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ways these may be related to dive fatalities and what divers can
do to mitigate their personal risks.
Sudden cardiac death
Sudden cardiac death (SCD) describes the unexpected
natural death from a cardiac cause within a short time period
(generally within one hour of symptom onset) in a person
without any prior condition that would appear fatal. Such a
rapid death is often attributed to a cardiac arrhythmia, but
because 40 percent of sudden deaths may be unwitnessed it
is impossible to tell with certainty.
SCD may be preceded by nonspecific symptoms such as
chest pain (indicating ischemia), palpitations (arrhythmias)
or difficulty breathing (indicating congestive heart failure).
In cases of ischemia or congestive heart failure, the heart
muscle fails, and in cases of arrhythmia the synchronization
and timing of heart contractions fail. Both result in an
inability to maintain circulation, loss of consciousness and,
several minutes after circulation stops, death.
SCD occurs annually in 1 out of 1,000 adults in the U.S.,
accounting for more than 300,000 deaths each year. The risk
of SCD in adults increases up to sixfold with age and parallels
the risk of ischemic heart disease. Risk is greater in people
with structural heart diseases, but in 50 percent of SCD
cases individuals were not previously aware of heart disease,
and in 20 percent no structural cardiovascular changes
could be found during autopsy. Divers with symptoms of
cardiovascular disease should be evaluated by a cardiologist
and a physician trained in dive medicine regarding their
further participation. In people without symptoms, the risk
of SCD may be evaluated using known cardiovascular risk
factors like smoking, high blood pressure, high cholesterol,
diabetes, lack of exercise and being overweight. For example,
people who smoke have a risk of SCD two and a half times
that of nonsmokers.
effectS of “healthy” aging on the
cardiovaScular SyStem
We all know a team of young adults will usually outrun and
outplay another team made up of middle-aged adults. Those
in their 30s and older have already experienced a decline
in their personal ability to sustain a high level of exercise
I MA G E S T H I S P A G E : I S T OC K P HO T O . COM