Inflammation and infection in nine surgically explanted Medtronic Freestyle stentless aortic valves.
BACKGROUND
The Medtronic Freestyle valve is fixed in glutaraldehyde at zero pressure on the cusps and treated with alpha-amino oleic acid. This valve reportedly has excellent clinical and hemodynamic results, but little has been reported about its long-term pathology.


RESULTS
Nine Freestyle valves explanted between 2003 and 2005 were reviewed to assess the reasons for bioprosthesis failure (six implanted at our institution). All valves were examined in detail, using histochemistry and immunohistochemistry to identify the cellular response. One Freestyle valve, explanted for mitral valve endocarditis on the fifth postoperative day, was excluded from analysis. Average implant duration was 52.8+/-35.5 months. Four valves were explanted for infective endocarditis, three for aortic insufficiency, two for aortic stenosis with cusp calcification seen in five valves, pannus and thrombus in all valves and a chronic inflammatory reaction involving the xenograft arterial wall seen in eight of nine valves. This was associated with significant damage to the porcine aortic wall in seven cases, and cusp myocardial shelf damage in six cases.


CONCLUSIONS
In this series of valves, we found (1) infective endocarditis; (2) pannus, thrombus, and calcification; and (3) unusual and significant inflammatory reaction and aortic tissue damage, which could by itself lead to aortic incompetence.
Butany
Jagdish
J
Department of Pathology, Toronto General Hospital/University Health Network, Toronto, Canada. jagdish.butany@uhn.on.ca
Zhou
Taylor
T
Leong
Shaun W
SW
Cunningham
Kristopher S
KS
Thangaroopan
Molly
M
Jegatheeswaran
Anusha
A
Jeggatheeswaran
Anusha
A
Feindel
Christopher
C
David
Tirone E
TE
D000328:Adult; D000368:Aged; D000818:Animals; D001021:Aortic Valve / Q000473:pathology / Q000601:surgery*; D001705:Bioprosthesis; D002114:Calcinosis / Q000209:etiology; D020878:Device Removal; D019544:Equipment Failure Analysis; D005260:Female; D005404:Fixatives; D005976:Glutaral; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000295:instrumentation; D006801:Humans; D007249:Inflammation / Q000209:etiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000209:etiology* / Q000473:pathology; D012189:Retrospective Studies; D013552:Swine; D013927:Thrombosis / Q000209:etiology; D013997:Time Factors; D016707:Tissue Fixation / Q000379:methods; D016896:Treatment Outcome
D005404:Fixatives; D005976:Glutaral