As Arsenal didn't have a single shot (the first time ever in a CL knock out match according to Opta) then whinging about RVP getting sent off as affecting the game is simply rubbish.
Arsenal were beaten the second Fabregas tried a fancy back heel on his own 18yd line that gifted Barcelona the first goal, and the fact is, if the ref was biased why didn't he give a pen in the first half when Messi was tripped by Djouru right on the line (the line is in btw)?
Arsenal are the least well equipped English team to deal with Barcelona; you can't imagine anyone else giving that Barcelona midfield the time and space to weave their magic.