The human
heart doesn't actually look very much like a valentine, but it is nevertheless
a wondrous and beautiful muscle. About the size of a clenched fist, it
begins to beat only a few weeks after conception and thereafter pumps forth the
rhythm of our lives through every moment of our uterine and earthly existence.
Only at the moment of our death does it
cease.
This beating has a definite purpose: to pump blood to all parts
of the body. The life of our very cells depends on the oxygen and nutrition
brought to them by the flow of our blood. If for some reason any muscle did not receive a
fresh flow of blood, it would quickly die.
Since the heart is also a muscle, it, too, must continuously
receive a fresh flow of blood, and you might think that receiving a blood supply
would never be a problem for the heart, since its chambers are always full of blood. But the heart is not
able to directly use any of the blood contained within its pumping chambers,
any more than a stereo amplifier can plug into itself. Instead, the heart
muscle feeds from, the blood supplied to it through two specific vessels,
called the coronary arteries.
In a healthy person, the blood flows freely and easily
through the coronary arteries, and the well-fed heart keeps pumping away as it
should. But if one of the coronary arteries, or one of its branches, should
become blocked off and so be unable to supply the heart with blood, then even
though the heart's chambers are full of blood, that part of the heart dependent
on the blocked-off artery will die.
In medical terminology, this is called a myocardial
infarction. Most of us know it by another name -- a heart attack. Heart attacks
are by far the largest cause of death in the United States today. Every 25 seconds
another person is stricken. Every 45 seconds another person dies.
If a heart attack victim is fortunate, and the part of the
heart that dies is small, he or she will survive, and the dead tissue will come
gradually to be replaced by scar tissue. But if a larger part of the heart is
deprived of blood, there really isn't very much that can be done to save the
person's life. Many heart attack victims die within minutes of the unexpected
seizure.
Heart attack victims often never have the slightest warning
anything is wrong. There are no bodily symptoms to signal the oncoming disaster.
They may have only that morning heard their physician pronounce them fit as a fiddle.
But, then, suddenly, the victims feel a sudden, severe, crushing pain in their
chests. Often the pain shoots down the arm, and sometimes it flares up the
neck, particularly on the left side. There may be cold sweating, nausea,
vomiting, and shortness of breath. The symptoms are accompanied by a feeling of
being overwhelmed by enormous terror and dread.
Though heart attacks strike suddenly, and often without
forewarning, they do not just happen. A heart attack is the inexorable final
step of a slow and lengthy process. You can put cold water in a pot, put the pot on
the stove, and turn on the heat. For a while nothing much will seem to change as
you watch. But if the heat is high enough, at a certain point bubbles will
appear on the surface of the water. You will see very little change all the
while the water heats from 32 degrees
toward 212 degrees. But then,
suddenly, just as it approaches the threshold of 212, there are dramatic visible changes, and the water boils.
Similarly, the apparent suddenness of a coronary artery
closing off and the consequent heart attack is actually quite misleading. In
reality, for this final step to occur, our arteries must have been approaching
"the boiling point" for some time.
The slow and steady process that takes place in our arteries
and inexorably increases our heart attack susceptibility has a name. This
process, which is, in fact, the deeper cause of almost all heart attacks, is
called atherosclerosis.
Atherosclerosis is often referred to in common speech as hardening
of the arteries, and although this is not an entirely inaccurate way of
describing what happens, "narrowing of the arteries" would be a
better catchphrase, though this, too, would be less than exact.
Atherosclerosis is the process by which arteries gradually
accumulate fatty and waxy deposits on their inner walls-thus reducing the size of the openings
through which the blood can flow. The foreign deposits that adhere to the inner walls of
the arteries are called atheromas or plaques.
When these plaques become advanced enough, the fatty
contents of the deposits will rupture into the artery and form a clot. These clots may clog
up the already reduced arterial opening and thus entirely prevent the flow of blood
through the artery.
If a clot forms in one of the two coronary arteries that
supply the heart with its only source of life-giving blood, and the coronary
artery becomes blocked by the clot, the heart is deprived of its supply of
life-giving blood, and the result is a heart attack.
There could be no heart attack unless the coronary arteries
had already become partially closed and irritated by atherosclerotic deposits.
Atherosclerosis, the real culprit, is what must be eliminated to prevent heart
attacks. (‘Diet for a New America’, by John Robbins)