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96

I S S U E S E V E N

H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L

www.horizon2020projects.com

P R O F I L E

M E D I C A L T E C H N O L O G Y & R E S E A R C H

arteries; and (c) pick up cardiac contraction abnormalities via

measurements on the chest.

LDV for measuring aortic and local PWV

LDV has been proposed as a new non-invasive method to

measure the aPWV as well as the local PWV of the common

carotid arteries (CCA).

3,4

UGent has successfully demonstrated

that aPWV can be measured correctly with LDV (Fig. 1). This

method greatly simplifies the procedures for measurement of

aPWV; however, the proposed LDV set-up for these measurements

is still bulky and expensive, which prevents this technique from

being widely used.

LDV for detection of stenosis-induced vibrations

The concept that flow through an arterial stenosis becomes

turbulent downstream and induces subsequent mechanical

vibrations is not new and has been studied since the 1970s.

5,6

The turbulent flow also induces low amplitude, acoustic shear

waves through the soft tissue in the thorax which then appear at

the chest wall. It has been demonstrated in a series of

in vitro

set-

ups that these shear waves are effectively detected using

accelerometers attached to the phantoms.

7,8

LDV for detection of cardiac contraction abnormalities

LDV can assess cardiac contraction in heart failure patients where

the correlation between electrical and mechanical dysfunction is

still a challenge.

9,10

In fact, it has been shown that LDV is

comparable to the gold standard assessment of cardiac

function.

11,12

All the classical signs of heart failure obtained by

auscultation (gallop sounds, increased B1, mitral valve

regurgitation, B2 duplication, etc.) can be detected with much

more sensitivity and, in addition, can be quantified.

Europe is at the forefront in the field of integrated photonics. Imec

has developed over the last decade an impressive integrated

silicon photonics technology platform, with successful R&D

results having been achieved. In fact, it is capable of investigating,

developing, prototyping and manufacturing low volumes of silicon

chips and, together with Tyndall (University of Cork), delivering

packaged silicon photonics chips.

Medtronic, a leader in medical devices, has identified the unique

opportunity of bringing SIOS, a commercial supplier of homodyne

laser interferometers, together with Imec, Tyndall, UGent and

QMUL to make, for the very first time, a mobile, low cost, point of

care screening LDV for CVD.

The technology will be validated

in vivo

by two academic

hospitals, Hôpital Européen Georges-Pompidou (HEGP) and

Maastricht University Hospital (UM), for the three envisioned

applications. The concept will be validated in a clinical context as

a proof of concept study to assess usability and the preliminary

level of effectiveness (Fig. 2).

The technology development will be driven and validated by end

users renowned for their expertise in diagnosis of CVD and more,

in particular on the base of PWV determination, screening of

vascular lesions, and screening of cardiac function.

Ultimately, the diagnosis of cardiac disease and dysfunction has

to be confirmed in specialised cardiological centres by advanced

ECG analysis, cardiac ultrasound, exercise testing, blood tests and

specific biomarkers or other imaging tests (MRI, nuclear imaging);

the novel device is seen as a screening tool, not a diagnosis tool.

CARDIS objectives

The objective of CARDIS (Early stage CARdio Vascular Disease

Detection with Integrated Silicon Photonics) is to investigate and

demonstrate the concept of a mobile, low cost device based on

a silicon photonics integrated LDV and validate the concept for

the screening of arterial stiffness, detection of stenosis and

heart failure.

We will:

n

Investigate, design and fabricate the optical subsystems and

components: silicon photonics chip with integrated Ge-detectors,

micro-optics, micro-optical laser bench, optical package;

n

Integrate the subsystems and build a multi-array laser

interferometer system;

n

Develop a process flow scalable to high volumes for all

subsystems and their integration steps;

n

Investigate and develop the biomechanical model to translate

optical signals related to skin-level vibrations into underlying

CVD physiological events; and

n

Validate the system in a clinical setting. Photonics integration is

needed to enable a device that is mobile (small size, small

weight and robust (no moving parts)) and low cost (high volume

scalable process flow) and allows fast screening (laser array).

Fig. 1 Laser Doppler vibrometry preliminary set-up