Current ventricular assist devices (VADs) are rotary blood pumps used to treat end-stage heart failure. VADs are operated at a constant speed that is manually adjusted by a clinician based on the patient's cardiac demand during routine medical examinations. VADs operated at a constant speed have inadequate passive flow regulation due to the inherent mechanical pressure-flow characteristics of the pump; this can lead to harmful situations where the VAD is overpumping or underpumping. Typically, patients on long-term VAD support are discharged to an outpatient setting where the VAD speed can remain the same for weeks or months at a time, impacting patient safety and quality of life. Previously, physiological controllers for VADs have been proposed, which automatically adjust VAD speed to meet patient cardiac demand. Clinical implementation of physiological control is currently hindered by the lack of clinically available, implantable, and continuous hemodynamic sensors. This study describes the physiological control of a VAD using a fiber Bragg grating (FBG) sensor previously developed for measuring VAD inlet pressure. The FBG sensor was used as a feedback to a Starling-like physiological controller, and the control quality was compared against the same controller with feedback from a nonimplantable industrial pressure sensor (Omega sensor). Experiments were conducted in a bench-top cardiovascular simulator under various simulated patient scenarios. The average steady-state difference in VAD flow across all experiments was 0.1 L/min with a maximum difference of -0.4 L/min. Similarly, the average steady-state difference in left ventricular end-diastolic pressure was 0.02 mmHg with a maximum difference of -0.2 mmHg. The clinically insignificant differences found between the two feedback methods indicate that the FBG pressure sensor is viable for the physiological control of VADs.
- Fiber Bragg grating (FBG)
- implantable pressure sensor
- physiological control
- ventricular assist device (VAD).