Exploring Further Utilization of Biomechanical Characterization of the Vascular Systemvia Ultrasonography

Objectives Stress and strain measurements have been used in clinical settings to predict and describe functions of the human body. However, the role of this modality in the analysis of the vascular system, for both pathologies and physiology, has not been heavily studied. Yet, stress and strain measurements may potentially be a more sensitive modality to evaluate the vascular system. In this abstract, we highlight the concept of utilizing wall biomechanical for enhanced characterization of targeted vascular physiology and pathology. Methods This abstract highlights three studies approved by the Institutional Review Board. Various components of the vascular system were analyzed. These included pathological (aneurysmal aorta vs non-aneurysmal aorta), reaction of normal physiology (carotid artery strain pre-and post-exercise) and change in physiology to stress (concomitant carotid and left ventricular strain pre- and post-major surgical intervention). Longitudinal and circumferential strain on the vessel wall was obtained by using two-dimension (2D) speckle tracking ultrasonography. All analysis was electrocardiogram (ECG)-gated as well. Strain patterns for each region of the targeted components of the vascular system were analyzed. Results For normal responses to the physiology of the carotid following exercise, there was a marked increase in the percent change of strain in response to small change in the conventional hemodynamic measurements. Consistency strain curves obtained at baseline compared to variable dispersion of strain curves obtained immediately following exercise was noted and had higher sensitivity in detecting changes to physiology compared to conventional methods ( Figure 1 Download : Download high-res image (306KB) Download : Download full-size image Figure 1 . Biomechanical analysis of the carotid artery before exercise (A, C) and after exercise(B, D). , Table 1 Table 1 . Volunteer demographics, conventional hemodynamic and strain measurements. ). Additionally, there were consistent strain patterns noted of the carotid and left ventricle at the various time points pre- and post- stress following major surgery ( Figure 2 Download : Download high-res image (388KB) Download : Download full-size image Figure 2 . Biomechanical analysis of the left ventricle pre-operatively (A), immediate post- operatively (B), immediately after extubation (C), and at least 6 hours post-extubation (D). ). Similarly, consistent strain patterns were noted in aneurysmal aorta segments compared to non- aneurysmal segments ( Figure 3 Download : Download high-res image (391KB) Download : Download full-size image Figure 3 . Biomechanical analysis of aneurysmal (A) vs non-aneurysmal (B) aorta with circumferential strain curve patterns. ). Table 1 . Table 1 Volunteer demographics, conventional hemodynamic and strain measurements. Conclusion The concept of utilizing 2D speckle tracking ultrasonography to characterize the wall biomechanics within vascular system (aorta, carotid artery, and left ventricle) may be a feasible new modality for evaluating pathology, normal physiology, and the impact of surgical stress on the vascular system. Consistent patterns of stress and strain curves, which were more sensitive in change following pathological/physiological stress compared to conventional measures, were noted in each setting. Future research evaluating the specific strain patterns and their clinical implications is warranted.