Get another dog! Lol Seriously that was the only thing for us that worked. We have a Weimaraner who had severe separation anxiety, she would thrash in her crate, drool so bad she would dehydrate and she broke teeth chewing on the door to be let out. If we left her out she would chew the house up, anything we left out, furniture, bedding etc. Got so bad we couldn't leave her even for 10 minutes! Our vet suggested trying a new pup. We knew it might not work, but it did! We are so lucky. She treats the new dog like her baby. Now we can leave her for several hours free in the house and she is fine. Obviously this doesn't work for everyone maybe you could try a behavior specialist or ask your vet.
True separation anxiety is a medical issue. Your vet can prescribe anti anxiety drugs. But, true separation anxiety usually involves what Greyghosts describes: thrashing, drooling, broken teeth, bloody paws from scratching, stuff like that.
Chewing up the blinds sounds like a bored dog that might be a bit anxious, but, without more information, I'd doubt it's true separation anxiety. How much exercise is the dog getting? Do you leave anything for the dog to do? Toys, a frozen, stuffed kong, stuff like that?