Are you using vaping to quit smoking? If so, vaping is probably not the worst thing you can do. You could stick to milder devices and low nic juices to avoid overdoing it with the nicotine. From there, you can start weaning yourself down by diluting your low-nic with no-nic. Not a bad way to cut out that risk factor if you ask me! And from there, you can probably continue vaping the no-nic for psychological satisfaction or just stop completely.
I agree that you should discuss it with your doctor. A cardiologist might not be necessary, here. Your GP or Physician can probably answer the questions you have. Just make sure that you have as much information as you can gather going in. In my experience, if you ask a doctor a general question, they tend to give you a general, dumbed down answer that doesn't really say much of the actual risk. Ask informed questions and you get more concrete and relevant answers.
But as an ignorant-ass layman, I don't see how it doesn't stand to reason that any step away from heavy nicotine intake is the direction you should be moving in, yanno? And the thing is, nicotine isn't the only pharmacologically active substance in tobacco products. It's a cocktail of stuff that boosts and adds to nicotine's effects.
Nicotine by itself is a mild stimulant. It's everything else in the cigarette that elevates it to the level of being one of the most addictive known substances. Other alkaloids present that compete for the same spaces in your liver/brain upscale the pharmacological profile of nicotine... ...toxic solvents that convert nicotine to a more potent, freebase form (essentially the crack equivalent to nicotine) and thus increase its absorption... ...MAOI's which, in addition to being active themselves, also directly inhibit your liver's capacity to move all of this stuff out of your bloodstream, thus leading to an accumulation of higher blood concentrations and longer duration of effects.
It's this mess of interactions (which I've grossly oversimplified,) along with all of the toxins in the smoke that are to blame for the massive cardiovascular strain. It's not that we believe that cutting these things out greatly reduces the harm that comes with nicotine consumption. It is simply a well-known and studied fact.
For most of us, nicotine on its own presents very little risk. It's on the order of a cup of coffee a day or less. For you, this may not be the case.
Again, ask your doc. Make sure you specify that it's nicotine on it's own, not from tobacco. Very different connotation there.
This is all assuming you are currently addicted to tobacco. If not, it doesn't take a doctor to tell you that taking up vaping wouldn't be the best idea. I think no-nic would be fine, as there really isn't much going on with your cardiovascular system that way, but obviously you would want to avoid nicotine. Vaping, as an ROA for nicotine, is markedly less effective than most tobacco products, but it still gets the nicotine in your system. Less of a risk, if you're mindful of how you go about it, but still not nonexistent.