Fast heartbeat any medical people around?

[WildFlowerBees]

I had an odd experience earlier whereby I suddenly felt my heart beating really fast. No anxiety wasn't doing anything strenuous not stressed. Started to feel a bit dizzy so sat down and took some deep breaths. Took my blood pressure 117/74 but my heart rate was 202.

After an hour it was 101, today it's between 89 and 91 my usual rate is around 55 to 60.

I didn't call 111 as I didn't want to sit in A&E for hours and I had no pains.

Is there any particular reason why this might happen?

There are a number of possible causes, some transient, others more serious.

Tachycardia

See your doctor if it's not back to normal soon or spikes again.

Have you drank enough today or perhaps too much? Electrolyte imbalance can cause tachycardia.

Sounds like SVT. talk to your GP and go to A&E if it recurs. Could be a form of AF. If you attend A&E with a HR of 200 you will be seen immediately unless there's a major trauma or cardiac arrest in the department

It could be SVT, which is a fairly common form of tachycardia where your heart suddenly starts beating at 200bpm or more, because of an electrical short circuit. These can come out of nowhere.
Ideally you want to try to get an ECG trace if it happens again, to show what sort of tachycardia it is. If it is SVT, and if it happens often enough to interfere with your life, it can be fixed by a day patient catheter procedure. However, often the tricky thing is getting to A&E in time to get a trace.
I'd report it to your GP so that it's on your record, and note down now all you can remember about this episode. If you have any others in future, note them too. We were advised that if a heart rate that high has continued for 30 minutes, make your way to hospital as you may need some help resetting it. Letting it run at that rate can tire your heart. There are various DIY techniques which can stop a tachycardia and help your heart return to a normal rhythm, and these are worth looking up in case it happens again. Examples:

• Run a basin of cold water. Hold your breath and put your face in. Keep repeating.
• Valsalva manoeuvre : shut your mouth and bear down hard with your tummy.
• Search YouTube for "modified valsalva SVT" for some other moves.

There are some contraindications to vagal manoeuvres and it’s best to know what the problem is (or what the problem has been in the past) before attempting them. They should not be first line treatment in the context the OP describes. HTH.

Thanks @Greybeardy . That was what the cardiologists advised us to do but it makes sense that some screening would have occurred first. There's no substitute for trying to get a trace.

Here's a useful article : www.healthline.com/health/vagal-maneuvers

If your heart rate ever goes to that number again, you go straight to a and e.

my usual rate is around 55 to 60.
That seems low unless you are actually laid in bed.
However over 200 is A&E territory.
I have SVT and my cardiologist advises A&E if heart rate remains very high for 20 minutes. I take medication and it happens rarely now. When it does a vagal manouvre often sorts it.
However mine has been investigated and diagnosed. I recommend you go to A&E if it goes above 150 and doesn't start coming down again quickly. If it happens again but goes down, see your GP who may arrange various tests.

Do you have any other symptoms? If you are also suffering any of weight loss, trembling hands, disrupted sleep, diarrhoea etc then it could be hyperthyroidism.

You see @WildFlowerBees those fast beats are inefficient and don’t properly pump the blood. And improperly pumped blood can clot and turn into a bigger problem like a heart attack or stroke. Besides rechecking by hand that your heart rate is really that fast do seek medical attention.

Thank you, no other symptoms and I'm absolutely fine now. Heart rate is 90 feeling fine!

My DH had this ( though not that high) when he had Covid. Dr told him he could monitor at home but to go to A&E if it went over 200.