The Guidewire Technique for Transseptal Puncture

The determination of the puncture point in the frontal view by atrial angiography. Left panel, frontal view of right atriography. Radio-opaque ruler is seen (small arrow). Y1 means the top of the tricuspid ring at systole. X1 means the same point of horiz
The point of septal puncture in the frontal fluoroscopic view. The point (white arrow in left panel and filled ellipsoid in right panel), that is determined by the method described in Figure1, is easily recognized by the fluoroscopic landmark of the radio
The intraatrial septum of enhanced CT image. Left panel, appropriate section for showing the atrial septum. Right panel, schematic presentation of the same image in left panel.
The angle of Brockenbrough needle indicator is directly related to the angle of intraatrial septum (IAS) of enhanced CT image in Figure 3. This figure shows that the angle of the stopcock (5’clock) (right panel) is same with the angle between postero-ante
(A) Right panel; the tip of Brockenbrough needle is just inside left atrium. (B) Left panel; after the gentle pushing of the guidewire, it advances to the left superior pulmonary vein without resistance.
Author(s): 

Seiichi Haruta, MD, Hiroki Kouno, MD, Hiroshi Akanuma, MD, Hiroyuki Ichinose, MD, Tadayuki Shimakura, MD

Transseptal puncture has recently been a very important therapeutic technique in the treatment of mitral stenosis1,2 and radiofrequency ablation of a left-sided accessory pathway.3 It has increased in importance since ablation for atrial fibrillation is performed in the left atrium by this technique. However, occasional puncture of the atrial free wall may result in bleeding into the pericardial space, which limits this method and increases the difficulty in mastering this technique. We present an improved method for the transseptal approach using a guidewire technique.

Methods
Patients. Eight patients were included in this study from October 1997 to October 1998. We performed percutaneous tranvenous mitral commissurotomy (PTMC) in all of the patients. One patient had PTMC and ablation for left Kent bundle at the same time. All patients provided written informed consent.
Visual identification of puncture point. A radio-opaque ruler was placed between the patient’s back and the angiographic table as a reference marker for the puncture site (Figure 1). Right atriography was performed with 30 ml of contrast media following opacification of the pulmonary artery, pulmonary vein, left atrium, left ventricle, and ascending aorta.
The puncture site was determined by the method described by Inoue et al.4 They supposed an X-Y axis on the frontal plane of the right atriography (Figure 1). The Y point (longitudinal axis) of the septal puncture site was about two-thirds the length of a vertebral body height from the bottom of the left atrium. The X point (horizontal axis) was determined to be at the middle point between the right edge of the right atrium and the top of the tricuspid ring at systole. The puncture site was easily recognized in relation to the radio-opaque ruler (Figure 2).
Preparing the guidewire. We used a 70 cm curved Brockenbrough needle (USCI, Billerica, Massachusetts) and a 0.014 inch PTCA guidewire. Various types of 0.014 inch guidewires were able to be inserted into the stopcock lumen of the needle with an introducer. Before the procedure, we tried to move the guidewire through the sharp edge of the needle two or three times, and obtained confirmation of safety.
For the Inoue technique, a Mullins dilator alone was advanced to the junction of superior vena cava and right atrium over a 0.032 inch Terumo J guidewire from the right femoral vein. After removing the 0.032 inch Terumo guidewire, the Brockenbrough needle with a 0.014 inch guidewire was advanced through the Mullins dilator. To avoid perforation of the dilator wall during needle advancement, we protruded the 0.014 inch guidewire slightly beyond the tip of the needle and moved the needle-wire combination through the Mullins dilator. The septal puncture was then performed by pulling the 0.014 inch guidewire slightly below the tip of the needle.
The angle of the needle-base indicator. The angle of the needle was determined by using dimensions from a previous contrast-enhanced CT scan of the left atrium, which we also used to determine the presence of thrombus. The most appropriate CT slice of the left atrium was the plane that showed the longest length of the atrial septum. Figure 3 shows the usual pattern of the atrial septum. The angle of the puncture needle was then determined simply as the perpendicular angle of the atrial septum. In this case, the 5 o’clock position was indicated (Figure 4).
The guidewire technique. After transseptal puncture with the needle, the operator advanced the guidewire slowly (Figure 5A). When the needle did not enter the left atrium, the guidewire would not change in position at the tip of the needle. When the operator felt resistance in advancing the guidewire from the tip of the needle, he had to pull back the needle into Mullins dilator and re-attempt the transseptal puncture. When the tip of the needle was in the left atrium, the guidewire slipped into the left atrium smoothly. It was easy to confirm that the guidewire entered the left atrium (Figure 5B).
When the guidewire passed through the atrial septum into the left superior pulmonary vein, the operator had to advance the needle and the dilator as a unit into the left atrium over the guidewire. When the Mullins dilator slipped inside the left atrium, both the needle and guidewire could be pulled back together.

Results
We performed this transseptal technique successfully in all eight patients for percutaneous transvenous mitral valvuloplasty and in one patient for radiofrequency ablation. All procedures were performed without complication.
Previously, we had performed the successful insertion of a guidewire into the left atrium following the needle puncture in 1 patient, but we failed to advance the Mullins dilator alone along the needle and bend of the guidewire at the atrial septum. In this case, we were able to pull back the apparatus to the inferior vena cava without difficulty and able to re-attempt septal puncture with a new guidewire. After this episode, when the guidewire entered the left atrium smoothly, we decided that we should advance the needle-dilator combination over the guidewire until the dilator entered the left atrium. By this method, the advancement of the Mullins dilator into the left atrium was smooth and safe.

Discussion
Although the precise positioning of the puncture site is the basic technique of septal puncture, the previous method of feeling the fossa ovalis by sliding the needle-dilator unit is difficult to learn. In particular, the right or left atrium is dilated as in the case of mitral stenosis. There have thus been many reports on determining the proper puncture site using the transseptal approach.
The echocardiographic approach by either the transesophageal method5 or intravascular method6 may confirm the fossa ovalis more accurately. The tenting sign by the needle is reliable, especially if the left atrium is small. However, transesophageal echocardiography requires expertise in echocardiography in the catheterization laboratory.7 Furthermore, this method is very uncomfortable for the patient without sedation. On the other hand, intravascular echocardiography is costly. Furthermore, the best puncture site for the Inoue technique is usually not the point of the fossa ovalis. Since the most suitable puncture site of the large left atrium is usually below the fossa ovalis,6 the puncture must be carried out through the proper part of the atrial septum to allow easy access to the mitral valve orifice.
Our method, using only frontal fluoroscopic views to determine the precise puncture site, has many advantages compared with the echocardiographic method. First, the patient usually has a large left atrium, so the puncture window determined by angiography is very wide. Second, the operator will be able to concentrate the fluoroscopic image. Third, the radio-opaque ruler and the patient’s spine are usually fine landmarks of the frontal fluoroscopic view when employing our method. The inexperienced operator can safely move the needle-dilator unit into the supposed puncture point. Since the puncture site is a three-dimensional configuration, the Z-axis is the angle of the Brockenbrough needle-base indicator. We described that this Z-axis is simply determined by enhanced CT.
After transseptal puncture by needle, it is essential to determine whether the tip of the needle is in the left atrium. Pressure monitoring, contrast injection, and withdrawing oxygenated blood from the Brockenbrough needle are all standard techniques to confirm the needle’s position. However, following confirmation of successful puncture, it is necessary to advance the needle-dilator unit into the left atrium without injury to the left atrial structures. To avoid these injuries, repeated injections of contrast media may be helpful. However, holding the needle so that it does not advance forward and placing the injector to the stopcock or pulling the injector, are very dangerous maneuvers.
The operator will have two advantages if the guidewire, which is already in the needle, is utilized. First, successful left atrial puncture can be confirmed by simply advancing the guidewire. If the tip of the needle is not in the left atrium, advancing the guidewire is impossible. Second, the needle-dilator combination is safely advanced into the left atrium over the guidewire. For the Inoue balloon technique, since the target atrial septum of the large left atrium may be thick, it would be very difficult to advance the Mullins dilator alone into the left atrium over the needle. Thus, we often advance the needle-dilator unit in small increments to penetrate the atrial septum. However, it is dangerous if the needle injures the other cardiac structure. On the other hand, the presence of the guidewire will prevent this complication since the radio-opaque guidewire in the left atrium is the hallmark for the distance from the left atrial wall. Furthermore, it is particularly useful in a small atrium to avoid perforation of the upper wall of the left atrium.
The cardinal point of this procedure is the smooth advancement of the guidewire into the left atrium. If the operator feels any resistance upon advancing the guidewire, the needle must be pulled back into the Mullins dilator.
Conclusion. The Brockenbrough technique is revised by this guidewire technique through the Brockenbrough needle. Since the operator is able to cover the dangerous tip of the needle by a guidewire, the sharp edge of the needle is advanced only once through all procedures, which is when the Mullins dilator is placed at the target point. Successful atrial septal puncture is very easy to confirm and the advancement of the Mullins dilator-needle combination is not only smooth, but also safe when employing this guidewire technique.


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