This is just a guess but I wonder if it was a spell of syncope?  It
sounds like that and if so then her meds are even more important to
continue.  If it was such a fainting spell, then the vets often can find
out if there may be an inclination in that direction by doing an EKG/ECG.
Meltdown used to have those.  Actually, she had bad ventricular bigemini
and sometimes ventricular trigemini -- to the point where she was
expected to die at any time when her cardiomyopathy was first found.  In
her case Digoxin was the answer since it controlled her type of rhythm
problems wonderfully for a long time and she went on to have about a year
and a half with her cardiomyopathy if memory serves.
 
These may help you and anyone else with a ferret who has cardiomyopathy:
 
past posts on the topics at
http://fhl.sonic-weasel.org (FHL Archives)
the year old compilation at
http://www.smartgroups.com/vault/ferrethealth/cardiomyopathy.txt (in FHL Files)
http://www.miamiferret.org/fhc/cardiomyopathy.htm
http://www.miamiferret.org/fhc/cardio.htm
http://home.att.net/~hhoefer/ferret_heart.htm
http://www.vetheart.com/diseases.html
some of the other vet write-ups you can link to through the critical
refs section at
http://www.ferretcongress.org
 
(BTW, there is another compilation in the files at the FHL on a different
type of serious but more rare heart problem, A/V Node Block.)
 
Yes, ferrets get heartworms, and there are effective things for
prevention which have been in long use.  Again, in the FHL Files at
http://www.smartgroups.com/vault/ferrethealth/ you will find a
compilation on parasites (and past posts in the FHL Archives) which will
help you learn more.
 
BTW, MANY of the very, very best and most useful vet posts from the FHL
are in the FML Archives to reduce the risk of them not being available to
folks, a service Bill Gruber is very kind to provide (among the many he
provides).  The FML Archives are always easy to find because the address
is in the header of every day's FML.  If you ( plural -- ALL FML READERS
WHO HAVE NEVER DONE THIS BEFORE) take a second to just scroll up to the
top you will all find this very useful section:
 
>* Use "SEND FERRET nnnn" to get backissues of this newsletter.
>* Searchable archives:
   <http://listserv.cuny.edu/archives/ferret-search.html>
[Posted in FML issue 4284]