Paroxysmal Atrial Tachycardia

Excerpt

Atrial tachycardia is a form of supraventricular tachycardia (SVT) usually seen in patients with structural heart abnormalities but can be seen in patients with structurally normal hearts. Unlike other SVTs, atrial tachycardia does not depend upon the atrioventricular junction or accessory pathways for initiation or maintenance.

Typical with most SVTs, atrial tachycardia exhibits a narrow QRS complex tachycardia. A narrow complex tachycardia is defined as a QRS complex <120 milliseconds. A compound this short illustrates the rapid activation of the ventricles, which indicates that the arrhythmia is originating above the ventricles.

Heart rates are highly variable in atrial tachycardia producing a rate usually between 100-250. The rhythms of atrial tachycardias are commonly regular, but irregular variants can be seen. P wave morphology is highly variable and can indicate the location and origin of the arrhythmia. The arrhythmias can originate in either the left or right atrium, superior vena cava and as well as some lesser common areas such as the hepatic veins and noncoronary aortic cusp. The basic anatomy of the heart is vital to consider the origins of reentrant circuits. The orifices of the vena cava, coronary sinus, and pulmonary veins are common anatomical sites where reentry can occur.