Coronary disease diagnosis by impedance spectroscopy (Cor-IS)

Contact Persons: S. Evgenidis [sevgenid@chem.auth.gr], K. Zacharias [ko_zach@yahoo.gr], G. Karagiannis [giorgos35doct@yahoo.gr]

 

Coronary artery disease (CAD) is the most common type of heart disease and cause of heart attacks. The disease is caused by plaque building up along the inner walls of the arteries of the heart, which narrows the lumen of arteries and reduces blood flow to the heart.

This study aims to evaluate the functionality of the brachial artery endothelium and, consequently, of the coronary circulation system by means of a patented electrical impedance spectroscopy device of exceptional high spatial and temporal resolution (European Patent Office, 3005942 Α1/2015). Non-invasive bio-impedance measurements are based on the vasodilation caused by ischemic cuff of the upper arm and subsequent hyperemia through the Nitric Oxide (NO) release from the endothelium (Figure 1). Until now, ultrasound imaging of the brachial artery is applied in clinical practice, but this has major disadvantages like poor repeatability, extensive fluctuation in the measured values, low imaging resolution and being dependent on ultrasound operator. The aforementioned drawbacks are not present when applying the impedance spectroscopy device, which is capable of measuring with unprecedented sensitivity not only the impedance variations caused by the ischemic cuff and release but even the minuscule pulsatile impedance undulations of the blood flow. Sophisticated signal analysis tools are employed to acquired bioelectrical signals in order to provide information on a patient’s brachial artery performance after an ischemic cuff and subsequent hyperemia e.g., expansion and recovery rate, span of artery size response, periodic and non-periodic features of coronary circulation, etc.

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Figure 1: Bio-impedance measurements for the evaluation of the coronary circulation system functionality.

It is interesting to notice that Cor-IS measurements have been successfully validated against ultrasound ones as regards the detection of post-dive endothelium dysfunction. A test campaign was performed in the NEMO 33 swimming pool in Brussels, Belgium. Volunteer divers were subjected to a well-defined dive profile at 33m depth for 20 minutes with water at 31oC, while endothelial functionality was investigated for 2h post-dive by means of Cor-IS and ultrasound Flow Mediated Dilation-FMD (Figure 2).

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Figure 2: Detection of post-dive endothelium dysfunction.

Currently, two Cor-IS medical devices are under development: The first refers to the early diagnosis of Coronary Artery Disease (CAD) at home and the second one concerns a professional medical tool for both diagnosis and monitoring of CAD to be used by medical doctors (Figure 3).

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Figure 3: Cor-IS medical devices under development.