The lack of direct measurement of left ventricular unloading is a significant impediment to the development of an automatic speed control system for continuous-flow left ventricular assist devices (cf-LVADs). We have developed an inlet cannula tip for cf-LVADs with integrated electrodes for volume sensing based on conductance. Four platinum-iridium ring electrodes were installed into grooves on a cannula body constructed from polyetheretherketone (PEEK). A sinusoidal current excitation waveform (250 μA pk-pk, 50 kHz) was applied across one pair of electrodes, and the conductance-dependent voltage was sensed across the second pair of electrodes. The conductance catheter was tested in an acute ovine model (n = 3) in conjunction with the HeartMate II rotary blood pump to provide circulatory support and unload the ventricle. Echocardiography was used to measure ventricular size during pump support for verification for the conductance measurements. The conductance measurements correlated linearly with the echocardiography dimension measurements more than the full range of pump support from minimum support to suction. This cannula tip will enable the development of automatic control systems to optimize pump support based on a real-time measurement of ventricular size.
From the *Department of Surgery, Penn State College of Medicine, Hershey, Pennsylvania
†Department of Medicine, Penn State College of Medicine, Hershey, Pennsylvania
‡Department of Comparative Medicine, Penn State College of Medicine, Hershey, Pennsylvania.
Submitted for consideration December 2017; accepted for publication in revised form March 2018.
Disclosure: The authors have no conflicts of interest to report.
This project is funded, in part, under a grant with the Pennsylvania Department of Health using Tobacco CURE Funds.
Correspondence: Joshua Cysyk, Division of Artificial Organs, Department of Surgery, College of Medicine, The Pennsylvania State University, 500 University Drive, Hershey, PA 17033. Email: email@example.com.