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Catheter AblationCatheter Ablation

in the Treatment ofin the Treatment ofAtrial FibrillationAtrial Fibrillation


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First described in

1903 by Hering

Most common

sustained arrhythmia

Atrial FibrillationAtrial Fibrillation


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Atrial fibrillation accountsAtrial fibrillation accounts

for 1/3 of all patientfor 1/3 of all patient

dischargesdischarges

with arrhythmia aswith arrhythmia as

principal diagnosisprincipal diagnosis

2% VF

Baily D. J Am Coll Cardiol. 1992;19(3):41A.

34%

Atrial

Fibrillation

18%

Unspecified

6%

PSVT

6%PVCs

4%

Atrial

Flutter

9%

SSS

8%

ConductionDisease

3% SCD

10% VT


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What is Atrial Fibrillation?

Chaotic circular impulses in the atria

Several reentrant circuits moving simultaneouslyAtrial rates

300 to 600 beats per minute

Ventricular rates regulated by the AV node Irregularly irregular due to partial depolarization of AV

node

Results in loss of AV synchrony 20% to 30% decrease in cardiac output


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Incidence and PrevalenceIncidence and Prevalence

Prevalence increases with age

4.8 % in the 70-79 age group

Increases to

8.8% in the 80-89 age group

During the next 7-8 years, the number of

people over the age of 80 is expected toquadruple


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Atrial Fibrillation Demographics by AgeAtrial Fibrillation Demographics by Age

Adapted from Feinberg WM. Arch Intern Med. 1995;155:469-473.

U.S. population

Population with

atrial fibrillation

Age, yr

95

U.S. population

x 1000

Population with AF

x 1000

30,000

20,000

10,000

0

500

400

300

200

100

0


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Stages of Atrial FibrillationStages of Atrial Fibrillation

Paroxysmal

Persistent

Permanent


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Paroxysmal (23% of AF population)

Self limiting

Spontaneous conversion to sinus rhythm within 24 hrsafter onset is common

Once the duration exceeds 24 hrs, the likelihood of

conversion decreases

After one week of persistent arrhythmia, spontaneousconversion is rare

30% of these patients develop Persistent AF


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Persistent (38% of AF population)

Requires intervention to restore normal rhythm

Cardioversion Electrical or Chemical (drugs)

Can lead to electrophysical and structural changes

in the myocardium (remodeling) that can lead to

Permanent AF

AF with duration of greater than 7 days rarely

spontaneously converts


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Permanent (39% of AF population)Unable to convert Electrical or Chemical (drugs)


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Mechanisms of AFMechanisms of AF

Theories of the mechanism of AF involve

2 main processes:

- Enhanced automaticity in one or several rapidly

depolarizing foci

- Reentry involving one or more circuits


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Mechanisms Contributing to AF


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Mechanisms of AFMechanisms of AF

Rapidly firing atrial foci, located in one or

several pulmonary veins (PVs), can initiate AFin susceptible patients

Foci also can occur in RA and infrequently inthe superior vena cava or coronary sinus


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Pulmonary Vein MyocardialPulmonary Vein Myocardial

SleevesSleeves


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Factors Involved in the Pathogenesis of AFFactors Involved in the Pathogenesis of AF

Studies in man have shown that increased inhomogeneity ofrefractory periods and conduction velocity is present in AF

patients.

Structural changes in atrial tissue may be one of the underlyingfactors for dispersion of refractoriness in AF.

Other factors involved in the induction or maintenance of AF

include premature beats, the interaction with the autonomicnervous system, atrial stretch, anisotropic conduction, and theaging process, vein of Marshall.


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Mechanisms contributing to AFMechanisms contributing to AF


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Atrial Fibrillation: Clinical ProblemsAtrial Fibrillation: Clinical Problems

Embolism and stroke (presumably due to LA clot)

Acute hospitalization with onset of symptoms

Anticoagulation, especially in older patients (> 75 yr.)

Congestive heart failure

Loss of AV synchrony

Loss of atrial kick

Rate-related cardiomyopathy due to rapid and irregular ventricularresponse

Rate-related atrial myopathy and dilatation

Chronic symptoms and reduced sense of well-being


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Therapeutic Approaches toTherapeutic Approaches to


Anticoagulation

Antiarrhythmic suppression

Control of ventricular response

Pharmacologic

Catheter modification/ablation of AV node

Curative procedures

Catheter ablation

Surgery (maze)


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Disadvantages

High recurrence rate

High long-term cost

Non-curative

Adverse effects

Potential proarrhythmia

Antiarrhythmic Therapy for Atrial FibrillationAntiarrhythmic Therapy for Atrial Fibrillation

Advantages

High efficacy for some

patients, at least

initially

(< 50% of all patients)

Low initial cost

Noninvasive


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Antiarrhythmic SuppressionAntiarrhythmic Suppression

DrugsConversion of AF

Class 1A (decrease conduction velocity, increase refractoryperiods of cardiac tissue, suppress automaticity)

Quinidine

Procainamide

Class III (decrease conduction velocity, increase refractoryperiods of cardiac tissue, suppress automaticity)

Amiodarone

Sotalol

Ibutilide (Corvert)

Dofetilide


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Antiarrhythmic SuppressionAntiarrhythmic Suppression

Drugs

Maintenance of normal rhythm

Class 1A

Class III

Class 1C (decrease conduction velocity)

Flecainide

Propafenone

Drug choice depends upon patients underlying

heart disease


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Nonpharmacological Approaches toNonpharmacological Approaches to


1. Pacemaker therapy

2. AblationAblation

3. Surgery


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RF Ablation TechniquesRF Ablation Techniques

A)A) Focal ablation of PV (Pulmonary vein) triggersFocal ablation of PV (Pulmonary vein) triggers

B)B) Segmental PV isolationSegmental PV isolation

C)C) Wide Area Circumferential AblationWide Area Circumferential Ablation

D)D) Ablation of Fractionated Complex ElectrogramsAblation of Fractionated Complex Electrograms

E) Targeted ablation of ganglionated autonomic plexi in theepicardial fat pads


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Focal Ablation of TriggersFocal Ablation of Triggers


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Focal AblationFocal Ablationof Atrial Fibrillationof Atrial Fibrillation

95% of foci are located within a pulmonary

vein ( PV).

Focal sources of AF may be found in the RA,

LA, coronary sinus, superior vena cava or vein of

Marshall.Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic

beats originating in the pulmonary veins. N Engl J Med 1998;339:65966.

Chen SA, et. al: Initiation of atrial fibrillation by ectopic beats originating from the pulmonary

veins: Electrophysiologic characteristics, pharmacologic responses, and effects of

radiofrequency ablation. Circulation 1999;100:1879-1886.


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Pulmonary Vein Spike DischargesPulmonary Vein Spike Discharges


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Pulmonary Vein Spike DischargesPulmonary Vein Spike Discharges


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Initiation of AF by PV DischargesInitiation of AF by PV Discharges


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PV potentials

PV Potentials


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PV Potentials


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PV Potential on 6-10


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PV potentials

disappeared

during

radiofrequency

currentapplication


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Loss of PV Potentials


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Focal Ablation of Pulmonary VeinsFocal Ablation of Pulmonary VeinsComplicationsComplications

The most common complications associated with thefocal ablation of the PVs are pericardial effusion(


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PV Stenosis


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PV Stenosis


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Multi-slice CT Endocardial View


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PV StentingPV Stenting

T d I t di hTamponade: Intra cardiac echo


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Tamponade: Intra-cardiac echoTamponade: Intra-cardiac echo

The incidence of perforation during ablation of the left atrium is relatively low


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Segmental PV IsolationSegmental PV Isolation


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Segmental PV IsolationSegmental PV Isolation

Limitations associated with focal ablation have

prompted the development of other techniques foreliminating the PV arrhythmias.

Anatomically PV isolation has significant advantages

over focal ablation.

L S i l C th t


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Lasso or Spiral Catheters


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Dissociation of the

PV potential aftersuccessful isolation


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Segmental Ostial Pulmonary VeinSegmental Ostial Pulmonary Vein

IsolationIsolation

The initial experience with segmental ostial

ablation of PVs guided by PV potentials is

encouraging, with a long-term success rate of 90%

in patients with paroxysmal AF

Minimal risk of PV stenosis when the power of

radiofrequency energy applications is limited to 30W.


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Wide Area CircumferentialWide Area Circumferential

AblationAblation


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Circumferential AblationCircumferential Ablation

It is an anatomic approach in which circumferential lines ofblock are created using 3D maps ( Carto, NavX..) around the

ostia of PVs for isolation of PVs from LA.

Additional linear lesion from LIPV to mitral annulus for

preventing LA incisional tachycardia ( 2%).

Additional linear lesions (posterior, roof, right isthmus.)

may be created deepening on operators preference.

Pappone C, et al. Atrial electroanatomic remodeling after circumferential radiofrequency

pulmonary vein ablation: efficacy of an anatomic approach in a large cohort of patients

with atrial fibrillation. Circulation 2001;104:25392544.


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NavX MapNavX Map


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Anatomical Reconstruction of LAAnatomical Reconstruction of LA


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Circumferential AblationCircumferential AblationCarto MapCarto Map


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Magnetic Resonance Image Electroanatomic Map


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Magnetic Resonance Image Electroanatomic Map


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Effective in both paroxysmal and chronic AF

(81%, 76%) Bipolar amplitude < 0.1 mv inside and aroundBipolar amplitude < 0.1 mv inside and around

the lesion may be acceptable for showing PVthe lesion may be acceptable for showing PV

isolation.isolation.

Post Circ mferential PV ablation


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Post Circumferential PV ablation

BipolarBipolar

amplitudeamplitude< 0.1 mv< 0.1 mv

inside theinside the

lesionlesion


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Mitral Isthmus LineMitral Isthmus Line

The addition of mitral isthmus line to the PVdisconnection may allow a significant improvement ofsinus rhythm maintenance rate, particularly in patientswith persistent AF, without the risk for major

complications.

J Cardiovasc Electrophysiol, Vol.

16, pp. 1150-1156, November 2005

C li ti t f ll i i f ti lC li ti t f ll i i f ti l


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Complication rates following circumferentialComplication rates following circumferential

pulmonary vein ablationpulmonary vein ablation

Death 0%

Pericardial effusion 0.1%

Stroke 0.03% Transient ischemic attack 0.2%

Tamponade 0.1%

Atrio-esophageal fistula 0.03% Pulmonary vein stenosis 0%

Incisional left atrial tachycardia 6%

Phrenic nerve injury


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Topographic

Variability of theEsophageal Left

Atrial Relation

CT


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CT

reconstruction

of the LA, the

pulmonary

veins, and theesophagus


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Topographic Variability of the

Esophageal Left Atrial Relation


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Phrenic Nerve Injury


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Phrenic Nerve Injury


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Ablation of Fractionated ElectrogramsAblation of Fractionated Electrograms

Hypothesis being that these are consistent sites whereHypothesis being that these are consistent sites wherefibrillating wavefronts turn or split.fibrillating wavefronts turn or split.

By ablating these areas the propagating randomBy ablating these areas the propagating randomwavefronts are progressively restricted until the atriawavefronts are progressively restricted until the atriacan no longer support AF.can no longer support AF.

Nademanee demonstrated 70% freedom from AFNademanee demonstrated 70% freedom from AFfollowing a single procedure for permanent AFfollowing a single procedure for permanent AF

patients.patients.

Nademanee K, et al. A new approach for catheter ablation of atrial fibrillation: mapping of the

electrophysiologic substrate. J Am Coll Cardiol 2004;43:204453.

Segmental Ablation vs CircumferentialSegmental Ablation vs Circumferential


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Segmental Ablation vs. CircumferentialSegmental Ablation vs. Circumferential

Ablation?Ablation?

Is either of the two ablation strategies superior to the other?

Oral et al. showed that, during the 6 months following a singlecatheter procedure, Circumferential Ablation was associated witha significantly better outcome with no differences between thetwo ablation strategies in the complication rates.

Schmitt et al. reported opposite results to those of Oral et al.

The opposite results in the two studies were obtained because ofthe large variability in the success rate observed in patientsundergoing Circumferential Ablation (88 vs. 47%) while thesuccess rates in patients undergoing Segmental Ablationremained unchanged (67 vs. 71%).

Integrated ApproachIntegrated Approach


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Integrated ApproachIntegrated Approach

Journal of Cardiovascular Electrophysiology Vol. 16, No. 12, Dec. 2005


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Frequently Asked QuestionFrequently Asked Question

Who is currently a candidate forAF ablation?

Patient selection criteriaPatient selection criteria


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Patient selection criteriaPatient selection criteria

Inclusion criteria At least one monthly episode of persistent symptomatic AF or At least one weekly episode of paroxysmal AF or

Permanent AF

And

At least one failed trial of antiarrhythmic drugs or More than one antiarrhythmic drug to control symptoms

Exclusion criteria NYHA functional class IV

Age > 80 years

Contraindications to anticoagulation

Presence of cardiac thrombus

Left atrial diameter 65 mm

Life expectancy < 1 year

Thyroid dysfunction

Recent updates Patients with mitral and/or aortic metallic prosthetic valves are

not excluded Previous repair of atrial septal defects is not an absolute contraindication


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Frequently Asked QuestionFrequently Asked Question

AF ablation for asymptomaticindividuals?

Asymptomatic PatientsAsymptomatic Patients


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Asymptomatic PatientsAsymptomatic Patients

To date there is no evidence that treatment of AF byablation improves mortality, although there are uncontrolled

data suggesting that this may be the case.

Therefore, asymptomatic patients should not be offeredcurative ablation of AF, except in the case of those patients

undergoing cardiac surgery who may benefit from surgical

ablation of their AF as an adjunctive procedure.

There is also evidence that patients with heart failure have

significant improvements in left ventricular function

following successful catheter ablation of AF.


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ConclusionConclusion


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ConclusionConclusion

For many patients with a previously untreatable heartrhythm, ablation has dramatically improved their symptomsby restoring and maintaining sinus rhythm.

Preliminary randomized studies of catheter ablation of AF

provide evidence that ablation (with or without concurrentanti-arrhythmic drug use) effectively improves maintenanceof sinus rhythm when compared with current anti-arrhythmicdrugs.

Although prognostic and quality of life data from long termrandomized trials of catheter ablation for AF are still inpreparation, the non-randomized data comparing ablation tocontinued medical treatment suggests a strong benefit from

ablation.

Tehran Arrhythmia CenterTehran Arrhythmia Center


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WWW.IranEP.orgWWW.IranEP.org

[email protected]@IranEP.org

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