3D mapping for the identification of the fossa ovalis in left atrial ablation procedures: a pilot study of a first step towards an electroanatomic-guided transseptal puncture

AIMS

Transseptal puncture (TP) for left atrial (LA) catheter ablation procedures is routinely performed under fluoroscopic guidance. To decrease radiation exposure and increase safety alternative techniques are desirable. The aim of this study was to assess whether right atrial (RA) electroanatomic 3D mapping can reliably identify the fossa ovalis (FO) in preparation of TP.

METHODS AND RESULTS

Between May 2019 and August 2019, electroanatomic RA mapping was performed before TP in 61 patients with paroxysmal or persistent atrial fibrillation. Three electroanatomic methods for FO identification, mapping catheter-induced FO protrusion, electroanatomic-guided analysis, and voltage mapping, were evaluated and compared with transoesophageal echocardiography (TOE). Mapping catheter-induced FO protrusion was feasible in 60 patients (98%) with a mean displacement of 6.8 ± 2.5 mm, confirmed by TOE, and proofed to be the most valuable and easiest marker for FO identification. Electroanatomic-guided analysis localized the FO midpoint consistently in the lower half (43 ± 7%) and posterior (18.2 ± 4.4 mm) to a line between coronary sinus and vena cava superior. Analysis of RA voltage maps during sinus rhythm (n = 40, low-voltage cut-off value 1.0 and 1.5 mV) allowed secure FO recognition in 33% and 18%, only. A step-by-step approach, combining FO protrusion (first step) with anatomy criteria in case of protrusion failure (second step) would have allowed for the correct localization of a TP site within the FO in all patients.

CONCLUSION

Right atrial electroanatomic 3D mapping prior to TP proofed to be a simple tool for FO identification and may potentially be of use in the safe and radiation-free performance of TP prior to LA ablation procedures.

Subxiphoid left atrial ablation for atrial fibrillation

Atrial fibrillation is becoming a disease that needs to be addressed with definitive long-term treatment as opposed to medical management options. Ablation or isolation of focal triggers around the pulmonary veins can eliminate arrhythmia substrates for patients with paroxysmal, lone atrial fibrillation. However, limited pulmonary vein isolation strategies do not address reentrant circuits common in persistent and longstanding persistent patients with structural heart disease and enlarged atria.  The convergent procedure is a hybrid ablation treatment for atrial fibrillation. It consists of surgical ablation of the posterior left atrium through a minimally invasive closed-chest approach followed by endocardial catheter ablation. The convergent procedure was developed to treat atrial fibrillation by creating a complete and comprehensive pattern of linear lesions on the left atrial backwall under direct endoscopic visualization while avoiding chest incisions and deflation of the lungs. Endocardial ablation follows the epicardial procedure to confirm lesion integrity and supplement the epicardial procedure, which is performed in a staged fashion.

P-wave pseudonormalization after iatrogenic coronary sinus isolation

We report a case of a 58 year old gentleman with prior history of catheter ablation for persistent atrial fibrillation (AF). His baseline ECG showed sinus rhythm with a broad and notched P-wave in lead II and biphasic P-wave (positive/negative) in leads III and aVF previously described as advanced interatrial block. A redo ablation procedure was performed due to AF recurrence. An iatrogenic isolation of the coronary sinus (CS) was observed during ablation with marked narrowing and loss of the terminal negative component of the P-wave on the surface ECG.