A Question About Priapism

I'm a sexually healthy adult male with fairly regular
erections, but was starting to encounter some
slowing down as I approach 40 compounded possibly by a
familial high cholesterol, which I was recently diagnosed for
and which I am currently under supervision.
    So I went to a clinic to find out if I might be a
candidate for Viagra. They first tested me with
ultra sound and noted lower blood flow in one of the arteries.
Then they tried a penile injection to see if I'd be a candidate for Viagra. It gave me and erection that did not subside for
a little over 5 hours (after which it was no longer solid hard but still remained larger that usual for maybe another 2 hours).
    Starting two days later (it is now 6 days later) I am no longer getting erections (maybe only very very weak ones in the morning upon waking).
My question therefore is: Can you become temporarily or permanently impotent from one 5 hour occurrence of Priapism?
If it's only temporary how long can it take before normal erections resume?

I've since learned that from Priapism there can be damage in the form of ruptured blood vessels, which can heal, and dead nerves, which don't. Are either or both possible from my described occurrence?

Thanks for any information

[hfhs M.D.-AK]

Dear Scott,
A prolonged, painful erection is the most troublesome of the complications of intercavernous drugs.  This complication was very soon discovered with papaverine and has been less common with PGE1.  Neverthless, it can occur (not, it is to be hoped, on the first visit), and it is extremely off-putting for the patient. Care taken to select the initial dose should preclude this; if the patient has good early morning erections he should be given a small dose.  It sounds like you did have a prolonged erection but I don