Left Atrial Blood Flow Dynamics: Preliminary Observations Using HyperDoppler

Background: Evaluation of blood flow dynamics within the left atrium (LA) using cardiac imaging techniques, such as four-dimensional (4D) flow magnetic resonance imaging (MRI) and contrast and non-contrast ultrasound, is an area of increasing interest, especially in patients with atrial fibrillation (AF). While 4D flow MRI and contrast ultrasound are limited in their application in routine clinical practice, non-contrast ultrasound techniques have the potential for extensive clinical application. However, there are no studies on LA flow dynamics evaluated using these latter techniques. Here we present the first application of HyperDoppler, a non-contrast color Doppler-based technique, to the assessment of LA flow dynamics in a case series. Methods: The transthoracic color Doppler modified apical 4-chamber view of a normal healthy subject and two patients with AF (one with persistent and the other with permanent AF) were analyzed using HyperDoppler. The resulting velocity vector map was visually examined frame-by-frame to describe LA flow dynamics. Results: In the healthy subject, HyperDoppler showed a LA flow behavior consistent with findings from the literature employing 4D flow MRI. In both patients with AF, HyperDoppler showed alterations of the LA flow dynamics pattern. Conclusions: Our preliminary observations suggest that HyperDoppler may be a valuable tool for characterizing physiological and pathological LA flow dynamics. Further studies are needed to confirm, explain and expand our initial findings.