Oh no.... poor Giz.....
Please start his treatment asap, even if they tell you to wait! This is the disease that my Sydney had:"FELINE HYPERTROPHIC CARDIOMYOPATHY" They told me to wait with medication and come back 6 months later. But he died 4 months later.... .
Sorry, I didn't want to scare you, but it is necessary to act, so I wanted to tell you about my Sydney! Feel free to read his story on my web-site!

I did some googling for you:

http://members.aol.com/jchinitz/hcm/definitn.htm

http://dsl.org/hcm/

http://www.acay.com.au/~j-kivits/feline.html

http://en.wikipedia.org/wiki/Hypertr...cardiomyopathy