Abstract 1881: 2D Speckle Track Strain Measurements From High Resolution Dynamic Ultrasound Images Can Provide Clues to Functional Architecture of the Heart
Background: This study evaluated regional and global strain in subendocardial (s-endo) and subepicardial (s-epi) layers of the left ventricular (LV) wall on high frame rate high resolution images from open-chest pigs.
Methods: We anesthetized 25 piglets (3–5kg) and did a midline sternotomy to expose the heart. Short axis views were acquired at mid cavity level directly from the heart surface, using a 14 MHz microlinear epicardial probe on a GE Vivid 7 Dimension system. LV pressure was recorded by a catheter placed in the LV cavity and dP/dt values were extracted. Strain measurements were obtained for subendocardial and subepicardial layers of the LV wall (s-endo, s-epi) around the circumference.
Results: The s-endo region showed higher peak global circumferential strain (16.08 ± 7.63) compared to s-epi (7.65 ± 6.44) (p=0.00018). This difference was highest in regional strain values of the septum (p= 0.00013) (21.73 ± 11.15 for the LV inner layer adjacent to the RV and 10.85 ± 6.85 for the septum adjacent to the RV) and lowest in the inferior wall (p=0.03) (18.66 ± 8.04 for s-endo and 12.42 ± 5.94 for s-epi). There was a delay of 55 ± 25 msec in time to peak strain for the s-epi, highest in the anterolateral wall (p=0.18) and lowest in the septum (p=0.96).The dP/dt values correlated moderately well with s-endo global strain especially with regional s-endo strain in the anteroseptal segment (r=0.75).
Conclusions: Our results confirm that circumferential shortening is greatest in the s-endo zone, especially in the septum.