You can use your fingers to feel your pulse like the images below.
From Google image search.
If you count out the beats for 30 seconds, you can double your count to figure out beats per MINUTE.
Look for a heartbeat that is:
- Too fast. In adults, you should be below 100 beats per minute when you are at rest.
- Too slow. In adults, a resting heart rate below 60 beats per minute is sometimes a sign of bradycardia.
- Irregular / not a steady rhythm (e.g. skipped beats)
You can also check to see if your heart rate quickly shoots up when you go from lying down to standing, e.g. when you get out of bed in the morning.
If you experience that, you can do a poor man’s tilt table test at home as described in Youtube videos such as this one:
If you feel faint while standing up, please have somebody watch you in case you pass out.
A tilt table test at a specialist will be more reliable. It will measure both heart rate and blood pressure.
The NASA Lean Test may be a more sensitive test for spotting issues with orthostatic intolerance (development of symptoms when standing upright that are relieved when reclining). The Health Rising ME/CFS website has an analysis of the NASA Lean test along with simple instructions for performing the test in a doctor’s office. While the guide suggests stopping certain medications, please note that discontinuing many anti-depressants (e.g. TCAs, SNRIs) can be very dangerous and sudden withdrawal is often the most dangerous way of stopping those medications. (That part of the guide may be highly questionable and unnecessarily dangerous.)
If you know that you have a problem with your heart, there are devices that you can buy and use at home. This can help you objectively track your symptoms over time.
Pulse oximeter - some of these will measure heartrate. This can be useful/convenient if you have POTS and want to measure the severity of your POTS over time.
Blood pressure monitor - a lot of these will measure heartrate at the same time. They may display an icon if you have an irregular heartbeat.
Smartwatches, fitness devices like FitBit Charge, KardiaMobile, Oura Ring - These can help you monitor your heartrate throughout the day. They can let you do an ECG at home, which can be useful if you have an irregular heartbeat. If you have an irregular heartbeat, the software may think that the data is faulty and will ignore data when your heartrate is really low or high. That feature may not work if you have an irregular heartbeat. (The professional devices like the one for a mobile ECG test should not have that problem. They are designed for sick people rather than fitness enthusiasts.)
Some of the wearables can also measure sleep disturbances, though the monitoring can be a little hit or miss (e.g. it may think you’re sleeping if you’re not moving).
If you spot problems, it can be a great idea to seek out follow-up testing from the mainstream medical system. We do know that some long haulers get myocarditis and pericarditis (e.g. from the vaccines), among other side effects. You cannot diagnose myo/peri at home by yourself.