Of the examples you gave, I would say that ECG would definitely be ok, and HCA and IBS might be ok, though I would try not to use them.
I agree with Democracy though, you shouldn't be including any of this technical stuff. Remember you will be competing against people who have never worked in a medical environment, so while you should use those experiences if you have them, the goal of the PS is NOT to show off how much medicine you've seen, nor to present histories or explain pathologies. You want to draw on these experiences to show reflection, an understanding of the job, a suitability for it, and an interest in it