Evaluation of vortex flow in left ventricle by echo-dynamography and phase contrast magnetic resonance angiography

Abstract

Echo-dynamography (EDG) is a method for visualizing left ventricular (LV) blood flow based on cardiac Doppler measurement in which blood flow component perpendicular to the ultrasonic beam is deduced by applying fluid dynamics theories to two-dimensional (2D) distribution of blood flow component along the ultrasonic beam. EDG has been validated by numerical simulation and particle image velocimetry of model circulation. However, these validations were too simple to reproduce unstable and asymmetrical flow in a beating heart. In the present study, EDG is compared with three-directional (3D) blood flow distribution on the same plane obtained with phase contrast magnetic resonance angiography (PCMRA) for clinical validation. Moreover, the location and vorticity of the vortex flow in LV are measured quantitatively and the relation to echocardiographic parameters of systolic and diastolic functions is discussed. 3D components of blood flow on a plane were obtained with triple scans of the same plane with ECG trigger and breath holding; 1) phase encode (x-axis), 2) read out (y-axis) and 3) slice selection (z-axis). After the acquisition of MRA dataset, color Doppler dataset of the same plane was acquired and 2D velocity distribution was obtained with EDG in MATLAB programs. EDG and PCMRA showed similar velocity vector distribution and formation of LV vortex flow. The vortex at mid diastolic phase was strongly affected by early diastolic filling while the vortex at isometric contraction was affected by atrial filling. EDG gained a new insight on systolic-diastolic coupling from the view point of LV blood flow such as LV vortex formation.