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    • br Discussion In the present report we describe a

    2019-06-26


    Discussion In the present report, we describe a technique for the cystic fibrosis chloride channel of a 6.0 Fr active fixation atrial lead in the inferior IAS using a 9.0 Fr GC. Previous studies have indicated that inferior IAS pacing significantly reduces paroxysmal AF burden and recurrence and slows the progression to chronic AF [1–5]. Moreover, compared to a tined lead, an active fixation lead is easier and safer to remove, when required. However, in certain cases, the insertion of an active fixation lead in the inferior IAS can be technically difficult and time-consuming, which may negatively impact its application in daily practice. De Voogt et al. recommended the use of a deflectable stylet (Locator™; St. Jude Medical Inc., St. Paul, MN) for screwing into the inferior IAS [12]. However, in our experience, during lead insertion into the inferior IAS, the deflectable curve remains very large in Japanese patients, and therefore, we routinely avoid using this procedure, as in the present case. Acosta et al. introduced a modified J-form stylet method [14]. However, of the first 36 patients who underwent this technique, immediate lead dislodgement was observed in six cases (16.7%), indicating that the procedure is particularly difficult to perform during the learning curve phase. To maintain the optimal position of the tip of the lead in the inferior IAS, both of these stylet-guided techniques require continuous counter-clockwise torque at the proximal tab of the stylet while maintaining the appropriate push pressure during fixation. However, this technique makes the subsequent screw-in maneuver with a pinch-on tool somewhat difficult and awkward. Moreover, fine adjustment of the tip location is also difficult. Thus, when we encounter difficulties, we have few choices except an alternative technique involving the insertion of a lead into the RAA despite the fact that this procedure does not have the merits of IAS pacing and it is potentially associated with subsequent cardiac perforation when compared with primary tined RA lead selection. The inferior IAS has a smooth-walled surface with irregularities formed by several important landmarks, including the coronary sinus ostium, Thebesian valve, sinus septum, Todaro tendon, Eustachian ridge, and infero-anterior rim of the oval fossa. Their alignment reflects the complex embryological development of this area, which is primarily derived from the primary atrial septum and vestibular spine, and is surrounded by sinus venosus posteriorly and inferior endocardial cushion anteriorly [15,16]. In addition, there are individual variations in the leaning angle of IAS, and the size and rotation of the RA. We believe that this anatomical complexity and variation around the inferior IAS is another factor contributing to the procedural difficulties. GC-guided fixation has several merits compared with conventional stylet-guided fixation. First, it does not require counter-clockwise torque both at the lead and the proximal tab of the stylet. Therefore, the screw-in maneuver is simple and smooth, and both the hands are free as no torque maintenance is required (Fig. 4). Second, it is not necessary to bend the stylet, and therefore, it is quite easy to transmit the proximal screw-in torque to the tip screw. Generally, in Japanese patients, a smaller and more acute curve for the stylet is required, as compared to the method proposed by Acosta et al. to deliver the lead to the optimal position around the inferior IAS. This prevents the transmission of the proximal screw-in torque to the tip screw with a one-to-one response. In certain cases, a few dozen repetitions of torque manipulation were required before the screw protruded from the outer lead. Third, firm fixation of the screw in the inferior IAS can be easily confirmed. A stylet-guided bare lead insertion has intrinsically poor back-up support. Occasionally, during the screw-in maneuver, the tip slips and becomes dislodged. However, due to the support provided by the GC, easy slipping of the lead against the smooth IAS surface is prevented, and it is not pushed back during the screw-in maneuver. As shown in Fig. 3c and d, screwing into the inferior IAS and firm fixation were clearly confirmed fluoroscopically by the protrusion of the screw from the tip of the GC, which attaches to the IAS. Finally, fine adjustment of the insertion location is easy because of the better intrinsic torque transmission and local fixation of the 9.0 Fr GC compared to those associated with the use of a stylet-guided bare lead.