Ascending Aortic Wall Mechanics In The Stanford Type B Aortic Dissections Assessed By Two-dimensional Ultrasound Speckle Tracking

Objective: In the cardiac surgery, the aortic diseases is challenging and have high mortality rate for surgery, therefore prevention therapy is more important than surgery. The techniques of two-dimensional ultrasound speckle tracking were originally developed to assess the deformation of the cardiac muscle, it is angle free. Recently, the ultrasound speckle tracking is used to assess the movement of the aortic wall. Hypertension is the predominant cardiovascular risk factor in patients with aortic dissection. Our aim was using the novel techniques of two-dimensional ultrasound speckle tracking to detect the mechanical properties of ascending aorta of type B dissections with hypertension, and to evaluate the aortic mechanical changes made by hypertension.Methods: 50 patients of type B dissections with hypertension, 50 hypertensive patients as control group and 50 healthy adults as normal group were examined. Aortic B-mode parameters were measured from the long-axis view of the ascending aorta. Aortic distensibility(D), aortic stiffness index(ASI) were calculated using accepted formulas. Aortic anterior wall distension velocity, aortic posterior wall distension velocity and max aortic diameter distension velocity were determined.Results: Aortic stiffness index(ASI)(3.7±2.1)was lower in normal subjects compared with both the type B dissections group(4.8±3.4)and hypertension group(4.7±1.9). Increased aortic distensibility(D) was found in normal group(32.6±16.6 m2/N) compared with both the type B dissections with hypertension group(24.6±14.2 m2/N)and hypertension group(20±8.7 m2/N). Increased max aortic diameter distension velocity was found in normal group(37.8±10.1mm/s) compared with both the type B dissections with hypertension group(28.8±12.0mm/s) and hypertension group(29.2±16.7mm/s). No statistically significant differences were found in distensibility(D), aortic stiffness index(ASI) and max aortic diameter distension velocity between the type B dissections with hypertension group and hypertension group. Ascending aorta ultrasound speckle tracking provides wall velocity data sufficient to detect the ascending aorta mechanics. The max aortic diameter distension velocity is a supplemental index to the conventional aortic elasticity indexes of distensibility(D), aortic stiffness index(ASI).Conclusions: Ascending aorta ultrasound speckle tracking provides wall velocity data sufficient to detect the ascending aorta mechanics. The max aortic diameter distension velocity is a supplemental index to the conventional aortic elasticity indexes of distensibility(D), aortic stiffness index(ASI).