[HSF] ATS valve

[prasannasimha]

I got what you meant but this would be about 30 -40 Deg off Joachim 
Laas's positioning as mentioned by Bojan. The greater curvature 
orientation of the monoleaflet valves has been well described but there 
seems to be a paucity of data wrt bileaflet valves and i remember seeing 
a supercomputer simulation study of these in a model aorta and the 
simulation was spot on for the monoleaflet valve but no position seemd 
to be better for a bilaflet valve. That is what started my confusion. Is 
there any literature to support theseptalbulge to aortic greater 
curvature position ?
Prasanna
Rwmfglycar at aol.com wrote:
> Dear Prasanna,
> That is a fair description but since the positions of coronary ostia do  vary 
> I would prefer for you to look carefully down into the ventricle and see  
> where the septum is and whether it has a bulge and then look at the aorta and  
> see how the curve lines up; you want the hinge line to bisect the curve so that  
> there is equal access of each orifice of the bileaflet valve to the space  
> that the greater curve supplies. For the Medtronic Hall the larger orifice must  
> be placed so that the flow through it is  directed to the greater  curve.
> Placing the latter valve the other way around actually produces more of a  
> difference in flow patterns than placing a bileaflet valve with one  orifice 
> opening to the lesser curve and one to the greater curve.
> I am reluctant to get into the current discussion on ATS valves. I have as  
> you all know a consultant job with SJM. The hinge on the ATS looks good and  
> does not have the spaces that recessed hinges of other bileaflet  valves have 
> had. The claim however that an open hinge will definitely result in  a lower 
> embolism and thrombosis rate than a recessed hinge is a marketing claim.  Some 
> designs with recessed hinges from a variety of companies have turned out to  
> develop thrombi in the recesses. By good luck more than design the SJM hinge  
> over the last 30 years has performed very well and as advanced methods of  
> studying fluid flow at the hinges have come along they have confirmed good flow  
> patterns in the SJM hinge area and revealed undesirable flow patterns  that 
> explained hinge thrombosis in other bileaflet valves.
> There are some studies of ATS that report good performance but I will have  
> to dig through my files to find  comparative studies with other valves. 
> The hinge of course is not the only site of thrombus formation in bileaflet  
> valves. There are separate trials underway in which the SJM and  Onyx are used 
> with aspirin and plavix. With regard to lower INR's the  current AHA ACC 
> guidelines advise 2-3 for low risk patients with "newer  generation valves", by 
> which the authors mean pyrolytic carbon bileaflet  valves.
> Bob
>  
>
>
>
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