Ascending aorta dilation with aortic mechanical valve

[green881]

I am a 55 years old male. I had AVR with 21 mm diameter of St. Jude mechanical valve 23 years ago because of the calcifiend aortic stenosis . It might be BAV. After the AVR the mechanical valve has been working well with a pressure gradient of 25 mmHg thru the valve. Recently I found a dilation of ascending aorta, 47mm by the 2nd CT. The first CT about two years(21 months) ago showed 45 mm in diameter at ascending aorta 5 cm above the valve. Many research papers have been published numerous surgical procedures and their results. But I am not quite sure of the best option for me. If a surgery is needed, should the diseased part of ascending aorta only be replaced with dacron graft while the 23 years old mechanical valve is left in place, or should both the diseased aorta and the mechanical valve, which is working well, be replaced, or any other methods such as wrapping, and so on.  Would anyone who has experienced this kind of case give some comments or information to share?

[kenkeith]

The following link may be able to provide information regarding your concern. http://www.valvereplacement.org/forums/archive/index.php/t-709.html

[green881]

Dear Ken,

I am so grateful to you for your information.

I would also like to share the following papers published:

http://cat.inist.fr/?aModele=afficheN&cpsidt=18501755
http://ejcts.ctsnetjournals.org/cgi/content/full/31/4/614
http://www.cardiothoracicsurgery.org/content/5/1/58
http://asianannals.ctsnetjournals.org/cgi/content/abstract/17/2/162

The above papers are suggesting an alternative for asending aorta dilation.

http://ejcts.ctsnetjournals.org/cgi/reprint/32/4/683:

This paper  above does not seem to accept the alternative such as wrapping procedures for the ascending aorta dilation.

For BAV patients, I thought, the wrapping procedure with external support over the ascending aorta should be helpful to prevent a future dilation even if the ascending aorta size is normal during AVR. But I couldn't find the case, which may indicate that the wrapping would have some risks in the long term.

I would like to inquire on the following questions:
Regarding to Dacron graft for the ascending aorta are there many selections like artificial valves ? Does its type and structure depend on manufactures?  Are there risks of dacron graft in the long term and are they manageable?

Thank you so much.

[kenkeith]

With mechanical valves shear stress is the major cause for clotting, and anti-platelet medication is required for a lifetime as you well know.  I understand there is a design of a mechanical valve that eliminates the major cause of clotting complications in mechanical valves – increased shear stress created by recessed areas in the pivot area.  It seems the focus is on engineering a better mechanical valve design to prevent turbulance rather a more durable graft.  

"The ATS Open Pivot® design reduced average shear stress and platelet activation during the regurgitant flow phase while the cavity pivot generated higher platelet activation values during the reguritant flow phase at all ranges of shear stress accumulation. Overall, the ATS valve may offer a lower thrombogenic potential owing to its different hinge mechanism design".

Regarding a Dacron graft my source that it is  completely compatible with the body that rejection and calcification do not occur and there is a growth of new tissue. "The grafts are strong, flexible and collagen impregnated, making them impervious to blood. The durability of these grafts exceeds that of the human life span".

Ken

[green881]

Thank you for your comments.
I appreciate your concern and information.

I have further questions.

I have read research papers published about an ascending aorta dilation.
The issue, I think, could be controversial. The two causes of a ascending aorta dilation of AVR patiens has been reported as follows, respectively.:

- The hemodynamic force of a jet type of flow from the mechanical valve
- Aorta wall weakness, especially in many BAV patients progressive   dilation has been found even after AVR

The combination of these two would be also a cause.

If the hemodynamic force of the jet flow produced from the mechanical valve is a cause, I would like to know whether a future possible distal aora either by a replacement of dacron graft or by reduction aortoplasty  is durable enough for the hemodynamic force for lifetime. In valve sparing surgical procedures, which procedure would be the most appropriate technique for the ascending aorta dilation with mechanical valve?

Thank you again.

[kenkeith]

Your question may require a surgeon's opinion, but having read many posts on the subject it is generally agreed that often there can be valve sparring procedures that can preserve the natvie aorta valve during an aorta graft for an aneursym. A mechanical valve has a very long span and may not need replacing.  I don't know the contingent issues involved  to replace or not replace a good mechanical valve...the pressure gradient appears to be normal and no problem.

Thanks for sharing, I wish you well going forward, take care,

Ken