Cardiac Catheterization

Overview

Cardiac catheterization is performed to further diagnose coronary artery disease, valvular heart disease, congestive heart failure, and/or certain congenital (present at birth) heart conditions, such as atrial septal defect or ventricular septal defect. A brief explanation of these diseases and conditions follows.

Coronary Artery Disease
Coronary artery disease (CAD) is the narrowing of the coronary arteries (the blood vessels which supply oxygen and nutrients to the heart muscle), caused by a buildup of fatty material within the walls of the arteries. This buildup causes the inside of the arteries to become rough and narrowed, limiting the supply of oxygen-rich blood to the heart muscle.

To better understand how coronary artery disease affects the heart, a review of basic heart anatomy and function follows.

The heart is basically a pump. The heart is made up of specialized muscle tissue, called the myocardium. The heart's primary function is to pump blood throughout the body, so that the body's tissues can receive oxygen and nutrients and have waste substances taken away.

Like any pump, the heart requires fuel in order to work. The myocardium requires oxygen and nutrients, just like any other tissue in the body. However, the blood that passes through the heart's chambers is only passing through on its trip through the body - this blood does not give oxygen and nutrients to the myocardium. The myocardium receives its oxygen and nutrients from the coronary arteries. The coronary arteries lie on the outside of the heart and supply oxygenated blood to the heart tissue.

When the heart tissue does not receive an adequate blood supply, it cannot function as well as it should. If the myocardium's blood supply is decreased for a length of time, a condition called ischemia may develop. Ischemia can decrease the heart's pumping ability, because the heart muscle is weakened due to a lack of food and oxygen. Think about how you may feel when you go too long without eating - you may become tired and feel weak. The heart muscle reacts in a similar way when its blood flow (food) is decreased.

Unfortunately, you may not have any symptoms of beginning coronary artery disease, yet the disease will continue to progress until sufficient artery blockage exists to cause symptoms and problems. Some symptoms of coronary artery disease include chest pain, fatigue, palpitations, and shortness of breath. If the blood supply to the heart muscle continues to decrease as a result of increasing obstruction of a coronary artery, a myocardial infarction, or heart attack, may occur. If the blood flow cannot be restored to the particular area of the heart muscle affected, the tissue may actually die, just as you could die without food.

Fortunately, the technology is available to restore blood flow to heart tissue when the coronary artery blockages are diagnosed. One of several diagnostic procedures used to diagnose and evaluate coronary artery disease is cardiac catheterization.

Valvular Heart Disease
As mentioned above, the heart is a pump made of muscle tissue. The heart has four pumping chambers: two upper chambers, called atria, and two lower chambers, called ventricles. The right atrium pumps blood into the right ventricle, which then pumps the blood into the lungs where wastes such as carbon dioxide are given off and oxygen and other nutrients are taken into the blood.

From the lungs, the blood flows back into the left atrium, is pumped into the left ventricle, then is pumped through the aorta out to the rest of the body and the coronary arteries. When the atria are pumping, the ventricles are relaxed in order to receive the blood from the atria. Once the atria have pumped their entire blood load into the ventricles, they relax while the ventricles pump the blood out to the lungs and to the rest of the body.

In order to keep the blood flowing forward during its journey through the heart, there are valves between each of the heart's pumping chambers:

• tricuspid valve - located between the right atrium and the right ventricle.
  
  
• pulmonary (or pulmonic) valve - located between the right ventricle and the pulmonary artery.
  
  
• mitral valve - located between the left atrium and the left ventricle.
  
  
• aortic valve - located between the left ventricle and the aorta.
  

If the heart valves become damaged or diseased, they may not function properly. Dysfunction of heart valves may be either stenotic (stiff) or insufficient (leaky). When one (or more) valve(s) becomes stiff, or stenotic, the heart muscle must work harder to pump the blood through the valve. Some reasons why heart valves become stenotic include infection (such as rheumatic fever or staph infections) and aging. If one or more valves become leaky, or insufficient, blood leaks backwards, which means that less blood is pumped in the proper direction.

Valvular heart disease may cause the following symptoms:

• dizziness
• chest pain
• breathing difficulties
  
• palpitations
  
• edema (swelling) of the feet, ankles, or abdomen
• rapid weight gain due to fluid retention

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