16

Luigi Di Biase, MD, PhD; Jorge Romero, MD; Carola Gianni, MD, PhD;
Pasquale Santangeli, MD, PhD; Andrea Natale, MD1

Introduction

Long-standing persistent atrial fibrillation (LSPAF) is one of the most difficult arrhythmias to treat. Results are not yet satisfactory, although the outcomes improve after a more extensive ablation and repeated procedures. The approach utilized may influence the outcome. This chapter describes our approach for the treatment of LSPAF, which we have named the “Natale approach” because it reflects the approach followed by Dr. Natale and colleagues.

Preprocedural Management

All patients are required to undergo at least 4 to 6 weeks of effective thromboprophylaxis with oral anticoagulant therapy prior to the procedure. Warfarin or one of the new oral anticoagulants (NOACs), such as rivaroxaban or apixaban, is initiated in an outpatient setting; if warfarin is chosen, all patients receive weekly international normalized ratio (INR) monitoring during the 4 to 6 weeks preceding the procedure with a target INR of 2 to 3. If a NOAC is chosen, the patients should also be on anticoagulation for at least 4 weeks before ablation. We currently do not perform AF ablation while patients are on dabigatran since the use of periprocedural dabigatran has been associated with increased risk of bleeding or thromboembolic complications compared with uninterrupted warfarin therapy in patients undergoing AF ablation.¹ If a patient is on this NOAC, we routinely switch them to another NOAC drug for the periprocedural period. We will probably reevaluate our practice after the results of the randomized controlled trial (The RE-CIRCUIT Trial) comparing dabigatran to warfarin are published (NCT02348723). However, the trial will mostly include patients with paroxysmal AF. Therefore, the safety of uninterrupted dabigatran in patients with nonparoxysmal AF will still remain controversial. We do not discontinue warfarin or NOACs before the procedure, and we do not bridge with low-weight or unfractionated heparin.^2–9 The last dose of NOACs is taken the morning of the procedure for apixaban and the night prior to the procedure for rivaroxaban.

Preprocedural transesophageal echocardiography (TEE) is not routinely performed unless patients cannot show a history of therapeutic INR in the 4 to 6 weeks preceding the procedure in the case of warfarin or are subtherapeutic on the day of the procedure. Likewise, TEE is usually performed only if a dose of the NOAC has been missed. All patients are type and cross-matched, and packed red blood cells, fresh frozen plasma, and prothrombin complex concentrate are made available for infusion in case of hemorrhagic complications. If the preprocedural INR is above 3.5, we partially reverse the anticoagulant effect with 1 or 2 units of fresh frozen plasma. In a large cohort study including patients with persistent and LSPAF, this approach has been proven to significantly decrease the risk of bleeding and thromboembolic complications when compared to warfarin discontinuation and bridging with low-molecular-weight heparin.^3,10,11 Antiarrhythmic drugs are discontinued 3 to 5 days prior to the ablation.^3,10,11 Amiodarone is discontinued 4 to 6 months prior to the procedure; patients are usually switched to dofetilide, which is discontinued 5 days before the procedure. Periprocedural continuous amiodarone has been associated with higher organization rate and lower radiofrequency ablation rate, suggesting that its use may be masking triggers outside the pulmonary veins (PVs), leading to an increased late recurrence rate.¹²

Preoperative cardiac computed tomography (CT) scan or magnetic resonance imaging (MRI) for imaging of PVs is generally performed only in patients undergoing “redo” procedures unless a history of congenital heart disease is known. Postoperative CT or MRI scan is performed in the majority of patients at the 3-month follow-up.13,14

Anesthesia Protocol

All patients undergo ablation under general anesthesia. Anesthesia is initiated with propofol (2 mg/kg) and fentanyl (1 to 2 mg/kg), followed by a neuromuscular blocking agent (usually rocuronium 0.6 to 1 mg/kg) and by endotracheal intubation with intermittent positive-pressure ventilation. Nevertheless, paralytic agents are strongly discouraged in order to localize right phrenic nerve prior to delivering radiofrequency (RF) ablation. An esophageal probe is inserted in all patients to monitor esophageal temperature during ablation.¹⁵ We do prefer general anesthesia using IPP rather than Jet ventilation due to the more complexity and risks of the latter.

Instrumentation for Electrophysiological Study

After anesthesia induction, two right groin femoral accesses (8-F sheath) are used to perform a double transseptal catheterization. For the physicians who are concerned about the risk of vascular injury while inserting sheaths under full anticoagulation, ultrasound guidance (Figure 16.1) might be useful as well as the use of micropuncture needle. In addition, cannulation of the right internal jugular vein can be performed with the use of a mapping catheter or a wire advanced into the superior vena cava (SVC) as a marker for the vein access during fluoroscopy (Figure 16.1) and with the use of ultrasound guidance. Left femoral venous access is obtained with an 11-Fr venous sheath to insert a 10-Fr 10 MHz phased-array ultrasound imaging catheter (SOUNDSTAR Ultrasound Catheter, Biosense Webster, Diamond Bar, CA) in the right atrium under fluoroscopic guidance. The intracardiac echocardiography (ICE) catheter is positioned in the mid-right atrium. Clockwise rotation of the ICE catheter provides posteriorly directed views. Therefore, clockwise torque to the ICE catheter brings into sequential view the aortic arch (more anterior), followed by the anterior left atrium (LA), mitral valve and LA appendage (LAA), the left PVs, the posterior wall, and the right PVs. The intra-atrial septum (IAS) is always visualized in the near-field; if the IAS is too close to the probe, gentle bending of the transducer toward the RA free wall moves the imaging plane of the septum toward the mid-field of view (Figure 16.2). Prior to performing transseptal puncture, the left atrial anatomy is constructed using CARTOSOUND. A 20-mm decapolar circular mapping catheter is used for mapping the LA (Lasso, Biosense Webster), and a 3.5-mm open irrigated-tip ablation catheter is used for ablation. Before transseptal access, all patients received a heparin bolus, and extra heparin boluses are administered to maintain the activated clotting time (ACT) greater than 350 seconds.⁹

LA access is obtained with a double transseptal puncture (see Chapter 12). Briefly, a long 0.032-inch J guidewire is advanced via the right groin venous access to the SVC at the level of the tracheal carina under fluoroscopic guidance. A long transseptal sheath (LAMP 90° 8.5-Fr, (St. Jude Medical, St. Paul, MN), for the first transseptal and SLO 50° 8.5-Fr (St. Jude Medical), for the second transseptal) is advanced over the wire to reach the tracheal carina; the long wire is withdrawn and the sheaths are continuously flushed with heparinized saline. During this stage, we usually administer a bolus of unfractionated heparin (10,000 units in males and 8000 units in females on warfarin). Not surprisingly, it has been well demonstrated that patients on NOACs require higher dose of heparin to reach ACT > 350 seconds (i.e., 15,000 units in males and 12,000 units in females).^16,17 To maintain an ACT > 350 seconds, an additional heparin bolus may be administered. It is imperative for our approach that the heparin bolus is administered before the transseptal access is performed.

A flushed Brockenbrough transseptal needle armed with its stylet or the Baylis needle is then introduced into the sheath and advanced to within 2 to 4 cm of the tip of the dilator. When a Brockenbrough needle is used, the stylet is removed and the needle is flushed with heparinized saline and radiopaque contrast. The entire system is gently withdrawn under fluoroscopic left anterior oblique (LAO) or anteroposterior views, with the arrow-shaped handle of the needle usually oriented at between 4 and 6 o’clock. Correct positioning of the tip of the apparatus in the fossa ovalis for puncture is assessed by fluoroscopic visualization of a second “jump” into the septum (most easily assessed in the LAO projection), and definitely confirmed by ICE imaging. Once the correct trajectory is confirmed, the entire system is gently advanced to obtain tenting of the fossa ovalis; therefore, the needle is advanced to further tent the IAS (Figure 16.2).¹⁸ Usually, the needle crosses the fossa ovalis applying a gentle pressure, and a small injection of contrast or normal saline is sufficient to confirm the LA access with ICE. In cases of thickened or hypertrophied IAS resistant to transseptal puncture (such as the cases of lipomatous degeneration or postcardiac surgery patients), RF energy application to the external end of the needle during septum tenting is of invaluable aid to access the LA. This is usually performed applying energy at the hub of the needle through an electrocautery in the “cut” modality or using the Baylis needle (Radiofrequency NRG® Transseptal Needle) ( Videos 16.1 and 16.2).

Once LA access has been confirmed by ICE imaging (1 second after RF energy application), the dilator is advanced over the needle and the sheath is advanced over the dilator to finally reach the LA. At this stage, the needle and dilator are removed, and the sheath is accurately aspirated and flushed with heparinized saline.

The best sites for transseptal puncture can only be assessed with ICE guidance to facilitate catheter maneuverability in the LA. A more anterior stick is usually performed for the first transseptal access (LAMP sheath), in which the circular mapping catheter is inserted; a more posterior stick, facing the left PVs where the distance from the aortic root and the posterior LA wall is maximal, is performed for the second stick, in which the open irrigated ablation catheter is inserted (SLO sheath).

The PV antra include the entire posterior wall between the PVs and extend anteriorly to the right PVs along the left side of the IAS. Given that, the endpoint of the procedure is the complete elimination of local potentials that can be assessed only by means of circular catheter mapping (Figures 16.3 and 16.4). RF energy is delivered with a power control mode (40 W up to 45 W) (down to 35 W for posterior wall) with a maximum temperature setting of 30°C using the standard SF and the new SF SmartTouch catheter (Biosense Webster). Both catheters deliver RF ablation with a flow rate of 15 cm3/min. Alternatively, the SmartTouch catheter can be used with the same parameters but a higher flow rate at 30 cm3/min. Of notice, the power is titrated based on the measured contact force. Therefore, when contact force is below 10 grams power is increased up to 45 W. Importantly, we limit each RF application per ablation site to 10–15 seconds. At the posterior site close to the esophagus, energy delivery is discontinued when the esophageal temperature probe has a rapid increase and reaches 39°C, while the power is reduced if the temperature slowly increases.

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