𝐀𝐧𝐚𝐭𝐨𝐦𝐢𝐜 𝐚𝐩𝐩𝐫𝐨𝐚𝐜𝐡 𝐭𝐨 𝐬𝐥𝐨𝐰 𝐩𝐚𝐭𝐡𝐰𝐚𝐲 𝐚𝐛𝐥𝐚𝐭𝐢𝐨𝐧 𝐢𝐧 𝐀𝐕𝐍𝐑𝐓.

𝐀𝐧𝐚𝐭𝐨𝐦𝐢𝐜 𝐚𝐩𝐩𝐫𝐨𝐚𝐜𝐡 𝐭𝐨 𝐬𝐥𝐨𝐰 𝐩𝐚𝐭𝐡𝐰𝐚𝐲 𝐚𝐛𝐥𝐚𝐭𝐢𝐨𝐧 𝐢𝐧 𝐀𝐕𝐍𝐑𝐓. 

The septal aspect of the tricuspid annulus from the CS ostium to the His bundle is divided in posterior (Post), mid (Mid), and anterior (Ant) sections (from the RAO view). The ablation catheter is initially placed in the posterior section and RF applications are started here. Successful ablation may require progressive advancement of the ablation catheter to the mid and then to the anterior sites with increased risk of AV block in the more superior and anterior sites.

The anatomic method targets the slow pathway region in the right atrial posteroseptum, guided by fixed landmarks rather than detailed electrogram criteria.

Key Anatomical Landmarks

1. Triangle of Koch — the critical map:

Apex: His bundle region

Base: Ostium of the coronary sinus (CS)

Septal leaflet of the tricuspid valve (TV) forming the third border

2. Slow pathway zone:

Located inferior and posterior to the His region

Typically around the posterior third of the triangle near the CS ostium

Target Site (Preferred Ablation Region)

Inferior/posterior part of the Triangle of Koch, between:

the CS ostium,

the tricuspid annulus, and

just inside the Eustachian ridge area.

This region often shows A < V electrograms but EGM quality is not mandatory in the pure anatomic technique.

Technical Steps

1. Place His catheter to mark the apex (avoid ablation too close).

2. Engage CS catheter to define the base.

3. Position the ablation catheter just anterior (septal) to the CS ostium, sliding slightly upward if needed.

4. Deliver RF energy at 30–50W (temp-limited if using older generators).

5. Watch for:

Accelerated junctional rhythm → indicates correct slow pathway modification.

Avoid prolonged AV block—stop if VA dissociation or PR prolongation occurs.

Endpoints

Non-inducibility of AVNRT (with/without isoproterenol).

Preserved fast pathway conduction (normal AV conduction).

Occasional single echo is acceptable if no sustained tachycardia.

Advantages of Anatomic Approach

Faster

Less mapping-dependent

Very high success (≈95%)

Extremely low AV block risk when targeting the posteroinferior zone