Aortic valve stenosis, ultrasound treatment

Paris Match. What causes narrowing of the aortic valve?
Professor Emmanuel Messas. It is the most frequent attack of the heart valves. It affects 5% of those over 65 and 10% of those over 70. It comes from the calcification of the aortic valve (exit door of the heart) which no longer opens normally, or even freezes and forms an obstacle to the ejection by the left ventricle of blood towards the aorta. It goes unnoticed for a long time until the warning signs: shortness of breath on exertion, chest pain, syncope. The risk without treatment at two or three years is sudden death, heart failure and death from heart fatigue.

How is this calcified aortic stenosis (CAR) currently treated?
1. By open-heart surgery for the installation of a mechanical or biological valve (of animal origin). Benefit: Replacing the valve in the open provides an optimal functional repair. Disadvantages: the mechanical valve requires anticoagulant treatment (hemorrhagic risk which increases with age); the biological valve does not impose it, but it deteriorates after ten or fifteen years, requiring reoperation. 2. By Tavi (Transcatheter Aortic Valve Implantation). This revolutionary advance developed twenty years ago by Pr Alain Cribier (CHU Rouen) allows the placement of a biological valve by endovascular route (without opening the thorax). It is preferred when there is an operative risk. The act remains invasive and can lead to vascular complications or require the installation of a pacemaker.

What is the principle of your new approach?
1. It allows to leave the original valve in place with its insertion ring. 2. To soften the calcified and rigid leaflets of the valve so that they remobilize and open the aortic orifice (whose normal surface is 2.5 cm2 but less than 1 cm2 in tight RAC). For this, we use high-energy, high-frequency ultrasound which is emitted discontinuously, which ensures an effect (known as “cavitation”) targeted on the valve, not releasing heat and leaving the surrounding tissues intact. 3. To act externally through the thorax in a non-invasive way and under ultrasound control. 4. Allow iterative processing as needed. This new technology required (in collaboration with the Langevin Institute and the Physics Unit for Medicine, Inserm, Paris) the development of suitable software, a robot (arm that guides the shot) and tests at the animal. We were thus able to verify that our system (Valvosoft, experimental device not yet CE marked, developed by Cardiawave) is not a source of gaseous or calcium emboli that can migrate to the brain or a source of locally harmful heat.

What results have you obtained in humans?
The results of a multicenter study in 40 patients too at risk to benefit from the usual therapies because they were very old, carriers of severe ACR and comorbidities, were as follows: average increase of 20% in the aortic surface, sufficient to significantly improve the quality of life of patients. No intraoperative or postoperative death was attributable to the technique. No cerebral embolism detectable by imaging controls (MRI performed before and after the procedure) was observed. Cardiac ultrasound was able to objectify the increase in the opening surface of the valve induced by the micro-fragmentation of calcium in the valve leaflets as well as that of their mobility. At twelve months, these results persisted without the occurrence of cardiovascular complications.

Next step ?
A new study in ten centers (in France, the Netherlands and Germany) to obtain CE marking. It will only include fragile patients, but future indications will be to treat patients before the advanced stages (beginning calcification) to slow down the process, postpone the time of surgery or Tavi (as well as their risky reoperations), even stop it.