Ebook Practical approach to catheter ablation of atrial fibrillation: Part 2

(BQ) Part 1 book Practical approach to catheter ablation of atrial fibrillation presents the following contents: Ablation procedures (circumferential atrial ablation, electrogram guided ablation, tailored approach to ablation,...), ablation strategies (emerging technologies, identification and elimination of ancillary arrhythmias, complications, the challenges of monitoring outcomes,...).

PART

Ablation Procedures

Recent studies have demonstrated that myocardium around the pulmonary vein(PV) ostia plays an important role in the initiation and perpetuation of atrial fibril-lation (AF) (1) This important finding has led to the development of segmental PVostial isolation (2,3), circumferential ablation (4), or isolation around the PVsguided by 3-D electroanatomic mapping (5) Also, substrate modification with theuse of limited linear ablation (such as roof line and left isthmus line) (6,7) or abla-tions of the areas associated with complex fractionated electrograms (8,9) havebeen demonstrated to improve the clinical outcome after PV isolation in patientswith AF inducibility

The method most used in the majority of ablation centers is PV isolation eitherusing segmental PV isolation or circumferential complete PV isolation guided by 3-Dmapping In these procedures the Lasso catheter recording within the PV plays animportant role in identifying electrophysiological connections between the PV andthe left atrium (LA) Also, electroanatomic mapping provides more precise infor-mation on the anatomy of atrial chambers and contributes to shorter fluoroscopictime

In this chapter we describe our circumferential ablation technique for PV tion guided by the Lasso catheter and electroanatomic mapping in patients withparoxysmal or persistent AF

isola-137

Feifan Ouyang Kazuhiro Satomi

Complete PV Isolation Using 3-D Mapping and Lasso Technique

The ablation procedure is routinely performed under sedation with a continuousinfusion of propofol in our center Transesophageal echocardiography (TEE) is per-formed in all patients to rule out LA thrombi Anticoagulation treatment with war-farin is stopped on admission and replaced by intravenous heparin to maintain partialthromboplastin time at two to three times higher than the control value in allpatients All procedures consist of the steps described below (5,10,11)

Transseptal Puncture

Three 8F SL1 sheaths (St Jude Medical, Inc., Minnetonka, MN) are advanced to the

LA by a modified Brockenbrough technique in the majority of patients: two sheathsover one puncture site and the third sheath via a second puncture site One puncture

is always performed at the inferoposterior site of the foramen ovale for easy access tothe right inferior vein and the atrial myocardium (Fig 9.1) After transseptal catheter-ization, intravenous heparin is administered to maintain an activated clotting time of

250 to 300 seconds Additionally, continuous infusions of heparinized saline are nected to the transseptal sheaths (flow rate of 10 mL/h) to avoid thrombus forma-tion or air embolism

con-LA Reconstruction

Electroanatomic mapping is performed with a 3.5-mm-tip catheter (ThermoCoolNavi-Star or ThermoCool, Biosense-Webster, Inc., Diamond Bar, CA) during coro-nary sinus (CS) pacing, sinus rhythm (SR) or AF by using the CARTO system

138 Part IV ■ Ablation Procedures

Figure 9.1. The right and left images show, respectively, fluoroscopic right and left anterior oblique views

(LAO and RAO) during transseptal puncture One puncture is always performed at the inferoposterior site

of the foramen ovale for easy access to the right inferior vein and the atrial myocardium CS, coronary sinus; His, His bundle; RA, right atrium.

(Biosense-Webster, Inc.) or the NavX system (St Jude Medical, Inc.) Mapping isonly performed in the LA; all mapping points deep within the PV must be deleted toensure that the posterior wall is flat in the right lateral and left lateral views (Fig 9.2)during ablation.

Selective Venography of PV and Identification of PV Ostium

After LA reconstruction, each PV ostium is identified by selective venography(Fig 9.3) and carefully tagged on the electroanatomic map We arbitrarily defined

Figure 9.2. The left upper and lower images show right lateral and left lateral 3D-MR views of the LA The dle and right images show, respectively, electroanatomic maps of the LA in the right lateral and left lateral view before

mid-and after correction of map in same patient The PV ostia (identified by angiography) are tagged by white dots Note that (a) in the MR imaging view the ostium of the right superior pulmonary vein (RSPV) are more anterior than the ostium of the right inferior pulmonary vein (RIPV); (b) in the original map (middle images) the LA posterior wall

is not flat due to many mapped points within the right- and left-sided PVs, whereas in the corrected map in the right images the LA posterior wall is very flat after the deletion of the points within the PVs on both sides; (c) the ante- rior wall is prominent due to points obtained with excessive pressure on the LA anterior wall in the original map in the middle image, whereas the anterior wall is smooth after the deletion of these points in the corrected map in the right image RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pul- monary vein; LIPV, left inferior pulmonary vein See color insert 2.

any point with clear PV-LA inflection and marked the opposite points with dicularity to the PV on the right anterior oblique (RAO) 30 or left anterior oblique(LAO) 40 (Fig 9.2) This step is the most important part to achieving a successful

perpen-PV isolation In our experience, the misunderstanding of the perpen-PV ostium may times make the ablation more difficult or create a potential risk for PV stenosis Forexample, the isolation of the left-sided PVs in the setting of a narrow ridge betweenthe left atrial appendage and the left PVs can be very difficult if the anterior edge ofthe left PV ostia is inappropriately marked in the left atrial appendage On the otherside, severe PV stenosis can be produced if the PV ostium is tagged inside the PVs(12,13)

some-140 Part IV ■ Ablation Procedures

Figure 9.3. The images show, respectively, fluoroscopic right and left anterior oblique views (RAO and LAO) of the left atrium The PV ostia are marked by points The lines indicate the ablation line around the right-and left-sided PVs CS, coronary sinus; RSPV, right superior pulmonary vein; RIPV, right infe- rior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein.

Double Lasso Technique

Two decapolar Lasso catheters (Biosense-Webster, Inc.) are placed within the eral superior and inferior PVs or within the superior and inferior branches of a common

ipsilat-PV before radiofrequency (RF) delivery in the majority of patients with AF (Fig 9.4)

In our series of more than 1,300 AF ablations, in only 2% of patients could only oneLasso catheter be placed in the PVs due to very difficult transseptal puncture ormanipulation of the sheaths

The Lasso catheters within the ipsilateral PVs should be located with the catheterplaced in a stable position to obtain a good signal during the procedure If the Lassocatheter is placed too distally, the PV potential could be too small or unrecordable,especially in patients with a damaged atrium due to longstanding AF If the Lassocatheter is located in the LA outside of the PV, it could result in misunderstanding ofthe LA and PV signal In addition to the exact tagging of the PV ostium on theCARTO map, keeping in mind the Lasso catheter position and the placement of itselectrodes enables mapping by using only an electroanatomic map without frequent

Figure 9.4. Fluoroscopic right and left anterior oblique views (RAO and LAO) show two Lasso catheters

within right- and left-sided PVs, mapping catheter (Map) in left atrium and catheter inside coronary sinus (CS) Numbers indicate the location of the electrodes of the Lasso catheter RSPV, right superior pul-

monary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein.

B

Figure 9.5 A: 3-D anatomic maps and MR images combined with CARTO map of the LA in a left lateral (LL),

posteroanterior (PA), and right lateral (RL) view are shown Note that (a) the angiographic ostia of all PVs are tagged

with white points; (b) the right and left continuous circular lesions are marked by multiple red dots around the PVs; (c) the two brown dots located in the right posterior CCLs and in the left anterior CCLs indicate the sites of simul-

taneous isolation of the ipsilateral PV when both CCLs are complete B: MRI-derived, virtual endoscopic views of

the junction of the right- and left-sided PVs and LA on CARTO merge imaging are shown The ostia of the RSPV and RIPV are shown in the left panel and LSPV, LIPV, and LAA in the right panel Note that (a) the right and left

CCLs are marked by multiple red dots around the PVs in the left and right panels; and (b) CCLs are located on the

ridge between the left PV and the LAA in the right panel CCLs, continuous circular lesions; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior pul- monary vein; LAA, left atrial appendage See color insert 2.

use of fluoroscopy during the procedure, which contributes to shorter fluoroscopicand procedure time.

Continuous Circular Lines Surrounding the Ipsilateral PVs

Irrigated RF energy is delivered with a target temperature of 45C, a maximal powerlimit of 40 W, and an infusion rate of 17 mL/min In all patients, maximal power of

30 W is delivered to the posterior wall to avoid the potential risk of LA–esophagealfistula RF ablation sites are tagged on the reconstructed 3-D LA RF energy isapplied for 30 seconds until the maximal local electrogram amplitude decreases to lessthan 70% or double potentials appear, and the sequence of PV activation recordedfrom the double Lasso catheters changes RF ablation is performed in the posteriorwall more than 1 cm and in the anterior wall L5 mm from the angiographicallydefined PV ostia (Figs 9.5, 9.6)

Procedure Endpoint

More than 90% of right PVs are isolated by completing anatomic continuous cular lines (CCLs) alone, however 30% of left PVs are still conducted after thecompleted CCLs even in highly experienced physicians (Fig 9.7) The remainingconduction gaps can easily be found with 3-D mapping and two Lasso catheterswithin the ipsilateral PVs The additional applications at the conduction gapbetween the LA and PV are delivered according to the activation sequence of theLasso catheters In patients with paroxysmal or persistent AF, the ablation end-point of CCLs is defined as absence of all PV spikes during SR documented withthe two Lasso catheters within the ipsilateral PVs at least 30 minutes after PV iso-lation Termination of AF is not included in the endpoint in our procedure Elec-trical cardioversion is performed after complete isolation of the bilateral PVs incase of AF persistence

cir-Figure 9.6. 3-D anatomic maps of the LA by NavX in posterior-anterior and anterior-posterior views The

angio-graphic ostia of all PVs are tagged with black lines The right and left CCLs are marked by multiple red dots around

the PVs Two Lasso catheters are located in the left and right PVs to confirm isolation of both PVs CCLs, ous circular lesions; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein; LAA, left atrial appendage; MVA, mitral valve annulus See color insert 2.

continu-Electrophysiologic Findings of Double Lasso Catheters during CCLs

The double Lasso technique provides better information on LA-PV conduction andinteresting electrophysiologic findings about the PV activation This technique is alsohelpful for complete PV isolation by CCLs The comprehension of the electrophysiologicfindings recorded by the Lasso catheter is the most essential for electrophysiologic PVisolation Careful analysis of the signal at the LA-PV is required to avoid a wronginterpretation

Complete PV Isolation by CCLs

Our studies have demonstrated that CCLs can be performed during SR or CS ing or during AF (5,11) During SR or CS pacing, CCLs resulted in progressive pro-longation and sequence change of PV activation recorded from two Lasso catheterswithin ipsilateral PVs, and finally isolation of the ipsilateral PVs is achieved withoutamplitude reduction of the PV spike (Fig 9.8) We immediately stop the RF

pac-144 Part IV ■ Ablation Procedures

Figure 9.7. Tracings during sinus rhythm are ECG leads I, V1 and intracardiac electrograms recorded

from two Lasso catheters within the left superior and inferior pulmonary veins (LSPV, LIPV), a mapping catheter (Map), a catheter inside the coronary sinus (CS) during RF application in a patient with paroxys-

mal AF Note a simultaneous isolation of both LSPV and LIPV when the right CCLs are complete CCLs, continuous circular lesions; LA, left atrium; PV, pulmonary vein.

B Figure 9.8 A: 3-D anatomic maps of the LA in a left lateral view Note that (a) the left continuous circular lesions

(CCLs) are marked by multiple red dots around the PVs; (b) the two sites with a brown dot located in the left

pos-tero-superior CCL indicate the change of PV sequence and another brown dot in the left anterior CCLs indicates

simultaneous isolation of the ipsilateral PVs See color insert 2 B: Tracings during sinus rhythm are ECG leads I, V1

and intracardiac electrograms recorded from two Lasso catheters within the left superior and inferior pulmonary veins

(LSPV, LIPV), a mapping catheter (Map), a catheter inside the coronary sinus (CS) during RF application in a patient with paroxysmal AF Note: (a) the earliest activation of PV recorded by Map (arrow); (b) a sequence change of both

LSPV and LIPV and all LIPV signals significantly delayed in the second beat compared to the first beat during the

RF application at left anterior CCLs (continued)

application to avoid the potential risk of PV stenosis in case of ablation catheter lodgement into the PV In our previous experience without using double Lasso tech-niques, the application at the inside the PV causes to the attenuation of the PV sig-nals or isolation of only the distal part of the PV and makes identification of the PVactivation sequence more difficult (Fig 9.9).

dis-During AF, the disorganized PV activation within the PVs becomes progressivelyorganized with the same or similar PV activation sequences and prolonged cyclelength (CL), and finally the ipsilateral PVs are simultaneously isolated The fibrilla-tory CL recorded from the CS was also longer after ablation than that before abla-tion in patients without the termination of AF (Fig 9.10) The ipsilateral PV spikesdisappeared simultaneously in more than 90% of patients at completion of the respec-tive CCL during SR or AF This important finding provides the scientific evidencethat complete PV isolation by CCL can be confirmed in clinical practice by using asingle Lasso catheter in one of the ipsilateral PVs

146 Part IV ■ Ablation Procedures

C

Figure 9.8 (continued) C: Note: (a) a simultaneous isolation of both LSPV and LIPV when the left CCLs are

complete at the left posterior region; (b) the earliest activation of PV recorded by Map (arrow) LA, left atrium, PV,

pulmonary vein.

Automatic Activity and Tachycardia in PVs

After the complete isolation of the PVs, regular or irregular automatic activity ciated from the atrial activity was observed in L95% patients Also, induced or spon-taneous sustained fast PV tachyarrhythmias were observed within the isolated PVafter complete isolation of the PV in L45% patients (Fig 9.11) The high incidence

disso-of automatic activity and fast PV tachyarrhythmias within the PVs may be due tomore myocardium within the isolated area compared with previous studies usingsegmental PV isolation

AF Termination during CCLs

In our recent study, 51 patients with paroxysmal AF underwent complete PV tion during AF After complete PV isolation, external cardioversion (CV) wasrequired to terminate AF only in five patients (9.8%); in the remaining 46 patients(90.2%), AF termination occurred before or immediately after complete PV isolation

isola-A Figure 9.9. Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso

catheters within the right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV), a mapping catheter (Map d, Map p) and a catheter inside the coronary sinus (CS) in a patient with parox-

ysmal AF A: Note that (a) significantly delayed second potential (PV) following the left atrial (LA)

potential only recorded by Lasso catheter in RSPV; (b) automatic activity dissociated from the atrial and

PV activity (*) in both RSPV and RIPV, suggesting that a distal part of the CCLs of the right PVs is

isolated (continued)

148 Part IV ■ Ablation Procedures

B Figure 9.9 (continued) B: Note the elimination of the second potential (PV) by a single application at

the posterior region of RSPV This phenomenon suggests that a junctional region between the LA and RSPV was separately isolated.

(14) Importantly, a single PV as AF origin was demonstrated in five patients (9.8%),

in whom sustained PV fibrillation or tachycardia was always observed within the PVbefore isolation during AF and after isolation during SR However, in patients withpersistent AF lasting more than 7 days and less than 1 year, AF termination onlyoccurred in 30% of cases (11) Also, in the majority of cases, AF termination occurredbefore isolation of the bilateral PVs AF termination in patients with paroxysmal orpersistent AF may be explained by the fact that CCLs eliminate a number of randomre-entries and consequently result in inability of AF perpetuation Based on our data,

AF termination should not be the endpoint for catheter ablation, because AF nated before complete isolation in most cases

termi-Electrical cardioversion is performed after complete isolation of the bilateral PVs

in case of AF persistence Interestingly, in some patients the PVs are still conductedwith marked conduction delay during SR immediately after cardioversion The con-duction through CCLs between LA and PV may depend on the cycle length (Fig 9.12)

B

Figure 9.10.Tracings are ECG leads I, II, V1 and intracardiac electrograms recorded from two Lasso catheters within the right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV), a mapping catheter

(Map), a catheter inside the CS, and a catheter at the His bundle region (HBE) in a patient with persistent AF.

In (A), note that the PV spikes recorded within the RSPV and RIPV are disorganized, with beat-to-beat

varia-tion of PV activavaria-tion sequences and cycle length (CL) before the right-sided continuous circular lesions (CCLs).

In (B), note that the PV spikes within the RSPV and RIPV become organized with a similar beat-to-beat PV

acti-vation and a variation of CL during RF application on the CCLs (continued)

150 Part IV ■ Ablation Procedures

C

Figure 9.10 (continued) In (C), note that the slow PV spikes with identical activation sequence (*) suddenly

dis-appear when CCLs are completed during RF application.

A

Figure 9.11. Tracings during sinus rhythm are ECG leads I, II, V1 and intracardiac electrograms recorded from a Lasso

catheter within the left common pulmonary vein (LCPV), a catheter inside the coronary sinus (CS) and a mapping

catheter (MAP) in a patient with paroxysmal AF Numbers indicate the cycle length of PV activation A: The initiation

of AF by PV tachycardia (PV) originating from the LCPV before PV isolation with an irregular cycle length (continued)

152 Part IV ■ Ablation Procedures

B

A

Figure 9.12. Tracings are ECG leads I, II and intracardiac electrograms recorded from two Lasso catheters

within the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter (Map), a catheter inside the coronary sinus (CS), and a catheter at the His bundle region (HBE) in a patient

with persistent AF A: Note: (a) persistent tachycardia demonstrated by surface ECG and CS catheter; (b)

auto-matic activity dissociated from the atrial activity (*) in both LSPV and LIPV, resulting from complete left PV

isolation B: 1 Sinus rhythm is recovered restoration after external cardioversion, 2 Marked delayed PV signals (*)

in LSPV and LIPV, showing that PVs still have conduction during sinus rhythm (continued)

Figure 9.12 (continued) C: A simultaneous isolation of both LSPV and LIPV by a single application.

Therefore complete PV isolation should be confirmed during SR according to ourexperience

Identification of PV Potential and Far-Field Atrial Potential

Identification of the PV and far-field atrial potentials on the Lasso recording is veryimportant during a procedure In anatomy, the superior vena cava (SVC) is locatedjust anterior to the right superior PV Also, a myocardial sleeve from the RA canextend deeply into the SVC, and produce a discrete spike within the SVC (15–17).Therefore, the far-field potentials originating from the SVC can be recorded withinthe RSPV in patients undergoing PV ablation (17) Generally, these far-field potentialsare small and are recorded only in the anterior part of the Lasso catheter within theRSPV (Fig 9.13)

On the other hand, PV activations from both left PVs are generally fused withthe activation from the left atrial appendage (LAA) during SR Both fused compo-nents can be separated by pacing from the catheter within the CS or LAA (18) Thesecond PV potential follows the far-field LAA potential during pacing at the LAA orpacing at the CS The amplitude of each potential depends on the location of theLasso catheters The Lasso catheter just at the ostium of the PV demonstrates a far-field potential of high voltage (Fig 9.14)

For the ablation of the left PVs, we usually start the RF applications at the roofand the anterior superior part of the ridge between the left superior PV and the LAAduring SR When these lesions are continuous and transmural, the PV signals are

154 Part IV ■ Ablation Procedures

A

B

Figure 9.13 A: Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso catheters within

the right superior pulmonary vein (RSPV) and right inferior pulmonary vein (RIPV) and a catheter inside the coronary sinus (CS) in a patient with persistent AF Ipsilateral right pulmonary vein tracings are shown during AF Note that the

slow PV spikes with identical activation sequence (*) suddenly disappear when CCLs are completed during RF tion Sharp potentials still persist in RSPV 6–7 to 9–10 (▼) B: In the left panel, tracings are ECG leads I, V1 and intra-

applica-cardiac electrograms recorded from a Lasso catheter within the RSPV, a mapping catheter in the superior vena cava

(SVC) and a catheter inside the CS Fluoroscopic right and left anterior oblique views (RAO and LAO) are shown in

the right panel Note: (a) Dissociated PV activation recorded by Lasso catheter within the RSPV (*); (b) The ablation catheter placed in the SVC opposite to RSPV 7–8 to 9–10 (catheter positions shown on the right panel) records sharp potentials (▼) with a timing identical to the residual potentials in the RSPV (despite AF).

separated from the LAA potential and become visible in almost all patients (Fig 9.15).This can easily facilitate RF ablation at the ridge between the left PVs and the LAA.After the RF lesions at the ridge, triple potentials consisting of double LAA poten-tials and the one PV potential were occasionally observed from the Lasso catheter due

to the conduction delay in some patients (Fig 9.16) However, it is more difficult todistinguish both PV and far-field LAA potentials during AF Careful judgment of acti-vation sequence during ablation (such as organized PV activation or prolonged CL

of PV activation) can help identify both components Furthermore, it is quite cult to assess the reduction of local signal by the RF application during AF This mayresult in inadequate applications in some areas In our experience, stable SR can bemaintained after isolation of the right-sided PVs in most patients with failed car-dioversion before ablation Therefore, we strongly recommend performing the leftCCLs during SR in clinical practice

diffi-A

Figure 9.14. Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso catheters within

the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter (Map), and a

catheter inside the coronary sinus (CS) during RF application for the left pulmonary veins A: In the left panel note

that during CS pacing RF application eliminates spiky potentials recorded by Lasso catheters in the LIPV ( ▼) and two separate components of signals are still recorded in the LSPV (*) In the right panel, during SR the two com-

ponents of the signal in LSPV are fused LA, left atrium activation (continued)

Figure 9.14 (continued) B: A mapping catheter placed in the left atrial appendage (LAA) records sharp

potentials (arrow) with timing identical to the residual potentials in the LSPV (*) This phenomenon

shows that CS pacing could lead to misunderstanding of a delayed LAA potential as PV potential.

Figure 9.15 A: 3-D anatomic maps of the LA in a posterior-anterior view Note that (a) the left PV

ostium is marked by white dots; (b) the left continuous circular lesions (CCLs) are marked by multiple red

dots around the PVs; (c) the one site with a brown dot located in the left anterior-superior CCLs indicates

the change of PV activation sequence See color insert 2 (continued)

B Figure 9.15 (continued) B: Tracings are ECG leads II, V1 and intracardiac electrograms recorded from two Lasso

catheters within the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter (Map) and a catheter inside the coronary sinus (CS) during RF application for the left pulmonary veins The change

of activation sequence of both the LSPV and the LIPV, and the marked delay of all LSPV signals in the second beat compared with the first beat during RF application at the left antero-superior CCL indicates that conduction block created by the ablation has made the PV spike visible LA, left atrium; PV, pulmonary vein.

Recovered PV Conduction after the Initial Ablation Procedure

The recurrence rate after initial PV isolation seems to be different depending onthe ablation technique and the follow-up In our experience, without any blank-ing period, the recurrence rate of atrial tachyarrhythmias was 25% in patients withablation during stable rhythm and 37.5% in patients with ablation during AF dur-ing more than 6 months of follow-up Interestingly, recovered PV conduction hasbeen demonstrated in 80% to 90% of patients with recurrent tachycardia afterCCLs, and the recovered PV activation presented as significant delay during SRcompared with that before the initial ablation (Fig 9.17) During the secondprocedure, the conduction gap was found in all regions of the previous CCLs Allconduction gaps were easily identified in the previous CCLs by using two Lassocatheters within the ipsilateral superior and inferior PVs, and could be successfullyclosed by a few RF applications in the previous CCLs during the second procedure(Fig 9.17)

158 Part IV ■ Ablation Procedures

A

Figure 9.16. Tracings are ECG leads I, V1 and intracardiac electrograms recorded from two Lasso catheters within

the left superior pulmonary vein (LSPV) and left inferior pulmonary vein (LIPV), a mapping catheter (Map), and a

catheter inside the coronary sinus (CS) during RF application for the left PV A: Note that the signals on the Lasso

catheters in LSPV and LIPV are isolated simultaneously after a sequence change of Lasso recordings without any

applications at the anterior part of the LSPV (continued)

Interestingly, the surface ECG showed a constant P-wave morphology and anidentical atrial activation sequence before complete PV isolation in some patients withrecurrence of PV tachycardia The atrial tachycardia (AT) with irregular or regular CLresulted from the PV tachycardias, sometimes from the PV fibrillation, conductingthrough the gap between the PV and the LA, which was demonstrated by Lassocatheters within the respective ipsilateral PVs After complete PV isolation, SRoccurred in the setting of continuous PV tachyarrhythmias within ipsilateral PVs (Fig.9.18) The PV tachyarrhythmia required external cardioversion for termination dur-ing SR, strongly suggesting that the PV tachyarrhythmia is due to re-entry (14) Thisinteresting finding using our techniques suggests that a single PV can act as AF sub-strate

Our data were consistent with previous studies showing that recovered PV duction is a dominant finding in patients with recurrent atrial tachyarrhythmias after theinitial procedure (10,19) Importantly, the majority of patients were free of recurrenceafter the second procedure The clinical success was 95% after permanent complete

con-PV isolation including the second ablation procedure in patients with paroxysmal andpersistent AF These data strongly support the concept that permanent PV isolationshould be the endpoint of CCLs

In patients without recovered PV conduction, we attempted to uncover non-PVfoci triggering AF by stimulation and provoked maneuvers to abolish all non-PV foci

Figure 9.16 (continued) B: Note that the

local potential recorded by a mapping catheter placed on at the anterior region of the LSPV shows three components of sig- nals before isolation, indicating double potentials of LA and PV potential, respec-

tively (LA1, LA2, PV) This phenomenon

may suggest a spontaneous block at the anterior region of the left PV (between left

PV and LAA) C: 3-D anatomic maps of the

LA in a posterior-anterior view Note that

(a) the left PV ostium is marked by white

dots; (b) the left continuous circular lesions

(CCLs) are marked by multiple red dots

around the PVs; (c) the region showing triple potential by a mapping catheter is

marked by a green dot; (d) the two sites with

a brown dot located in the left posterior

CCLs indicate the change of PV activation

sequence and another brown dot in the left

anterior inferior CCLs indicates ous isolation of the ipsilateral PV without any applications at the anterior region of the left PV See color insert 2.

simultane-B

C

160 Part IV ■ Ablation Procedures

A

B

Figure 9.17 A: Tracings during a repeat procedure are ECG leads I, II, V1 and intracardiac electrograms recorded

from two Lasso catheters within the right superior and inferior pulmonary vein (RSPV, RIPV), a mapping catheter (MAP dis and MAP prx) in the LA, and a catheter within the coronary sinus (CS) Note (a) a recovered PV con-

duction with a significant conduction delay during SR in the left panel; (b) a simultaneous isolation of both RSPV

and RIPV by a single application at the conduction in the right posterior region in the right panel B: Fluoroscopic

right and left anterior oblique views Note the catheter’s position at the posterior region of the right PV Numbers indicate the electrode of Lasso catheter.

B

Figure 9.18 A: Fluoroscopic right and left anterior oblique views (RAO and LAO) in a patient with recurrent

tachycardia Note a dual-chamber pacemaker with an atrial and a ventricular lead, a Lasso catheter within the left

common pulmonary vein (LCPV), a catheter inside the coronary sinus (CS) and contrast in the left veins

show-ing a common ostium B: Tracshow-ings are 12 surface ECG leads and intracardiac electrograms recorded from a

catheter within the CS Note that tachycardia presents with the monomorphic P-wave morphology on the face ECG and irregular cycle length (CL) recorded from the CS catheter (continued)

sur-by irrigated RF ablation In patients with recovered conduction, frequently non-PVextrasystoles activated the PV and induced fast PV tachycardia, which then activatedthe atria via the conduction gaps and resulted in atrial tachycardia and AF The atrialextra beats persisted but could not induce AF after the recovered PV conduction wasabolished (Fig 9.19) Consequently, in our ablation strategy extra beats were nottargeted in the majority of patients Based on our data, the incidence of 10% to 20%triggers being non-PV foci from previous reports could be an overestimation

162 Part IV ■ Ablation Procedures

C

D

Figure 9.18 (continued) C: Tracings are ECG leads I, II, V1, and intracardiac electrograms recorded from one

Lasso catheter within the LCPV, a mapping catheter (Mp dis and Mp prx) at the inferior gap of the previous

contin-uous circular lesions (CCLs) around the left-sided PVs in the patient during clinical tachycardia Note (a) LCPV

fib-rillation with continuous change in CL and activation sequence activating the LA via an inferior conduction gap and

resulting in irregular CL of the tachycardia; (b) the local left atrial potential following fractionated electrogram

recorded by mapping catheter D: Fluoroscopic right and left anterior oblique views Note that a mapping catheter

was located at the inferior conduction gap of the previous CCLs (continued)

Additional Linear Lesions of the LA with CCLs

Macroreentrant tachycardia has been reported as a complication of circumferential

PV ablation The incidence of this complication is 5% to 20% depending on the tion techniques and additional linear lesions in the LA (20–22) In contrast, addi-tional linear lesions have been demonstrated to prevent macroreentrant tachycardiasafter circumferential PV ablation Recent studies have demonstrated that additionallinear lesions can reduce AF inducibility and improve clinical outcome after PV isola-tion (7) In clinical practice, it is very difficult to create conduction block over the leftisthmus between the left inferior PV and the mitral annulus (23) In our experiencethe clinical success was L95% after permanent complete PV isolation (including thesecond ablation procedure) without additional linear lesions in the LA in patientswith paroxysmal and persistent AF Based on our data, we do not routinely create anyadditional linear ablation in the LA except in patients with left atrial macroreentranttachycardia after ablation for paroxysmal and persistent AF

abla-164 Part IV ■ Ablation Procedures

Figure 9.19. Tracings during a repeat procedure are ECG leads I, II, V1 and intracardiac electrograms recorded from

one Lasso catheter within the left common PV (LCPV), a mapping catheter (MAP) in the LA, and a catheter within the coronary sinus (CS), in a patient with recurrent atrial tachycardia after the initial ablation Note that (a) there is a recov- ered PV conduction with a significant conduction delay during SR; (b) the initial atrial extrasystole (arrow) has similar P-

wave morphology and atrial activation to the SR, which indicates non-PV origin most likely from the right atrium after exclusion of recovered PV conduction to the right-sided PVs; (c) the non-PV atrial extrasystole activates the LCPV and initiates a fast PV tachycardia with a cycle length of 144–238 ms within the LCPV; (d) the fast PV tachycardia activates the atria via a conduction gap with two-to-one conduction SR, sinus rhythm; Extra, atrial extrasystole; AF, atrial fibrillation;

PV, pulmonary vein; A, atrial activation; V, ventricular activation (Modified from Satomi K, et al How to determine and

assess endpoints for left atrial ablation Heart Rhythm 2007;4:374–380, with permission from the Heart Rhythm Society.)

Inducibility of AF after PV Isolation by CCLs

It has been reported that sustained AF could be induced by burst stimulation after mental PV isolation or circumferential ablation around the PVs in 46% to 60% ofpatients with paroxysmal AF (6,24) Also, it has been demonstrated that additional lin-ear lesions in the LA can improve clinical outcome and reduce inducibility (7) How-ever, in our experience with 60 patients with paroxysmal AF, sustained AF lasting formore than 10 minutes was induced after the complete isolation of the ipsilateral PVsonly in 13% of patients by burst pacing to 2:1 capture with maximum output (2.9 mspulse duration and 20 mV output) Interestingly, there was no significant difference inrecurrence rate between patients with inducible and noninducible AF during 5.7  2months follow-up after complete CCLs (unpublished data)

seg-These data may support the hypothesis that the circumferentially isolated areas

by our technique are much larger than in the previous study based on much higherincidence of AF termination during ablation in patients with paroxysmal and persist-ent AF, higher incidence of spontaneous automatic activity and induced PV tach-yarrhythmias within isolated areas, and lower incidence of induced AF after complete

PV isolation This may result in the elimination of triggered activity and/or motherwaves outside the PV ostia that drive AF More importantly, based on our experience

of more than 1,300 AF ablation procedures guided by double lasso and 3-D ping, only permanent PV isolation can achieve long-term success in patients with nor-mal LAs regardless of whether the AF is paroxysmal or persistent

map-Complications

In our experience with more than 1,300 AF ablation procedures using irrigated tion and a 3-D mapping system, cardiac tamponade occurred only in five patients,and minor embolism occurred in one patient, with complete recovery 3 days afterablation Most complications were local hematomas in L2% of patients

abla-Conclusion

Based on our experience with few complications and high success rates, the ideal tion procedure consists of performing minimal lesions Our present strategy is toachieve permanent PV isolation by CCLs Complete circumferential PV isolation isthe preferable endpoint for catheter ablation of paroxysmal and persistent AF

abla-References

1 Hạssaguerre M, Jạs P, Shah DC, et al Spontaneous initiation of atrial fibrillation by

ectopic beats originating in the pulmonary veins N Engl J Med 1998;339:659–666.

2 Hạssaguerre M, Jạs P, Shah DC, et al Electrophysiological end point for catheter

abla-tion of atrial fibrillaabla-tion initiated from multiple pulmonary venous foci Circulaabla-tion.

2000;101:1409–1417.

3 Oral H, Knight BP, Tada H, et al Pulmonary vein isolation for paroxysmal and persistent

atrial fibrillation Circulation 2002;105:1077–1081.

4 Pappone C, Rosanio S, Oreto G, et al Circumferential radiofrequency ablation of

pul-monary vein ostia: a new anatomic approach for curing atrial fibrillation Circulation.

2000;102:2619–2628.

5 Ouyang F, Bansch D, Ernst S, et al Complete isolation of left atrium surrounding the monary veins: new insights from the double-Lasso technique in paroxysmal atrial fibrilla-

pul-tion Circulapul-tion 2004;110:2090–2096.

6 Hạssaguerre M, Sanders P, Hocini M, et al Changes in atrial fibrillation cycle length and

inducibility during catheter ablation and their relation to outcome Circulation.

2004;109:3007–3013.

7 Jais P, Hocini M, Sanders P, et al Long-term evaluation of atrial fibrillation ablation

guided by noninducibility Heart Rhythm 2006;3:140–145.

8 Nademanee K, McKenzie J, Kosar E, et al A new approach for catheter ablation of atrial

fibrillation: mapping of the electrophysiologic substrate J Am Coll Cardiol 2004;43:

2044–2053.

9 Oral H, Chugh A, Good E, et al A tailored approach to catheter ablation of paroxysmal

atrial fibrillation Circulation 2006;113:1824–1831.

10 Ouyang F, Antz M, Ernst S, et al Recovered pulmonary vein conduction as a dominant factor for recurrent atrial tachyarrhythmias after complete circular isolation of the pul-

monary veins: lessons from double Lasso technique Circulation 2005;111:127–135.

11 Ouyang F, Ernst S, Chun J, et al Electrophysiological findings during ablation of ent atrial fibrillation with electroanatomic mapping and double Lasso catheter technique.

persist-Circulation 2005;112:3038–3048.

12 Schmidt B, Ernst S, Ouyang F, et al External and endoluminal analysis of left atrial anatomy and the pulmonary veins in three-dimensional reconstructions of magnetic resonance

angiography: the full insight from inside J Cardiovasc Electrophysiol 2006;17:957–964.

13 Ernst S, Ouyang F, Goya M, et al Total pulmonary vein occlusion as a consequence of

catheter ablation for atrial fibrillation mimicking primary lung disease J Cardiovasc

Elec-trophysiol 2003;14:366–370.

14 Huang H, Wang X, Chun J, et al A single pulmonary vein as electrophysiological

sub-strate of paroxysmal atrial fibrillation J Cardiovasc Electrophysiol 2006;17:1193–1201.

15 Ho SY, Sanchez-Quintana D, Cabrera JA, et al Anatomy of the left atrium: implications

for radiofrequency ablation of atrial fibrillation J Cardiovasc Electrophysiol 1999;10:

1525–1533.

16 Marrouche NF, Natale A, Wazni OM, et al Left septal atrial flutter: electrophysiology,

anatomy, and results of ablation Circulation 2004;109:2440–2447.

17 Shah D, Burri H, Sunthorn H, et al Identifying far-field superior vena cava potentials

within the right superior pulmonary vein Heart Rhythm 2006;3:898–902.

18 Shah D, Hạssaguerre M, Jạs P, et al Left atrial appendage activity masquerading as

pul-monary vein potentials Circulation 2002;105:2821–2825.

19 Cappato R, Negroni S, Pecora D, et al Prospective assessment of late conduction rence across radiofrequency lesions producing electrical disconnection at the pulmonary

recur-vein ostium in patients with atrial fibrillation Circulation 2003;108:1599–1604.

20 Gerstenfeld EP, Callans DJ, Dixit S, et al Mechanisms of organized left atrial tachycardias

occurring after pulmonary vein isolation Circulation 2004;110:1351–1357.

21 Pappone C, Manguso F, Vicedomini G, et al Prevention of iatrogenic atrial tachycardia after ablation of atrial fibrillation: a prospective randomized study comparing circumferen-

tial pulmonary vein ablation with a modified approach Circulation 2004;110:3036–3042.

22 Chugh A, Oral H, Lemola K, et al Prevalence, mechanisms, and clinical significance of macroreentrant atrial tachycardia during and following left atrial ablation for atrial fibrilla-

tion Heart Rhythm 2005;2:464–471.

23 Ouyang F, Ernst S, Vogtmann T, et al Characterization of reentrant circuits in left atrial macroreentrant tachycardia: critical isthmus block can prevent atrial tachycardia recur-

PV isolation that only target triggers are insufficient to cure permanent AF that ents at the end stage of the disease and is the most challenging clinical form.The circumferential atrial ablation or CPVA consists of large circumferentiallesion lines to perform a point-by-point tailored proximal disconnection of all PVsand additional lesion lines that further reduce the anatomic, electrophysiologic, andautonomic substrates (1–21) The procedure can be performed either by manuallydeflectable catheters (standard CPVA) or remotely (remote CPVA) by a soft magneticcatheter, and has been demonstrated to be effective in curing patients with AF(1–21) In patients with permanent AF, further lesions are performed to achieve sinusrhythm (SR) and noninducibility of both AF and atrial tachycardia (AT) at the end

pres-of the procedure The ablation lines are guided by 3-D electroanatomic mapping tems (CARTO or NavX)

sys-Standard CPVA Mapping and Ablation

Prior to ablation, patients have transesophageal echocardiography to exclude a leftatrial thrombus Before transseptal puncture, a catheter is placed inside the coro-nary sinus to map for left atrial activity, and a multipolar catheter is placed insidethe right atrium to map for right atrial activity The procedure requires a singletransseptal puncture for the mapping/ablation catheter Following transseptalaccess a single bolus of heparin is administered and two blood samples are takenevery 15 minutes in order to monitor the activated clotting time, which needs to

be 250 seconds

Circumferential Atrial Ablation

Approximately 10 years ago, the use of 3-D nonfluoroscopic technology was one

of the initial developments that permitted advances in cardiac mapping CARTO(Biosense-Webster, Diamond Bar, CA), EnSite-NavX (St Jude Medical, St Paul, MN),LocaLisa (Medtronic, Minneapolis, MN), and RPM (Boston Scientific, Natick, MA),have all been used for positioning of catheters in virtual 3-D space in a real-time fash-ion with reduced use of fluoroscopy and with enhanced safety The 3-D nonfluoro-scopic technology has advantages and disadvantages

All of these navigation systems primarily require catheter movement to create a tual geometry, which is mostly operator dependent and cannot predict anatomy on itsown The 3-D maps are formed by the maximum excursion of the mapping catheterwithin the chamber of interest If an inadequate number of points are used to construct

vir-a mvir-ap, the mvir-ap will not be vir-accurvir-ate vir-and mvir-ay underestimvir-ate the true vir-anvir-atomy size, dering it useless If a greater number of points are utilized, then the result may be adeformed virtual chamber, with both the surface and volume overestimated

ren-Over the years, we have adapted to the use of 2-D fluoroscopic images in bination with electrogram signals to know the position of the navigating catheter inthe heart For AF ablation, fluoroscopy alone does not show the complex anatomy ofthe LA and is unable to show whether lesions are contiguous, thus allowing to per-form complete lines of block Advanced technology offers the virtual 3-D view of thecardiac chamber of interest, as opposed to the real 2-D view provided by fluoroscopy

com-As a result of the enhanced spatial resolution that 3-D anatomic views provide, theability to obtain highly detailed activation maps, and catheter navigation features ren-der an accurate mapping and ablation at specific endocardial targets The ability totag points of interest enables the operator to return to ablation sites at any time dur-ing the procedure to make contiguous lesion lines This facilitates precise left atrium(LA) ablation, entrainment mapping, identification of atrial scar, validation of con-duction block with linear lesions, identification of sites of vagal stimulation, or imped-ance gradients

Currently we use both CARTO and NavX technology for intracardiac try reconstruction, mapping, and ablation of patients undergoing CPVA Becausethese two electroanatomic systems are different as they utilize different sources andalgorithms, for clarity we will describe mapping and ablation with CARTO andNavX separately

geome-Mapping and Navigation with the CARTO System

The first to be used was the CARTO system for both mapping and ablation of AF.This 3-D system accurately determines the location and orientation of the mapping/ablation catheter using three ultra-low magnetic fields, which are generated by coilswithin a locator beneath the operating table and simultaneously records the localelectrogram from its tip While reconstructing the virtual 3-D geometry by ade-quately sampling density, color-coded electrophysiologic data can be superimposed

on the anatomy with a complete representation of endocardial voltage distribution.Accurate acquisition of points requires an adequate wall contact of the catheter tipand continuous catheter stability, both of which are operator dependent In experi-enced hands, an adequate LA geometry for an optimal ablation can be reconstructed

in less than 10 minutes

At present open irrigated-tip catheters are used with an irrigation rate of 2 to

50 mL/min to maintain the desired power (50W) The irrigation allows one to

per-168 Part IV ■ Ablation Procedures

form deeper lesions at constantly lower power settings, compared with nonirrigated4- to 8-mm catheters used in the past, without the risk of carbonization of the tip,which could lead to left atrial thrombus formation Throughout the whole mappingprocedure the tip is irrigated at a rate of 2 mL/min An example of step-by-stepreconstruction of LA electroanatomic map by CARTO is shown in Figure 10.1.The first step is to reconstruct all PVs To better define the PV ostia, it is nec-essary to acquire more than one point inside each PV In order to be certain that themapping catheter is inside the PV, simultaneous confirmation by fluoroscopy,impedance gradients, and electrograms is necessary When using fluoroscopy, oncethe catheter enters the PV, the tip is characteristically seen outside the cardiacshadow Second, the operator checks for impedance values, which significantly risewhen each PV is entered while atrial electrograms simultaneously disappear Imped-ance mapping (impedance rise 4 Ohms relative to the LA indicates PV ostium) inconjunction with 3-D mapping reliably identifies the LA-PV transitional zone,allowing safe ablation within the LA, and its use is associated with a low incidence

of PV stenosis (20)

After PVs are acquired we perform a point-by-point reconstruction of the rior and anterior walls, left atrial appendage (LAA), roof, mitral annulus with its isth-mus, ridge between the LAA and LSPV, and septal region (Fig 10.1) As shown,acquisition of many more points is required to better delineate challenging areas forablation such as the septum and the ridge between the LAA and the LSPV (Fig 10.1,Panel C) When mapping the right inferior or superior PVs, far-field electrical activ-ity may be recorded from the proximal electrodes So when validating this region it

poste-is important to push the catheter deeper in order to reduce thposte-is influence

Figure 10.1 Final detailed virtual map of the left atrium with CARTO shown in different anatomic views (A–F).

See color insert 2.

The LAA is one of the latest areas to be mapped (Fig 10.1, Panel C) It is aneasy region to identify because its potentials are characteristically not fractionated and

of high amplitude When mapping the LAA every effort should be made to accuratelydefine the ridge, which characteristically shows potentials that are higher and morefractionated than in the rest of the atrium, but smaller than those of the LAA If theridge is not accurately reconstructed, the left-sided circumferential lesion line may bedeployed too close to the LAA or within the PV ostium, which may result in poorefficacy and major complications

The septal area, which is close to the inferior portion of the right inferior PV, alsorepresents a challenging region for both mapping and ablation and it should be accu-rately reconstructed by acquiring many points, requiring a stable catheter–wall con-tact (Fig 10.1, Panel E) When reconstructing the roof we acquire sufficient points

to avoid an inadequate interpolation by the CARTO system (Fig 10.1, Panels A, B,and E)

Ablation with the CARTO System

After reconstruction of the LA shell with CARTO, ablation is started to encircle theleft- and right-sided PVs, 1 to 2 cm from their ostia, with additional linear lesions inthe posterior wall between the superior and inferior PVs and mitral isthmus (Fig 10.2).When ablation starts, the irrigation rate of the catheter tip is raised from 2 to 17 mL/min Impedance, ablation time, and tip temperature values are constantly monitored

RF energy is immediately discontinued if an increase 10 Ohms in impedance occurs.Irrigation rate is titrated to achieve the desired power Energy output is limited to

170 Part IV ■ Ablation Procedures

Figure 10.2. Using a cooled-tip catheter with a dragging technique, a point-by-point continuous ablation line (red

dots) begins from the mitral annulus toward the left-sided PVs (isthmus line) (A, B) Further sequential RF

applica-tions on the ridge between the LAA and the left superior PVs complete the circular line that encircles the left PVs

(C, D) and then, the right-sided PVs (E) The line between the right PVs is usually deployed at the end of the

abla-tion procedure (F) G: An addiabla-tional line connects the superior (roof line) and inferior PVs on the posterior wall In

this patient a linear lesion line on the septum starting from the anterior lower part of the right circumferential lesion

up to the mitral valve has been deployed (H) See color insert 2.

50W and 48C throughout the entire ablation procedure RF energy is delivered to theentire circumference around all PVs by the creation of circular lesions outside each PVostium or by the creation of two larger circumferential lesions around the right and left

PV ostia

Visualization of ablation lines by 3-D mapping facilitates creation of a ous line and helps to avoid repeated unnecessary energy delivery at sites that havealready been targeted Demonstration of electrical isolation by a circular mappingcatheter is not required because we create a true proximal electrical disconnection bycomplete potential abatement not only on the lesion line but also within the encir-cled areas For this purpose, careful attention should be given to catheter stability andattenuation of the local electrogram during each RF energy application or partiallyablated signals before moving on the next ablation site

continu-We tailor ablation lines according to the single patient’s anatomy, and vagalreflexes elicitation may vary between different subjects In some patients we performlarger encircled areas, up to 30% of the LA, mainly depending on the atrial dimen-sions, which are larger in patients with longstanding or permanent AF Usually, repeat

RF applications are deployed in challenging areas particularly around the LSPV whereatrial electrogram potentials may be difficult to eliminate Sequential images showing

a step-by-step ablation by continuous point-by-point RF applications up to the finaland complete set of lesions are shown in Figure 10.3 RF applications start by per-forming a large left-sided circumferential lesion line and the perimitral isthmus line

Figure 10.3.A postablation color-coded voltage map by CARTO with typical circumferential radiofrequency lesions

as performed by CPVA is shown in different anatomic views Note that inside encircled areas no voltage gradients are

evident (red color) A: LAO (left anterior oblique) view B: LL (left lateral) view C: PA (postero-anterior) view D: RL

(right lateral) view E: RAO (right anterior oblique) view F: AP (antero-posterior) view The voltage map represents

the potential distribution into the left atrium with a scale of colours from red (0 mV) to violet (1.57 mV) See color insert 2.

(Fig 10.2, Panels A and B) Attention must be paid when the catheter is movedtoward the ridge, keeping away from the LSPV ostium passing between the LAA,located anteriorly, and the PV, posteriorly This is a very challenging area becausecomplete abatement of potentials usually requires longer RF applications If the ridge

is too narrow, the ablation line is performed at the base of the LAA If anatomicallypossible, we also perform a lesion line between the two PV ostia to further reduce thesubstrate (Fig 10.2, Panels D and G)

Characteristically, in this area RF applications using a dragging technique are ofshorter duration particularly if associated with rapid, stable, and complete abatement

of potentials The operator completes anteriorly and posteriorly the circumferential PVlines To minimize the risk of esophageal injury, in the posterior LA the power is lim-ited to 40 to 50 W whenever ablation is performed When connecting the encircledareas (Fig 10.2, Panel G) we prefer to deliver repeated RF applications of short dura-tion instead of a single longer RF application to avoid the risk of cardiac perforation

In our center, only one case of a nonfatal atrioesophageal fistula has occurred out

of more than 10,000 patients undergoing CPVA While performing the lesion set inmore than 30% of patients we evoke vagal reflexes (hypotension, sinus bradycardia,asystole, AV block) after a few seconds by the onset of RF application If a reflex iselicited, RF energy is delivered until such reflexes are abolished, for a maximumperiod of 30 seconds The endpoint of ablation at these sites is termination of thereflex, followed by sinus tachycardia or AF Failure to reproduce the reflexes withrepeated RF applications is considered confirmation of denervation Complete localvagal denervation is defined by the abolition of all vagal reflexes We always attempt

to elicit and then ablate potential sites of vagal reflexes to induce a transient vagaldenervation, which enhances the long-term benefits of CPVA (4)

We first reported a detailed “autonomic map” of the LA as a target for ablationand we have found that like the left superior PV, the septal region is richly innervated(4) At the end of the standard procedure, if AF persists after cardioversion, furtherlinear lesions are deployed on the septum or in the coronary sinus to achieve a stable

SR and noninducibility of AF or AT Once the lesion set is complete we accuratelyrevisit lesion lines and encircled areas to check for residual gaps and apply radiofre-quency where needed The mitral isthmus line is validated by activation and voltagemaps and differential pacing maneuvers In many patients all endpoints are reached

at the end of the procedure and double potentials or no potentials are found on thetargeted areas

Mapping and Navigation with the NavX system

In our center for AF mapping, navigation, and ablation we also use the Ensite NavXtechnology (Endocardial Solutions, St Paul, MN), which may utilize up to 64catheter electrodes to sense a 5.6-kHz, low-current electrical field generated in thethorax by externally placed electrodes for faster data collection and improved orien-tation The CARTO and NavX systems use different technologies, which ultimatelyallow 3-D mapping and navigation for AF ablation with different advantages and dis-advantages Unlike CARTO, the NavX system creates 3-D images of the catheters,based on the electrical field generated by three pairs of orthogonal skin patches in X,

of the location of the catheter in 3-D space Like CARTO, the current version of theNavX system may project electroanatomic information using a color-coded 3-D mapsuperimposed on the virtual anatomy by contact electrodes Multiple surface geome-tries can be performed faster and easier than CARTO usually within a few minutesand, unlike CARTO, we can obtain a 3-D reconstruction of both the tip and the shaft

of the catheter, which is particularly useful in difficult regions such as the PV ostia,the ridge, or the mitral valve annulus (Fig 10.3)

Unlike CARTO, this technology allows one to minimize respiratory artifacts bythe respiratory compensation function, to create separately all desired anatomies byopening a new geometry window for each target, and to collect many more pointssequentially just by moving the catheter in different directions giving the impressionthat the catheter is painting the chamber The fact that many more points can be rap-idly and sequentially collected on and between electrodes of the roving catheter rep-resents a great improvement compared to the single-point acquisition by the CARTOsystem, which is much slower, less accurate, and requires a minimum number ofpoints homogenously distributed

After the PV anatomies are reconstructed separately under NavX guidance (Fig.10.3, Panel A), a new geometry can be opened to rapidly reconstruct the left atrialchamber (Fig 10.3) When mapping challenging areas we prefer to acquire pointsmanually rather than sequentially The final map is very accurate although the highestdensity of points characteristically appears on the left side, which is the easiest region

to reach and map At the end of the mapping procedure we delineate on the map theperimeter of the mitral valve, which is cut out like the transseptal puncture area

Ablation with the NavX System

Using the NavX navigation system we perform the same lesion set in the same order

as described above with the CARTO system The NavX system allows reliable toring of the ablation catheter offering a proximity indicator that, based on the inten-sity of the color of the tip, allows the operator to monitor the optimal tissue contact

moni-of the ablation catheter, which when associated to the atrial potential abatement firms the achievement of our ablation endpoint The NavX software also allows amore detailed anatomy reconstruction of the left atrial appendage and the ridge asshown in the lateral projection of the LA (Fig 10.3, Panel G), which is also due tothe stability of the catheter obtained thanks to the respiratory compensation function The ablation procedure is accurately followed on the NavX screen by 3-D rota-tions, which are particularly useful in challenging points such as the ridge Whenablating the posterior wall, the occurrence of pain may cause the patient to changehis respiratory frequency and a new respiratory compensation is useful for catheterstability Another advantage of the NavX system is that patient movements during themapping or ablation procedure do not affect the reconstruction of the map becausethe reference catheter moves equally to the patches attached to the patient’s body.During RF energy delivery, assessment of catheter stability and catheter movement isperformed without the use of fluoroscopy Therefore, catheter displacement andinsufficient wall contact are readily recognized, resulting in reduction of radiationexposure, procedure duration, and reduced RF energy delivery In addition, the featurepermitting acquisition of fixed anatomic points allows identification of narrow ridgesfacilitating the positioning of the ablation catheter in the anterior aspect of the left PVs

con-to avoid ablation within the appendage As with the CARTO system (Fig 10.4), after

ablation an endocardial voltage map is constructed and displayed as color gradients

to verify complete abatement on the lesion lines and within them (Figure 10.5) Ifany electrical activity persists on the map, further RF applications are performed until

no detectable electrical activity in the target regions is evident

Remote Mapping and Ablation with Stereotaxis

Catheter ablation of AF using manual catheters may be limited by the need for ping accuracy and detail, which requires advanced operator skills and experience withcatheter manipulation Remote navigation technology may facilitate both mappingand ablation in patients with AF independent of operator dexterity The MagneticNavigation System (MNS) uses soft catheters equipped with three small magnetsembedded in the tip for accurate catheter orientation in the magnetic field generated

map-by using two large magnets positioned on either side of the procedure table Theremote system consists of two independent but communicating components: theNiobe Stereotaxis MNS (Stereotaxis, Inc., St Louis, MO) and an electroanatomicmapping system (CARTO-RMT, Biosense-Webster, Inc., Diamond Bar, CA).Briefly, the Niobe system includes a computer interface system (Navigant), which

is managed by a keyboard and joystick able to change the two magnets’ orientationmodifying the magnetic field and thus the catheter tip orientation and location Theoperator stays in a separate room, virtually at any distance from the x-ray beam and

174 Part IV ■ Ablation Procedures

Figure 10.4. Final anatomic and color-coded voltage postablation maps in different views (low in red and high in

violet) (A–F) using the NavX system A: postero-anterior view B: antero-posterior view C: left anterior oblique view.

D: right anterior oblique view E: left lateral view F: right lateral view See color insert 2.