Abstract 2720: Diagnostic Efficacy of Velocity Vector Imaging for Detecting Acute Myocardial Ischemia
Background: Velocity Vector Imaging (VVI) can display the velocity of endocardium as a vector overlaid onto the B-mode images. However, its diagnostic efficacy for identifying ischemia has not been revealed.
Methods: In 18 open-chest dogs, the left circumflex artery was occluded totally and/or partially, in which the flow was reduced by 45±9% of that at baseline. Short-axis images were acquired at baseline and during ischemia using a Sequoia ultrasound system. The risk area was evaluated by real-time contrast echo. In the center of risk area, three measurements were compared: peak systolic radial velocity, radial velocity at the mitral valve opening (MVO), and %wall thickening (%WT). The sensitivity and specificity for detecting ischemia were calculated by the receiver operating characteristics (ROC) curve analysis.
Results: In a total occlusion model, radial velocity at the MVO demonstrated the best sensitivity and specificity, although other two parameters showed relatively good accuracy (figure⇓). In a partial occlusion model, radial velocity at MVO significantly increased, indicating postsystolic shortening during ischemia, in comparison with that at baseline (ischemia: −0.12±0.6, baseline: −0.96±0.7 cm/s, p<0.01). On the other hand, neither %WT nor peak systolic radial velocity did change significantly. The ROC curve analysis demonstrated that radial velocity at the MVO was more sensitive and specific for diagnosing myocardial ischemia than other parameters (figure⇓).
Conclusion: The analysis of postsystolic shortening using VVI permits better diagnostic efficacy for detecting acute myocardial ischemia than conventional parameters of systolic wall motion.