Paroxysmal atrial tachycardia (PAT) is associated with a number of findings on the electrocardiogram (ECG). The arrhythmia may be episodic (paroxysmal) or sustained.



(1) atrial rate

(2) P wave morphology

(3) ventricular rate and rhythm


Atrial rate: 100-250 beats per minute


P waves often have an abnormal morphology. At higher ventricular rates the P waves may be masked by the preceding T waves.


Ventricular rate: variable, depending on the degree of atrioventricular block. If there is no block, then the rapid ventricular rate may be associated with clinical symptoms (hypotension, altered mental status, heart failure, and/or chest pain).


Ventricular rhythm is usually regular, but may be irregular if the AV block is variable.


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