The Depolarization Amplitude of the Electromyogram is a Measure of End-Diastolic Ventricular Volume

Purpose Ventricular end-diastolic volume (EDV) is an important parameter for monitoring patients with heart pumps, and for informing an algorithm to adapt the pump speed in a smart way. Continuous information on the EDV is unavailable to date. We hypothesize that the depolarization amplitude of the non-contact intra-cardiac electromyogram (iEMG) is physically related to the EDV. Thus, it could serve as a useful measure for predicting EDV in these patients. Methods The study was performed in six pigs while undergoing a series of significant changes in hemodynamic states. Four conventional pacemaker electrodes measured the far-field iEMG inside the left ventricular blood pool, using a novel unipolar amplifier. Simultaneously, measurements of preload and hematocrit were recorded. The proposed EDV predictor was tested for statistical significance using a mixed effect model and associated confidence intervals. Results A statistically significant (p Conclusion The amplitude of the iEMG proved a significant, independent predictor of the EDV. Electrodes are simple to integrate into the cannula of a heart pump. Because of their simplicity, electrodes shall be incorporated in the inflow cannula of heart pumps. Given the manifold determinants of the depolarization amplitude, a combination with a mechanical signal, such as pump flow, is likely to further increase robustness. In this way, the iEMG has the potential to inform the clinician about the state of the patient in real-time and to control the pump in a smart way.