Magnetic Sensor Validation of Hemodynamic Non-invasive Measurements Pressure During Cardiac Catheterization

Among the 1% of live births with congenital heart disease, 20% have complex congenital heart disease (CHD). Their life expectancy, initially low, is constantly improving due to diagnostic, follow-up and therapeutic advances, particularly surgical. The pediatric population surviving the neonatal period is increasingly high and the number of people reaching adulthood has even exceeded the pediatric population for the last 3 years, a number that puts adult cardiologists in difficulty as they have little knowledge of the natural history of these pathologies. Indeed, it is difficult to predict or diagnose early decompensation or deterioration of cardiac function, especially for those affecting right heart function, because the anatomic and hemodynamic particularities of these CHDs make the usual functional exploration parameters not very sensitive. Indeed, the dysfunction of ventricular function is progressive and these patients remain asymptomatic for a long time and then decompensate suddenly. The late symptoms and the anatomic difficulty in adapting paraclinical criteria used for morphologically normal hearts explain their difficult interpretation and a delay in management. The current evaluation of these CHDscombining ultrasound imaging or even MRI or cardiac CT and stress testing is often flawed in terms of their sensitivity, because of the anatomic geometric complexity of these heart diseases.

Thus, the development of a non-invasive jugular venous pressure sensor, reflecting the hemodynamic function of the right heart, would be very useful to the clinician responsible for the follow-up of subjects with CHD, in order to detect early a deficit in right ventricular function.

1. Terki and H. Tran of the DynaCar team "Dynamics of cardiac couplings" of the Laboratory of Physiology Experimental Medicine (PhyMedExp), have developed an innovative medical detection device in partnership with the Laboratory of Coordination Chemistry LCC of the CNRS of Toulouse (A. Bousseksou) and the company eV-technologies (S. Wane and H. Tran), allowing to measure this jugular venous pressure by simple apposition of this one on the vein. A small magnet of 1cm X 1cm is placed beside the sensor. The very weak magnetic field of this magnet (0,02 Tesla) will generate a voltage at the terminals of the micro-sensor placed just beside. This voltage will reflect the pressure force related to the blood flow circulating in the cardiovascular network and give information on the heartbeat by magnetic measurements. The magnet and the micro-sensor are encapsulated in a plastic support of 3cm X1 cm and clipped on a flexible bracelet that can be affixed to the neck.

The magnetic field of the magnet used is of the order of magnitude of that of the fridge magnets (0.02 Tesla). It is therefore not harmful. It is 75 times weaker than that used in MRI (1.5T).

This device does not require the use of contrast agents, no patch and no adhesive product and is without direct contact with the skin.

The signals detected by the microchip (microsensor) are then transmitted to a tablet or laptop computer via a wired USB connection. A second sensor will be positioned on the radial artery through a bracelet placed around the wrist. Thus a magnetic arterial measurement will be simultaneously recorded.

It is therefore proposed that this magnetic sensor, affixed to the jugular vein, which empties into the right atrium, has the same sensitivity as the bloody measurement of central venous pressure. For that purpose, in a first study, the research team want to compare, during a right catheterization, the blood venous pressure curve, which is the reference method, with the one obtained by the innovative magnetic sensor. Indeed, before evaluating the interest of this medical device on patients with a dysfunction of the cardiac pump, the sensitivity of the measurements obtained in subjects who will benefit from an invasive hemodynamic evaluation during their follow-up must be validated, which will allow us to obtain a reference measurement.

The technology proposed in this study is totally innovative. It is based on the measurement of the magnetic field generated by the blood fluid during its passage in a vessel, which is detected by a micro-sensor placed on the skin. Although the structure and measurement principle are completely innovative for this study, magnetic ultrasensitivity has been demonstrated. Validation of the sensitivity of these sensors to non-invasively detect variations in venous pressure at the jugular vein will allow the future development of non-invasive miniature 'smart devices' with very low energy consumption (80 microWatt) and high early prognostic value in relation to right heart failure, allowing the refinement of monitoring and re-evaluation of therapeutic management of patients with CHD. These devices will be developed, characterized, tested and deployed in Occitania. The synergy between academic (University of Montpellier, CNRS Toulouse, INSERM, CHUM) and industrial (eV-Technologies) actors will ensure that the entire value chain from the development of the microsensors to the acceleration of their valorization and technology transfer will be anchored in Occitanie.