FREQUENCY ANALYSIS OF MOTOR CURRENT WAVEFORM OF THE IMPLANTABLE CENTRIFUGAL VAD FOR THE ASSESSMENT OF VENTRICULAR RECOVERY

Abstract

The recovery of ventricular function after a prolonged support with ventricular assist devices (VAD) has been found in recent reports. This fact shows that the importance of ventricular function monitoring. However, the stable evaluation of ventricular function with implantable sensors has problems in durability. For the stable assessment and successful recovery of the ventricle, we examine the frequency characteristic changes of the relations between moto current (MC) waveform and left ventricular pressure (LVP) during partial to full bypass with centrifugal pump. [Method] The moc circulatory loop simulated the left ventricular apex to aorta bypase model with a centrifugal blood pump. The peak LVP of the pulsatil ventricle was varied from 20 to 150 mmHg to simulate recovery pattern of the left ventricle. The experiment was repeated at the pump RPM of 1500, 1700 and 1900. The power spectral density (PSD) of MC waveform was analyzed and its relation to LVP wa evaluated. [Results] The PSD of fundamental frequency of M waveform had a strong correlation with LVP level during full and partial bypass conditions. As the aortic valve opened with the recovery of the LV, ejection through the aortic valve affected the diastolic level of the MC waveform, hence increasing the PSD-LV slope. [Conclusion] From the slope change of the MC-LVP relations it would be possible to assess opening of the aortic valve due to recovery of the ventricle.