Non-Contact Measurement of Aortic Compliance

Study Overview
=================
Brief Summary
-----------------
Reduced aortic stiffness is a powerful way to predict the outcome of cardiovascular (CV) disease. There are several non invasive methods for its estimation, most of which are based on the measurement of speed of the arterial pulse wave. (The stiffer the artery, the faster the pulse wave travels.) They rely on detecting the arterial pulse with 2 sensors placed on the skin a known distance apart and measuring the time for the pulse to travel between them. However all current methods require skilled operators and are of limited accuracy. Thus, there is a need for an easy to use and reliable device to measure pulse speed. The aim of this project is to develop a non contact device to detect the aortic pulse as it moves into the small arteries following the ribs, using the principle of thermal imaging, by means of a high sensitivity infra red camera, directed towards the subjects back. The investigators plan to validate the device and conduct a small feasibility study in patients undergoing elective angiography, by simultaneously measuring pulse speed using established methods. These are Doppler ultrasound (non-invasive) and direct intra-arterial measurement (the gold standard).

Official Title
-----------------
Non Contact Measurement of Aortic Pulse Wave Velocity

Conditions
-----------------
Vascular Disease

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Age 18 years and above Patients eligible for coronary angiography Informed consent obtained Able to complete experimental protocol Exclusion Criteria: Refusal of consent Age below 18 years Breast feeding Known or suspected pregnancy Patient participating in another study at time of study entry or previous participation in this registry diagnosed but untreated hypertension

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Angiography high risk<br>Patients with multiple risk factors, positive non-invasive test, or known pre-existing coronary artery/vascular disease. Patients with diabetes mellitus will be identified, and subject to a sub-group analysis. | |
| Angiography Low Risk<br>Patients with chest pain symptoms, minimal risk factors, and inconclusive evidence of myocardial ischaemia on non-invasive testing. | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Quantitative agreement between intra-arterial measurement of aortic pulse wave velocity and transcutaneous values: a) Contact PPG from probes on the skin of the back in the intercostal spaces and b) non-contact from infra-red camera imaging the back. |  | Single measurement to be made between January 2010 and June 2010 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of differences in aPWV and between low and high risk groups of patients undergoing elective coronary angiography. |  | Single measurement to be made between January 2010 and June 2010 | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Pulse wave velocity, Non contact, Non-invasive, Photoplethysmography, Doppler flow velocimetry