You get what you inspect, not what you expect: can we make the transseptal puncture safer?

Abstract

Progress in the field of catheter ablation for atrial fibrillation has resulted in a renaissance of the technique of transseptal (TS) catheterization. Conventionally, the procedure is performed under fluoroscopic guidance and pressure monitoring. In experienced hands, various modifications of this method have a reasonable safety profile. However, serious complications such as cardiac tamponade (1.31%) or aortic perforation can still occur 1 and can lead to death (0.15%). Even in a more recent, large Italian survey on 5520 TS procedures performed between 1992 and 2003 at 33 centres, some severe complications were reported. 2 Although the complication rate was low (0.79% in 2003 and 0.74% in the previous years), one death was described. To reduce the incidence of such complications, TS puncture can be done under transoesophageal echocardiography (TEE) or intracardiac echocardiography (ICE) guidance. 3,4 Transoesophageal echocardiography in these settings necessitates a higher level of sedation and is often poorly tolerated. Intracardiac echocardiography requires an additional expertise and significantly increases the cost of the procedure. Mitchell-Heggs et al. 5 describe an alternative TEE technique to guide the TS puncture during atrial fibrillation ablation procedures using an ICE catheter introduced transnasally into the oesophagus. This technique was well tolerated and successfully performed in all 79 successive patients without any sedation. Insertion of the catheter was without any mechanical complication and TS puncture was successful and uneventful. The mean duration between the probe insertion and successful TS puncture was 4.5 min and the mean time of ICE in the oesophagus was only 10 min. The authors have concluded that the technique is safe and well tolerated. They recommend it for widespread use, especially due to its good value for money. At first sight, this report may not be so appealing for the electrophysiology community. However, it is an important online imaging strategy which can be used during complex interventions to maximize safety and efficacy. The use of echocardiographic guidance for TS puncture allows direct visualization of the tip of the TS needle within the fossa ovalis and thus, a safe TS puncture in every patient. In this respect, there seems to be no difference between the TEE and ICE approach. Our retrospective analysis of 1692 TS punctures guided by ICE between 2006 and 2009 revealed no complications associated with the puncture (unpublished data). This provides indirect evidence that the use of online imaging may increase the safety of the procedure, especially in anatomical variants of the intraatrial septum that make the procedure challenging (e.g. lipomatous hypertrophy, septal aneurysm, thick septum, or double membrane fossa, etc.). The safety of the echocardiographically guided TS puncture supports the use of a double TS access to prevent interference between the mapping and ablation catheters and to achieve greater mobility and manoeuvrability in the left atrium. It is also important to emphasize that the use of echocardiographic guidance enables selection of the site of the puncture within the fossa ovalis according to the expected type of the procedure (e.g. more anterior puncture for ablation of an accessory pathway at the mitral annulus or for ablation of ventricular tachycardia vs. a lower and more posterior puncture for ablation of atrial fibrillation). Although it is difficult to quantify the benefit of such a selective TS puncture, our experience has shown that even ,1 cm difference in the location of the puncture site can make a significant difference in manoeuvrability of the mapping and/or ablation catheter (Figure 1). This seems to be even more important when using ‘one-size-fits-all’ devices such as a cryoballoon or laser balloon. Today, we use an ICE-guided TS puncture even in cases of a patent foramen ovale since it allows us to optimize puncture in the lower and more posterior portion of the fossa ovalis. A group from Bordeaux has clearly documented that isolation of the pulmonary veins performed via a patent foramen ovale is more difficult, both for the left- and right-sided pulmonary veins. 6 Very superior and anterior location of the foramen ovale changes the radial movement of the catheter entering the left atrium and impedes the manipulation around the pulmonary veins. This results in less accurate positioning of the catheter and its greater instability. Although the authors did not