Cardiac tamponade may be caused by any of the following:

• Critical illnesses such as advanced cancer or renal kidney failure
  
  
• Pericarditis (inflammation or scarring of the pericardium)
  
  
• Penetrating traumas, such as from an accident, knife or gunshot wound
  
  
• Non-penetrating (blunt) trauma, such as that caused by a steering wheel in automobile accidents
  
  
• Heart catheterization and invasive surgery, including open-heart surgery
  
  
• Recent heart attack
  
  
• Aortic aneurysm
  
  
• Radiation or drug therapies
  
  
• Lupus erythematosus and other connective tissue diseases
  
  
• Hypothyroidism (underactive thyroid gland)
  
  
• HIV (Human Immunodeficiency Virus) infection

Any of these conditions can lead to the leakage of blood or other fluids into the pericardial sac (pericardial effusion). During cardiac tamponade, the heart adapts to its restricted motion with an increase in heart rate (tachycardia) to maintain adequate cardiac output. Furthermore, the septum of the heart may be bowed into the left ventricle, impairing blood flow out of that chamber.

All these changes may lead to potentially fatal right-sided heart failure, abnormal heart rhythms (arrhythmias) or cardiogenic shock, or low blood flow to the body as a result of a lack of delivery of oxygen-rich blood.

Although dangerous, cardiac tamponade is a relatively uncommon occurrence in the United States. Only about 2 percent of penetrating trauma patients experience cardiac tamponade and, overall, approximately two out of every 10,000 persons will develop this condition.