mos

[lydsing]

37d surgical tube which prevents a vessel closing
?t?n?

[johnnyb.com]

stent

[lydsing]

thanks johnnyb, i would nver have found that

[whitehill]

Strangely, I thought stent was the answer but looked in my dictionary to check - neither my Chambers nor Bloomsbury gives this word; at least Chambers does, but only with a completely different meaning but my more modern Bloomsbury not at all. I though it was a word in fairly common usage nowadays and was bound to be in the dictionaries.