Measurement of Heart-carotid Pulse Wave Velocity (hcPWV) by Laser Doppler Vibrometry (LDV)

Overview

Aortic stiffness is an important imaging biomarker of vascular aging. The ascending aorta is the most elastic segment, and it is excluded by reference non-invasive method carotid to femoral pulse wave velocity (PWV). We propose to use laser-doppler vibrometry (LDV) to record superficial vibrations generated by cardiac activity and arterial pulses for measuring heart carotid PWV, a surrogate for ascending aorta. The trial aims to demonstrate the equivalence between heart-carotid PWV made by laser-doppler vibrometry (LDV) with the reference MRI measurement (4D-FLOW MRI). As secondary objectives, A) we aim to assess the reproducibility of LDV, compared with MRI, B) show that aortic stiffness measured by LDV fulfils international recommendations, C) to study the association between PWV and age or other cardiovascular risk factors, D) assess the acceptability of the measurement. For this, we include 100 consecutive patients, 50 women, 50 men, scheduled for clinically indicated thoracic aorta MRI.

Cardiovascular (CV) diseases and their risk factors are the leading causes of morbidity and mortality in the world. They are responsible for more than 17.3 million deaths per year worldwide, accounting for 30% of all causes of death. The measurement of arterial stiffness is useful to estimate the global CV risk with more precision than the simple point assessment of the classical cardiovascular risk factors. Carotid-femoral pulse wave velocity (cfPWV) by tonometry is the reference method. However, it excludes by principle the ascending aorta, which is the most distensible and physiologically the most important segment. The InSiDe project aims to measure heart - carotid pulse wave velocity (hcPWV) from the measurement of skin vibrations on the chest and neck by laser doppler vibrometry (LDV), enclosing principally the ascending aorta. This will allow the measurement and validation of a new biomarker that quantifies the stiffness of the ascending aorta. We have demonstrated a very good agreement of the LDV-based cfPWV with the reference technique by tonometry. Our hypothesis, based on physiological reasons, is that heart-carotid PWV will surpass carotid-femoral PWV as a biomarker of large artery stiffness. The trial aims to demonstrate the equivalence between heart-carotid PWV measured by laser-doppler vibrometry (LDV) with the reference MRI measurement (4D-FLOW MRI). MRI, the gold standard comparator is technically demanding and uncomfortable for the patient, much more expensive and not applicable at the general population level. It is therefore likely that measurement by laser-doppler vibrometry, without contact, more comfortable, acceptable and fast, could replace MRI for mass applications. For this, we include 100 consecutive patients, 50 women, 50 men, scheduled for clinically indicated thoracic aorta MRI. ENDPOINTS Primary endpoint: • Heart-carotid PWV measured by LDV. To evaluate the agreement between heart-carotid PWV measured by LDV and the same measurement made by MRI (plus 4D-FLOW MRI) of the thorax. Secondary endpoints: * Reproducibility of the LDV hcPWV * Measurement of LDV cfPWV compared with tonometry * Association between PWV (hc, cf, LDV, MRI), and age, other risk factors * Assessment of patient acceptability of the measurement Statistical analysis The statistical technique used will be the Bland - Altman plot and the corresponding bias assessment (mean Bland-Altman bias and limits of agreement, defined as the mean bias ±1.96 - standard deviation, are provided); the coefficient of variation (CV) will also be used. Description of the device being investigated: The LDV device, developed by the European consortium CARDIS (Medtronic,SIOS, iMEC, Tyndall Institute) uses two arrays with 6 laser beams. It is a non-invasive exploration, by category 1 laser without any risk for the patient and allows to measure the local arterial stiffness (to evaluate the heart-carotid PWV) and segmental without contact with the skin by using the LDV technique. In practice, this device allows the evaluation of the hcPWV from the measurement of skin vibrations on the chest and neck. Description of the device used as a comparator: The reference technique is MRI, used in combination with 4D-FLOW MRI, an innovative technique that allows full 3-dimensional anatomical coverage as well as velocity coding in all 3 directions, opening new and unique possibilities for visualizing and quantifying complex cardiovascular blood flow