TBME presents

Dual-Modality Volume Measurement Integrated on a Ventricular Assist Device

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One in ten people currently suffer from diagnosed heart disease, which is treated with heart transplantation in advanced cases. However, the shortage of donor organs have led to the development of implantable heart pumps. To date, heart pumps operate at a fixed speed and do not adapt to variations in the patient’s need caused, for example, by exercise or sleep. Evidently, this leads to medical complications and, in the long term, to an inadequate supply of life-sustaining oxygen and nutrients. In order to adapt the pump settings to the need of a patient, we need a dependable measurement of heart volume signals in real-time that works for every individual patient.

We present an approach for dependable and individualized measurement of heart volume in patients with advanced heart disease. On the benchtop, we integrate ultrasound and impedance volume measurement modalities in a heart pump, implant the heart pump in multiple silicone patient hearts, and test if a combination of both modalities is beneficial. Both modalities were combined by quadratic optimization. We found that the dual-modality approach was accurately measuring heart volumes, when validated against calibrated gold standard measurements. In contrast to established methods, our combination of modalities results in valid volume signals over a wide range of heart sizes and no longer requires calibration in the hospital. Thus, by combining ultrasound and impedance measurements, heart volume can be measured more dependably and across a larger range of patients. Our study increases the chance that heart pumps could in the future adapt to the need of the patient, even in the critical period after heart pump implantation.

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