An optical device to measure the dynamics of apex rotation of the left ventricle

A device to measure apex rotation of the left ventricle (LV) was built and tested in 8 open-chest anaesthetized dogs. The device is composed of a light source which illuminates via a rotating mirror a position-sensitive diode which converts the position of the light beam into degrees of rotation. The rotating mirror is coupled to the apex of the heart with a stiff wire. Apex rotation was measured simultaneously with the hemodynamic events. Confirming previous observations, the device showed twist during ejection and rapid untwisting during isovolumic relaxation. In addition, the device was used to characterize the dynamics of apex rotation during load manipulation. We conclude that construction of a device for measuring the dynamics of apex rotation throughout the cardiac cycle is feasible; the twist-meter provides important information about systolic and diastolic ventricular mechanics.