Congrats.
If you are thinking cardio or ortho you must have good grades in medical school. I don't know what year you are, but if 2nd or 1st, then try and get to know at least one cardiology and one orthopedics attending this year. Just know them enough so they will remember you when you become a 3rd year.
For both residency and fellowship match, unfortunately it's "who you know" as much as "what you know" and how hard you work. It's just the way of the world. People don't see it as "corruption" it's just kind of the old boys' network. I don't really like it personally, but it just is how the world is. Now that I'm over 30, I just realize this (* sigh *).
Here is what I would do. I'm assuming you have good grades and your Step scores are OK (like USMLE step 1 average or better). 230+ is good but contrary to popular belief not mandatory and it won't necessarily get you in. Good grades = more important, although there is LOTS of subjectivity in 3rd and 4th year grading. If you want to do ortho, you've GOT to find 2 ortho surgeons who LOVE you and want to write you good letters of recommendation. If they don't love you yet, MAKE them love you. No amount of kissing up is too much. If you want to do cardiology, then start scoping out one of the "ABIM research pathway" schools for internal medicine residency. If you match into one of these, then you only have to do 2 years of medicine residency, then straight into fellowship (though doing 4 rather than 3 years of cardiology fellowship). This is good because (A) you get a GUARANTEED cardiology spot with no need to spend thousands of dollars and lots of money on cardiology interviews with no guarantee of a fellowship, and
(B) you get to skip your 3rd year of IM residency. IM residency can be fun, but honestly by the time I got to my 3rd year I had learned what general med I would need to be a cardiologist, and also the once/week resident clinic is a huge pain and I would have been oh so happy to avoid it. Also, no reason to take a 3rd year of call as a resident (read: scut monkey) when you could be learning stuff and doing call as a cardiology fellow.
Just my 2 cents, but it is definitely worth your consideration.