially for the detection of one-vessel coronary artery disease, during stress echocardiography.