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Circulation – background
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Heart transplants
The first heart transplant operation was performed by the late Dr Christiaan Barnard in South
Africa in 1967. The donated heart was rejected and the recipient died eleven days later.
"On Saturday, I was a surgeon in South Africa,
very little known. On Monday I was world
renowned."
Dr Christiaan Barnard
Information on heart transplants in Ireland can be obtained at http://www.ihlta.com (the website
of the Irish Heart and Lung Transplant Association).
Artificial Pacemakers
The heart's natural pacemaker is a small mass of specialized cells in the top of the heart's right
atrium which makes the electrical impulses that cause a heart to beat. The natural pacemaker
may be defective, causing the heartbeat to be too fast, too slow or irregularly. An artificial
pacemaker is a small, battery-operated device that helps the heart beat in a regular rhythm.
People with artificial pacemakers fitter are advised to be aware that certain items can interfere
with the operation of their pacemaker, e.g. powerful magnets (as in medical devices, heavy
equipment or motors) and therapeutic radiation (used in treating cancer).
Coronary Bypass surgery
Sometimes the arteries that supply
the heart muscles with oxygen get
blocked, and the heart cannot work
efficiently. Coronary bypass surgery
may help to solve the problem and
prevent a heart attack. A blood
vessel from another part of the body
is used to get around or “bypass” the
clogged artery, so blood can flow
through the new vessels to the heart
muscle the way it should.
Pic: www.about.com
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JSSS
Teacher support material
Heart murmurs
Murmurs are caused by valves which malfunction. Listen to many recorded heart murmur
sounds at http://www.med.ucla.edu/wilkes/Physiology.htm
Artificial valves
Faulty heart valves disrupt blood flow and may need to be replaced. There are two types of
artificial valve (i) mechanical valves, made from metal, plastic or carbon, which last for a long
time but as they tend to cause blood to clot the recipient must take anti-clotting medication (ii)
biological valves, from pig tissue or donated human tissue, which lower the clotting risk but do
not last as long.
World’s biggest heart?
A blue whale heart is the size of a Volkswagen Beetle and pumps 10 tons of blood through the
massive blue whale body. A blue whale aorta (the main blood vessel) alone is large enough for a
human to crawl through.
Heart beats
A sleeping bat's heart beats as seldom as one to three times a minute; a flying bat's heart races at
anything up to 1 200 beats per minute.
“Heartburn”
This is the name given to the pain caused when acid from the stomach leaks up into the
oesophagus. It has nothing to do with the heart, but in the past the pain caused was often so
severe that sufferers may have been convinced they were having a heart attack!
Blood donation
In Ireland patients who undergo surgery are not charged for blood transfusions they may receive.
(In the USA it can cost over $400 per pint). The blood comes from voluntary donors over the age
of eighteen. Each donation takes about ten minutes to remove 470 ml blood (less than a pint).
This is treated, typed and stored until needed. Of the four main blood types – A, B, AB and O –
the most common in the Irish population is O (55%), followed by A (31%), B (11%) and AB
(3%). Here are some facts from www.ibts.ie

Over 1,000 people receive transfusions every week in Ireland

Only 3% of our population are donors, providing for a population of almost 4 million

One in four people will need a transfusion at some point in their lives

A car accident victim may require up to 30 units of blood

A coronary artery bypass may use between 1-5 units of blood.
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