Point of View---A Life or Death Matter
Howard H. Wayne, M.D., F.A.C.C., F.A.C.P.
The Noninvasive Heart Center of San Diego
San Diego, California, U.S.A.
NARROWING OF ARTERIES CORRELATES POORLY WITH CLINICAL PICTURE
In spite of considerable evidence to the contrary, the general emphasis in
cardiology today is on the anatomy of coronary artery disease; that is, which
coronary arteries are involved, and how much narrowing or obstruction there is.
Increasingly it is becoming apparent that the amount of narrowing of the coronary
arteries is of only minor importance. Such narrowing does not correlate with the
patient's symptoms, the motion of the muscular walls of the heart, the
performance of the heart, the blood flow through the coronary arteries, the
patient's prognosis, and the results of coronary artery bypass surgery. Importantly,
when the angiograms of patients with stable and unstable angina are compared,
there are no distinguishing anatomical differences to separate the two groups.
LIMITATIONS OF THE CORONARY ANGIOGRAM
There is good reason to believe that the reason for these poor relationships
is because the main coronary arteries, the visualization of which is the main
objective of coronary angiograms, contain only about 25% of the total coronary
blood flow. Indeed, the vast majority of the total coronary circulation cannot even
be seen on an angiogram simply because the angiographic technique is unable to
visualize vessels smaller than 0.5 mm. A analogy would be looking at a large city
from a high altitude. One would be able to see the major freeways but the city
streets would be invisible. Thus, if the objective of coronary angiograms is visualize
the amount of blood flow to different regions of the heart, it fails miserably.
SINGLE ANGIOGRAM CANNOT INDICATE HOW LONG ARTERY IS OBSTRUCTED
Even if a coronary angiogram could determine the approximate amount of
blood flow to a given area of the heart, the technique would still have major
limitations. Most patients with chest pain due to coronary artery disease (angina
pectoris), or with other symptoms such as exertional fatigue or shortness of breath,
usually have had some reduction in blood flow to one or more areas of the heart
for years without change. Unfortunately, mere reduction in blood flow is not
sufficient to establish the cause of someone's chest pain that is of recent onset.
What the cardiologist really needs to know is whether there also has been a recent
major change in the amount of blood flow to a specific area of the heart. That kind
of information cannot be provided by a single angiogram; serial angiograms would
be required. Because angiograms are invasive procedures that are costly and not
without risk, repetitive tests are impractical. Thus, although a single angiogram will
tell us if coronary artery disease has been present, it cannot tell us if that disease has
become acutely worse, and is the direct cause of the patient's new symptoms, or
alternatively, the presence of coronary artery disease is merely coincidental, and
there is some other explanation for the patient's symptoms.
OTHER CAUSES OF CHEST PAIN
What might these other causes be? A wide variety of conditions may
produce chest pain that may be confused with chest pain due to coronary artery
disease. For example, chest wall pain due to muscular or nerve root injury, diseases
of the lung or esophagus, particularly gastroesophageal reflux disease (GERD),
abdominal diseases such as gallstones, peptic ulcer, and colon disorders with excess
amounts of abdominal gas. In addition, a number of conditions may trigger
previously existing but silent coronary artery disease. By far the most common is
high blood pressure or hypertension. Hypertension is usually a disease of later life
while coronary artery disease usually occurs earlier but remains silent. As we age
our blood pressure begins to rise. Initially this usually occurs only during periods of
stress or physical activities. When this happens it may produce chest pain. Because
at rest the blood pressure is still normal, its presence is often overlooked. If
angiograms are done, coronary artery disease may be coincidentally present, and
the patient's symptoms blamed on it rather than his hypertension. Such a patient
is often made to undergo unnecessary angioplasty or coronary artery bypass
surgery when simple blood pressure medication will correct the problem. There
are still other conditions that may trigger previously silent coronary artery disease
such as prostate and kidney disease, thyroid disease and many others. Even certain
drugs that cause fluid retention such as the nonsteroidal anti-inflammatory drugs
can elevate the blood pressure and cause chest pain.
Because the elimination of all these various causes of chest pain often takes
weeks to months, and because of the limitations of the angiographic procedure
just described, as well as the costs and risks of angiograms, it seems more rational
to direct our attention to the use of other tests that will noninvasively detect any
impairment of muscular contraction due to coronary artery disease. Long before
the heart muscle becomes permanently damaged due to insufficient blood supply,
that muscle fails to perform in a normal manner. It can't, it doesn't have the
OTHER WAYS TO TEST CARDIAC FUNCTION AND BLOOD FLOW TO HEART MUSCLE
A number of new or relatively new diagnostic tests are available for studying
the various phases of the heart's function. These tests continuously image the
motion of the muscular walls that surround the heart's chambers as they contract
and relax. In effect, the rate and degree to which the chambers empty and fill are
revealed. Even events lasting only one-tenth of a second or one-hundreds of a
second can be studied. Consequently, the individual functions of every portion of
the heart that contributes to the total performance of the heart can be measured
and permanently recorded.
The result is a complete picture of the heart's mechanical activities during
every phase of the cardiac cycle. If total performance is reduced, that portion of
the heart that is responsible not only can be identified, but when its function is
impaired as well. This increases the likelihood that the abnormality can be
selectively treated with the drug most likely to be beneficial. This is vastly superior
to tests, i.e., the electrocardiogram that records only the electrical activity of the
heart, or the stress test that measures only total performance, and provide no
input as to what part or what phase of the heart's function is impaired, nor insight
as to what drug to selectively use to improve the heart's contraction.
Collectively these tests and procedures are called noninvasive tests because
they do not invade the body or penetrate the skin. Those noninvasive tests that
study the mechanical function of the heart are sometimes referred to as
mechanocardiographic tests. Of prime importance is the fact that many of these
tests are adaptable for use in the doctor's office. This will have a profound
influence on the way heart disease is diagnosed and treated. For the first time,
detailed facts about how a patient's heart is functioning will become available on a
VALUE OF NONINVASIVE TESTS AND LESSONS LEARNED
The value of such information can be enormously enhanced by the ease with
which it can be updated each time the patient returns for follow up visits. The
rewards will be a low cost, safe, easily reproduced group of tests for follow up
comparisons that provide early warnings of impairment of any phase of the heart's
contraction or relaxation processes.
As a result of the repeated use of these tests in coronary artery disease
patients over a period of many years, important new information has come to light
about the reasons why patients with stationary disease seemingly become worse.
Contrary to today's present held concepts, the development of new symptoms, or
the return of old ones, is uncommonly due to progression of the patient's
underlying coronary artery disease. The usual cause appears to be some form of
functional overload that causes the heart to work beyond its capabilities.
Symptoms, when they do appear, do not allow identification of the underlying
problem. Thus, it is understandable that the first thought is the patient's disease is
getting worse and angioplasty or bypass surgery is recommended.
NONINVASIVE TESTS AS A GUIDE TO TREATMENT AND PROGNOSIS
In reality, the cause of the temporary functional overload is usually easily
correctable with medication. However, because it may exist in silence, it may
progress to an advanced state before symptoms appear. By that time it may be
too late to treat, and even may remain hidden by its own complications.
Because the precise cause of the functional overload can usually be identified,
the specific drug that will be the most effective can be selected to correct the
problem, rather than having to use shotgun therapy because the patient's
symptoms are nonspecific.
Importantly, as long as there are no changes in the various component
functions of the heart that go to make total cardiac performance, the patient will
do well. He or she will have little in the way of symptoms, and minimal progression
of the disease itself. The changes that eventually do occur appear to be more the
result of aging which cannot be avoided. The major problems of heart attacks,
premature deaths, unnecessary angioplasty and coronary artery bypass surgery
have been drastically reduced or avoided altogether by the above approach. For
patients who do not receive the benefits of such diagnosis and treatment because
their doctor still employs older methods, that doctor may be more dangerous than