I had my first artificial aortic valve fail after only one year. It happened because I had an aortic root aneurysm that was not repaired in the first surgery. The aneurysm continued to grow, and eventually the stitches pulled loose, 2/3 of the way around. I was lucky to have a better surgeon the second time around. It's now been 11 years since my re-operation, and I'm doing well.
Ger57 had some good points and some good questions for you. I agree with him that it's hard to give specific feedback without knowing your age, type of valve (tissue vs. mechanical), and where it is leaking (through the leaflets vs. around the sewing ring).
The least likely cause of your problem, in my opinion, is that the valve has a manufacturing defect. Those are very, very rare. To my knowledge, St. Jude has not had any valve recalls, and I would be interested if they had, because I now have a St. Jude Masters aortic valve myself.
I'm hoping you live near a thoracic aortic center where you can have your next surgery done. If at all possible, you need for your surgeon to be someone who does aortic valve re-ops on a regular basis, and that may take some looking. Good luck, and feel free to post back with the details of your case, if you wish.
What kind of valve did they implant 7 years ago? What is your age?
The lifetime of a tissue valve is typically 10 to 15 years, often less in younger patients, as mechanical ones normally last a lifetime.
Leakage can take place at different positions. It can be the valve itself that is leaking, it can be that the leakage is between the valve annulus and your heart tissue.
After 7 years in need of replacement is not very common but those statistics do not help you. If your valve is severely leaking, you need replacement or repair to avoid irreversible damage to your heart.
earlier topic on these forums brings up some interesting points:
http://www.medhelp.org/posts/Heart-Disease/Leaky-St-Jude-aortic-valve/show/1142443
You can google the company to find St Jude Medical's contact number (at sjm.com), they may provide some useful info. The fda.gov site publishes consumer updates that may include your model.