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t o r e g . c o m
Dr. Mete ALPASLAN
Atrial Fusion Beat
The atria are depolarized partially by the atrial ectopic beat
and partially by the sinus beat.
Atrial fusion beat arises due to fortuitous meeting of an atrial ectopic beat and a sinus beat in the atria.
The morphology of an atrial fusion beat is different from that of a sinus beat.
The width of an atrial fusion beat is generally more than the width of a sinus beat.
Remember: If an atrial premature beat comes too early and merges with its preceding U wave, it may falsely give the impression of atrial fusion.
Remember: interatrial block in the differential diagnosis of widened P wave.
Reference
Chou's Electrocardiography in Clinical Practice. Adult and Pediatric. 6th ed. Philadelphia. WB Saunders 2008:345-346.
ECG 1. The ECG above belongs to a middle-aged woman.
The fifth P wave from the left is an atrial fusion beat. This P wave is wider than a sinus P wave.
An atrial premature beat has merged with a sinus beat resulting in an atrial fusion beat.
Click here for a more detailed ECG
ECG 2a. The ECG above belongs to a 66 years-old man who had undergone coronary artery bypass grafting operation.
ECHOcardiography (ECHO) showed inferior and posterior hypokinesia (mild left ventricular systolic dysfunction).
Limb leads were recorded at a calibration of 20 mm/mV while chest leads were recorded at a standard calibration of 10 mm/mV.
Therefore, at first glance it may seem like the left ventricle is hypertrophic. However, ECHO didn't show hypertrophy.
At first glance, the second P wave from the right side seems like a wide P wave, suggesting the diagnosis of atrial fusion.
However, this P wave widening is due to fusion of the atrial premature beat with its preceding U wave.
Similar QU intervals from other leads support U-P wave fusion.
Click here for a more detailed ECG
ECG 2b. The above ECG belongs to the same man.
This time, it is recorded at a standard calibration of 10 mm/mV.
At first glance, the fourth P wave from the left seems like a wide P wave, suggesting the diagnosis of atrial fusion.
However, this P wave widening is due to fusion of the atrial premature beat with its preceding U wave.
Similar QU intervals from other leads support U-P wave fusion.
Click here for a more detailed ECG
ECG 3. The ECG above belongs to a 54 years-old man.
The second P wave in lead I may seem like a widened P wave suggesting atrial fusion at first glance.
However, checking other leads will show that it is due to baseline drift.
The amplitude of baseline drift is unacceptably high for a partial P wave depolarization.
Click here for a more detailed ECG
The atria are depolarized partially by the atrial ectopic beat
and partially by the sinus beat.
Atrial fusion beat arises due to fortuitous meeting of an atrial ectopic beat and a sinus beat in the atria.
The morphology of an atrial fusion beat is different from that of a sinus beat.
The width of an atrial fusion beat is generally more than the width of a sinus beat.
Remember: If an atrial premature beat comes too early and merges with its preceding U wave, it may falsely give the impression of atrial fusion.
Remember: interatrial block in the differential diagnosis of widened P wave.
Reference
Chou's Electrocardiography in Clinical Practice. Adult and Pediatric. 6th ed. Philadelphia. WB Saunders 2008:345-346.
ECG 1. The ECG above belongs to a middle-aged woman.
The fifth P wave from the left is an atrial fusion beat. This P wave is wider than a sinus P wave.
An atrial premature beat has merged with a sinus beat resulting in an atrial fusion beat.
Click here for a more detailed ECG
ECG 2a. The ECG above belongs to a 66 years-old man who had undergone coronary artery bypass grafting operation.
ECHOcardiography (ECHO) showed inferior and posterior hypokinesia (mild left ventricular systolic dysfunction).
Limb leads were recorded at a calibration of 20 mm/mV while chest leads were recorded at a standard calibration of 10 mm/mV.
Therefore, at first glance it may seem like the left ventricle is hypertrophic. However, ECHO didn't show hypertrophy.
At first glance, the second P wave from the right side seems like a wide P wave, suggesting the diagnosis of atrial fusion.
However, this P wave widening is due to fusion of the atrial premature beat with its preceding U wave.
Similar QU intervals from other leads support U-P wave fusion.
Click here for a more detailed ECG
ECG 2b. The above ECG belongs to the same man.
This time, it is recorded at a standard calibration of 10 mm/mV.
At first glance, the fourth P wave from the left seems like a wide P wave, suggesting the diagnosis of atrial fusion.
However, this P wave widening is due to fusion of the atrial premature beat with its preceding U wave.
Similar QU intervals from other leads support U-P wave fusion.
Click here for a more detailed ECG
ECG 3. The ECG above belongs to a 54 years-old man.
The second P wave in lead I may seem like a widened P wave suggesting atrial fusion at first glance.
However, checking other leads will show that it is due to baseline drift.
The amplitude of baseline drift is unacceptably high for a partial P wave depolarization.
Click here for a more detailed ECG