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
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
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.
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,
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