Dear Francesca. I don't know if there are ISO standards for cardiac patches, but if not, I suggest you try/adapt the Method to determine suture retention strength of vascular grafts in: American National Standard by the AAMI (American Assoc. for Advancement of Medical Instrumentation) on Cardiovascular Implants - Vascular prostheses. I have a hard copy of the 1994 edition which prescribes putting a suture (size you would use on the patch) loop 2mm from the edge and extending on a tensile tester at 150±50mm/min and recording the average force (expressed in grams) for the suture to break through the sample (the suture should of course be strong enough not to break before the pullout).  Tests is performed orthogonal to and at 45 degrees to the cut edge. There seems to be a later edition (2003) available online, of which I only have a sample copy (attached). Regards. Deon

Thank you so much Deon!!!