A new approach to assessment of the left ventricle

Cardiac motion is a continuous process; however most measurements to assess cardiac function are taken at brief moments in the cardiac cycle. Using functional data analysis, repeated measurements of left ventricular volume recorded at each frame of a continuous image measured with cardiac ultrasound (echocardiography) were turned into a function of volume over time. The first derivative of the displacement of volume with respect to time is velocity; the second derivative is acceleration. Plotting volume, velocity, and acceleration against each other in a 3-dimensional plot results in a closed loop. The area within the loop is defined by the kinematics of volume change and so may represent ventricular function.
• We have developed an approach to analyzing images of the left ventricle that incorporates information from throughout the cardiac cycle.
• Comparing systolic and diastolic areas within a loop defined by volume, velocity, and acceleration of left ventricular volume highlights imbalances in the kinematics of the two phases, potentially indicating early sub-clinical disease.
• Substantially more information about left ventricular function may be derived from a non-invasive clinically available tool such as echocardiography.