a heart attack? The heart is a muscular
organ that pumps blood to the body at an average
of 72 times per minute. The coronary arteries are
responsible for supplying oxygen and nutrients to
the heart muscle. A temporary decrease in blood
supply can cause the muscle to "starve"
for oxygen and result in chest discomfort or angina.
A prolonged total loss of supply can cause irreversible
damage of the heart muscle and produces a heart
attack. To understand this, let us imagine that
the heart is represented by a garden kept lush and
green by water sprinkler system. The lawn is divided
into three areas, each receiving water from a separate
pipe or coronary artery, as shown on the left (below):
Now imagine that
one of these pipes is partially blocked by debris
and rust. During a hot summer season, the rusty
pipe is unable to keep up with the water needs of
the garden. The area supplied by the partially blocked
pipe begins to dry and turns brown, but is still
alive, as shown on the right (above).. If the garden
had symptoms, it would feel pain as it starves for
water and nutrients.
If water flow is
now restored or increased, the garden once again
turns green and the pain goes away. This is equivalent
to angina. The big difference being that angina
usually lasts only a few minutes, while the garden's
"symptoms" occurs over a matter of weeks
Now let us imagine
that the pipe becomes abruptly and totally blocked
(above). Water supply to a section of the garden
is completely and permanently interrupted. The grass
turns brown and then dies. Once this happens, subsequent
restoration of water supply will never return that
section of the lawn to its original live, lush and
green status. The plant life in one section of the
garden has suffered the equivalent of a heart attack
and turned into "scar tissue."
The human heart, like the garden
example, can experience prolonged "starvation"
or angina before the affected muscle dies and turns
into scar tissue. Scar tissue looses a muscle's
power to pump. Thus, that portion of the pump becomes
stiff, moves sluggishly and decreases the ability
of the left ventricle (major pumping chamber of
the heart) to efficiently pump blood to the body.
The symptoms of chest pain preceding a heart attack
can last from several minutes to a few hours.
The pictures below
demonstrate the different phases of atherosclerosis
or blockage within a coronary artery. You may click
on the left and middle button to stop and then play
the slide show. The slides will "loop"
continually. You may click on the "Rewind"
button to restart the slide show from the beginning.
of heart attacks occur when a blockage plaque "ruptures"
or develops a crack on the inner aspect of the blood
vessel. Clot develops at this site and then grows
to completely block the channel of the artery. This
cuts off blood supply to the heart muscle supplied
by that artery and results in a heart attack.