- 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
- Fusion beats due to VT – the first of the narrower complexes is a fusion beat (the next two are capture beats)
Fusion beats are seen with:
- 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
- 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