Vector flow mapping analysis of left ventricular wall shear stress in normal subjects during diastole

Abstract

Objective To observe the change of the left ventricular(LV) wall shear stress (WSS) using vector flow mapping (VFM) in different segments at each phase of diastolic period among normal subjects. Methods From August 2018 to March 2019, 200 healthy volunteers selected from the Physical Examination Center of the Second Affiliated Hospital of Harbin Medical University were recruited. The WSS values of LV segments at the same and at different phases[isovolumic relaxation period(D1), rapid filling period(D2), slow filling period(D3), atrial contraction period(D4)] in diastole were measured and analyzed. Results ①The relationships of the WSS of LV different segments at the same phase of diastolic period: The WSS values of anterior septum, posterior septum and posterior wall during D1, and the WSS values of posterior septum, posterior wall and inferior wall during D2 showed basal>middle>apical segments, the differences were statistically significant (all P<0.05). ②The changes of the WSS values of LV different segments during diastolic period: During D1-D2-D3-D4 period, the absolute values of WSS in anterior septum, posterior septum, anterior wall, lateral wall and inferior wall showed an increasing-decreasing-increasing trend. During D2-D3-D4 period, the absolute values of WSS in the posterior wall showed a decreasing-increasing trend. During D1-D2-D3-D4 period, the absolute values of WSS in the apical segment of anterior septum, basal and middle segments of posterior septum, basal, middle and apical segments of anterior wall, basal segment of lateral wall, the middle and apical segments of posterior wall, basal and middle segments of inferior wall all showed an increasing-decreasing-increasing trend, the difference was statistically significant (all P<0.05). Conclusions The LV WSS in different segments at the same phase or in the same segment at the different phases in diastole exhibit a regular change and is consistent with the LV hemodynamic changes, which indicates that WSS can quantitatively reflect the hemodynamic changes of the LV in normal subjects. Key words: Echocardiography; Vector flow mapping; Wall shear stress; Hemodynamics; Left ventricular diastolic function