Diagnosis of Heart Disease

Modern medicine has a number of tools that are available to help determine what is happening inside your heart. They include:

• History and Physical Examination
• Electrocardiogram
• Chest X-Ray
• Blood Tests
• Stress Tests
• Echocardiogram
• Cardiac Catheterization

Each of these techniques is described in detail in the sections that follow.

History and Physical Examination
Even in this technologic age in which a wide assortment of tests are available to the physician, the primary source of information about your heart comes through a history and physical exam.

There are no symptoms that occur only in heart disease. However, one of the most common symptoms of heart disease is chest pain. When a part of the heart muscle (myocardium) is not getting enough blood (usually due to a blockage in one of the coronary arteries), chest pain can result. Chest pain from heart disease usually feels like a tightness, pressure or squeezing sensation. It is usually located in the center of the chest but can also be located off to the side. Usually it is brought on by exertion and relieved by rest.

Chest pain can also originate from other areas that are near the heart such as the Pericardium (the sac around the heart), Aorta, Lung, Pleura (lining of the Lung), muscles and bones of the chest or the Gastrointestinal Tract (Esophagus or Stomach). Also, someone can have heart disease and not have any chest pain.

Another symptom that can occur in heart disease is shortness of breath. This can occur at rest, with exertion, or when lying down. Palpitations are an awareness of one's heartbeat and can occur in heart disease. This can cause a feeling that your heart is beating too fast or too slow, skipping beats, or beating irregularly. Passing out (syncope) can occur from heart disease if the heart is temporarily not pumping out enough blood. Nausea or vomiting can also be a symptom of heart disease. Profuse sweating (diaphoresis) can sometimes accompany heart disease. Of course there are other causes for sweating.

During a physical exam, your physician listens to your heart with a stethoscope. The stethoscope is placed in certain pre-determined areas where each heart valve is heard loudest. If a murmur is heard loudest at that valve's location, chances are that that is the valve that is malfunctioning. Also, listening to the lungs with a stethoscope can reveal the presence of fluid which can be the result of heart disease.

Electrocardiogram
An Electrocardiogram (EKG or ECG) records the electrical activity of the heart from the surface of the chest using electrodes placed on each arm and leg and six placed on the chest. These electrodes are connected by wires to an EKG machine. 12 different tracings are produced and this is called a 12 lead EKG. Each tracing gives a view of the heart from a different angle. The 12 leads of an EKG are called I, II, III, aVR, aVL, aVF, and V1, V2, V3, V4, V5, and V6. Depending on which EKG lead is involved, your physician can tell during a heart attack which part of the heart it is occurring in. Then, based on his knowledge of anatomy, he can determine which artery is blocked.

The EKG gives the physician information about :

1. heart rate
2. heart rhythm
3. adequacy of blood supply to the heart
4. presence of a heart attack
5. enlargement of the heart
6. inflammation around the heart (pericarditis)
7. effects of drugs and electrolytes on the heart

Here is an example of a normal 12 lead EKG:

Chest X-Ray
A Chest X-ray is a useful tool in the evaluation of heart disease. It shows the size and shape of the heart, which can be enlarged in Congestive Heart Failure. Enlargement of the heart (cardiomegaly) can also be present in diseases of the heart valves and congenital heart disease. Enlargement of the outline of the heart can also be caused by excess fluid in the pericardium (sac around the heart). If too much fluid is present, it can compress the heart. Usually the most important part of the Chest X-Ray in the evaluation of heart disease is the condition of the lungs. Fluid build-up in the lungs is commonly caused by heart failure. The outline of the vessels near the heart can also be seen on a Chest X-Ray and can help the physician in the diagnosis of Aortic Aneurysm (localized enlargement in the wall of the Aorta) or Aortic Dissection (tearing of the wall of the Aorta). Here is an example of a normal Chest X-Ray:

Blood tests

A heart attack occurs when a coronary artery is blocked, causing a lack of blood and then death to the heart muscle served by that artery. When the muscle dies it releases certain chemicals into the blood that were present in those muscle cells. These can be measured and if present are evidence of a heart attack. Each chemical becomes measurable and persists in the blood for different times. These chemicals are CPK, CPK-MB, Troponin and Myoglobin. The following table shows the behavior of these chemicals in the blood:

Lab Test	Begins to rise	Peak	Duration	Found in
CPK	4-8 hours	-	48-72 hours	Heart, Brain, Skeletal Muscle
CPK-MB	3-4 hours	12-24 hours	48 hours	Heart
Myoglobin	1-2 hours	4-6 hours	24 hours	Heart, Skeletal Muscle
Troponin	3-6 hours	12-24 hours	1 week	Heart

Stress Test
A stress test is a commonly used procedure to evaluate coronary artery disease. It is also called an exercise stress test or an exercise tolerance test. Stress tests are useful because exercise can reveal abnormalities not seen on an EKG of a heart at rest. A person's EKG, blood pressure, and symptoms are monitored first at rest, then while walking on a treadmill or pedaling a bicycle, then after exercising. The exercise is gradually increased until a target heart rate is reached (85% of maximum heart rate). If severe EKG changes, chest pain, severe shortness of breath, blood pressure changes or cardiac arrhythmias occur then the test may need to be stopped.

When certain EKG changes occur the test is considered positive. If a person cannot exercise then medications can be given (dipyridamole) that stress the heart without exercise. Even more information can be obtained if certain radioactive materials (thallium-201 or Technetium 99m sestamibi) are injected into a patient during the stress test. These chemicals are then detected by a special camera just after exercise and 4 hours later. These materials can help detect areas of decreased blood flow as well as areas where heart attacks have occurred. The effectiveness of the heart's contraction can be determined by measuring the ejection fraction or percent of blood pumped out of the heart with each contraction.

Echocardiogram

An Echocardiogram is a painless procedure that uses an ultrasound beam to view the heart in motion. The procedure is similar to that used to monitor a fetus. An ultrasonic transducer, which looks like a microphone, transmits and receives the ultrasound waves. It is placed on the chest wall and moved around to view different heart structures. Ultrasound waves are reflected only when they reach the edge of two structures with different densities. The reflected waves produce a moving image of the edges of heart structures which are displayed on a screen and recorded on tape.

The types of Echocardiograms are M-mode, 2-D and doppler. M-mode is a one dimensional view of a small section of the heart as it moves. 2-D echocardiogram produces a moving two dimensional slice of the heart. Doppler ultrasound is used to evaluate the velocity and turbulence of blood flow in the heart.

Echocardiograms can evaluate:

1. the presence of any abnormal fluid collection in the sac around the heart (pericardium).
2. the chamber size, thickness of the heart muscle wall and how well it is functioning.
3. the function of the heart valves - whether they are obstructing blood flow or leaking.
4. any abnormal connections between chambers and vessels that may exist in congenital heart disease.
5. wall motion abnormalities that occur when the heart muscle is not receiving enough blood.
6. the presence of aneurysms, clots, tumors, vegetations (bacterial growths) on the valves.

Cardiac Catheterization
This procedure is the "gold standard" for evaluating cardiac anatomy and function. During a Cardiac Catheterization X-ray movies are taken to show the anatomy of the coronary arteries, heart chambers, major vessels, valves and congenital heart defects. It is also used to assess the adequacy of heart contractions (ejection fraction), pressures in different areas of the heart, output of the heart, or the amount of oxygen and carbon dioxide in different areas of the heart. It can also be used to treat blocked coronary arteries by blowing up a small balloon at the site of blockage to create a larger opening (called angioplasty).

After sedating the patient, the cardiologist places a catheter (small tube) into an artery (to look at the left side of the heart) or vein (to look at the right side of the heart) in the upper leg or arm. The catheter is advanced to the heart. Dye is injected into the catheter and X-rays movies are taken and recorded on film. The X-ray movies are taken at different angles to see if any blockages are present in the coronary arteries. This procedure is invasive and has rare complications such as heart attacks, stokes, abnormal heart rhythms, allergic reactions, perforation (puncture of a blood vessel or chamber of the heart), and even death.

Here is an example of a cardiac catheterization in which the catheter is placed into the Femoral Artery, it is then advanced through the Aorta and into the Heart.

About the Author
Carl Bianco, M.D., is an emergency physician practicing at Dorchester General Hospital in Cambridge, MD, located on the Eastern Shore of Maryland. Dr. Bianco attended Medical school at Georgetown University School of Medicine and received his undergraduate degree from Georgetown University majoring in nursing and pre-med. He Completed an internship and residency in Emergency Medicine at Akron City Hospital in Akron, Ohio.

Dr. Bianco lives near Baltimore with his wonderful wife and two wonderful children.