How Heart Disease Is Diagnosed
The ways doctors diagnose heart disease can vary quite a bit, depending on which kind of heart disease we’re talking about.
However, it is possible to outline the general method which most doctors use to make a diagnosis when they suspect you may have heart disease.
It looks like this:
- First, take a careful medical history.
- Second, perform a focused physical examination.
- Finally, decide which medical tests are likely to help complete the diagnosis.
“Taking a medical history” simply means that your doctor will interview you to learn what kinds of symptoms or medical complaints you may have (if any)
and tease out any features associated with those symptoms that might point toward their causes.
Depending on the symptoms you describe, your doctor may ask you a lot of questions detailing those symptoms—what seems to bring them on, what makes
them stop, how long they last, when they have occurred, and any other associated circumstances.
For certain potentially important cardiac symptoms—chest pain and syncope being two good examples—taking a careful medical history is often the most
important step in making the diagnosis.
The cardiac examination may also give some important clues as to the presence, absence, or type of cardiovascular problem a person may have. Cardiac
arrhythmias, heart valve disease, congestive heart failure, aortic aneurysm, and postural orthostatic tachycardia syndrome (POTS), are only a few of the
kinds of cardiovascular problems for which the physical examination often gives very important clues, or indeed, actually confirms the diagnosis.
A wide variety of sophisticated tests have been developed for diagnosing heart problems. While specialised cardiovascular tests are often the
“gold standard” for making or confirming a cardiac diagnosis, in general they are the most useful when your doctor already has a very good idea—
from performing a history and physical exam—of what the correct diagnosis is.
Cardiovascular tests can be expensive, difficult to perform, time-consuming, and in some cases invasive. So, diagnostic tests should be used, whenever
possible, in a targeted fashion to confirm the suspected diagnosis rather than just doing several tests, in shotgun fashion, to see what turns up.
In other words, doctors should rely on the information they obtain during their initial clinical evaluation to decide what in particular to look for, which
test or tests are best suited to look for it, and if more than one test is needed, which order they ought to be performed in. This way, if you have a
heart problem your doctor can get to the right answer as expeditiously as possible, without exposing you to unnecessary expense or risk.
The Electrocardiogram (ECG)
The ECG records the electrical activity of the heart and can reveal information about the heart rhythm and important clues about structural heart
disease that may be present (such as a prior heart attack, or ventricular hypertrophy.
The ECG is performed so commonly that many doctors consider it to be a routine part of an annual wellness examination.
Several systems are available that allow the recording of an electrocardiogram for days or weeks at a time, in order to record the heart rhythm over
a prolonged period. These systems allow doctors to diagnose cardiac arrhythmias that occur only infrequently and sporadically.
Echocardiogram or Cardiac Ultrasound
The echocardiogram study is a non-invasive test that uses sound waves to construct an image of the beating heart. The echo study is very useful for
detecting the enlargement of cardiac chambers, heart valve disease, and heart muscle problems such as dilated cardiomyopathy or restrictive cardiomyopathy.
It is a relatively quick study to perform, is non-invasive, and does not require radiation. This makes the echocardiogram a nearly ideal screening tool
if structural abnormalities of the heart are suspected or if you're at high risk for heart disease but don't have any symptoms. It is also a test that can be
performed repeatedly, over time, to monitor the status of a cardiac problem.
Cardiac CT Scan
A cardiac CT scan, like any CT scan, uses computerised x-ray equipment to make an image of the heart. This technique can also be used to look
for calcium deposits in the coronary arteries, which is an indication that atherosclerosis is present. The CT scan uses a substantial amount of radiation,
so it should only be performed if the information it gives is very likely to be clinically useful.
Cardiac MRI Study
The cardiac MRI study uses magnetic fields to construct an image of the heart and surrounding structures. This test can show impressive anatomic
details, and in certain circumstances can be very useful in diagnosing and characterising structural heart disease.
Cardiac stress testing has several potential uses, but it is used chiefly to help assess whether coronary artery disease is producing cardiac ischaemia
that may be responsible for angina, and if so, to help assess the severity of the problem.
A stress test is often combined with a thallium scan, which uses a small dose of a radioactive material to produce an image of the heart that reflects
whether the heart muscle is getting the blood flow it needs. Stress testing can also be very useful in monitoring the effectiveness of anti-anginal therapy.
With this invasive test, small catheters are inserted into the blood vessels and passed into the heart and/or coronary arteries.
Pressures can be measured inside the heart, and dye can be injected into blood vessels and cardiac chambers to make a moving x-ray image of blood flow.
The catheterisation study has many potential applications but is used most commonly to visualise the coronary arteries in people with known or
suspected coronary artery disease. Cardiac catheterisation is also used to deliver therapy, most commonly, by performing angioplasty and placing
stents in people with arterial blockages.
This is another form of cardiac catheterisation, but in this case the catheters are insulated wires instead of hollow tubes. This test is used to study the
cardiac electrical system to determine the presence or absence, and the mechanism, of various kinds of cardiac arrhythmias. This technique is also
used to deliver ablation therapy in order to treat several kinds of arrhythmias.
Tilt Table Study
A tilt table study is performed by strapping a person to a table that has a footboard on it, then raising the table to an upright position. With certain
cardiovascular conditions an upright tilt for 20 minutes or more can reproduce certain kinds of cardiovascular instability, particularly in people who
are suspected of having vasovagal syncope. The tilt study can help to confirm the diagnosis.