Morphological findings in explanted Toronto stentless porcine valves.
BACKGROUND
Stentless porcine valves have many documented advantages over stented valves. Since its introduction in 1991, the Toronto stentless porcine valve (T-SPV) has shown excellent hemodynamic performance.


METHODS
A total of 332 T-SPVs have been implanted at our institution up to December 2003, 25 of which have been explanted at surgery. Herein, we report a study of 30 explanted T-SPVs seen at our institution over a 5-year period.


RESULTS
The mean patient age at explant was 61.2+/-11.8 years with a mean implant duration of 100.7+/-27.8 months (after excluding one valve removed early postoperatively for infective endocarditis). Twenty-seven of 30 valves (90%) showed structural deterioration characterized by tissue degeneration, cusp tears, calcification, and lipid insudation. Eight valves (26.7%) showed evidence of calcification on gross inspection and a total of 23 valves (76.7%) showed at least one microscopic focus of calcification, located primarily in the basal and commissural regions of the cusp. Twenty valves (66.6%) showed cusp tears. Pannus was visible grossly on the surface of 27 of 30 valves (90%), while histologically, at least some degree of pannus was observed on both the inflow and outflow surfaces of all but two valves. Twelve T-SPV (40.0%) showed calcification in the porcine aortic tissue, four of which involved calcification of the porcine muscle shelf in the right coronary cusp. Two T-SPV showed no significant structural deterioration. Their clinical reason for explantation was incompetence or infective endocarditis.


CONCLUSIONS
With a freedom from reoperation of about 87.0% at up to 10 years, the T-SPV shows excellent durability. The majority of explanted valves show structural valve deterioration similar to that seen in other porcine heart valves.
Butany
Jagdish
J
Department of Pathology, E4-322, Toronto Medical Laboratories, Toronto General Hospital/University Health Network, Toronto, Ontario, Canada M5G 2C4. jagdish.butany@uhn.on.ca
Collins
Michael J
MJ
Nair
Vidhya
V
Leask
Richard L
RL
Scully
Hugh E
HE
Williams
William G
WG
David
Tirone E
TE
D000818:Animals; D001705:Bioprosthesis; D002114:Calcinosis / Q000209:etiology; D004697:Endocarditis, Bacterial / Q000209:etiology; D004868:Equipment Failure; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000295:instrumentation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000473:pathology*; D013552:Swine