Pumping Marvellous

A person’s heart rate, also known as their pulse, refers to how many times their heart beats per minute. Our heart rates vary tremendously, depending on the demands we make on our bodies – a person who is sleeping will have a much lower heart rate compared to when he/she is doing exercise.
There is a technical difference between heart rate and pulse, although they both should come up with the same number:

• Heart rate- how many times the heart beats in a unit of time, nearly always per minute. The number of contractions of the lower chambers of the heart (the ventricles).
• Pulse (pulse rate) – as the blood gushes through the artery from a heart beat, it creates a bulge in the artery. The rate at which the artery bulges can be measured by touching it with your fingers, as on the wrist or neck.

So what is your resting Heart Rate

For a human aged 18 or more years, a normal resting heart rate can be anything between 60 and 100 beats per minute. Usually the healthier or fitter you are, the lower your rate. A competitive athlete may have a resting heart rate as low as 40 beats per minute.
Champion cyclist, Lance Armstrong has had a resting heart rate of about 32 beats per minute (bpm). Fellow cyclist Miguel Indurain once had a resting heart rate of 29 bpm.
According to the NHS the following are ideal normal pulse rates at rest, in bpm (beats per minute):

• Newborn baby – 120 to 160
• Baby aged from 1 to 12 months – 80 to 140
• Baby/toddler aged from 1 to 2 years – 80 to 130
• Toddler/young child aged 2 to 6 years – 75 to 120
• Child aged 7 to 12 years – 75 to 110
• Adult aged 18+ years – 60 to 100
• Adult athlete – 40 to 60

Measuring your own Heart Rate

Although their are numerous areas you can measure your Heart Rate these are the two most common -

• The wrist (the radial artery) – place the palm of your hand facing upward. Place two fingers on the thumb side of your wrist gently, you will sense your pulse beating there. Either count them for up to one minute, or thirty seconds and then multiply by two. Counting for 15 seconds and then multiplying by four is less accurate. It is also possible to test the pulse by touching the other side of the wrist, where the ulnar artery is.
• The neck (the carotid artery) – place the index and third fingers on the neck, next to your windpipe. When you feel your pulse, either count for the whole sixty seconds, or do it in a 30 or 15 second spell and multiply by two or four.

What are are Implantable cardioverter defibrillators

People who have a particular sort of abnormal heart rhythm, called pulseless VT (ventricular tachycardia) or VF (ventricular fibrillation), may need to have a device fitted called an ICD. Ventricular tachycardia is when the heart beats too fast, and this means that there is not enough time for the heart to fill with blood properly between beats (contractions), so not enough blood is pumped round the body.

In ventricular fibrillation, the heart rhythm is so abnormal that the heart no longer contracts, but quivers instead. This results in death, unless an electrical shock is given to the heart to restart it.

An ICD works by constantly monitoring the heart rhythm. If ventricular tachycardia is detected, the ICD will try to correct it. If this does not work, the ICD will try to bring the heart back to normal by giving it a small, controlled electrical shock. If this fails, the ICD will deliver a larger shock, which is known as defibrillation.

If the ICD detects ventricular fibrillation, it will defibrillate the heart immediately.

As with pacemakers, ICDs are implanted in hospital, usually under local anaesthetic and complications are rare. Like pacemakers, you will need to avoid things that can interfere with the way in which the ICD works, such as airport security systems.