Pericardium

The pericardium is a thin, double-walled membranous sac that envelops the heart and the roots of the major blood vessels connected to it. Its primary function is to provide protection and lubrication for the heart, limiting its motion and preventing excessive dilation during activity.

Blausen heart wall

Anatomy

The pericardium is made up of two layers:

1. Fibrous Pericardium: The outermost layer that is tough, inelastic, and adheres to the diaphragm and the mediastinal walls. This layer provides protection against sudden over-expansion of the heart.
2. Serous Pericardium: Lining the inside of the fibrous pericardium, it's thinner and consists of two parts:

• • Parietal Layer: Adheres to the fibrous pericardium.
  • Visceral Layer (or Epicardium): This layer is in direct contact with the heart and is also a part of the heart's external surface.

Between the parietal and visceral layers of the serous pericardium lies the pericardial cavity, which contains a small amount of pericardial fluid. This fluid serves to reduce friction between the two layers as the heart beats.

Functions

The pericardium has several essential functions:

• Protection: It shields the heart from infections and malignancies and also prevents the spread of infections from nearby organs like the lungs.
• Lubrication: The pericardial fluid acts as a lubricant, decreasing friction between the heart's movements and the pericardial sac.
• Prevention of Excessive Dilation: The fibrous pericardium restricts the excessive dilation of the heart, especially during moments of increased volume or pressure.
• Anchoring: The pericardium anchors the heart within the mediastinum and maintains its position in the thorax.

Clinical Significance

• Pericarditis: An inflammation of the pericardium, often caused by infections, heart surgery, or traumatic injury. Symptoms might include chest pain and fever.
• Cardiac Tamponade: A life-threatening condition where fluid, blood, or pus fills the space between the myocardium (heart muscle) and the pericardium, leading to reduced cardiac output. Immediate medical intervention, like pericardiocentesis, is required.
• Constrictive Pericarditis: A chronic condition where the pericardium becomes thickened, fibrous, and adherent to the heart, restricting its function. It can be the result of a prior episode of acute pericarditis or other causes.
• Pericardial Effusion: The accumulation of excess fluid in the pericardial cavity. Causes can range from inflammation, infection, trauma, or malignancy.

See Also

• Heart
• Cardiovascular system
• Pericarditis
• Cardiac Tamponade
• Constrictive Pericarditis
• Pericardial Effusion

References

• Braunwald, E. (2001). Heart Disease: A Textbook of Cardiovascular Medicine. W.B. Saunders.
• Lilly, L. S. (2016). Pathophysiology of Heart Disease: A Collaborative Project of Medical Students and Faculty. Wolters Kluwer Health.

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