Fusion Beats

Fusion Beats

A fusion beat occurs when a supraventricular and a ventricular impulse coincide to produce a hybrid complex. It indicates that there are two foci of pacemaker cells firing simultaneously: a supraventricular pacemaker (e.g. the sinus node) and a competing ventricular pacemaker (source of ventricular ectopics).

• The fusion beats are of intermediate width and morphology to the supraventricular and ventricular complexes.
• Originally described by William Dressler in 1952

ECG Example

Causes

Fusion beats are seen with:

• Ventricular tachycardia
• Accelerated idioventricular rhythm (AIVR)

Related Topics

• VT versus SVT with aberrancy
• Ventricular tachycardia
• Accelerated idioventricular rhythm (AIVR)
• Wilhelm Dressler (1890–1969)
• Dressler Beat (Fusion Beat) 1952

LITFL Further Reading

• ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
• ECG A to Z by diagnosis – ECG interpretation in clinical context
• ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
• 100 ECG Quiz – Self-assessment tool for examination practice
• ECG Reference SITES and BOOKS – the best of the rest

Advanced Reading

• Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric
• Wagner GS. Marriott’s Practical Electrocardiography 12e
• Chan TC. ECG in Emergency Medicine and Acute Care
• Rawshani A. Clinical ECG Interpretation
• Mattu A. ECG’s for the Emergency Physician
• Hampton JR. The ECG In Practice, 6e