Re:Myth.
Greetings All,
Not into that particular Kink Myself.
But with regards to the "Myth". Consider this.An engored penis that cannot deflate(Priapic) becomes intensly painful, not a lot of men can maintain an erection when they are in intense pain.
Such a device can restrict blood flow in the surface vessels(Superficial External Pudential Vessels) but not the deeper blood vessels (the Internal Pudential vein, drains the external genitalia, through the Deep vein of the penis, of which a tributary is the Deep Dorsal vein,which is a deep vein between the Dorsal arteris and deep in the facia of the penis)[anatomy of the human body.Lockhart.Hamilton. and Fyfe]
I get a bit foggy about the names of the vessels considering I've been retired for 10 years, so I still have to look up My anatomy book from time to time.
The short answer is it could cause a temporary priaptic state but when the pain became severe enough the body would automaticaly drain the blood from the penis through the deep veins. So it is unlikely to cause any Permanant damage.(I have never heard of any-one having permanant damage, in my 26 years as an Ambo or in my dozen years in the BDSM scene)