aortic stenosis

  i lead an extremely active life style.my aortic stenosis has been very mild up until several months ago.my latest echo indicates a mean gradient of 18mm with a peak of 50mm and the valve area is 1.0cm. i've had some mild momentary dizziness when standing up or getting out of bed and ocassionally when i go out for a run i can experience some light headedness that goes away if i rest for a moment.i have about a million questions and concerns. but a few are; is aortic stenosis considerd mild or moderate based on the mean or peak gradient?my tolorance and desire to be very active are still very high,if i maintain a cardiac output or heart rate that is within my areobic range is that ok? what about light weight work?lastly, everything i've heard to date has been to "keep whatever plumbing you've got" until you absolutely have to replace it.but if i have to lead a life where i'm always anxious about what i can and can't do,wouldn't it be better to just replace it sooner rather than later?    

[Cleveland Clinic, MD]

Dear Ron,
Q: Is aortic stenosis considerd mild or moderate based on the mean or peak gradient?
A: It is actually based on the valve area.  The peak and mean gradients are a function of the valve area and are interconnected.
Q: If i maintain a cardiac output or heart rate that is within my areobic range is that ok?
A: Specific recommendation are up to your doctor but in general exercise as tolerated is OK.
Q: Lastly, everything i've heard to date has been to "keep whatever plumbing you've got" until you absolutely have to replace it.but if i have to lead a life where i'm always anxious about what i can and can't do,wouldn't it be better to just replace it sooner rather than later?
A: The timing of valve surgery is more of an art than science.  However, if you are starting to experience symptoms due to the stenosis I would say it is time to get the surgery.  
Here are some questions from other patients you may find useful:

Q: I am concerned about the amount of fatigue I am experiencing. I usually wake up feeling rested and feel pretty good for about four hours, then I seem to really wind down. Is this normal with my condition?
A: Your symptoms of progressive fatigue are common with aortic stenosis (AS) and relate to a reduced cardiac output. With AS, there is a fixed obstruction to blood flow from the left ventricle  to the rest of the body which worsens with time. With this obstruction, fatigue occurs because the heart is unable to pump enough blood to the rest of the body.
Q: My cardiologist said that my left ventricle has begun to dilate (I think internal dimensions of 6.6 up from 5.9 last year?) He also mentioned a shortening fraction of 32% Can you explain these numbers to me please?
A: The normal distance between the walls of the left ventricle is about 5 cm.  When the heart starts to dilate (get larger) these dimensions increase.  The ejection fraction is a measure of the pumping capacity of the heart.  Normal is 50-65%.  Mildly decreased is 40-49%.  Moderately decreased is 25-39% and severly decreased is <20%.
Q: If I take Altace until November, will it reverse the dilation to my left ventricle,
and if so would that be a longer term treatment alternative to surgery?
A: There may be some decrease in the dilation.  This is called remodeling and is somewhat controversial.  It is not a long term solution to heart failure caused by valvular stenosis.
I hope you find this information useful.  Information provided in the heart forum is for general purposes only.  Only your physician can provide specific diagnoses and therapies.  Please feel free to write back with additional questions.
If you would like to make an appointment at the Cleveland Clinic Heart Center, please call 1-800-CCF-CARE or inquire online by using the Heart Center website at www.ccf.org/heartcenter.  The Heart Center website contains a directory of the cardiology staff that can be used to select the physician best suited to address your cardiac problem.