854 Different recovery (rate) of longitudinal and radial function after an episode of acute ischemia

Abstract

Background: Previous studies have shown that the cyclic variation of integrated backscatter returns prior to wall thickening (i.e. radial strain) after acute ischemia. This might be due to a different rate in recovery of radial (R) and longitudinal (L) deformation. In our laboratory, a new ultrasound methodology for the estimation of all in-plane myocardial strain components has been developed. The aim of this study was to measure the amount and the rate of recovery of both R and L deformation after acute ischemia. Material and methods: In 9 closed-chest pigs, a 5 min PTCA circumflex occlusion was used to induce myocardial ischemia. This was followed by 130 min of reperfusion. Radio-frequency (RF) ultrasound data with high spatial and temporal resolution (>160 fps) were acquired in a parasternal longaxis view (Toshiba Aplio) at baseline (BL), after occlusion and at selected points during the following reperfusion. Data were transferred to a personal computer for off-line analysis using dedicated software (SPEQLE-2D). Endsystolic R and L strain were extracted from the „at risk” posterior wall segment and the remote non-ischemic septal segment. For each animal, strain data were normalized to its BL value and a logarithmic fit was made. Finally, an average fit over all animals was determined. Results: During reperfusion of the ischemic segment, L strain showed faster recovery than R strain. However, after 130 min of reperfusion R strain had almost completely recovered while L strain remained reduced. No changes were found in the septal segment during the reperfusion period. Conclusions: The amount of rate of recovery after an episode of acute ischemia is different for radial and longitudinal function. This might be related to a epito endocardial recovery of function in combination with fiber orientation.