ECG?

Hello - thanks in advance for your time.
I am 30, female, fit and generally very healthy although been under a fair bit of personal stress in the last month or so.
I guess I have been lacking in sleep and proper meals in the last month too.
Have been feeling a bit off colour for a few weeks now and have also been aware of some missed heartbeats followed by some irregularity which is a little disconcerting to say the least as I am about to start some high intensity physical training. I guess I am now over focussed on checking my heart beat and am very aware of anything. They happen when I stand up, get out of the car or when playing golf.
The doctor has done blood tests for liver function, kidney function, potassium, sodium, calcium (?), haemoglobin and magnesium. She has also done an ECG.
All looks fine and she has suggested I see what happens although she will offer a halter monitor.
What does the ECG rule out? My understanding is very little so are there any other tests I should request?
I am also aware of being really tense in my shoulders and I dont know if this manifests itself in holding my breath - what effect would this have on heart rates?
Thank you so much.

[Michael J. McWilliams, M.D.]

Over 99.9% of young people like yourself with these symptoms either have extra beats or just feel their heart beat and their is no danger to your health.   In general, many internists can safely play the odds and if you have a benign history and physical exam, normal labs and normal EKG, they do no further testing.  If you end up seeing a cardiologist, you are likely to get an echocardiogram, heart monitor and maybe a stress test.  If all these tests are normal, you prognosis is excellent despite the extra beats.  From a cost containment and safety perspective,  no further tests are usually done.  If you people are still anxious after reassurance, they sometimes get the echo, stress test and monitor.

EKGs are an ok screening and if it is abnormal, more tests are likely needed.  It rarely lends a specific diagnosis unless there is a clear abnormality.  This is rare in cases like yours.

Holding your breath with general slow down you heart beat at first and then it increases after time has based.

I hope this helps.