You don’t say what sort of heart/ circulation problems you are being tested for, but just to say I have had high BP, and high HR for 4 1/2 years after originally getting Covid. Had ecgs, 24-hour BP monitor, echocardiogram and cardiologists declaring no problem; similarly respiratory consultants cannot detect anything wrong with chest x-rays and respiratory tests. Yet even with 5 different hypertensive drugs my BP is high, I get breathless doing a small domestic job from brushing my teeth to ( most noticeably) standing cooking at a stove. I actually started to faint completely ( followed by vomiting…not nice when out in town!). I DIY a NASA lean test and diagnosed PoTS, but local hospital not so sure. Saw a specialist Falls consultant with tilt test table and she diagnosed ‘postural hypotension, definitely not PoTS’, as BP plummeted to 61/40 after 8 mins.standing and HR driven upwards to compensate , to get oxygen to brain. She removed and altered timing of hypertensives but released me back to my GP, who seems to be unable to understand diagnosis, and has put me back on one of the hypertensive drugs. He meanwhile is insisting my existing hypothyroidism, or rather the hormone replacement treatment, is causing the high HR! Anyway cardiologists where I live completely uninterested in circulation/ heart etc problems…hope you get better results/ treatment.