Thrombogenicity of polyethylene oxide-bonded Dacron sewing ring in a mechanical heart valve.
OBJECTIVE
The aim of the study was to evaluate the effect of binding hydrophilic polyethylene oxide (PEO) onto Dacron fibers in the sewing ring of a mechanical heart valve (MHV), in terms of thrombogenicity of the prosthesis.


METHODS
The study was performed in blinded fashion. Six Yorkshire-cross pigs (bodyweight 35-45 kg) were implanted with MHVs, in the mitral annulus, with the PEO-treated sewing ring. An additional five pigs implanted with identical MHVs, but with untreated sewing rings, served as controls. PEO of chain-length 10,000 Da was grafted to Dacron fibers using gamma irradiation. PEO-bonded Dacron fibers (diameter 100 microns) were used to weave the sewing ring, which was then assembled on a titanium stent (OD 25 mm). Autologous platelets were labeled with 111In-tropolone and injected intravenously (850-1250 microCi per injection) into the pigs on removal from cardiopulmonary bypass (CPB). At 20-24 h after surgery, platelet thrombi adherent to MHV components, and shed emboli trapped in the brain, lung, heart, kidneys and other organs/connective tissues were imaged using a gamma camera. The animals were killed and the amounts of thrombi adherent to MHV components and organ-trapped emboli quantified using an ionization chamber and gamma counter.


RESULTS
There was no statistically significant difference in the adhesion of 111In-labeled platelets to either control sewing rings (0.08 +/- 0.06% dose) or PEO-treated rings (0.19 +/- 0.21% dose). The thrombogenicity of MHV components in both animal groups was in the ascending order: Dacron ring > Teflon pledgets > polypropylene sutures > titanium housing > pyrolytic carbon. The number of platelet-emboli trapped in the organs was not significantly different between the two groups.


CONCLUSIONS
Simple modifications may not reduce platelet thrombosis or wound-healing of the sewing ring in the acute phase, at which time several complex processes are activating and inactivating platelets and coagulant factors during CPB and implantation of MHVs.
Dewanjee
M K
MK
Department of Veterinary Biosciences, University of Illinois at Champaign-Urbana 61802, USA.
Gross
D R
DR
Zhai
P
P
Lanzo
S
S
Shim
H
H
Park
K
K
Schaeffer
D J
DJ
Twardock
A R
AR
D000818:Animals; D003328:Coronary Thrombosis / Q000517:prevention & control*; D004195:Disease Models, Animal; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D008943:Mitral Valve; D015539:Platelet Activation; D011092:Polyethylene Glycols; D011474:Prosthesis Design; D013552:Swine
D011092:Polyethylene Glycols