Sudden Death & Exercise InformationDocument Transcript
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SUDDEN DEATH AND
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3. Causes of Sudden Death
4. Who is at risk? / Treatment
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Sudden death or sudden cardiac death (SCD) is when the heart stops
without warning. Most cases are related to an undetected heart disease,
which can be inherited or acquired in both young people and old. Athletes
and non athletes are at risk, it can occur in an apparently healthy person.
One in 500 people have a gene that can lead to a condition called
Hypertrophic Cardiomyopathy which if undiagnosed can cause SCD.
100 or more people under the age of 35 die each year from Sudden
Cardiac Death in Ireland.
Lack of physical activity is now considered to be the fourth major risk
factor for coronary heart disease. Yet, on occasion, trained and apparently
healthy athletes die suddenly during exercise. A graphic example of this
tragedy is that of a 57 year-old American who collapsed and died within
one minute after setting a regional master's record for the 3000-m run
indoors. The athlete had not previously reported cardiac symptoms and a
maximal exercise test performed 22 months before his death did not
reveal any cardiac abnormalities.
The first component of this issue that needs attention is whether these
deaths during exercise actually prove that exercise is the real culprit and
therefore a dangerous activity; or, stated differently, whether exercise and
sudden death are causally related. The overriding conclusion from a large
number of studies of sudden death, including sudden deaths that occur
during exercise, has shown that virtually all persons who die suddenly
during exercise have a serious disease, usually of the heart, that
adequately explains the cause of death.
HISTORY OF SUDDEN DEATH
The first modern sport to attract a concern was rowing. In 1845, the
seventh Oxford and Cambridge Boat Race was the first to be rowed on
the current course on the Thames between Putney and Mortlake. No
sooner had it moved to its longer course through the British capital than
an irate letter written by one Frederick C. Skey, past president and fellow
of the Royal College of Surgeons, appeared in the Times, charging that
"the University Boat Race as at present established is a national folly."
Skey claimed that rowing was bringing young men to an early grave.
Almost a century later a letter that appeared in the Journal of the
American Medical Association stating that all members of the 1948
Harvard rowing crew had since died "of various cardiac disease". The
assertion was enthusiastically denied by these oarsmen, who reported that
they were all alive and well.
Cycling was the next sport to attract attention. In the 1890s North
Americans suddenly discovered the bicycle, and medicine had another
sport about which to express its alarm. Cyclists were warned that a long
time spent cycling could cause "kyphosis bicyclistarum" or in lay terms
"cyclist's stoop". Then, as expected, there was "cyclist's heart". The heart
was limited to only a certain number of heart beats, these physicians
asserted, and the faster heart rate during cycling would only waste these
beats and lead to premature heart failure.
In 1909 five eminent British physicians who started a correspondence in
the Times by stating that "school and cross-country races exceeding one
mile in distance were wholly unsuitable for boys under the age of
nineteen, as the continued strain involved is apt to cause permanent injury
to the heart and other organs." From an analysis of 16,000 schoolboys
covering a period of twenty years, Lempriere could find only two cases of
sudden death during exercise that was not due to accidents. He concluded
that "heart strain through exercise is practically unknown", a conclusion
echoed by Sir Adolphe Abraham, who denounced the concept of the
strained athletic heart.
Running became a medical cause célébre in the 1970's as the popularity
of the sport bloomed. One of the first articles to question the safety of
such activity reported that half of 59 sudden deaths occurred during or
immediately after severe or moderate physical activity, especially
jogging. The authors questioned "whether it is worth risking an
instantaneous coronary death by indulging in an activity, the possible
benefit of which.....has yet to be proved." They also considered "the
possible lethal peril of violent exercise to [heart-disease] patients."
More fuel was added to this controversy in the early 1980's by the sudden
death while running of James Fixx, the celebrated American runner and
author. Fixx had achieved international celebrity status as author of the
book that became an international best-seller because it best captured the
mood of the running explosion that occurred in the late 1970s.
Paradoxically, in a later book Fixx had written an appropriate epitaph
both to himself and to the concept that runners could earn immunity from
both heart disease and death: "...runners are much like ordinary mortals.
They can, sad to say, get sick. They can even die."
CAUSES OF SUDDEN DEATH
Also called Sudden Cardiac Death (SCD), can be caused by a number of
different heart problems, many of which are inherited. Some of these
Hypertrophic Cardiomyopathy (HCM)
HCM which in simple terms is called a chunky heart muscle heart
disorder. This is the most common cause of Sudden Death in young
people. It is a relatively uncommon heart disease, but it is estimated that
ten thousand people in the UK have the condition.
The heart muscle may thicken in people who have high blood pressure or
who have prolonged athletic training, but in HCM patients the muscle
thickens without an obvious cause.
HCM is caused by abnormalities in genes which make the protein
responsible for contraction of the heart. It is a hereditary disease, in the
majority of cases the condition is inherited from a defective gene of one
of the parents. HCM can affect both men and women, but is most slightly
more common in the black population (African / Afro-Caribbean origin).
HCM is present from conception and excessive growth of the muscle can
begin before birth when the foetal heart is developing. The over growth
interferes with the hearts normal contracting and relaxing, which results
in reduced blood being ejected out from the heart.
Coronary heart disease (CHD)
CHD is caused by narrowing of the blood vessels in the heart which
restricts blood flow. CHD affects both young and old people.
Heart rhythm abnormalities (arrhythmia)
Arrhythmia (abnormal heart beat) such as Long QT Syndrome and
Brugada Syndrome may cause SCD.
Long QT syndrome: An inherited disorder from a family gene which
causes the heart to beat too quickly, too slowly or in an irregular way that
predispose to fainting, dizziness and palpitations.
Brugada Syndrome: also an inherited disorder related to the membranes
of the heart muscle cells. It can result in life threatening heart rhythms.
Disease of the hearts electrical system
The heart has electrical pathways into its chambers.
Wolff Parkinson White Syndrome: the heart has one or more extra
electrical pathways which cause’s a cross over of pathways to the hearts
chambers that can cause abnormal heart rhythms.
It is a result of extra pathways between the atrium (upper chambers of the
heart) and the ventricles (lower chambers of the heart) it is present in
approximately 1.5 people per 1000 people.
This picture shows the normal electrical pathways of the heart.
Anabolic steroid use,
Myocarditis: An inflammation of the heart muscle, most often caused by
a viral infection. However it may also be caused by a bacterial infection,
rheumatic fever or an adverse reaction to some types of drugs.
But the more important point is that none of these
conditions is caused by exercise, however vigorous. Rather,
the evidence is clear that regular exercise acts against the
development especially of coronary atherosclerosis. There is
also no evidence that exercise accelerates the progression of
these other potentially-lethal cardiac conditions. (Timothy
D Noakes MBChB MD )
Who is at risk? & Treatment
A person who has a family history of unexplained death
(including cot death) in people under 35 years old.
Someone who finds themselves breathless on effort.
If a person has chest pain on effort.
A person with unknown causes of dizziness, fainting and
People with a fast heart rate that comes and goes even when
Palpitations due to an irregular heart rhythm (arrhythmia).
If you have any of these symptoms you should speak to your doctor (GP).
Investigations for possible heart problems include:
Medical examination including questions from your doctor about
your family’s medical history for Sudden Cardiac Death.
An Echocardiogram also called an Echo which is an ultrasound
scan (same as a scan for pregnant women to see there baby’s) to
view moving images of the heart muscle and valves.
An electrocardiogram also called an ECG, this test measures the
rhythm and the electrical activity of your heart. Small sticky pads
are placed on the body connected to wires that are linked up to the
ECG machine. The machine reads and records, on paper, the
electrical signals from the heart.
Other test may be needed.
When a person’s heart stops, can anything help?
Yes. The chain of survival has 4 links that need to be made quickly to
give the best chance of survival.
Get help, dial 112 (the new emergency phone number that replaces
Perform (cardio pulmonary resuscitation) CPR, which helps pump
blood to the brain and other body organs
Defibrillation with an automated external defibrillator (AED)
delivers an electric shock to the heart. This is the only action that
can restore a normal heart beat rhythm
Advance care by a medical team
Timothy D Noakes MBChB MD
Physiology, University of Cape Town Medical School, Observatory
7925, South Africa.
IRISH HEART FOUNDATION
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