Speckle Tracking of Common Carotid Artery: A New Method for the Evaluation of Mechanical Vascular Function of Atherosclerosis

As cardiovascular death remains major cause of death worldwide , there are growing needs for risk evaluation for cardiovas-cular event. Arterial stiffness, which refers to the rigidity of arterial wall, increases in the elderly person as well as patients with atherosclerotic disease. Based on the belief that increased vascular stiffness precedes atherosclerotic vascular event, there were attempt to measure vascular stiffness. In this regard, ca-rotid-femoral pulse wave velocity (PWV) using tonometry has been proven to be simple, noninvasive measurement of vascu-lar stiffness, as it is inversely related with vascular compliance. Stiff and rigid vessel would transfer pulse wave faster and PWV be higher. On the other hands, carotid intima-media thickness (CIMT) using ultrasound is well correlated with cardiovascular risk and is commonly used as surrogate marker of systemic athero-sclerosis. 2)3) Current advance in automated imaging analysis made it much easier to obtain CIMT in daily clinic and repro-ducibility of the measurement got even better. Another approach to obtain information about vascular stiffness was ultrasound-based measurement of regional mechanical properties of arterial wall. 4) This method includes the measurement of changes in the dimension of an artery generated by each pulse pressure. From the pressure and diameter measurement, variables regarding vascular stiffness such as dis-tensibility, compliance, elastic modulus index and beta stiffness index can be calculated. More recently, technical advance in speckle tracking method , which originally used for the measurement of ventricular deformation, was applied to the evaluation of vascular stiffness. Automated analysis of vascular wall mechanics using speckle tracking became available not only to obtain longitudinal and radial displacement but also calculate circumferen-tial strain, which is theoretically equal to the radial change if the circumference of a vessel is circle because radius is linear to the circumference in a circle. In this issue of journal of cardiovascular ultrasound, they evaluated examine the additional value of multi-directional functional mechanics of the carotid artery in relation to cardio-vascular risk in the manuscript entitled as " the value of elastic modulus index as a novel surrogate marker for cardiovascular risk stratification by dimensional speckle-tracking carotid ul-trasonography ". 5) The main message was that assessment of the mechanical property of carotid artery using specialized software was feasible and that radial and longitudinal strain, CIMT as well as elastic modulus index could be obtained. Most importantly, mechanical vascular property assessed as elastic modulus index along with CIMT were independently associated with high risk profile …