Electrical alternans

Overview

Example of electrical alternans on an ECG.

Electrical alternans is a phenomenon observed in the electrocardiogram (ECG) characterized by alternating amplitude or axis of the QRS complexes. It is often associated with pericardial effusion and can be an important diagnostic clue in clinical practice.

Pathophysiology

Electrical alternans occurs due to the swinging motion of the heart within a large volume of pericardial fluid, which causes changes in the electrical axis and amplitude of the heart's electrical activity. This is most commonly seen in cases of cardiac tamponade, where the accumulation of fluid in the pericardial cavity exerts pressure on the heart, affecting its normal function.

Clinical Significance

The presence of electrical alternans on an ECG is a significant finding that can indicate the presence of a large pericardial effusion. It is important for clinicians to recognize this pattern as it may necessitate urgent intervention, such as pericardiocentesis, to relieve the pressure on the heart.

Diagnosis

Electrical alternans is diagnosed through careful analysis of the ECG. It is characterized by:

• Alternating QRS complex amplitude or axis in a regular pattern.
• It may be accompanied by other signs of pericardial effusion, such as low voltage QRS complexes.

Management

Management of electrical alternans involves addressing the underlying cause, typically a pericardial effusion. Treatment options may include:

• Pericardiocentesis to remove excess fluid from the pericardial space.
• Surgical intervention in cases of recurrent effusion or tamponade.
• Medical management of the underlying condition causing the effusion.

Related Pages

• Pericardial effusion
• Cardiac tamponade
• Electrocardiogram
• Pericardiocentesis