About

Needs

Given the increase in life expectancy, the prevalence of valvular diseases keeps raising in our western countries. Degenerative mitral regurgitation has become the second valvular heart disease in terms of frequency. It is due to an incontinence of the mitral valve which normally prevents the regurgitation of blood in the left atrial compartment. In case of severe mitral regurgitation, this could rapidly lead to a pulmonary edema or an abnormal secondary dilatation of the left ventricle, which results in heart failure and death of the patient. Yet, surgery is the standard treatment for this pathology. Only 50% of patients are referred to surgery and the rest of the patients are treated with suboptimal medical treatment. Various reasons explain this abstention from surgical treatment: comorbidities, advanced age, risk factors, aesthetic damage, loss of working time, impairment of body image...

What is the concept of this project ?


State of the Art

The craze for the transcatheter treatment of valvular heart diseases, especially the treatment of atrio-ventricular valve diseases has led to the development of large transcatheter devices (12-15mm), which have to be positioned in the center of the heart into the native valvular orifices. The delivery of these devices to their destinations is done inside vessels and through the cardiac septa using a delivery system. The devices are introduced inside the sheath of the delivery system after a crimping manoeuvre and radial reduction of their sizes. The radial reduction of the devices and their loading (term referring to the operation of reducing and crimping the stent inside the delivery system) inside the sheath of the delivery system turns the stent into a rigid tubular trunk because the manoeuvre consists of reducing the valvular stent as much as possible in order to introduce it into the smallest possible sheath and thus obtain the smallest possible diameter of the delivery system. Therefore, the amount of material to be reduced depends of the size of the valvular stent. Also, the atrio-ventricular valves are large, especially in the case of dilated heart where they can reach a diameter of 42 millimeters. As a result, the corresponding delivery systems of atrio-ventricular devices are large and very rigid. These rigid bodies make the delivery of the device through the vessels and the inter-auricular septa impossible. This is the reason why almost all the devices are introduced by the ventricular wall, which is already extremely fragile (trans-apical approach) and requires a thoracotomy. In the current state of the art, there is no device for the treatment of valvular pathologies that can be delivered by flexible delivery systems of small diameter and which do not cause significant damage to the myocardial septum and walls.

Innovation

By proposing its new stent design, OSS presents a technology breaking through the current state of the art. The stent of Open Stent Solution is designed to give the possibility to switch between three different configurations providing structural transformations, which is essential to be able to respond optimally to the constraints of each step between loading and delivery. The structural transition between these 3 configurations allows for the creation of a new loading mode. The longitudinal reduction and crimping mode differs from the radial mode, currently the only compression mode. This longitudinal crimping is associated with a compression of the stent height along its minor axis and is also coming with a longitudinal elongation of the armature, which does not affect the sutures and biological components on the armature's meshes. This longitudinal loading introduces into the sheath of the delivery system a metallic armature thickness and a valvular leaflet at the same time. Consequently, the diameter of the implanted valve does not affect the size of the delivery system that will always have the same diameter whatever the dimensions of the valve. This method of compression also has the advantage of not transforming, as in radial compression, the cylindrical armature of the stent into a rigid trunk, thus enabling to keep a great flexibility, suppleness and manoeuverability of the sheath of the delivery system. These features are fundamental to ensure delivery in native vessels and acute angle flexion, while minimizing damage to the inter-auricular septum. The device recovers its final shape leaving the sheath of the delivery system and unfolds progressively. It curves on itself and recovers its cylindrical form where the three leaflets are operational. The device is provided with locking members at both ends, so that they interact to lock the stent into its cylindrical working configuration. This last transformation will take place in the native valvular orifice which will serve as an expansion chamber for the final deployment. The prosthetic leaflets will be plated until the final locking of the armature and until a satisfactory anchorage is obtained. This device is completely refoldable and re-positionable until it is locked. Therefore, this solution makes it possible to propose a therapeutic solution that is non-invasive and non-traumatic for the cardiac structures and, consequently, offers the possibility of implanting a valvular substitute for the most fragile patients.