Dilated Aortic Root

My 18yr old daughter who is a senior in high school as of Dec. 2009 has a dilation or her aortic root and ascending aorta as well as main pulmonary artery.  Echo showed dilated main pulmonary artery 36m Z score 4.7, aortic annulus 23mm Z score 1.7, aortic root 35mm Z score 3 and ascending aorta 30mm Z score 3.  Mild plus tricuspid regurgitation with prolapse.  No mitral valve prolapse.  Trace aortic regurgitation.   In Nov. 2008 aortic root was 31.2 Z 1.86 and ascending aorta 27.8mm Z 2.16.

She is currently on her high school tennis team.  I have a couple questions. First is playing tennis a safe activity or is being on the team creating more pressure and making the dilation worse.  Also, she is on 12.5 atenolol once a day-is this dose high enough?  I was told the atenolol is just basically buying her some time and that eventually she will require a graft - what is the general time frame given her current measurements before surgery is generally needed?  1 year, 2 years?

Thank you for you input.

Worried Mom