Early identification of individuals at risk for Cardiovascular Diseases (CVD) allows early intervention to halt or reverse the pathological process. This is the driver of Medtronic and partners to develop a mobile, low-cost, non-invasive, point-of-care screening device for CVD.
Assessment of arterial stiffness by measurement of aortic pulse wave velocity (aPWV) is included in the latest guidelines for CVD risk prediction – arterial stiffness is an early marker for hypertension.
Early identification of arterial stenosis and cardiac contraction abnormalities can be used to improve CVD risk classification. However, no tools are available today to screen a large population under primary care for these indicators, and individuals that are considered to be at low or moderate risk are too often undiagnosed.
Over the past few years, The University of Gent and Queen Mary University of London 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 vibrometry. 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 (LDV) is an instrument that is used to make non-contact vibration measurements of a surface. The laser beam from the LDV is directed at the surface of interest (in our case the skin overlying the artery under investigation), 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 an LDV is generally a continuous analog 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 by making it possible to (a) measure aortic and local PWV; (b) detect vibrations induced by disturbed blood flow in stenosed arteries; (c) detect cardiac contraction abnormalities via measurements on the chest.