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

I S S U E S E V E N

95

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

E

arly identification of individuals at risk of cardiovascular

disease (CVD) allows early intervention to halt or reverse

the pathological process. This is driving Medtronic and its

partners to develop a mobile, low cost, non-invasive, point of care

screening device for CVD.

Over the last ten years, a large amount of evidence has

accumulated demonstrating that increased ‘arterial stiffness’ is an

important risk factor for cardiovascular disease.

1

Arteries are, due to their composition, elastic structures that

distend with each contraction of the heart, thereby buffering its

pulsatile action, damping the pressure pulsations in the arteries

and reducing the pulsatility of blood flow so that organs are

continuously provided with blood (and oxygen and nutrients). As

the aorta has the largest contribution to this damping action,

measurement of aortic stiffness has received much attention.

Aortic stiffness can be assessed in a number of ways, but the non-

invasive measurement of the carotid-femoral (aortic) pulse wave

velocity (aPWV) is regarded as the current gold standard,

2

and it is

included in the latest European Society of Cardiology/European

Society of Hypertension guidelines for CVD risk prediction.

However, the tools and devices available today do not allow for

mobile, low cost, point of care screening devices for reliable, fast

and non or minimally invasive measurement of arterial stiffness.

Improving risk classification

Besides arterial stiffness, early identification of arterial stenosis

can be used to improve CVD risk classification. Severe coronary

stenosis might be detected by ECG (electrocardiogram)

measurement, but this is only visible when there is already a clear

impact on myocardial function with elevation of the so-called ‘S-T

segment’ in the ECG recording. In any case, the presence of

coronary stenosis can only be confirmed by an invasive procedure

involving catheterisation and coronary angiography. The primary

point of care method to assess carotid stenosis is auscultating

the carotid artery with a stethoscope.

In the case of a stenosis, a swishing noise called a ‘bruit’ might be

observed, which may be a sign of turbulent blood flow caused by

atherosclerosis. However, a carotid bruit is unlikely to be heard if

the stenosis occludes less than 40% of the diameter of the artery.

Likewise, a stenosis of greater than 90% may not be heard, as the

flow may be too low. The diagnosis is very operator dependent

(audible perception) and is largely susceptible to environmental

noise. Just as in the arterial stiffness arena, it can be confidently

stated that, today, there are no mobile, low cost, point of care

devices for reliable, fast and non or minimally invasive detection

of coronary or carotid stenosis.

Last but not least, an early detection of cardiac decompensation

may dramatically improve the patient’s diagnosis and a related

timely intervention. Currently in the primary point of care unit,

cardiac dysfunction may be detected primarily based on clinical

symptoms (chest pain, exhaustion) and auscultation (e.g.

suspicious murmurs due to abnormal blood flow patterns). There

are thus no tools and devices available for a reliable, fast and non

or minimally invasive detection of heart failure in the primary point

of care unit.

Technology background and methodology

Over the past few years, the University of Gent (UGent), Queen

Mary University of London (QMUL) and others have gathered

evidence that mechanical vibrations induced by cardiovascular

dynamics actually propagate up to skin level, where they can be

picked up using laser Doppler vibrometry (LDV).

This is not surprising given the important role of auscultation (based

on acoustic waves travelling in the body) in primary care medicine.

A laser Doppler vibrometer is an instrument that is used to make

non-contact vibration measurements of a surface. The laser beam

from the vibrometer is directed at the surface of interest (in our

case the skin covering the artery or the chest wall), and the

vibration amplitude and frequency are extracted from the Doppler

shift of the reflected laser beam frequency due to the motion of

the surface. The output of a vibrometer is generally a continuous

analogue voltage that is directly proportional to the target velocity

component along the direction of the laser beam.

Preliminary data suggest that LDV can lead to an improved

screening and assessment of cardiovascular risk as a technique

that makes it possible to (a) measure aortic and local PWV; (b)

detect vibrations induced by turbulent blood flow in stenosed

As it becomes even more crucial to identify cardiovascular diseases as

early as possible to allow intervention, new screening devices could be the

key to saving lives

Unmet needs