clothes pegs/pins

[le forgeron]

You should worry about oxygen-deprivation of the tissue.
A long (thirty minute) block could lead to blood 'solidification' (missing the right term) and when you remove the pins, this little solid blob just jumps in the blood streams... if you're unlucky enough, it ends up in your heart coronary, or some part of the brains, blocking the circulation, resulting in an heart/brain attacks.
Death is the easy way out, but a partial disability (what about being unable to move that right leg again, for your remaining lifetime, or being unable to speak ?) is also a possible issue (and no, there is no safe-word for that scene!).
Asside from that, there is also the risk of some cangren at the pins place after such a long stop of oxygenation.
Rotting, litteraly, from your nipple is not something you might want either.

Also, lastly, if the quantity of blocked blood is of some importance (let's say you block an arm or a leg), when releasing the flow, the toxins build up in it while blocked might submerge your kidneys at once, leading to some additional troubles.