Abstract 2571: Two-dimensional Ultrasound Speckle Tracking Imaging is Useful in Assessing the Magnitudes of Inertia Force of Late Systolic Aortic Flow and Left Ventricular Elastic Recoil
We previously reported that an absence of inertia force (IF) of late systolic aortic flow is one of the causes of diastolic dysfunction through the loss of left ventricular (LV) elastic recoil in patients with coronary artery disease. Preserved LV apical wall motion is substantial to give IF to the aortic flow ( JACC 2006;48:983). A novel 2-dimensional ultrasound speckle tracking imaging (2D-STI) enables us to assess local LV myocardial function. We investigated whether LV longitudinal systolic strain, especially in apical region, obtained using 2D-STI had a relation with IF.
Methods: Study subjects were consecutive 59 patients who underwent diagnostic cardiac catheterization and 2D-STI (Velocity Vector Imaging, Siemens) on the same day. Thirty three of them had prior myocardial infarction (18 anterior wall, 9 infero-posterior wall, 2 lateral wall, and 4 combined). Five were diagnosed as dilated cardiomyopathy. The remaining 21 had no localized LV wall motion abnormality (8 stable angina pectoris, 2 exercise test abnormality, 2 atypical chest pain, and 9 reevaluation after coronary intervention). Longitudinal LV strain was measured on the sample line set along the endocardium in the both apical 4- and 2-chamber views. Zero strain was set at end-diastole. Strain profiles were obtained in 6 segments on each view. Then, an LV strain value at end-systole (Ses) in each patient was obtained as an average value from these strain profiles. LV pressure was obtained using a catheter-tipped micromanometer. From the recorded pressure waves, first derivative of LV pressure (dP/dt) and a time constant τof LV pressure decay during isovolumic relaxation were calculated. From LV pressure-dP/dt relationships (phase loop), IF was determined.
Results: The mean Ses had significant correlations both with the time constant τ(r=-0.74, p<0.0001) and with the IF (r=0.67, p<0.0001). Furthermore, the mean Ses at the LV apical region had much closer correlations both with the time constant τ(r=-0.77, p<0.0001) and with the IF (r=0.80, p<0.0001).
Conclusion: These findings indicate that the magnitudes of IF and LV elastic recoil could be noninvasively estaimated by Ses obtained using 2D-STI. LV apical wall motion abnormality has a strong impact on LV early diastolic function.