Objective: This study aims to investigate the clinical significance of vector flow mapping (VFM) by observing and quantifying energy loss (EL) during different phases and in different left ventricle (LV) segments.
Methods: 42 healthy physical examination subjects and 89 patients with hypertension (HTN) were enrolled in the present study. The patients with HTN were divided into two groups: the left ventricular hypertrophy group (LVH) (n = 51) and the non-left ventricular hypertrophy group (NLVH) (n = 38), while the healthy patients were control group. VFM analysis software DSA-RS1 was used to calculate EL during the rapid filling phase (P1), slow filling phase (P2), atrial contraction phase (P3), and rapid ejection phase (P4). The energy loss of basal segment (EL-B), middle segment (EL-M) and apical segment (EL-A) of left ventricle in different phases was calculated and compared among the three groups.
Results: In controls, segmental EL showed a gradual increase from the apex to the base during diastole; however, the regularity was not found in the HTN patients. During both P1 and P2 EL-B, EL-M and EL-A were significantly higher in the NLVH group and the LVH group compared with the control group (P < 0.05). EL in LVH group was the highest among the three groups (P < 0.05). During P3, EL-B, EL-M and EL-A were increased in the NLVH group and LVH group compared with the control group. However, EL-M and EL-A in LVH group were significantly lower than the NLVH group (P < 0.05). During P4, EL of all segments was significantly higher in the NLVH group and LVH group compared with the control group (P < 0.05).
Conclusion: VFM can visually quantify hydrodynamic LV changes in healthy subjects. The EL levels in the different LV segments during different phases were significantly higher in the patients with HTN compared with the healthy subjects.
Keywords: hypertension, ultrasound, vector flow mapping, energy loss