Proximal aortic compliance and diastolic function assessed by speckle tracking imaging

Abstract

Speckle tracking imaging (STI) is a recent technique that evaluates an echocardiographic image throughout the cardiac cycle and provides dynamic variables such as tissue velocities and strain rates. The objective of our study was to determine 1) if STI can be used to quantify proximal aortic compliance and 2) if decreased aortic compliance determined by STI will reproduce the previously reported correlation with diastolic function. This was a retrospective observational case series using previously obtained intraoperative transesophageal images. Diastolic performance was quantified by STI-based longitudinal velocities of the basal-septal and basal-lateral walls of the left ventricle in early diastole (LV E'). Change in proximal aortic volume was calculated using STI to measure peak longitudinal and radial velocities in early diastole. After normalizing for mean arterial pressure, compliance was calculated and then compared with basal-septal and basal-lateral LV E' using single regression analysis. Twenty patients were included in our analysis. Linear regression of basal-septal LV E' and basal-lateral LV E' vs proximal aortic compliance during diastole each resulted in an R(2) value of 0.26 (P < 0.05). Speckle tracking can be used to describe the physical motion of the aortic wall and to calculate its compliance. We confirm that variation in diastolic function can be attributed, in part, to aortic compliance. Our novel approach of measuring compliance throughout the cardiac cycle, isolating radial and longitudinal contributions, and evaluating previously obtained images retrospectively provides advantages over previously reported measures of aortic compliance. Speckle tracking promises new insights into ventricular function, aortic mechanics, and the interaction between these structures.