Which sites are commonly involved in atrial tachycardia?

• A. Crista terminalis, TV, CS os, Pulmonary Veins
• B. Atrial appendage, SA node, AV node
• C. Interatrial septum, fossa ovalis, mitral annulus
• D. Right atrial appendage, aortic valve, great cardiac vein

Answer: (D)

Atrial tachycardia is driven by ectopic atrial tissue outside the normal sinus node, so the arrhythmia can originate from focal areas where atrial myocardium is present or where muscular sleeves extend into adjacent structures. The right atrial appendage is a classic source because its wall is muscular and capable of automaticity, making it a common origin for focal AT. The aortic valve region is another plausible site because myocardial sleeves can extend into the aortic root, allowing ectopic impulses to originate near the aortic cusps. Likewise, the great cardiac vein lies close to left atrial tissue and can harbor atrial myocardial sleeves, providing another potential focus for AT. In practice, mapping that identifies the earliest activation at these sites guides targeted ablation, so including the right atrial appendage, the aortic root region, and the great cardiac vein reflects commonly encountered AT foci.