Heart Court - BY
PETER BRUNO, M.D
Players often talk about giving their lives to the
game. And some of them do.
Professional sports don't seem as safe as they used
to be. An alarming number of athletes have died on the
job lately, stunning sports fans and making weekend
warriors nervous. What exactly happened to these people,
and what are the implications for the amateur sportsman?
The relationship between the heart and athletics is
a fascinating one. The function of the heart is to get
adequate oxygen to the muscles so that work can be performed.
One standard that doctors use to measure this process
is cardiac output, or the amount of blood the heart
can pump per minute. At rest, the cardiac output of
the average adult is five to six liters per minute.
During exercise, the rate can be raised to as high as
40 liters per minute. For a tennis player, that can
be quite an advantage.
One way to get this effect is by hypertrophy, or enlargement
of the heart muscle. Hypertrophy increases the force
of the contraction of the heart muscle, which allows
the heart to pump blood with increased efficiency. The
other method of increasing cardiac output is by dilation,
where the ventricles, or the chambers of the heart,
enlarged and thus can accommodate more blood.
Interestingly, aerobic activities will tend to dilate
the chambers of the heart, while anaerobic activities
tend to enlarge the heart muscle itself. Marathon runners
are the prime example of the former and weightlifters
of the latter. Tennis players fall somewhere in between,
benefiting from both types of conditioning.
A study done on men aged 30 to 65 showed that the incidence
of sudden death during jogging was only one per year
for every 7,620 joggers. If joggers with known heart
disease were excluded, the incidence dropped to one
in every 15,240 joggers. These figures underestimate
the true incidence of cardiovascular events, however,
because non-fatal events were not recorded.
According to this and other studies, the risk of sudden
death is greater during exertion than it is at other
times. But the risk of heart attack during exercise
is much greater for men with a sedentary lifestyle than
it is for men who are habitually active. Most important,
an ongoing exercise regimen greatly reduces the risk
of a man dying suddenly when he is at rest.
Women appear to be relatively safe from sudden death
at all ages, possibly because of their higher levels
of estrogen and lower leve.ls of vigorous activity.
The most common cause of sudden death is pre-existing
coronary artery disease, or CAD. In fact, most of the
athletes who have died suddenly-Hank Gathers, Reggie
Lewis, Pete Maravich and Flo Hyman-had some form of
CAD. Both CAD and sudden death are rare among people
age 35 and under, however. When sudden death does occur
in this population, congenital heart disease is usually
the culprit. And hypertrophic cardiomyopathy is the
most common of such diseases. But wait a minute. Isn't
hypertrophy, or enlargement of the heart, supposed to
be a good thing in athletes? True, a heart that is symmetrically
or equally enlarged appears to be a good response to
exercise. But this needs to be carefully distinguished
from a more uneven enlargement of the heart, as seen
in congenital cardiomyopathies. In such diseased states,
the electrical system of the heart muscle is more likely
to cause potentially fatal arrhythmias, or extra heartbeats.
In some cases, this kind of hypertrophy will actually
squeeze blood out of the heart chambers and cause the
heart to fail. A good physical examination and an E
KG will suffice as a screening exam. Exercise stress
testing is warranted only in older patients, people
with abnormal EKGs and those with risk factors for heart
disease. An echocardiogram, or soundwave test on the
heart, which shows the size of the muscles and chambers,
will help the serious athlete but is not really cost-effective
for the average recreational player.
In short, exercise increases life expectancy. The risk
of sudden death .from exercise is very low in men and
even lower in women. Although the majority of us will
never perform at the level of Reggie Lewis, we need
not worry too much about exercising moderately after
getting a basic medical screening.