Cardiac catheterization is a procedure usually performed by an interventional cardiologist, a heart specialist who specializes in inserting a catheter either into the chambers of the heart or into an artery feeding the heart. This test is frequently performed prior to heart surgery to determine if surgery is necessary, and, if so, what surgery is to be performed. The interventional cardiologist may also carry out additional interventions such as balloon angioplasty and stenting.

Anatomy

• The heart is a muscular organ about the size of a clenched fist that lies in the chest beneath the sternum or breast bone (Figure 1A)
  
• The function of the heart is to supply blood to the body. The heart is divided into four chambers, two upper chambers called the right and left atria and two lower chambers called the right and left ventricles
  
• The left ventricle of the heart pumps blood through the aortic valve into the aorta, the largest artery in the body, and then out through a network of arteries to the whole body
  
• The valves control the direction of flow of blood through the heart (Figure 1B, 1C)
  
• After passing through the tissues of the body, the blood collects in the veins and returns to the right atrium
  
• Blood then passes through the tricuspid valve into the right ventricle
  
• The right ventricle pumps the blood through the pulmonary valve into the arteries of the lung where the blood picks up oxygen
  
• The oxygenated blood returns to the left atrium after which it passes through the mitral valve to the left ventricle and the cycle repeats
  
• Like all tissues in the body, the heart requires oxygen filled blood in order to function. Blood goes to nourish the heart through the coronary arteries
• The right and left coronary arteries come off the aorta just above the junction of the aorta with the heart (Figure 2)
  

Figure 1a - The heart viewed from in front showing the position of the right and left atria and ventricles.	Figure 1b - Diagram of the atria, ventricles and valves of the heart with the heart muscle relaxed (diastole). The yellow arrows show the direction of blood flow through the valves.
Figure 1c - Diagram of the heart during a contraction of the heart muscle (systole). The yellow arrows show the direction of blood flow through the valves.
Figure 2 Left - Angiogram of the right coronary artery. Courtesy K. Patel, MD.	Figure 2 Right - Angiogram of the left coronary artery. Courtesy K. Patel, MD.