Objective: Continuous Flow Left Ventricular Assist Devices (CFLVAD) are circulatory support devices that are implanted in patients with end-stage heart failure. We developed a novel control algorithm for CFLVAD to maintain physiologic perfusion while avoiding ventricular suction using only the intrinsic pump measurement of pump speed and without utilizing model-based estimation. Methods: The controller objective is to maintain a differential pump speed setpoint. A mathematical model of the circulatory system coupled with a model of a CFLVAD was used to test the control algorithm in-silico. Robustness and efficacy were evaluated by comparing the proposed control algorithm to constant speed control, differential pump pressure control, mean aortic pressure control, and ventricular end diastolic pressure control during (1) rest and exercise conditions, (2) a rapid eight-fold increase in pulmonary vascular resistance under rest and exercise, (3) transitions from rest to exercise, and exercise to rest, (4) safe mode during left ventricular asystole, and (5) RPM measurement noise of 1% to 10% for (1) to (4). Results and conclusion: The control algorithm provided adequate perfusion while preventing ventricular suction for all test conditions. Performance did not deteriorate significantly with pump speed measurement noise of up to 6%. The safe mode successfully detected asystole and maintained adequate perfusion to sustain life even when the differential pump speed was almost zero. Significance: Maintaining a constant differential pump speed can simultaneously achieve physiologic perfusion and suction prevention without needing unreliable, direct measurements of flow or pressure, or complex parameter or model-based estimation techniques.

Endovascular glue embolization is a minimally invasive technique used to selectively reduce or block the blood supply to specific targeted vessels. Cyanoacrylate glues, mixed with radiopaque iodized oil, have been widely used for vascular embolization owing to their rapid polymerization rate, good penetration ability and low tissue toxicity. Nevertheless, in clinical practice, the selection of the glue–oil proportion and the manual injection process of mixtures are mostly based on empirical knowledge of operators, as the crucial physicochemical effect of polymerization kinetics has rarely been quantitatively investigated. In this study, the Raman spectroscopy is used for studying the polymerization kinetics of n-butyl-cyanoacrylate-based glues mixed with an iodized oil. To simulate the polymerization process during embolization, glue–oil mixtures upon contact with a protein ionic solution mimicking blood plasma are manually constructed and their polymerization kinetics are systematically characterized by Raman spectroscopy. The results demonstrate the feasibility of Raman spectroscopy in the characterization of polymerization kinetics of cyanoacrylate-based embolic glues. The polymerization process of cyanoacrylate-based mixtures consists of a fast polymerization phase followed by a slow phase. The propagation velocity and polymerization time primarily depend on the glue concentrations. The commonly used 50% mixture polymerizes 1 mm over ∼21.8 s, while it takes ∼51 min to extend to 5 mm. The results provide essential information for interventional radiologists to help them understand the polymerization kinetics of embolic glues and thus regulate the polymerization rate for effective embolization.

CPD can replace CFVAD with pulsatile working modes to a certain extent to treat non-severe HF. The proposed in vitro microfluidic models provided scientific basis for selecting different mechanical circulatory support devices.

The best pulsation frequency mode of the RBP would be one that changes every 2–3 times of the cardiac cycle. The proposed in vitro microfluidic model could provide an effective platform to select the best working mode of the RBP for heart failure.