Dear F. Ampofo,
The medical suffix -ectasis refers to "expansion" or "dilation" of:
the abnormal expansion or dilation of the structure or organ in the body.
Depending on the specific medical diagnosis, in reference to "cardiovascular", may be related to the expansion of the heart or dilation of structure(s) (arteries, veins) related to the heart (cardiovascular system).
I wish you the very best!