sued, (good name!

)
I too, have always thought that all the attachments of culled arteries and veins into the cardiac circulation were made with tiny stitches. I have never heard of clamps being used instead.
I have a thought though. Since MANY clamps are used during the procedure on the vessels that are harvested in the arms, legs, and chest, THESE must, of course, be clamped shut at both ends of the cut after removing a section for the graft. Is it posssible that it's one of the harvested vessel remnants sprang it's clamp and that's what they are referring to as the source of the major bleed?