BROKEN HEARTS 113kink in a garden hose and watering a desperately dry garden with the
resulting trickle of water!
Why hadn't these soldiers had a heart attack already? After all, only
10% of the artery was open. How could that be enough? It turns out
that if the plaque on the inner wall of the artery accumulates slowly,
over several years, blood flow has time to adjust. Think of blood flowing
through your artery as a raging river. If you put a few stones on the sides
of a river every day over a period of years, like plaque accumulating on
the walls of the artery, the water will find another way to get to where it
wants to be. Maybe the river will form several smaller streams over the
stones. Perhaps the river will go under the stones forming tiny tunnels,
or maybe the water will flow through small side streams, taking a new
route altogether. These new tiny passageways around or through the
stones are called "collaterals." The same thing happens in the heart. If
plaque accumulates over a period of several years there will be enough
collateral development that blood can still travel throughout the heart.
However, too much plaque buildup can cause severe blood restriction,
and debilitating chest pain, or angina, can result. But this bUildup only
rarely leads to heart attacks.^9 , 10
So what leads to heart attacks? It turns out that it's the less severe ac-
cumulations of plaque, blocking under 50% of the artery, that often cause
heart attacks.ll These accumulations each have a layer of cells, called the
cap, which separates the core of the plaque from the blood flOwing by. In
the dangerous plaques, the cap is weak and thin. Consequently, as blood
rushes by, it can erode the cap until it ruptures. When the cap ruptures,
the core contents of the plaque mix with the blood. The blood then begins
clotting around the site of rupture. The clot grows and can qUickly block
off the entire artery. When the artery becomes blocked over such a short
period of time, there is little chance for collateral blood flow to develop.
When this happens, blood flow downstream of the rupture is severely
reduced and the heart muscles don't get the oxygen they require. At this
point, as heart muscle cells start to die, heart pumping mechanisms begin
to fail, and the person may feel a crushing pain in the chest, or a searing
pain down into an arm and up into the neck and jaw. In short, the victim
starts to die. This is the process behind most of the l.1 million heart at-
tacks that occur in America every year. One out of three people who have
a heart attack will die from it.^9 , 10
We now know that the small to medium accumulation of plaque, the
plaque that blocks less than 50 % of the artery, is the most deadly. II, 12