High-definition blood flow imaging in the assessment of left ventricular function: Initial experience and comparison with contrast echocardiography

Objectives: The study aimed to assess the accuracy and reproducibility of the high-definition blood flow imaging (HD-Flow) in evaluation of left ventricular (LV) function by comparison with contrast echocardiography (Contrast). Background: Contrast improves endocardial border visualization and assists in precise assessment of LV function. HD-Flow, a novel ultrasound technique that enhances blood flow discrimination in LV, could possibly be used for improving endocardial border definition without contrast. Methods: Eighty patients with technically limited transthoracic echocardiograms had HD-Flow, and contrast performed sequentially. LV endocardial visualization, image acquisition time, wall motion, volumes, ejection fraction (EF), stroke volume (SV), and stroke volume index (SVI) were compared. Inter- and intra-observer agreements were examined in a randomly selected subgroup. Results: Both HD-Flow and contrast significantly improved the percentage of the well-defined endocardial border segments (71% at baseline vs 94.1% by HD-Flow vs 94.9% by contrast, X ²  = 401, P < 0.001). The acquisition time for HD-Flow was significantly less when compared to contrast (2.13 ± 1.18 minutes vs 10.96 ± 3.51 minutes, P < 0.001). LV end-diastolic volume (EDV), end-systolic volume (ESV), EF, SV, and SVI measured by the two methods correlated well (EDVr = 0.97, ESVr = 0.96, EFr = 0.90, SVr = 0.77, SVIr = 0.74, all P < 0.001). In comparison, HD-Flow was neither significantly different in detecting LV wall motion abnormality nor in EF, SV, and SVI measurements, but slightly underestimated LV volumes. Conclusions: HD-Flow imaging is feasible and user-friendly in enhancing LV endocardial definition. This technique is useful in both qualitative and quantitative assessment of LV function.