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Patient
64-year-old man with a history of paroxysmal atrial fibrillation; consults for palpitations;
Trace
On this ECG, there is an initial atrial sinus activity with 2 premature atrial complexes (sharply modifying the T wave pattern); the QRS complexes following the premature beats are slightly altered with a right bundle branch block-type conduction aberration of varying degree; an apparently identical premature atrial complex (characteristic P-on-T pattern) initiates an atrial arrhythmia episode corresponding to an atrial fibrillation (very rapid, disorganized atrial activity);
Exergue
A particular type of premature atrial complexes (recognizable by their P-on-T pattern) plays a central role in the initiation and maintenance of atrial fibrillation episodes. This characteristic electrocardiographic pattern most often corresponds to foci localized in the ostium of the pulmonary veins.
This tracing shows an example of the triggering of an atrial arrhythmia by a premature atrial complex (occurring at the peak of the T wave) suggesting a focal origin. The determinants of the genesis and maintenance of atrial arrhythmias are complex, multiple and often linked.