Catheter AblationCatheter Ablationin the Treatment ofin the Treatment of

Atrial Fibrillation Atrial Fibrillation

• First described in 1903 by Hering

• Most common sustained arrhythmia

Atrial FibrillationAtrial Fibrillation

Atrial fibrillation accounts Atrial fibrillation accounts for 1/3 of all patient for 1/3 of all patient

discharges discharges with arrhythmia as with 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% Conduction

Disease

3% SCD

10% VT

Atrial FibrillationAtrial Fibrillation

• What is Atrial Fibrillation?• Chaotic circular impulses in the atria

– Several reentrant circuits moving simultaneously– Atrial 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

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 to quadruple

Atrial Fibrillation Demographics by AgeAtrial Fibrillation Demographics by Age

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

U.S. population

Population withatrial fibrillation

Age, yr

<5 5-9

10-14

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85-89

90-94

>95

U.S. populationx 1000

Population with AFx 1000

30,000

20,000

10,000

0

500

400

300

200

100

0

Stages of Atrial FibrillationStages of Atrial Fibrillation

• Paroxysmal

• Persistent

• Permanent

Stages of Atrial FibrillationStages of Atrial Fibrillation

• Paroxysmal (23% of AF population)– Self limiting

• Spontaneous conversion to sinus rhythm within 24 hrs after onset is common

• Once the duration exceeds 24 hrs, the likelihood of conversion decreases

• After one week of persistent arrhythmia, spontaneous conversion is rare

– 30% of these patients develop “Persistent” AF

Stages of Atrial FibrillationStages of Atrial Fibrillation

• 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

Stages of Atrial FibrillationStages of Atrial Fibrillation

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

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

Mechanisms Contributing to AFMechanisms Contributing to AF

Mechanisms of AFMechanisms of AF

• Rapidly firing atrial foci, located in one or several pulmonary veins (PVs), can initiate AF in susceptible patients

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

Pulmonary Vein Myocardial Pulmonary Vein Myocardial SleevesSleeves

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

• Studies in man have shown that increased inhomogeneity of refractory periods and conduction velocity is present in AF patients.

• Structural changes in atrial tissue may be one of the underlying factors for dispersion of refractoriness in AF.

• Other factors involved in the induction or maintenance of AF include premature beats, the interaction with the autonomic nervous system, atrial stretch, anisotropic conduction, and the aging process, vein of Marshall……….

Mechanisms contributing to AFMechanisms contributing to AF

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 ventricular response

• Rate-related atrial myopathy and dilatation

• Chronic symptoms and reduced sense of well-being

Therapeutic Approaches to Therapeutic Approaches to Atrial FibrillationAtrial Fibrillation

• Anticoagulation

• Antiarrhythmic suppression

• Control of ventricular response

– Pharmacologic

– Catheter modification/ablation of AV node

• Curative procedures

– Catheter ablation

– Surgery (maze)

• 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 somepatients, at leastinitially (< 50% of all patients)

• Low initial cost

• Noninvasive

Antiarrhythmic SuppressionAntiarrhythmic Suppression

• Drugs– Conversion of AF

• Class 1A (decrease conduction velocity, increase refractory periods of cardiac tissue, suppress automaticity)

– Quinidine– Procainamide

• Class III (decrease conduction velocity, increase refractory periods of cardiac tissue, suppress automaticity)

– Amiodarone– Sotalol– Ibutilide (Corvert)– Dofetilide

Antiarrhythmic SuppressionAntiarrhythmic Suppression

• Drugs– Maintenance of normal rhythm

• Class 1A

• Class III

• Class 1C (decrease conduction velocity)– Flecainide

– Propafenone

– Drug choice depends upon patient’s underlying heart disease

Nonpharmacological Approaches to Nonpharmacological Approaches to Atrial FibrillationAtrial Fibrillation

1. Pacemaker therapy

2. AblationAblation

3. Surgery

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 the epicardial fat pads

Focal Ablation of TriggersFocal Ablation of Triggers

Focal AblationFocal Ablation of 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;339:659–66.

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.

Pulmonary Vein Spike DischargesPulmonary Vein Spike Discharges

Pulmonary Vein Spike DischargesPulmonary Vein Spike Discharges

Initiation of AF by PV DischargesInitiation of AF by PV Discharges

PV potentials

PV Potentials

PV Potentials

PV Potential on 6-10

PV potentials disappeared during radiofrequency current application

Loss of PV Potentials

Focal Ablation of Pulmonary VeinsFocal Ablation of Pulmonary VeinsComplicationsComplications

• The most common complications associated with the focal ablation of the PVs are pericardial effusion (<4%), transient ischemic episodes (<2%) and symptomatic PV stenosis <2%).

• Asymptomatic PV stenosis may occur at as many as 40% of sites at which focal ablation is performed.

• Symptomatic PV stenosis seems to be infrequent if the number of radiofrequency applications delivered within PV is kept to a minimum.

PV Stenosis

PV Stenosis

Multi-slice CT Endocardial View

PV StentingPV Stenting

Tamponade: Intra-cardiac echoTamponade: Intra-cardiac echo

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

Segmental PV IsolationSegmental PV Isolation

Segmental PV IsolationSegmental PV Isolation

• Limitations associated with focal ablation have prompted the development of other techniques for eliminating the PV arrhythmias.

• Anatomically PV isolation has significant advantages over focal ablation.

Lasso or Spiral Catheters

Dissociation of the PV potential after successful isolation

Segmental Ostial Pulmonary Vein Segmental 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 30 W.

Wide Area Circumferential Wide Area Circumferential AblationAblation

Circumferential AblationCircumferential Ablation

• It is an anatomic approach in which circumferential lines of block 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 operator’s 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;104:2539–2544.

NavX MapNavX Map

Anatomical Reconstruction of LAAnatomical Reconstruction of LA

Circumferential AblationCircumferential Ablation

Circumferential AblationCircumferential AblationCarto MapCarto Map

Circumferential AblationCircumferential Ablation

Circumferential AblationCircumferential Ablation

Circumferential AblationCircumferential Ablation

Magnetic Resonance Image Electroanatomic Map

Circumferential AblationCircumferential Ablation

• Effective in both paroxysmal and chronic AF (81%, 76%)

• Bipolar amplitude < 0.1 mv inside and around Bipolar amplitude < 0.1 mv inside and around the lesion may be acceptable for showing PV the lesion may be acceptable for showing PV isolation.isolation.

Post Circumferential PV ablationPost Circumferential PV ablation

Bipolar Bipolar amplitude amplitude < 0.1 mv < 0.1 mv inside the inside the lesionlesion

Mitral Isthmus LineMitral Isthmus Line The addition of mitral isthmus line to the PV

disconnection may allow a significant improvement of sinus rhythm maintenance rate, particularly in patients with persistent AF, without the risk for major complications.

J Cardiovasc Electrophysiol, Vol. 16, pp. 1150-1156, November 2005

Complication rates following circumferential Complication 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

Topographic Variability of the Esophageal Left Atrial Relation

CT reconstruction of the LA, the pulmonary veins, and the esophagus

Topographic Variability of the Esophageal Left Atrial Relation

Phrenic Nerve Injury

Ablation of Fractionated ElectrogramsAblation of Fractionated Electrograms

• Hypothesis being that these are consistent sites where Hypothesis being that these are consistent sites where fibrillating wavefronts turn or split. fibrillating wavefronts turn or split.

• By ablating these areas the propagating random By ablating these areas the propagating random wavefronts are progressively restricted until the atria wavefronts are progressively restricted until the atria can no longer support AF. can no longer support AF.

• Nademanee demonstrated 70% freedom from AF Nademanee demonstrated 70% freedom from AF following a single procedure for permanent AF following 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;43:2044–53.

Segmental Ablation vs. Circumferential Segmental 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 single catheter procedure, Circumferential Ablation was associated with a significantly better outcome with no differences between the two 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 of the large variability in the success rate observed in patients undergoing Circumferential Ablation (88 vs. 47%) while the success rates in patients undergoing Segmental Ablation remained unchanged (67 vs. 71%).

Integrated ApproachIntegrated Approach

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

Frequently Asked QuestionFrequently Asked Question

Who is currently a candidate for AF ablation?

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

Frequently Asked QuestionFrequently Asked Question

AF ablation for asymptomatic individuals?

Asymptomatic PatientsAsymptomatic Patients

• To date there is no evidence that treatment of AF by ablation improves mortality, although there are uncontrolled data suggesting that this may be the case.

• Therefore, asymptomatic patients should not be offered curative 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.

ConclusionConclusion

• For many patients with a previously untreatable heart rhythm, ablation has dramatically improved their symptoms by restoring and maintaining sinus rhythm.

• Preliminary randomized studies of catheter ablation of AF provide evidence that ablation (with or without concurrent anti-arrhythmic drug use) effectively improves maintenance of sinus rhythm when compared with current anti-arrhythmic drugs.

• Although prognostic and quality of life data from long term randomized trials of catheter ablation for AF are still in preparation, the non-randomized data comparing ablation to continued medical treatment suggests a strong benefit from ablation.

Tehran Arrhythmia CenterTehran Arrhythmia Center

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