I have an induction cooktop (actually, just a disk with the magnetic stuff under the surface). I don't think there would be a problem with this oven. I doubt that, even if you were to rest your chest directly on top of the cooktop, that the magnetic drivers would be powerful enough to do anything to your mechanical valve.
It's not like the microwave oven / pacemaker issues that we used to (and possibly still do) hear about -- The magnetic stuff is too weak to have any effect.
One more thing -- I have a 25 year old St. Jude Valve ticking in my chest. I have a card that I got along with the valve - the valve was free but the card cost $8800 - and it said that this valve is safe for use in an MRI. MRIs generate many orders of magnitude stronger magnetic fields than an induction cooktop.
You can always call your valve manufacturer for an answer, but I'm pretty sure that you can get that cooker without concern about your valve.