Rossella Fontana

An innovative adaptive control strategy for sensorized left ventricular assist devices.

Nowadays advanced heart failure is mainly treated through heart transplantation. However, the low availability of donors makes the research of alternative therapies urgent. Continuous-flow left ventricular assist devices (LVADs) are going to assume a more significant role in assisting the failing heart. A recent challenge in clinical practice is the possibility to use LVAD as long-term therapy rather than as a bridge to transplantation. For this reason, more comfortable devices, able to dynamically adapt to the physiological cardiac demand in relation to the patient activity level, are needed in order to improve the life quality of patients with implants. Nevertheless, no control system has been developed yet for this purpose. This work proposes an innovative control strategy for a novel sensorized LVAD, based on the continuous collection of physical and functional parameters coming from implantable sensors and from the LVAD itself. Thanks to the proposed system, both the patient and the LVAD conditions are continuously monitored and the LVAD activity regulated accordingly. Specifically, a Proportional Integrative (PI) and a threshold control algorithms have been implemented, respectively based on flow and pressure feedbacks collected from the embedded sensors. To investigate the feasibility and applicability of this control strategy, an on-bench platform for LVADs sensing and monitoring has been developed and tested.

Experimental integration of Autoregulation Unit for left ventricular assist devices in a cardiovascular hybrid simulator

In this paper, an Autoregulation Unit (ARU) for left ventricular sensorized assist devices (LVAD) has been used with a cardiovascular hybrid simulator mimicking physiological and pathological patient conditions. The functionalities of the ARU have been demonstrating for the successful receiving and visualization of system parameters, sending of commands for LVAD speed changes, and enabling of the autonomous flow control algorithm. Experiments of speed changes and autoregulation are reported, showing the feasibility of the approach for both local and remote control of a LVAD.

An Innovative Wireless Endoscopic Capsule With Spherical Shape.

This paper aims to contribute to the advancement of the Wireless Capsule Endoscopy (WCE) field for ColoRectal Cancer (CRC) screening, by developing all electronic circuits to build an innovative wireless endoscopic capsule with a spherical shape, conceived to reduce the friction during its locomotion and thus improving patient’s acceptability. The proposed capsule embeds an image sensor with optics and Light Emitting Diodes (LEDs), a control unit with a telemetry module, an actuation system, a battery with a smart recharging circuit able to recharge in 20 minutes, a smart power-on circuit and a localization module. Everything is devised to fit in a small spherical shape with a diameter of 26 mm and a weight of 12.70 g. The authors present a description of the sub-modules involved in the capsule development, together with the firmware and hardware integration. In order to reduce the bandwidth for matching the specifications of the target commercial telemetry, the firmware interfacing of a custom encoder was performed, which is able to compress the incoming images with a negligible loss of information and occupying a number of Look Up-Tables (LUTs) less than 1780. As a preliminary work, a versatile Field Programmable Gate Arrays (FPGA) based demo-board system has been developed in order to test and optimize the functionalities and the performance of the single sub-modules and wireless vision chain system. This work allows to demonstrate the feasibility of a complex biomedical system, with severe constraints by highlighting the necessity to enhance the frame rate in the future.

A dynamic control algorithm based on physiological parameters and wearable interfaces for adaptive ventricular assist devices.

In this work we present an innovative algorithm for the dynamic control of ventricular assist devices (VADs), based on the acquisition of continuous physiological and functional parameters such as heart rate, blood oxygenation, temperature, and patient movements. Such parameters are acquired by wearable devices (MagIC & Winpack) and sensors implanted close to the VAD. The aim of the proposed algorithm is to dynamically control the hydraulic power of the VAD as a function of the detected parameters, patients activity and emotional status. In this way, the cardiac dynamics regulated by the proposed autoregulation control algorithm for sensorized VADs, thus providing new therapy approaches for heart failure.

An autoregulation unit for enabling adaptive control of sensorized left ventricular assist device

This paper describes an integrated system for facing heart failures (HF) in an innovative way. Existing left ventricular assist devices (LVAD or VAD) are usually devoted to blood pumping without the possibility to adapt the speed to patient conditions during everyday activities. This is essentially due to the lack of sensorization, bulkiness, and the need of relying on device-specific controllers with reduced computing ability for the existing ventricular assist systems. In this work, an innovative integrated and portable device, the ARU, is presented for enhancing VADs applicability as a long-term solution to HF. The ARU is an universal device able to fulfill with the needs of sensorized VADs in terms of data storing, continuous monitoring, autoregulation and adaptation to patient condition changes during daily activities. The ARU is able to wirelessly interface wearable devices for offering additional monitoring features from remote. The ARU functionalities on bench have been tested by the interfacing with a sensorized VAD platform in order to prove the feasibility of the approach. Experiments of local and remote VAD speed changes and autoregulation algorithms have been successfully tested showing response time of 1 s.

A hybrid cardiovascular simulator as test bench for VAD autoregulation control

Aim: Doppler ultrasound is standard for measurements of blood velocity. Aninherent limitation is that Doppler methods only measure the velocity parallelto the ultrasound beam. In Ultrasound Image Velocimetry (UIV) regions of two sequential B-mode images are cross-correlated to calculate 2-D velocity vectors. UIV results were compared with Doppler and transit-time flow measurements.Methods: In vitro experiments were performed in a pulsatile flow loop. Theworking fluid was water/glycerol with ultrasound contrast agent (microbubbles).The latex tube was imaged using an Ultrasonix RP500 and a novelimaging sequence was used to interleave two ultrasound frames, enabling ashort and variable (0.3-39 ms) interframe time separation (δt). A rabbit wasanaesthetised and imaged through the abdomen, with microbubbles administered via the ear vein. Radiofrequency data were post-processed offlineusing in-house code which calculates the local correlation between successiveframes, then sums correlation results for identical phases of all cardiaccycles.Results: Peak velocities >2 m/s were accurately measured across the entirefield-of-view in vitro, while peak systolic velocities in the rabbit were 0.99 m/sand 1.04 m/s with UIV and Doppler respectively. As δt was increased flow instability during deceleration caused the UIV velocity measurement to drop to zero. Comparing velocity measurements of decelerating flow with different values of δt leads to a new method for investigating flow instability.Conclusions: With short δt UIV and derived flow rates agreed excellently withDoppler and transit time flow rates.Aim: Topical application of ophthalmic drugs is very inefficient; contact lenses used as drug delivery devices could minimize the drug loss and side effects. Styrene-maleic acid copolymers (PSMA) can form polymer-phospholipid complexes with dipalmitoyl phosphatidylcholine (DMPC) in the form of nanometric vesicles, which can easily solubilise hydrophobic drugs. They can be dispersed on very thin contact lens coatings to immobilize the drug on their surface. Methods: Two types of complexes stable at different pH values (5 and 7 respectively) where synthesized and loaded with drugs of different hydrophilicities during their formation process. The drug release was studied in vitro and compared to the free drug. Results: The mean sizes of the complexes obtained by light scattering were 50 nm and 450 nm respectively with low polydispersities. However, they were affected by the drugs load and release. An increase was observed in the duration of the release in the case of hydrophobic drugs, from days to weeks, avoiding initial “burst” and with a lesser amount of total drug released due to the interaction of the drug with the phospholipid core. The size and charge of the different drugs and the complexes nature also affected the release profile. Conclusions: Polymer-phospholipid complexes in the form of nanoparticles can be used to solubilise and release hydrophobic drugs in a controlled way. The drug load and release can be optimised to reach therapeutic values in the eye.