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Ablation of Atrial FibrillationEmile Daoud, M.D.

Clinical Professor of MedicineDirector, Electrophysiology Section

Ross Heart HospitalOhio State University Medical Center

Atrial Fibrillation

Rapid and Irregular

Normal Sinus RhythmRight & Left Atria

Electrograms During AFSurface, Right & Left Atria

Right Atrium

Surface

Organized

Disorganized

Left Atrium

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Canadian Trial of AFMedications Rarely Provide

Long Term Efficacy1yr

50% of pts at 1 year still have

Atrial Fibrillation

Drug-Induced Proarrhythmia - Torsade

Just Say No to Drugs

Poor Efficacy and Excessive Side Effects

Beginnings of Curative Ablation for Atrial Fibrillation• Minneapolis Feb 1999• Haisseguerra – Bordeaux, France• “Pulmonary Vein Isolation”

Designed a circular catheter to map the pulmonary veinsAtrial muscle bundles span the transition zone from the pulmonary veins into the atria – trigger for AFib

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Pulmonary Vein AnatomyStructure-Function Substrate for

Ectopy

Low & high power magnification of PV muscle bundles

• Heart attack victims atBordeaux hospital are beinggiven two glasses of wine aday during their stay.

• Patients on the cardiac wardare being encouraged toenjoy a daily tipple to cuttheir risk of further heartproblems.

First in the US to perform PV Isolation

Hospital Gives Patients Wine

Left Atrium

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Pulmonary Veins Pulmonary

Veins

Left Atrium

Pulmonary Veins Pulmonary

Veins

Left Atrium

Ablation of Pulmonary Vein Muscle Bundles Identified By A Circular Mapping Catheter

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Ablation of Pulmonary Vein Muscle Bundles Identified By A Circular Mapping Catheter

**

*

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Circular Mapping & Ablation CatheterRight Pulmonary Vein

Case Study• 62 yo WF, H/O PAF with increasing

frequency and duration, 3– 4 episodes / wk.• Sx: Extreme fatigue, palpitations• PMHx: AF for 5 yrs; Multiple CV’s; HTN;

LVEF 40%; LA size 48mm• Failed AA therapy: Beta blockers, sotalol,

propafenone and amiodarone x 4 mos.

Sinus with PAC’s

Nonconducted & Conducted PV EctopyCircular Catheter in RSPV

RA

PV

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Spontaneous PAC-Induced AF Recorded With Circular

Catheter in RSPV

RA

PV

Atrial Pacing Post-CVRSPV - LA Dissociation

RA

PV

PV Potentials from LSPV

RA

PV

Final RF Site for LSPVRA

PV

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Goal: PV ElectricalEntrance & Exit BlockPre-RF Post-RF

∗∗

∗

Why Does Atrial Fibrillation Spontaneously Stop in Some Patients But Requires an

Electrical Shock in Others?

• Moe’s Wavelet theory

• Once a trigger (often from PV source) initiates AF, multiple wandering waves of depolarization are created, called wavelets

• These wavelets occur simultaneously and account for irregularity

• “Mother” waves give rise to “daughter”wavelets…together this process leads to persistent AF

• Rate-related adverse atrial remodeling

• Acute ChangesShortening of refractory periodsHeterogeneous refractory periodsFunctional conduction blockCalcium loading alters contractilityAlteration of atrial hemodynamics

• Chronic ChangesAltered mitochondrial functionAltered ion channel functionAltered expression of atrial myocyte proteinsAccelerated atrial fibrosis and apoptosis

What Sustains Wavelets and Thus AF?“AF Begets AF”

For Persistent AFNot just merely a TRIGGER problem• Rate-related changes result in pathologic

changes in atrial musculaturePV isolation alone provides low successRF ablation therefore must approach more than just the PV’s, but also the atrial musculature

• Since the strategy for ablation of persistent AF is to target the atrium as well as the PV’s, defining and navigating the LA anatomy becomes critical

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AortaEsophagus

Left Ventricle

Left Atrium & PV’s

Pulmonary Artery

Left Common PV

Right Middle PV

Right Superior PV

Right Inferior PV

Atrial appendage

Sup. branch

Inf. branch

Left Common Ostium

Atrial appendage

Anterior aspect of LA

Posterior aspect of

LA

Opening of atrial appendage

Red Circular Tags = Ablation Site

Final Lesion Set Isolation of the PV’s + Linear Connecting Ablation Lines

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Case Study• 58 yo Male, H/O persistent AF for 4

years• Failed sotalol, flecainide and

amiodarone• Sx: Extreme fatigue, palpitations• LVEF: 45%, LA Size 52mm• Referred for RFA AV node

Atrial Fibrillation

After RFA in LAII

RA-19, 20

RA-17, 18

RA-15, 16

RA-13,14

LA-5, 6

LA-3, 4

LA-2, 1

CS -LA

RA

Organized Activity in LA

“The AF Driver”Disorganized Fractionated

Signals = Wavelet

Organization of AF With RFA in RA

II

ABLATION

RA-19, 20

RA-15, 16

RA-13,14

LA-5, 6

LA-3, 4

LA-2, 1

RA-17, 18

RA-11, 12

RA-9, 10

RA-7, 8

RA

CS -LA

Organization during RFA at areas of micro-reentry

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Termination of AFBy RFA of “AF Driver”

Ablation of Areas of Microreentry

RA

II

RA-19, 20

RA-15, 16

RA-13,14

LA-5, 6

LA-3, 4

LA-2, 1

RA-17, 18

RA-11, 12

RA-9, 10

RA-7, 8

ABLATION

CS -LA

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Candidates for Catheter Ablation for Atrial Fibrillation• Patients with symptomatic AFib & failed 1

Class I or III antiarrhythmic medication (ACC/AHA Guidelines)

• Other considerations:AFib controlled with drug therapy but pt does not want to continue with life-long medical therapy / excessive side effectsDesire to eliminate anticoagulation

• Cornerstone of Catheter Ablation of AFib….Isolation of PV’s

Paroxysmal – Circular catheter guidancePersistent – Circumferential Ablation around each PV ± Linear ablation

• >1800 Procedures• All comers 86% cure at 1 year

91% paroxysmal83% permanent / persistent

• 1.35 procedures / pt• Complications 1.8%

OSU RFA Experience

Factors Associated with Successful AFib Ablation• Paroxysmal rather than Persistent AFib• Absence of LA enlargement• History of AFib < 5 years• Lower Body Mass Index

• Not Age

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Worldwide Registry:Complications Associated with

Curative Ablation for AF (n = 8,745)

516 (5.9%)Total 4 (0.05%)Death71 (0.81%)Other morbidities

10 (0.11%)Phrenic nerve injury / diaphragmatic paralysis

82 (0.94%)Cerebrovascular accident / transient ischemic attack

100 (1.14%)Vascular access complications107 (1.22%)Cardiac tamponade142 (1.63%)Clinically important PV stenosis

Number of Patients (%)Type of Complication

“If we pull this off, we’ll eat like kings.”

AF Cure

New Technologies for the Ablation of Atrial Fibrillation

John D. Hummel, M.D.Ohio State University Electrophysiology

Current State of CurativeAFib Ablation

• Total Patients > 1000 (65% Persis. AF)• Table Time ~ 4 hours• Expected success @ 1yr

≈ 75% after first procedure≈ 87% after second procedure

• Complications ≈ 1-2%Tamponade – 0.6%Pulmonary vein stenosis – 0.6%TIA / CVA – 0.5%Esophageal-LA fistula - 0Groin Bleeding / Hematoma(Last 200 pts complications < 1%)

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Atrial Fibrillation: Ablation vs Drug Rx.

Ablation87% successPV stenosisAE fistula TIA/CVA

Drug Rx.40% successProarrhythmiaEnd Organ Toxicity

No Free Lunch

PV stenosis

AE fistula

Torsades

New Technology to Increase Efficacy and Decrease Risk of

Complications• Catheter Navigation/Mapping

MagneticRoboticUltrasound

• Energy SourcesHigh Intensity Focused Ultrasound (HIFU)Cryoablation

• RF Energy Delivery:PV MeshLasso RF DeliveryClosed vs. Irrigated RF catheters

• Left Atrial Appendage Closure

Conventional Ablation: Limitations

• Power output limited due tooverheating of the ablation electrodeand the adjacent tissue

• Dependent on cavitary cooling –cavitary cooling is pulsatile,dependent on cardiac output andvaries in different parts of the heart.

Areas of thick tissue

Areas of low cavitary cooling

Coagulum formation due to highelectrode and electrode-tissueinterface temperatures

4mm, Temperature control mode

Irrigated (Cool Tip) Ablation Tissue Heating

• Active cooling• Lowers the temperature of

the ablation electrode and adjacent tissue

• Allows higher levels of power output, and results in a larger lesion.

• There are two types of irrigation technologies :

Closed loopOpen loop

Nakagawa et al. Circulation 1995,91:2264-73

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Irrigation TechnologyOpen Loop Irrigation

ExternalCooling

Thermocouple

•Irrigation fluid flows through tinyholes around the electrode tip. •The irrigation fluid is in directcontact with both the ablationelectrode and the surroundingtissue surface. •Directly cools the electrodetissue interface

Higher power delivery Higher perforation riskBubble riskFluid LoadEndocardial sparing

InternalCooling

Irrigation TechnologyClosed Loop Irrigation

Thermocouple

•Irrigation fluid is not released intothe blood thus no volume overload,bubble risk

•2 lumens for the internal circulation:

One bringing fluid to the tip

Other removing fluid from tip

•Irrigation fluid does not directly coolthe electrode-tissue interface

Lower power delivered due to lesscooling of ET interface

Higher Char Risk

Afib Ablation=TransseptalPuncture

Ablation Frontier PVAC Catheter in LSPV

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II

Pair 1

Pair 2

Pair 3Pair 4

Pair 5

Pre

II

Pair 1

Pair 2

Pair 3

Pair 4Pair 5

Post

LIPV RF Ablation

3 Spline Catheter – SeptalPositioning

LA Roof and Floor Ablation Sites

Stereotactic Navigation

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Automatic Catheter Access to Right Inferior Pulmonary Vein

Pre-Programmed Atrial Reconstruction and Linear Ablation

Accunav Fan Segmentation of LA With MRI Registration

Cartosound

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Esophagus near LIPV

Effect of Cryothermyon Cells

Cryo Applications to Complete PVI

Each Cryo Marker= 4mm

Arctic Front® Cardiac CryoAblation Catheter

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HIFU AblationRSPV LSPV

HIFU RFALSPV Baseline Recordings

III

V1Map 1,2Map 2,3Map 3,4Map 4,5Map 5,6

A PVP

HIFU RFALSPV Recordings During RFA

III

V1Map 1,2Map 2,3Map 3,4Map 4,5

Map 5,6

Isolated PVP

APVP A A

Implant Face Distal to Ostium

Barbs Engage LAA Wall

WATCHMAN® LAA Filter System

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Current State of New Technologies

1. Cool Tip technology currently in use with new designs in trials

2. Circular Ablative Tool in Trials3. Cryo focal approved, Balloon under Review

by FDA4. HIFU on Hold5. LA closure under FDA review (in trials)6. Magnetic Navigation in Use7. Ultrasound Registration in Use