Catheter Ablation

7/25/2019 Catheter Ablation

1/16

Catheter Ablation

Overview

Background

Radiofrequency (RF) catheter ablation (RFCA) has revolutionized treatmentfor tachyarrhythmias and has become first-line therapy for some tachycardias

Althou!h developed in the "#$%s and widely applied in the "##%s& formalized!uidelines for its use in clinical practice were not developed until some yearslater'"& & & *+

Catheters were first used for intracardiac recordin! and stimulation in the late"#,%s& but sur!ical treatment for refractory tachyarrhythmias was themainstay of nonpharmacolo!ic therapy until it was superseded by catheterablation he initial ener!y source used was direct current (.C) from astandard e/ternal defibrillator A shoc0 was delivered between the distalcatheter electrode and a cutaneous surface electrode1 however& this hi!h-volta!e dischar!e was difficult to control and could cause e/tensive tissuedama!e

RF ener!y& a low-volta!e& hi!h-frequency form of electrical ener!y familiar tophysicians from its use in sur!ery (e!& electrocautery)& quic0ly supplanted .Cablation he relative safety of RF ener!y has contributed to the widespreadadoption of catheter ablation as a therapeutic modality

RF ener!y produces small& homo!eneous& necrotic lesions by heatin! tissue2esion size is influenced& in part& by the len!th of the distal ablation electrodeand the type of catheter (standard vs saline-cooled) 3ith typical powersettin!s and !ood catheter contact pressure with cardiac tissue& lesions areminimally about 4-5 mm in diameter and -4 mm in depth

Future directions

A curative procedure for atrial fibrillation (AF) is a ma6or !oal in clinical cardiacelectrophysiolo!y 7uccess has been achieved in patients with paro/ysmal

lone AF by eliminatin! conduction from the pulmonary veins to the left atrium&as many of these episodes are tri!!ered by rapid electrical activity arisin!from tissue near the pulmonary vein ostia or from muscle sleeves surroundin!the pro/imal veins Other forms of AF may require some de!ree of substrateablation (e!& linear transmural lesions in the left atrium)


2/16

echniques are evolvin! to address the challen!e of a catheter-based cure forall forms of AF hree-dimensional electroanatomic maps& overlaid onma!netic resonance ima!in! (8R9) or computed tomo!raphy (C) scans ofthe left atrium& can facilitate navi!ation of the catheter and mappin! of thearrhythmo!enic substrate 9ntracardiac echocardio!raphy may also help inavoidin! collateral dama!e to the pulmonary veins or esopha!us& ensurin!adequate endocardial contact& and monitorin! for complications (e!&pericardial effusion and thrombus development)

Alternative ener!y sources are bein! investi!ated in the ablation of AF (e!&balloon-based technolo!ies usin! cryoablation&'4+ ultrasound& and laser) 9naddition& robotic catheter navi!ation is now available to deliver RFCA

Research is also focused on developin! better methods and tools for catheterablation of ventricular tachycardia(:)& and even ventricular fibrillation (:F)&

in patients with structural heart disease ;picardial electrophysiolo!y viasub/iphoid pericardial puncture is a relatively new frontier1 sometachyarrhythmia substrates (especially : in nonischemic cardiomyopathy)cannot be reached from the endocardium

Indications

here are three class 9 indications for catheter ablation he first issymptomatic supraventricular tachycardia (7:) due to atrioventricular (A:)nodal reentrant tachycardia (A:s preference

he second indication is AF with lifestyle-impairin! symptoms and inefficacy orintolerance of at least one antiarrhythmic a!ent',& + ?oth left atrial ablation forrestoration of sinus rhythm and A: 6unction ablation for rate control are class 9indications& dependin! on the circumstance

he third indication is symptomatic :'5+ Catheter ablation is first-line therapy

in idiopathic : if that is the patient>s preference 9n structural heart disease&catheter ablation is !enerally performed for dru! inefficacy or intolerance or asad6unctive therapy in patients with an implantable cardioverter-defibrillator(9C.) who are e/periencin! frequent 9C. dischar!es

@ncommon indications for catheter ablation include the followin!
http://emedicine.medscape.com/article/159075-overviewhttp://emedicine.medscape.com/article/162245-overviewhttp://emedicine.medscape.com/article/162245-overviewhttp://emedicine.medscape.com/article/159075-overviewhttp://emedicine.medscape.com/article/162245-overviewhttp://emedicine.medscape.com/article/162245-overview


3/16

7ymptomatic dru!-refractory (inefficacy or intolerance) idiopathic sinus

tachycardia

2ifestyle-impairin! ectopic beats

7ymptomatic 6unctional ectopic tachycardia

RFCA has been applied to most clinical tachycardias& even to polymorphic :and :F in preliminary studies 7uccess rates are hi!hest in patients withcommon forms of 7:& namely A:


4/16

tri!!erin! event monitor 7ome patients require the use of previouslyineffective antiarrhythmic dru!s to maintain success

Supraventricular tachyarrhythmias

he common forms of 7: (e!& A:


5/16

For patients with structural heart disease and stable :& the potential benefitof catheter ablation before implantation of an 9C. was demonstrated in the:entricular achycardia Ablation in Coronary Beart .isease (:ACB) study'#+ his prospective& randomized& controlled international trial in "%* patientsfound that time to recurrence of : or :F was lon!er in the ablation !roup(median& "$, months) than in the control !roup (4# months) At years&estimates for survival free from : or :F were *5 in the ablation !roup and# in the control !roup


6/16

=eriprocedural Care

Preprocedural planning

he preprocedural evaluation always includes a thorou!h history and physicale/amination& as well as a review of electrocardio!rams (;CDs1 "-lead& ifavailable) obtained durin! the tachycardia and in sinus rhythm At a minimum&preprocedural blood wor0 typically includes a complete blood count and anassessment of renal function and electrolyte levels

An echocardio!ram is frequently obtained to e/clude structural heart diseaseOther tests that are indicated in specific situations include e/ercise testin!

with or without cardiac ima!in! (especially for e/ercise-inducedtachyarrhythmias)& and cardiac catheterization

he patient should fast overni!ht before the procedure Cardiac medicationswith electrophysiolo!ic effects (e!& beta bloc0ers& calcium channel bloc0ers&di!o/in& and class 9 and 999 antiarrhythmic dru!s) are often tapered ordiscontinued before the procedure 3arfarin may or may not be held prior tothe procedure For e/ample& performin! left atrial ablation for atrial fibrillationon warfarin may reduce thromboembolic complications'"%+

Patient preparation

Catheter ablation typically requires that the patient be under conscioussedation with intravenous tranquilizers and narcotics Deneral anesthesiaisused in children and selected adults

Monitoring and follow-up

After !eneric supraventricular tachcardia (7:) ablation or idiopathicventricular tachycardia (:) ablation& some physicians empirically treatpatients with * wee0s of aspirin therapy with the aim of potentially reducin!the ris0 of thromboembolic sequelae

Anticoa!ulation with warfarin or one of the newer a!ents is typically employedfor at least " month after ablation for patients presentin! in persistent atrialflutter and for months after left atrial ablation for patients with AF
http://emedicine.medscape.com/article/1271543-overviewhttp://emedicine.medscape.com/article/1271543-overview


7/16

;chocardio!raphy is not routinely performed unless a complication (e!&pericardial effusion) may have occurred =ostprocedural electrophysiolo!ictestin! is not routinely performed unless recurrent tachyarrhythmias aresuspected

echniqueApproach considerations

ypically& two to five electrode catheters are percutaneously inserted via thefemoral or internal 6u!ular veins and are positioned within the left heart& theri!ht heart& or both 8ultiple catheters are needed to induce and map varioustachyarrhythmias before radiofrequency (RF) catheter ablation (RFCA)

Cannulation of the coronary sinus is helpful to map left-sided accessorypathways or evaluate other left-sided tachyarrhythmia substrates

For left-heart catheterization& one of the followin! two approaches may beta0en

ransseptal catheterization via the interatrial septum

Retro!rade catheterization across the aortic valve

he latter is typically reserved for ventricular tachycardia (:) ablations oraccessory pathway ablations

Anticoa!ulation with intravenous (9:) heparin is used to reduce the ris0 ofperiprocedural thromboembolism

Atrial fibrillation

RFCA of the atrioventricular (A:) 6unction is the simplest catheter ablationprocedure performed in patients with atrial fibrillation (AF) A: nodalmodification is less effective and is not frequently performed e/cept in anattempt to avoid pacema0er implantation ?oth of these approaches are usedto achieve !ood rate control in AF& but unli0e ablation techniques in atrialtissue& neither one restores normal sinus rhythm 9n addition& A: 6unction

ablation mandates permanent pacema0er implantation

Catheter ablation of atrial tissue to cure AF continues to evolve heprocedure is technically demandin! and is both more ris0y and lesssuccessful than A: 6unction ablation


8/16

e/citement that this common tachyarrhythmia may be amenable to a curativecatheter procedure

For catheter ablation of atrial tissue for AF& the most commonly usedtechnique is a wide circumferential ablation around the pulmonary veins (see

the ima!e below) he !oal is to electrically isolate rapid electrical activityarisin! from inside the veins& or ad6acent to the pulmonary vein ostia& from therest of the left atrium

;lectroanatomic map of posterior

left atrium& illustratin! pulmonary veins ri!ht superior pulmonary vein (R7=:)& ri!htinferior pulmonary vein (R9=:)& left superior pulmonary vein (27=:)& and left inferiorpulmonary vein (29=:) Red circles represent actual discrete radiofrequency (RF)applications& predominantly delivered in circumferential pattern around the pulmonaryveins his ablation strate!y can isolate pulmonary vein foci that initiate atrial fibrillation(AF) or alter substrate of left atrium to inhibit fibrillatory activity due to reentry 9ma!ecourtesy of American Colle!e of Cardiolo!y Foundation


9/16

curin! AF in all comers& re!ardless of chronicity or whether structural heartdisease is present he best success rates with left atrial catheter ablation arein patients with paro/ysmal AF and hearts that are not too structurallyabnormal

Atrial flutter

Atrial flutteris most commonly due to a lar!e reentrant circuit in the ri!htatrium& involvin! an isthmus of tissue between the tricuspid valve annulus andthe inferior vena cava 8ost commonly& reentry proceeds countercloc0wise upthe atrial septum and down the lateral wall of the ri!ht atrium& inscribin!inverted (ie& sawtooth) flutter waves in the inferior leads and upri!ht = wavesin :"(see the ima!es below)

7chema of common variety of atrial flutterReentry circuit is confined to ri!ht atrium and circulates as countercloc0wisemacroreentrant circuit proceedin! superiorly over atrial septum and inferiorly over lateralatrial wall 3ave front circulates throu!h narrow isthmus of tissue between tricuspid

valve annulus and inferior vena cava 2inear ablation across this isthmus (cavotricuspidisthmus) cures this common form of atrial flutter
http://emedicine.medscape.com/article/151210-overviewhttp://emedicine.medscape.com/article/151210-overview


10/16

ypical countercloc0wise atrialflutter (most common form of atrial flutter in patients who have not had prior ablation)Cardinal features are perfectly re!ular atrial rhythm with inverted = waves inferiorly thathave positive overshoot& upri!ht = waves in :"& and inverted = waves in :,

Cloc0wise reentry usin! this same circuit can also occur& !ivin! upri!ht =waves inferiorly and inverted = waves in :" 2inear ablation of thecavotricuspid isthmus cures these common forms of atrial flutter (7ee the

video below)

hree-dimensional electroanatomic map of cavotricuspid isthmus flutter Colorspro!ress from red to purple and represent relative conduction time in ri!ht atrium (earlyto late) Ablation line (red dots) has been created from tricuspid annulus to inferior venacava his interrupts flutter circuit


11/16

.ia!rammatic schema of typicaltype of atrioventricular (A:) nodal reentrant tachycardia (A:


12/16

and retro!rade = wave is hi!hly specific for atrioventricular (A:) nodal reentranttachycardia (A:


13/16

7chema of orthodromicreciprocatin! tachycardia (OR) Atrioventricular (A:) node serves as antero!rade limb&whereas accessory pathway (A: connection) serves as retro!rade limb

7upraventricular tachycardia(7:) in patient with orthodromic reciprocatin! tachycardia (OR) due to concealedpathway


14/16

olff-Parkinson-hite syndrome

3hereas OR uses an accessory pathway in the retro!rade direction& 3=3syndrome by definition indicates an accessory pathway capable ofantero!rade conduction and is manifest by pree/citation (delta waves) on the

sinus rhythm ;CD

AF in 3=3 syndrome may result in life-threatenin!ly fast antero!radeconduction over the accessory pathway& manifested by an irre!ular wide-comple/ (pree/cited) tachycardia that can sometimes de!enerate toventricular fibrillation (:F) AF in 3=3 syndrome may be tri!!ered by OR

Ablation of the accessory pathway cures 3=3 syndrome& eliminatin! OR& aswell as AF& in the ma6ority of patients

!nifocal atrial tachycardia

@nifocal atrial tachycardia& which can arise from either atrium or thenoncoronary cusp of the aorta& is somewhat more challen!in! to ablate thanthe more common forms of !eneric supraventricular tachycardia (7:) Forthose tachycardias ori!inatin! from the left atrium& transseptal catheterizationvia a patent foramen ovale or transseptal puncture is usually required

"entricular tachycardia

9diopathic : most commonly arises from the ri!ht ventricular outflow tractand less commonly ori!inates in the inferoseptal left ventricle about two thirds

of the way toward the ape/ from the base of the left ventricle hese forms of: are amenable to catheter ablation& thou!h success rates are somewhatlower than those for the common forms of 7:

: in structural heart disease is also amenable to ablation 7ome form ofthree-dimensional electroanatomic mappin! is employed for these comple/ablations to identify the scar that contributes to the anatomic substrate forreentry 9ntracardiac echocardio!raphy durin! the procedure andpreprocedural ima!in! with ma!netic resonance ima!in! (8R9) or computedtomo!raphy (C) are also used in some instances Anatomy from

such ima!in! can be inte!rated with the electroanatomic map ifnecessary 7ome : substrates& especially : in nonischemiccardiomyopathy& are not reachable from the endocardium 9n these instances&percutaneous epicardial mappin! and ablation are necessary

Complications


15/16

he radiation ris0 from catheter ablation is low& but it may e/ceed the ris0 fromcommon radiolo!ic procedures he avera!e ris0 of !enetic defects has beencomputed at " case per million births he avera!e ris0 of fatal mali!nanciesran!es from % to deaths per "%%% cases for every ,% minutes offluoroscopy'"+ 8any ablation procedures require less than ,% minutes offluoroscopy

8a6or complications occur in appro/imately of patients who under!oablation procedures& includin! thromboembolism in fewer than " (hi!her insome AF ablation series) and death in %"-% of all procedures heincidence of cardiac complications varies accordin! to the site and type ofablation Cardiac complications include the followin!

Bi!h-!rade A: bloc0

Cardiac tamponade (hi!hest in AF ablation& up to ,)

Coronary artery spasmIthrombosis

=ericarditis

:alve trauma

:ascular complications& which occur in appro/imately -* of procedures&include the followin!

Retroperitoneal bleedin!

Bematoma

:ascular in6ury

ransient ischemic attac0Istro0e

Bypotension

hromboembolism or air embolism

=ulmonary complications include the followin!

=ulmonary hypertension& with or without hemoptysis (secondary to

pulmonary vein stenosis)

=neumothora/

8iscellaneous complications include the followin!

2eft atrialGesopha!eal fistula

Acute pyloric spasmI!astric hypomotility

=hrenic nerve paralysis

Radiation- or electricity-induced s0in dama!e

9nfection at access site

9nappropriate sinus tachycardia


16/16

=roarrhythmia

Documents

Catheter Ablation