Your post is fine, Bob. Welcome to the site. I had very few symptoms until my stenosis became severe. There are others who have posted who had none at all before a sudden requirement for AVR.
Your situation is not all that unusual, actually, for a very atheletic person. Sometimes, very aerobically fit people don't develop or recognize symptoms until they are very nearly dead (and occasionally not quite that soon, unfortunately).
Your body's healing mechanisms are placing layers of calcium down on what they believe is an injured heart valve. They think they're protecting the valve (and you). That's what's making the valve area smaller and the valve less flexible.
Your body and heart have been trained hard, and have learned to deal with shortages of oxygen and performing on a shoestring. Basically, your fitness has enabled your body to adapt to your valve issue.
Unfortunately, your body cannot entirely overcome it. In the end, the restriction will become so great that your heart will not be able to pump enough blood to itself, or continue to force blood through the tiny, unmoving opening. It will convulse and cease. This is one of the "undiagnosed heart ailments" that you sometimes hear young atheletes dying of in the news.
OK, that's a little gruesome for a "welcome" post. However, it is important to realize that Aortic Stenosis causes cruel and deadly progressive damage to your heart. Like having your chain jump the sprocket halfway up a steep hill, being more fit will not prevent it, nor slow down its progression. You can't tough it out.
It can be depressing to address a critical physical failure, especially when you've always been fit, active, and in command of your body. People here have lived that part, too. You can shout "Unfair!" here, and be understood.
Here is the cheap tour of test usages, as I understand them:
The four tests that are generally used for this are the MRA (an MRI of the heart and surrounding area), the TEE or TOE (an echo done through a transducer that is lowered into the throat), Cardiac Catheterization (a transducer and other implements are inserted and snaked up to the heart, usually through the large femoral artery at the groin, and measurements are take from within), and the Echocardiogram (a sonogram taken by placing a transducer against the body), which you are already familiar with.
- The Echocardiogram (ECG) is the easiest to have done, and may be the least expensive. If you have a good echo technician, it can be quite accurate. It is usually not sole evidence for performing surgery. Plus, it cannot discern whether there are blockages in any of the coronary arteries. Most surgeons will do bypasses as a matter of common sense while the chest is open, if there are any blockages present. For that reason, a cardiac catheterization is usually also done before surgery.
- Cardiac Catheterization (cath) is done by an interventional cardiologist, with an anaesthesiologist's assistance and sometimes an xray technologist. You can be anaesthetised from an aware, bare minimum level to a barely responsive level, usually at your discretion. It generally yields slightly different results from an echo, and is considered a basis for surgery, especially in conjunction with the ECG, which usually precedes it. It has the added and critical advantage of allowing xrays of the valve and heart chambers, as well as the coronary arteries, where it can determine blockages. These xray views are possible because of an injected dye that illuminates the passages. Most surgeries are done on the basis of an ECG and a cath.
- TEE (Trans-esophogeal echocardiogram [in the U.K. - TOE: trans-oesophogeal echocardiogram]) is done by the cardiologist or a technician. Usually patients will take calming drugs and an unpleasant-tasting, numbing spray that deadens the gag response. It is not an enjoyable test, but most people do make it through the exam without forcing a halt. TEE is considered more accurate than the standard echo, and possibly more so than the cath. It is also used during the actual operation to allow the surgeon to check his work. A TEE is considered accurate enough to mandate surgery. However, like a standard echo, it cannot check the status of the coronary arteries. As such, a cath is usually also performed before surgery.
- MRA (Magnetic Resonance Angiography) is done in a closed-tube type MRI. Many people take Valium or other calming prescriptions before the test, as there are tight quarters inside the machine. Thoracic MRIs are done, and are then redone after a contrast medium is injected into your arm. MRA technicians believe that their results are extremely accurate and grounds for surgery. While the MRI should be able to view the coronary arteries with the contrast medium, that doesn't seem to be included in most cases, again leaving the requirement for a cath before surgery.
Stenosis generally goes to critical at about 1 cm². There appears to be concensus that, if no symptoms are present, aortic valve replacement is performed at .8 cm² regardless. There are those on this site who have had it performed (as an emergency) at smaller valve areas. Aortic stenosis is considered usually terminal at about .5 cm². Again, with variances between tests, some may have been listed at .5 cm² on an echo, but the valve area may actually show up as larger in the surgeon's final report of the physical valve after removal.
You should determine whether you want to choose the type of valve (tissue or mechanical), and if so, what brand. There are many threads here about valve choice. You should also consider whether you want to choose your surgeon, and/or the facility where you will have your surgery.
Everyone is different, but if your progress is similar to my stenosis, you have some time (months to years) to develop an understanding of the heart issues you face, the types of valves you might want to consider, what actually happens at operation time, and what your recovery may be like.
Probably, you've been gleaning a lot of that from reading the forums already. Use the search feature, and ask about existing threads or start another, as you did here.
Glad to have you aboard.
This, by the way, is a "large, rambling posting."
Best wishes,