The intersection between prostitution and cardiology skills is fairly low; you may or may not be paying your way through med school but you would have to have done it first to get the skills. Furthermore if you are indeed Australian then the cost of education being more in line the reasonable standards of not America means one is less likely to be driven into such a potentially high risk-high reward scenario (while not entirely deleterious to your career the ethics board would look unfavourably upon a conviction here). I cant' rule out there being a former trained person, self taught or active one supporting some kind of need but the numbers are likely to be low.
Similarly if you are a fat bastard and think sex is a workout (not to mention if you are at the point of a broken heart then a high cardio workout may be one of the last things you need/do) then sad to say that your fat bastard status coupled probably decreasing the already low duration of such a thing as a population average means not much, and that is before the general economics of the thing kicks in.
Depending upon the nature of contact as well then syphilis is fairly widely documented to have cardiac involvement in a lot of cases.
If we are to take the more psychological definition of your words then while many a prostitute could well be in possession of psychological skills (the fabled talk job) that would be at best a financial relationship (which is also a rather more specialised service of such fields, one possibly having to look up the term pay pig). Whether there is much validity to the phrase "the best way to get over someone is to get under someone else" remains to be seen and pining for an ex, and said ex coming back on the scene is the cause of breakdown/failure to launch of many relationships as well.