Another Trick to Improve the Safety of Transseptal Puncture

Transseptal puncture of the interatrial septum was introduced in 1960 by Brockenbrough.¹ The technique relied on fluoroscopic landmarks to identify anatomical boundaries. The movement of the tip of the needle, which resembles a “jump” from the thicker muscular septum to the thin wall of the fossa ovalis, is an indirect but nevertheless important radiological sign of the position of the fossa that can be detected by experts without the need for adjunct imaging modalities.^2,3 Inoue further devised a specific transseptal puncture technique designed for the Inoue balloon percutaneous mitral valve commisurotomy, incorporating the concept of a vertical “mid-line,” a line assumed to divide the atrial septum into anteromedial and posterolateral halves.³ Some investigators proposed additional anatomical landmarks such as a pigtail catheter in the aorta (which requires arterial puncture), or, in case of electrophysiological studies, the use of His bundle or coronary sinus catheters as a reference.⁴ Transseptal puncture remains, however, a difficult procedure that is burdened by rare but serious, or even life-threatening complications. Situations of specific difficulty are when transseptal puncture is performed on patients with dilated atria, or with prior heart surgery when traditional landmarks change. Most of the complications occur in the periprocedural period.^2,5 A review of 1,279 transseptal punctures in a single center registry found a 90% overall success rate, with 1.2% life-threatening complications such as pericardial tamponade, systemic embolization, and aortic perforation.² Another single center study demonstrated a 91% success rate, with a complication rate of 0.7% for tamponade, 3.2% for systemic embolization, and 1.1% for aortic perforation.⁵ Various methods have been proposed as adjuncts to this purely angiographic method to identify the appropriate puncture site. Imaging techniques such as transesophageal and transthoracic echocardiography, intravascular ultrasound, and intracardiac echocardiography have all been successfully employed as a means of determining the optimal transseptal puncture site. Transthoracic ultrasound, however, may not be capable of accurately locating the thin wall of the fossa ovalis. In addition, this method is fairly uncomfortable to perform without violating sterility during the intervention.^6,7 Transesophageal echocardiography has proven to be a feasible method in this setting, but presents several disadvantages such as limited communication with the patient (as it may require the patient’s sedation), risk of esophageal bleeding, longer procedure time, and even inadequate location of the fossa ovalis in some cases.^2,8,9 Intracardial echocardiography provides a view of the fossa ovalis with 100% accuracy.^4,10–12 However, its high cost is limiting. Furthermore, it has been reported that the identification of the dilator tip is difficult;¹³ this last finding was not replicated in a more recent study.⁴ It is worth noting that the use of this imaging method has not shown to significantly alter procedure outcomes. Second, the use of this approach can be time-consuming in centers with a low volume of transseptal procedures. Moreover, it is not uniformly affordable, especially in third world countries where rheumatic mitral stenosis — the main indication of this procedure — is more prevalent. In this issue of the Journal, we read about a study which expands the existing body of literature on this topic. The authors propose a novel approach for transseptal puncture with the use of a 0.014 inch coronary guidewire through the Brockenbrough needle as a system for the advancement of the Mullins catheter to the left atrium. Adopting this simple approach, the operator is able to cover the tip of the needle by the guidewire, and thus safely advance the Mullins dilator to the left atrium. As the authors point out, after transseptal puncture, the most important problem is to determine whether the tip of the needle is in the left atrium. The method may be hampered by the fact that one cannot have simultaneous access to pressure waveforms. According to the current study, the visual estimate of the coronary guidewire using only frontal views is adequate to determine the precise puncture site. Along with the standard practices of pressure monitoring, contrast injection, and withdrawal of oxygenated blood from the Brockenbrough needle, the use of a 0.014 inch coronary guidewire can be added to our armamentarium as a device to identify the optimal position of the puncture site and enhance procedure safety. No matter which technique the operator decides to use, we should bear in mind that the risk of injury with the needle tip is minimized by: (a) proper positioning of the sheath tip, verified in two fluoroscopy views (anteroposterior and lateral); (b) application of gentle and controlled pressure while doing the needle puncture; (c) allowing only 2 to 3 mm of the tip of the needle to enter the left atrium; (d) further advancement of the sheath only after confirmation of left atrial entry (pressure, saturation and, if needed, contrast injection); (e) last but not least: always administer heparin after withdrawal of the needle and advancement of the dilator. Renewed interest in transseptal left heart catheterization has recently occurred due to the development of left side catheter ablation and the emergence of percutaneous technologies to treat mitral and aortic valve disease. We believe that it is imperative for the practicing cardiologist to be familiar with the concepts of this technique. In light of this observation, new techniques that help the practicing cardiologist perform a simple and safe transseptal puncture are welcome.

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