Manor Field Blog 17 – Heart Rate

I was uncertain about writing this blog as most is self-evident or, if not, too obvious to say much about.

I will have a go anyway.

The issue of heart rate came to me last night when I discovered that a family member was 45. That is, 45 beats per minutes.

He was well and nothing to worry about, but, my point was really, it is quite difficult to determine another person’s heart rate by looking at them (this is the obvious part) – you need to check their pulse or look at the heart rate monitor or something similar.

What is the big deal?

Well, heart rate is quite central to being alive.

Or more simply, if you have no heart beat you are not alive.

Again, obvious.

I thought I would write about this in a little more detail, from a doctor – patient perspective.

There is no ‘normal heart rate’ – for, the rate of your heart beating is dependent upon several different factors, whether you are asleep, climbing a mountain, whether you are young or old, hot or cold.

It is mostly easy to work out based on what you or your body is doing.

Here are some definitions based upon an average adult – (whatever that is, I guess, traditionally someone between the ages of 18 and 65) (and, readers of this blog know what I think of such definitions…)

Normal heart rate, at rest is considered anything from 60 to 90.

Slower than 60 is sometimes too slow, and faster that 90, at rest (i.e. watching Country File) is considered too fast.

Below 50 is mostly considered abnormally slow and has a special medical name – bradycardia – from the Greek meaning, yes, slow heart.

Below 50 is considered OK if you are super-fit, outside this, something is possibly amiss.

Above 100 is considered fast and, yes, tachycardia – fast heart.

Here is a basic definition:

Less than 50 too slow

60 to 90 OK

More than 100 too fast

I know that someone is asking, ‘What if it is 99 or 51?’ well, I guess, you have to work out the context. Not everything is clear cut. (Officially <60 is bradycardia, 61 to 99 normal and >100 tachycardia; to me that feels a little too neat for something as dynamic as the heart).

Heart rate is also proportionate to body size and age; hence a baby – generally considered a small person has an average resting heart rate of 70 to 180; Gerbils on the other hand have heart rates that range between 250 and 500, elephants 20 to 40.

Yes, size matters.

There is big and small science behind this.

The small, is what I will explain, the big, is what someone who really knows about hearts could tell you, they are called cardiac physiologists.

Our hearts are pumps and they are responsible for sending blood round the body, with each beat, blood containing oxygen extracted by the lungs is squeezed-out and sent to the brain, the muscles, other organs.

If you pump a pump fast it tends to pump more, there is a certain point where you are pumping at a rate that is ideal – whereby, there is enough time for the heart to fill with enough blood to optimise what is pumped-out; too fast and potentially the heart hasn’t had enough time to fill and what is pumped out is less than ideal.

Generally, this works well, and people get by OK.

If the pump is broken or too weak, too slow or too fast, a condition called heart failure can develop and that, is for another blog.

Apple however (and other companies) made this a reality recently when they turned their watch into not just a heart rate monitor (HRM) which has been around for years, but an actual device able to measure heart rate and rhythm.

This was influenced by a desire to determine whether people have a condition called atrial fibrillation. This is when one part of the heart – the atria, beat very fast and without any regular rhythm, this leads the ventricles, the big, pumping muscle part of the heart to work inefficiently.

Most people are well when they have Atrial Fibrillation (capitals?) although it can cause problems when you exercise or are unwell, the main concern relates to the associated risk of stroke.

If you have Atrial Fibrillation your risk of stroke increases (for a variety of reasons) (Stroke will be a separate blog).

If you have Atrial Fibrillation, you can calculate your risk of stroke here.

The most common form of stroke happens when a blood vessel taking oxygen to the brain is blocked by a clot, risking the death of brain cells and all that goes with it – disability and so on.

Atrial Fibrillation (AF) increases the risk of clot formation and not everyone with the condition is aware, hence the idea to put it into the watch for people to self-monitor.

You could learn how to take your own pulse which costs a lot less, that isn’t however very 21^st Century.

For those people with AF, treatment with anticoagulants can dramatically reduce the risk of developing a stroke and is the most common reason for people taking blood thinners such as Warfarin, Apixaban and Rivaroxaban (there are many others).

I suppose the corollary of this blog is, like blood pressure, know your numbers (and rate).

I will include a little picture of how you can check your pulse. Please don’t rush out and but an Apple watch, although if you have the cash, go ahead, it is great fun.

Too slow, too fast or irregular – ask your doctor, nurse or pharmacist.

Just right and feeling poorly could still be a problem, so equally valid to ask.

Be well folks.