Case 1
A 50 year old woman had intermittent palpitations for several days and subsequently underwent electrophysiology study (EPS). Both right and left femoral veins were accessed but the diagnostic catheters could not be advanced to inferior vena cava (IVC). Venography revealed anomalous venous drainage of both femoral veins into azygous and hemiazygos veins with IVC agenesis. (Figure 1A and 1B). Owing to small lumen of azygos veins, only one decapolar catheter could be advanced through hemiazygos vein (via left subclavian vein to SVC) to the coronary sinus (CS). Programmed stimulation was done via coronary sinus pacing which confirmed the dual atrioventricular node conduction and subsequently induced AVNRT (Figure 1C). Another vascular access was established in the right internal jugular vein for the ablation catheter. His bundle signal was recorded and mapped using the 3-D mapping system (EnSite NavX system) (Figure 1D and 1E). Radiofrequency energy was applied over the low Koch area with transient accelerated junctional rhythm. Slow pathway was successfully eliminated and the tachycardia was no longer inducible after the ablation.