Description of Condition:
Myocardial infarction (MI),
or heart attack, occurs when damage to the heart muscle cells
results from interrupted blood flow to the tissue. Risk factors
for heart attack are the same as those for coronary arterial disease.
Most commonly, a myocardial infarction is the direct consequence of
coronary atherosclerosis, or hardening of the arteries. The blocked
arteries stop blood flow to the heart tissue and deprive the cells
of necessary oxygen. Small areas of heart muscle may sustain damage,
resulting in a scar; this may even occur without the individual
experiencing significant symptoms. If larger areas of the heart
are deprived of oxygen or if the cells that conduct the primary
electrical impulses are within an area where blood flow is decreased,
the heart may beat irregularly or even stop beating altogether.
It is not unusual for sudden cardiac death to be the first symptom of
coronary artery disease.
Fitness and Diving Issue:
Cardiovascular events cause 20 to 30
percent of all deaths that occur while scuba diving. For many people,
the real problem is that the first sign of coronary artery disease is
a heart attack. The only realistic approach is to recommend appropriate
measures to prevent the development of coronary atherosclerosis and to
encourage regular medical evaluations for those individuals at risk.
Prudent diet and regular exercise should be habitual for divers.
Older individuals and divers who have a family history of
myocardial infarctions, especially at an early age, should receive
appropriate evaluations to detect early signs of coronary artery disease.
Individuals who have experienced previous heart attacks are at risk
for additional cardiac events in the future, and damaged heart
tissue may have compromised cardiac function. The damaged left
ventricle may not be able to pump blood as efficiently as it
could prior to the MI.
Regardless of whether an individual has had a revascularization p
rocedure (see "Coronary Artery Bypass Grafting"), strict criteria
must be met prior to an individual's safe return to diving.
After a period of healing A six to 12 months is recommended.
An individual should undergo a thorough cardiovascular
evaluation, which includes an exercise stress test.
The individual should perform at a level of 13 mets
(stage 4 on Bruce protocol). This is a fairly brisk level
of exercise, equating to progressively running faster until
the patient reaches a pace that is slightly faster than running
an 8-minute mile (for a very brief period of time).
Performance at that level without symptoms or ECG changes indicates
normal exercise tolerance.
(James Caruso MD, Alert Diver, Jul-Aug 1999.)
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Cardiovascular Topics
- Hypertension
- Coronary Artery Disease
- Myocardial Infarction (Heart Attack)
- Coronary Artery Bypass Graft
- Mitral Valve Prolapse
- Cardiac Dysrythmias
- Cardiac Mumurs
- Atrial & Ventrical Septal Defects
- Raynaud's Syndrome
- Patent Foramen Ovale (PFO)
- Heart Valve Replacement
- Pacemakers and Diving (.pdf)