preexisting condition

My Father had heart surgery 4 years back. After that he is doing fine. I read in all the postings that heart problems are not covered thru insurance and is considered as prexisting condition. My Father is coming here after 2 weeks. Which insurance can i buy to cover his heart problems? Heart problems is such which can occur anytime and if that is not covered thru the insurance then it's a big problem. Please advice.

No VISITOR Insurance will cover Pre-existing conditions (as far as I Know )