Evaluating the left ventricular hemodynamic phenomena of DDD septum pacemaker implants using vector flow mapping.

PURPOSE: We set out to undertake a preliminary assessment of the left ventricular hemodynamic status with right ventricular double-chamber pacing by energy loss (EL), wall shear stress (WSS), and circulation intensity (CIR) of vector flow mapping (VFM). We also planned to evaluate the value of VFM technology by measuring cardiac function after pacemaker implantation. METHOD: Data from 58 patients living with right ventricular double-chamber (right ventricular septal) pacemakers as well as 58 healthy volunteers matched in age and gender were collected. The EL, numbers of vortex cycles (n), area (A), CIR, and WSS of the left ventricle with different phases of the same cardiac cycle were obtained. RESULTS: The EL of the left ventricle was significantly higher in the pacemaker group than the control group at partial section of atrial contraction (AC), isovolumetric contraction (IVC), and rapid ejection (RE) (P < 0.05). The WSS of the left ventricle was significantly lower in the pacemaker group than the control group at part of the section in the rapid filling (RF), the AC, IVC, and RE phase (P < 0.05). DISCUSSION: EL in the left ventricular was significantly increased, while related WSS was significantly decreased in patients with right ventricular double-chamber pacing. Our exploration of the state of the flow field in the left ventricular cavity revealed that the implantation of the right ventricular double-chamber pacemaker led to an abnormal left ventricular hemodynamic state, reducing the left ventricular systolic efficiency.

Vector flow mapping in obstructive hypertrophic cardiomyopathy to assess the relationship of early systolic left ventricular flow and the mitral valve.

BACKGROUND: The hydrodynamic cause of systolic anterior motion of the mitral valve (SAM) is unresolved. OBJECTIVES: This study hypothesized that echocardiographic vector flow mapping, a new echocardiographic technique, would provide insights into the cause of early SAM in obstructive hypertrophic cardiomyopathy (HCM). METHODS: We analyzed the spatial relationship of left ventricular (LV) flow and the mitral valve leaflets (MVL) on 3-chamber vector flow mapping frames, and performed mitral valve measurements on 2-dimensional frames in patients with obstructive and nonobstructive HCM and in normal patients. RESULTS: We compared 82 patients (22 obstructive HCM, 23 nonobstructive HCM, and 37 normal) by measuring 164 LV pre- and post-SAM velocity vector flow maps, 82 maximum isovolumic vortices, and 328 2-dimensional frames. We observed color flow and velocity vector flow posterior to the MVL impacting them in the early systolic frames of 95% of obstructive HCM, 22% of nonobstructive HCM, and 11% of normal patients (p < 0.001). In both pre- and post-SAM frames, we measured a high angle of attack >60° of local vector flow onto the posterior surface of the leaflets whether the flow was ejection (59%) or the early systolic isovolumic vortex (41%). Ricochet of vector flow, rebounding off the leaflet into the cul-de-sac, was noted in 82% of the obstructed HCM, 9% of nonobstructive HCM, and none (0%) of the control patients (p < 0.001). Flow velocities in the LV outflow tract on the pre-SAM frame 1 and 2 mm from the tip of the anterior leaflet were low: 39 and 43 cm/s, respectively. CONCLUSIONS: Early systolic flow impacts the posterior surfaces of protruding MVL initiating SAM in obstructive HCM.

The impact of different infarction sites on left ventricular systolic vortex-a pilot study / 中华超声影像学杂志

Objective To compare the impact of anterior and inferior-posterior regional wall motion abnormalities on the vortex in systolic phase by vector flow map(VFM) technique.Methods Sixty patients with myocardial infarction were divided into 2 groups:the left anterior descending artery single branch lesion group (LAD group) and the left circumflex artery and/or right coronary artery lesion group (LCX/RCA group).By VFM technique,left ventricular systolic blood flow field was observed.Parameters such as the vortex duration were calculated and compared between two patient groups and also with healthy control group.Results LAD group did not show significant difference from the control group in isovolumic systolic vortex,this group was characterized with large size of vortex and usually forming local vortex at the apex in early ejection.On the contrary,LCX/RCA group had small isovolumic systolic vortex,the early ejection vortex of this group was significantly smaller than that of LAD group and larger than that of control group.The phenomenon was usually observed in the center of the lumen.Both LAD and LCX/RCA group had longer total vortex duration and vortex collapse time than the healthy control group,these differences were not significant between LAD and LCX/RCA group.There were no significant differences in isovolumic vortex duration among the three groups.Conclusions Anterior wall infarction had more impact on systolic blood flow field than inferior-posterior wall infarction.The VFM technique could be applied for observation and evaluation of the changes in vortex characteristics.