Unipolar Amplifier Enabling Measurement of Far-field Intra-cardiac Electromyogram for Blood Pump Control

Abstract

Heart pumps are implanted as an alternative to heart transplantation in patients with heart failure. Future devices are expected to respond to the physiological need of each patient automatically. Physiological control algorithms have shown to be robust if based on the measurement of end-diastolic volume (EDV); but real-time measurements of EDV are not available. In theory, the EDV has been shown to correlate with the maximum depolarization amplitude (DA) of the intra-cardiac electromyogram (iEMG). In practice, this requires the unipolar measurement of an electric signal, which has not been attempted inside the heart. We herein present a custom-built unipolar amplifier, which we connected to a heart pump cannula prototype with four integrated off-the-shelf pacemaker electrodes. The recorded signals from the unipolar amplifier showed excellent agreement with the gold standard measurement of surface electrocardiogram (ECG) using a commercial ECG simulator and in-vivo data acquired in fo ur pigs. We present recordings of unipolar iEMG from the cannula of a heart pump. The new unipolar amplifier makes it possible to measure the DA of the iEMG and therefore potentially provides a real-time EDV signal to heart pumps for physiological control in the future.