Aims: The aim of this study was to investigate whether multi-layer radial strain and strain rate analysis is superior to one-layer strain analysis for confirming reperfusion following a non-occlusive coronary stenosis.
Methods and results: In 10 anaesthetized pigs, an extracorporeal shunt was inserted from the brachiocephalic to the left anterior descending coronary artery. Microspheres were injected and left ventricular (LV) short- and long-axis echocardiographic views were recorded with the open shunt, during the 120 min of severe stenosis and 20 min (early) and 100 min (late) after reperfusion. The anterior wall was analysed for radial one-layer and three-layer tissue Doppler imaging (TDI) strain and strain rate, in addition to radial, circumferential, and longitudinal speckle-tracking echocardiography (STE) strain. During stenosis, perfusion was reduced in the two inner wall layers (P< 0.01). All peak systolic strain and strain rate parameters were reduced, whereas post-systolic longitudinal strain and post-systolic strain in the two inner layers increased (P< 0.001). At early reperfusion, hyperaemia was evident in all layers (P< 0.01). Peak systolic TDI strain and strain rate increased in the mid- and subendocardial layer, whereas post-systolic strain decreased (P< 0.05). Peak systolic STE strain increased in the circumferential and longitudinal direction, whereas post-systolic longitudinal strain decreased (P< 0.05). At late reperfusion, strain and strain rate were unchanged while perfusion returned to baseline values in the mid- and subendocardium.
Conclusion: Both multi-layer radial TDI strain and strain rate and one-layer STE strain measurements in the circumferential and longitudinal direction can confirm reperfusion early after a non-occlusive coronary stenosis. An advantage of multi-layer analysis was not evident.