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SAN DIEGO -- How transcatheter heart valves (THVs) are washed before use in transcatheter aortic valve replacement may be important in whether these devices develop leaflet thrombosis down the line, a researcher said here.

In a lab experiment, Neovasc valves (bovine pericardial tissue stored in 0.5% glutaraldehyde solution) were washed in 0.9% saline for 2 minutes -- repeated three times -- or just blotted briefly before placement in fibrinogen solution and incubation for 2 hours. In both cases, the samples then underwent a saline wash and were cut up for analysis.

Against the researchers’ expectations, the lightly blotted tissue had markedly lower fibrinogen binding, reported Mark Hensey, MBBCh, previously of St. Paul's Hospital in Vancouver, B.C., and now at St. Vincent's University Hospital in Dublin, Ireland, during a moderated poster session at the annual meeting here.

The hypothesis had been that the aldehyde solutions, used to process and store transcatheter heart valves, promote protein cross-linking that can contribute to leaflet thrombosis. Hensey and colleagues were surprised that this was not the case, at least under the study's conditions.

"We certainly can't say at this point that the valves should be washed any differently but we are continuing to look at the effect that we saw in our bench study. It remains a work in progress," Hensey told 番茄社区app. His group is now assessing the effects of glutaraldehyde on valve leaflet thrombosis with thrombin and activated platelets.

"Each manufacturer has different directions in the instructions for use as to how long each valve needs to be washed for and in how many bowls, the most stringent being Medtronic, who suggest washing the valve for 2 minutes in normal saline and then repeating this twice in two further bowls," according to the researcher.

Reached for comment, a spokesperson for Edwards Lifesciences -- maker of the Sapien line of THVs -- noted that Edwards has a proprietary tissue treatment process (Thermafix) in addition to a longer rinse protocol detailed in the instructions.

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