Electrophysiology 101: What Do Surgeons Need to Know · Damiano RJ et al. J Thorac Cardiovasc Surg 2011;141:113-21. Department of Surgery ... • Narayan (2012) 1-2 Stable Rotors

Electrophysiology 101: What Do Surgeons Need to Know

Richard B Schuessler PhD

Department of SurgeryDivision of Cardiothoracic Surgery

Disclosures• Research Grant from Atricure, Inc.


Arrhythmias Where The Surgical Approach Has Been Used

• WPW• AVNRT• Automatic Ectopic Atrial Tachycardias• Inappropriate Sinus Tachycardia• Atrial flutter/fibrillation• Ischemic and Non-ischemic VT• ARVD Tachycardia • Congenital Post Repair Arrhythmias (i.e. flutter following

the Fontan procedure)


Factors Common to All Arrhythmias

1. Abnormal Impulse Formation• Number• Timing

2. Velocity of propagation• Magnitude• Anisotropy

3. Refractory period• Magnitude• Homogeneity

4. Anatomic Geometry• Macroscopic• Microscopic

Each of these factors are dynamic. They remodel with pathology (i.e. MR) and AF.


Arrhythmia Mechanisms

Non Reentrant Reentrant


Arrhythmia Mechanisms

Kneller et al Circ Res. 2002;90:e73-e87.

Spiral Wave Reentry (rotors)


Nishida et al Circ Res:214:1447-1452


Abnormal Impulse Formation: PACs

David Conen, et al . Premature Atrial Contractions in the General Population: Frequency and Risk FactorsCirculation.2012;126:2302-2308.

PACs are common, and their frequency is independently associated with age, height, history of cardiovascular disease, natriuretic peptide levels, physical activity, and high-density lipoproteincholesterol.

24-hour Holter electrocardiograms to assess PAC prevalence and frequency were performed in a random sample of 1742 (Swiss) participants aged >50 years.


Remodeling of Refractory Period

Increased rate, with AF, cause the action potential and refractory periodto decrease. This makes it easier for AF to be maintained (shorter wavelength). This is why “AF begets AF”.

Many other pathologies alter refractoryPeriod. For example, heart failureprolongs refractory period.


Remodeling Conduction: Increased Fibrosis

Yonjun Q et al:Cardiovascular Pathology 22 (2013) 211–218

Increased fibrosis slows and blocksconduction.


Hansen BJ et al: J Am Coll Cardiol EP 2017;3:531–46

Remodeling Conduction: Fibrosis


Anatomy: Complexity


Anatomy: Size Matters

Damiano RJ et al. J Thorac Cardiovasc Surg 2011;141:113-21


Subdivision of Atria in an Intact Pig

Lesions are created using a bipolar RF clamp

Lee AM et al. J Thorac Cardiovasc Surg 2013;146:593-8


Probability of AF vs. ERP vs. Area

AUC is 0.878

ERP p=0.00004

Area p=0.0058

ERP=50

2000 4000 6000 8000 10000 12000Atrial Surface Area (mm**2)

0.0

0.2

0.4

0.6

0.8

1.0Pr

ob [A

F]

ERP=75

ERP=100

ERP=125

ERP=150

ERP=175ERP=200

ERP=225ERP=250

Lee AM et al. J Thorac Cardiovasc Surg2013;146:593-8


History of AF Mechanisms

• Engelman (1895) Multiple Foci• Rothberger &Winterberg (1914) Single Rapid Focus• Garrey (1914) Reentry In A Critical Mass• Lewis (1921) Single Reentrant Circuit With Fibrillatory Conduction• Scherf (1947) Single Rapid Focus (Aconitine)• Moe (1962) Multiple Wavelet Hypothesis• Allessie (1984) Multiple Wavelets• Cox (1991) Multiple Changing Mechanisms- Macro Reentrant

Circuit, Focal Activation, Spiral Rotor• Haissaguerre (1998) Focal PV Source• Narayan (2012) 1-2 Stable Rotors Or Focal Sources• Federov(2015) Micro Anatomic Reentry• Allessie (2016) Multiple Wavelets with Epi-Endo discordance


Atrial Fibrillation

• There is a great deal of controversy at the moment over the underlying activation patterns that cause AF.


Mechanisms of Atrial Fibrillation


Intraopertive Mapping of Human AF

Cox JL, et al. “The Surgical Treatment of Atrial Fibrillation”. JTCVS, March 1991.

-Macro reentrant circuit-Small rotor-Focal activation pattern-Pattern changed over time


ECGI Activation Mapping - Long Standing Persistent AF

Cuculich P et al: Circulation. 2010;122:1364-1372.


Jordi Heijman et al. Circ Res. 2014;114:1483-1499

The Time Course And Evolution Of AF


Progression From Paroxysmal to Persistent Atrial Fibrillation Clinical Correlates and Prognosis

Cees B. de Vos, MD, et al: J Am Coll Cardiol 2010;55:725–31.

… included 1,219 patients with paroxysmal AF who participated in the Euro Heart Survey on AF and had a known rhythm status at follow-up. Patients who experienced AF progression after 1 year of follow-up were identified.


Charles R. Kerr et al: Am Heart J 2005;149:489- 96.

Progression to chronic atrial fibrillation after the initial diagnosis of paroxysmal atrial fibrillation: Results from the Canadian Registry of

Atrial Fibrillation


Progression of paroxysmal atrial fibrillation to persistent atrial fibrillation in patients with bradyarrhythmias

Sanjeev Saksena, MD, FHRS, FESC, FACC,a Douglas A. Hettrick, PhD,b Jodi L. Koehler, MS,b Andrea Grammatico, BS,b and Luigi Padeletti, MDc Am Heart J 2007;154:884-92.


The Prevalence of Sinus Rhythm in Patients with “Permanent” Atrial Fibrillation

PAUL D. ZIEGLER, et al: PACE 2014 :1–8


Why the Maze Works• Focal (Abnormal Automaticity, EAD, DAD)• Micro [<1 cm] Reentrant Rotor Fixed Spiral(s)• Micro Reentrant Rotor Meandering Spiral(s)• Macro Reentrant Rotor Around Fixed Obstacle• Macro Reentrant Meandering Rotor• Multiple Wavelet

The good news is that the Cox Maze procedure does not depend on any one

mechanism. By using an anatomic approach we do not need to determine a

specific mechanism to direct the treatment.


The Future

Marrouche NF et al: JAMA February 5, 2014 Volume 311, Number 5 Zahid S et al: Cardiovascular Research (2016) 110, 443–454

Atrial DE MRI ECGI

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Electrophysiology 101: What Do Surgeons Need to Know · Damiano RJ et al. J Thorac Cardiovasc Surg 2011;141:113-21. Department of Surgery ... • Narayan (2012) 1-2 Stable Rotors