Asclepius and Yellow Ribbon techniques: Efficacious alternative strategies for advancing a coronary sinus electrophysiology catheter

Abstract Background Inserting an electrophysiological (EP) catheter into the coronary sinus (CS) via the femoral vein can be difficult and time‐consuming in patients with variants of the CS orifice or lumen curve. Our experience with such patients inspired us to develop two new techniques: the Asclepius and Yellow Ribbon techniques. Methods Data from a 4‐year period were retrieved from records of patients undergoing radiofrequency ablation for paroxysmal supraventricular tachycardia (PSVT) or Wolff–Parkinson–White (WPW) syndrome. Data were analyzed to determine the success and complication rates of conventional and alternative techniques for catheter placement. Results The success rate of the Asclepius technique was 96.7% (30/31) and that of the Yellow Ribbon technique was 100.0% (7/7). The overall success rate of these two techniques was 97.3% (37/38). Conclusions With a high success rate, shorter procedure time, and no complications, the Asclepius and Yellow ribbon techniques may be safe, inexpensive, and effective alternative strategies for EP catheter placement in patients with difficult coronary sinus orifice access.


| INTRODUC TI ON
The detection and recording of electrical signals is essential to the assessment of cardiac conduction for diagnosing cardiac dysfunction and planning treatment. Multi-electrode catheters are routinely used in clinical electrophysiological (EP) assessments. To assess the coronary sinus (CS) (the vein situated between the left atrium and left ventricle), a decapolar catheter is advanced through a central venous access. In our hospital, the catheter is typically inserted via the femoral vein rather than the internal jugular or subclavian vein to avoid complications such as pneumothorax or neck hematoma with airway compromise (Eisen et al., 2006;Parienti et al., 2015). Femoral access is also more acceptable to patients who are nervous about the neck insertion approach.
Occasionally, we encounter challenging variations in CS anatomy related to the vessel size, orifice direction, or lumen curvature (Mak, Hill, Moisiuc, & Krishnan, 2009;Mlynarski, Mlynarska, Tendera, & Sosnowski, 2011). These variants make advancement of the EP catheter tip more difficult owing to the fixed curve of the decapolar catheter. Difficulties in catheter advancement lead to prolonged operation time and greater radiation exposure. An alternative method involves the use of a steerable decapolar EP catheter. This device has ergonomic handling and a rotary dial designed for fine tip movements that allow for catheter advancement through challenging anatomy (Er, Yuksel, Hellmich, & Gassanov, 2015;Manolis, Koulouris, & Tsiachris, 2018). However, the steerable EP catheter is expensive, costing 17,189 New Taiwan Dollars (557 USD), 40% more than the fixed-curve decapolar EP catheter. As an alternative, we have developed two innovative, safe, and highly successful procedures, the "Asclepius technique" and "Yellow ribbon technique," for advancing the standard EP catheter into the CS.

| Subjects
This study was performed in a tertiary care center. We reviewed a total of 226 cases in 4 years from August 1, 2015 to July 31, 2019 involving catheter radiofrequency ablation in patients with paroxysmal supraventricular tachycardia (PSVT) or Wolff-Parkinson-White (WPW) syndrome. Difficulty was encountered with the CS approach in 38 of these cases (16.8%), prompting application of the Asclepius or Yellow Ribbon technique ( Figure 1). We compared the characteristics and outcomes between patients undergoing conventional and alternative insertion procedures (Table 1).

| Asclepius technique
Our newly developed Asclepius technique begins with the preparation of a fixed-curve decapolar EP catheter (French gauge 6) (Response, Abbot Laboratories, Chicago, IL, USA) for the CS, a fixedcurve quadrapolar EP catheter (French gauge 6) (Response, Abbot Laboratories) for the right atrium, and a steerable decapolar EP catheter (French gauge 6) (Livewire, Abbot Laboratories) for the HISright ventricle (HIS-RV). The angles of the fluoroscopy are 60 degree straight LAO. First, the HIS-RV steerable catheter was introduced into the CS. Once in position, we place the fixed-curve decapolar EP catheter with the tip toward the orifice of the CS. This second catheter then winded around the steerable catheter and up into the CS smoothly and quickly, resembling an Asclepius-the medical symbol depicting a snake winding around a staff ( Figure 2). Finally, we withdrew the steerable catheter from the CS and back into the HIS-RV (Video S1). The entire procedure takes no more than 5 min.

| Yellow Ribbon technique
The fixed-curve decapolar EP catheter was placed with the tip near the orifice of the CS. The catheter was then advanced around the right atrial chamber in a circle, until the tip, headed toward the end of the circle, spontaneously entered the CS. The shape of the tip movement through the process resembles a yellow ribbon ( Figure 3). The angles of the fluoroscopy are also 60 degree straight LAO. This procedure proceeds quickly and smoothly (Video S2).

| Statistical methods
Continuous variables are presented as the mean ± standard deviation (SD). The chi-squared test was used for categorical variables, and the independent samples Student's t test was used for continuous variables. All statistical analysis was carried out using SPSS 23 for Windows (IBM Corp.).

| RE SULTS
Alternative techniques were needed to insert the catheters in 38 of the patients. No significant differences in baseline characteristics were observed between those treated using alternative and con-   In the Yellow ribbon technique, the circumferential shape of the catheter tip movement returns the tip back to the starting point near the CS orifice, providing a better curve that takes shape naturally and strong support. As in the ancient Chinese martial art Tai Chi, taking advantage of the internal leverage of circular motion makes a forward pushing motion easier.

| LI M ITATI O N S
Theoretically speaking, those patients with right atrial dilation or enlargement are difficult for engagement of the CS to a certain extent, by using nonsteerable CS catheter as the original method. One of limitations in our retrospective study is lack of robust formal echocardiography report in each patients received the procedures. We just prove and assure that these new techniques provide a better cost-performance way to overcome some structural heart diseases such as atrial dilation or enlargement.
According to the rare case failure to apply such techniques, the possible causes lead to unworkable including extreme chamber size with CS orifice in sharp angle, anomaly of CS opening, or operator's technical experience.

| CON CLUS IONS
The Asclepius and Yellow Ribbon techniques are safe, cost-effective, and highly successful alternative strategies to facilitate catheter placement for electrophysiological assessments.

CO N FLI C T O F I NTE R E S T
The authors would like to thank the Ministry of Science and