Vector Flow Imaging in Pediatric Cardiology - Extracting and Validating Data

In the field of bedside cardiac diagnostic imaging, Doppler Ultrasound (DU) is the gold standard for diagnosing heart conditions. The largest benefit of DU is its ability to noninvasively image cardiac flow and allow the estimation of blood velocity and quantification of anatomical disease. However, to get correct velocity estimation, the position of the transducer in relation to the flow field needs to be known. This is the problem of angle/direction dependency and limits DUs accuracy when imaging in areas where perfect alignment or exact position of the transducer in relation to flow field is not possible or known, such as in the left ventricle. As a solution to the problem of angle dependency, Vector Flow Imaging (VFI) is used because it is non-invasive and angle-independent. In this study, VFI was used in 12 pediatric patients from Arkansas Children’s Hospital to analyze left ventricular flow using the 4-chamber view. The shape, in the form of ellipse Major:Minor axis ratio, of ventricular vortices was then measured. The deviation of an individual patients heart flow from what is theoretically healthy as defined in literature, an ellipse with Major:Minor axis ratio of 1.9, was compared to what was measured with VFI. The average directional deviation for these 12 patients was 64.85o±10.34o from what is theoretically healthy. After optimizing ellipse parameters to actual patient flow, the true average optimal ratio was found to be 1.98 ±0.58. Additionally, it was found that heart rate (p < 0.0001), age (p = 0.003), and weight (p < 0.0001) had a significant effect on angle deviation. However, there was no trend in the data. This preliminary study paves the way for using VFI to define healthy parameters for left ventricular flow and assist clinicians with more accurate diagnoses in anatomical areas with complex flow.