No
Pre - existing conditions cannot be covered under any medical policy. (May cover in the group policy)
There are two solutions to the pre-existing mediacal condition problem.
1- Shop around for insurance as if you had no pre existing medical conditions. Then after identifying the cheapest, ring them up and ask to speak the underwriter. They will ask many questions and will probably not cover any incident that related back to the pre-existing medical condition. But at least you will get cover for everything else. Mention every detail you know about pre-existing conditions.
2- Get a credit card with travel insurance cover included. These often exclude pre-existing medical conditions but will provide automatic cover for all else.