25 | Thoracic Key

PAROXYSMAL ATRIAL FIBRILLATION WITH PULMONARY VEIN TRIGGERS

Case presented by:

PASQUALE SANTANGELI, MD, LUIGI DI BIASE, MD, PHD, AND ANDREA NATALE, MD

A 62-year-old patient with weekly symptomatic episodes of paroxysmal atrial fibrillation (AF) after a previous failed ablation is referred for repeat catheter ablation. During the procedure, the intracardiac tracing shown in Figure 25.1 is recorded.

Figure 25.1. Intracardiac tracings during the procedure as well as the catheter location.

Question No. 1: What does the intracardiac recording show?

A.Sinus rhythm.

B.Premature atrial contractions arising from the distal coronary sinus (CS).

C.Premature atrial contractions arising from the left superior pulmonary vein (LSPV).

D.Both A and B.

E.Both A and C.

Discussion

Our approach at conventional intracardiac mapping during AF ablation involves placing a duo-decapolar catheter with the distal 10 poles in the CS and the proximal 10 poles along the high right atrium (HRA)/crista terminalis, and a decapolar circular mapping catheter within the PV antra.

During normal sinus rhythm, atrial activation begins from the HRA (more proximal poles of the 20-pole catheter), spreads toward the low-right atrium and then to the left atrium. The activation of the left atrium during normal sinus rhythm may occur through 3 different routes: (1) cranially through the Bachmann’s bundle (up to 70% of patients); (2) at the level of the fossa ovalis; or (3) caudally at the region of the triangle of Koch. Predominant left atrial activation through the Bachmann’s bundle can be demonstrated by distal CS activation (superior and lateral) preceding mid-CS activation (inferior and septal). On the other hand, predominant left atrial activation through the fossa ovalis/caudal right atrium is suggested by a proximal-to-distal activation of the CS.

In Figure 25.1, the first and third beats of the intracardiac tracing show normal sinus rhythm. The left atrial activation occurs predominantly at the level of the fossa ovalis/caudal right atrium. The contribution of the Bachmann’s bundle to left atrial activation in this patient cannot be well-evaluated, due to the position of the CS catheter, which is not advanced to cover the more lateral aspect of the atrioventricular (AV) groove (Figure 25.2).