Download Cryoablation Lesion with Atrial Arrhythmia after Fontan Operation

Surgery for Atrial Fibrillation
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Mechanisms of Atrial Fibrillation
 Etiology
Incompletely understood pathogenesis.
Ectopic foci, single circuit reentry, multiple circuit reentry have
been implicated in initiating and maintaining the condition
 Prerequisite ; substrate & trigger
1. Substrate is an atrial abnormality, frequently inflammation or
fibrosis causes atrial electrical dysfunction that favors
development of AF
2. Triggers include atrial ectopic foci, changes in atrial wall tension,
and alterations in autonomic tone
3. Although substrate & trigger may vary, evidence points to the
primary importance of pulmonary veins and left atrium initiating
& maintaining
Origin of Atrial Fibrillation
Paroxysmal AF
Originates from ectopic beats in the pulmonary veins in 94% of cases .
This likely relates to the anatomic transition from pulmonary vein
endothelium to left atrial endocardium; at this junction, two types of
tissue with different electrical properties are juxtaposed and this may
potentiate development of AF.
Although there is the critical importance of pulmonary vein in
patients with paroxysmal AF, it may not apply to persistent or
permanent AF.
As regards persistent & permanent AF
Direct evidence is lacking , but clinical experience implicates the
posterior left atrium & possibly the pulmonary veins in their
pathogenesis and maintenance .
And in most patients, the left atrium acted as the electrical driving
chamber
Intermittent Atrial Fibrillation
• Induction of atrial fibrillation by a premature atrial beat
originating in the orifice of one of the pulmonary veins
Intermittent Atrial Fibrillation
• Once induced, all atrial fibrillation is characterized by the
presence of multiple macroreentrant circuits in the atria.
Intermittent Atrial Fibrillation
• Trigger for the induction of intermittent atrial fibrillation
is located in the pulmonary veins in 90% of patients &
outside the pulmonary vein area in 10% of patients.
Intermittent Atrial Fibrillation
• Each subsequent episode of atrial fibrillation requires another
premature atrial beat to initiate the episode, with the trigger
again being the pulmonary veins in the majority of cases.
Re-entry & Implications for AF
(Allessie, 1977)
Origin of Sinus Tachycardia Impulses
Atrial Fibrillation
Clinical Significance of AF
• AF affects nearly 1% of the general population,
with a striking increased incidence in the elderly.
• High morbidity & increased mortality rates
because of tachycardia-induced cardiomyopathy,
hemodynamic compromise, & thromboembolism,
causing serious health concern &financial costs.
• The aims of treatment are resortation of normal
sinus rhythm, normal atrial contraction &
atrioventricular conduction, rate control, and
prevention of thromboembolic complications.
Preoperative Assessment for AF
Being considered for Maze procedure
• Evaluation of ventricular function either by
echocardiography or contrast ventriculography
• Coronary angiography for those older than 40
years & with risk factors
• Concomitant heart diseases should be evaluated
• Patients with paroxysmal flutter or fibrillation
should be evaluated electrophysiologically for
AV reentrant circuit
Intermittent Atrial Fibrillation
Pulmonary Vein Isolation
• Simple pulmonary vein encirclement will cure 90%.
However, 10% of patients with intermittent AF will
not be cured with simple pulmonary vein isolation.
Continuous Atrial Fibrillation
• Failure of pulmonary vein isolation in patients with
continuous atrial fibrillation
Surgery for Cardiac Arrhythmias
• Isolation procedures do not actually terminate
arrhythmias but rather confine them, their
trigger mechanisms, or both to a desired region
of the heart to minimize their adverse effects.
• Ablation procedures preclude arrhythmias
from developing either by destroying their
trigger mechanism or by altering (or removing)
the substrate that allows the arrhythmia to be
induced and maintained.
Surgical Isolation Procedures
• Elective His bundle ablation for any type of
supraventricular tachycardia
• Left atrial isolation procedure for automatic
left atrial tachycardias and atrial fibrillation
• Right atrial isolation procedure for automatic
right atrial tachycardias
• Corridor procedure for atrial fibrillation
• Right ventricular isolation procedure for
nonischemic ventricular tachycardia
• Pulmonary vein isolation for the intermittent
atrial fibrillation
Surgical Ablative Procedures
• Surgical intervention for the Wolff-Parkinson-White
syndrome, which interrupts macroreentrant circuit
• Discrete cryosurgery for atrioventricular node reentry
tachycardia, which interrupts microreentrant circuit
• Focal cryoablation for automatic atrial tachycardias,
which destroys the trigger mechanism
• Endocardial resection for ischemic ventricular
tachycardia, which removes the microreentrant circuit
• Endocardial cryosurgical procedures for ischemic
ventricular tachycardia, which destroys the
microreentrant circuit
• Maze procedure for atrial fibrillation, which destroys
macroreentrant circuits
Ideal Ablative Procedures
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Elimination of AF as an arrhythmia
Restoration of sinus rhythm
Maintenance of AV synchrony
Restoration of atrial transport function
Elimination of thromboembolic risks
Ablative Procedures
Ablation for Supraventricular Arrhythmias
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Right atriofascicular accessory pathways
Ebstein’s anomaly
Coronary sinus abnormalities
Triangle Koch & AV node-His bundle (AVNRT)
Atrial tachycardia of ectopic origin
Atrial flutter
Atrial fibrillation
Indications for Maze Procedure
Failure of medical therapy as a result of
• Symptomatic intolerance of the arrhythmia
despite phamacologic rate control
• Inability to achieve satisfactory phamacologic
rate control
• Patient intolerance of requisite drug therapy
• Occurrence of at least one previous
thromboembolic episode
Surgical Techniques for AF
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Cox-Maze III
Partial Mazes
Radiofrequency
Microwave
Cryothermy
Assessing Results of AF Surgery
 Permanent AF
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Detection requires at least 2 EKG examination separated by 7 days or
more
Data analysis is done after 6 months more because atrial healing and
stabilization of rhythm may take up to 6 months after surgery
 Surgical failure
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Presence of AF at 6 months or more after operation that is permanent or
paroxysmal and unresponsive to antiarrhythmic medication
 Prevalence of AF
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Paroxysmal, persistent, or permanent
 Other events
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Stroke, pacemaker implantation(sick sinus syndrome), atrial
dysfunction(atrial activity)
Map of Maze I Procedure
• Two dimensional original maze I procedure
Map of Maze II Procedure
Map of Maze III Procedure
Maze III Procedure
Maze III Procedure
Maze III Procedure
Maze III Procedure
Maze III Procedure
Maze III Procedure
Maze III Procedure
Maze III Procedure
Maze III Procedure
Standard Maze III Procedure
• The 5 left atrial lesions of the standard maze III
surgical procedure for atrial fibrillation.
Mini-Maze Procedure for AF
• Pulmonary vein encircling incision, left atrial isthmus lesion
with coronary sinus lesion, & right atrial isthmus lesion
Postoperative Complications
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Atrial dysrhythmias, flutter & fibrillation
Sinus node dysfunction
Blunted tachycardia response to exercise
Absence of detectable sinus activity
Complete heart block
Early postoperative fluid retention
Postoperative pericardial effusion
Results of Surgery for AF
• Cox-Maze III
1. Late freedom from AF is around 90% (Cox group;98%)
2. Temporary postoperative AF is common(30~40%) due to
shortened atrial refractory period & did not diminish
longterm results(return sinus rhythm over ensuing 3 months)
3. 15% require new pacemaker therapy
4. Atrial transport function in 98%(Rt),93%(Lt)
• Partial Mazes
1. Restore sinus rhythm around 80%
2. Increased risk of atrial flutter, usually right origin(5~10%)
3. Radial incision approach provides results comparable to
those of Cox-Maze III
4. More effective restoration of atrial transport function
Results of Surgical Treatment
1. Cox-Maze procedure: Cox & Colleagues
@ Among 346, 2% op.mortality, AF was cured in 99%, 2%
required long-term postoperative antiarrhythmic medication
@ Successful ablation was unaffected by presence of mitral valve
disease, LA size, type of AF
@ Temporary postoperative AF in 38%
@ New pacemaker was required in 15%
@ RA transport function in 98%, LA transport function in 93%
2. Cox-Maze III: Other centers
@ Around 90% of late freedom from AF Cured AF in 75-82%
in most series of mitralvalve surgery+ Cox-Maze III
@ Amplitude of the AF wave and diameter of the LA :
independent predictors of sinus restoration after operation
Coexistence of Sinus Rhythm & Segmental
Atrial Fibrillation after Maze
Partial Maze Procedures
“Simple left atrial procedure” (Sueda et al. 1996)
“Partial Maze procedure” (Takami et al. 1999)
“Mini-Maze” (Szalay et al. 1999)
More simplified, take less time, use alternative
energy sources
Include some of the incisions and cryoablation
lesions of the Cox-Maze III, but not all
Focus on the left atrium, including PVI, LAA
excision or exclusion
Energy Sources for Ablation
 Radiofrequency
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Alternating current of 350 KHz to 1 MHz to heat the tissue
Heating tissue for approximately 1 minute at 70~80C produces
lesions 3 to 6 mm deep to create a transmural line of conduction
block by tissue vaporization and surface cooling
 Microwave
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Thermal damage & subsequent scar formation , by high-frequency
electromagnetic radiation(microwave) causes oscillation of water
molecules in tissues, converting electromagnetic energy into kinetic
energy(heat)
Depth & volume of heated tissue are greater than radiofrequency,
and not char the endocardial surface
 Cryothermy
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Application of nitrous oxide-based cryoprobe to atrial tissue for 2
minutes at -60C produces a transmural lesions , leaving a smooth
endocardial surface
Radiofrequency (RF)
• Uses alternating current of 350kHz to 1 MHz to heat tissue
• Experimental data : 1min at 70-80°C produces 3-6mm
deep lesions
• Unipolar vs. bipolar system
• Dry vs. SIRFMM
• Multiple RF systems : long flexible, rigid, pencil-like
probes with a cool tip, bipolar clamp
• Either epicardial or endocardial ablation
• Time : 10-20 min for creation of left-sided lesion sets vs.
1hr. for Cox-Maze procedure
Surgical Techniques for RF
Radiofrequency Ablation
Bipolar RF
Microwave
• Interest is growing in microwave energy
• High-frequency electromagnetic radiation causes
oscillation of water molecules in tissue, converting
elctromagnetic energy into kinetic energy (heat).
• Depth and the volume of heated tissue are greater,
resulting in a higher probability of transmural lesions
• No char, which may reduce risk of thromboembolism
• Shielded probes produce safe epicardial ablation
• Available probes : 2-,4-,10 cm
• Energy set at 65W, 45 second application time
(Gillinov AM et al. Ann Thorac Surg 2002;74:1259-61)
Microwave System
• The FLEX 2™, FLEX
4™ and FLEX 10™
Microwave Ablation
Probes are sterile,
single-use, hand-held,
surgical devices used
exclusively with the
AFx Microwave
Generator
Cryothermy
• Well-established modality in arrhythmia surgery
and an important component of the Maze III
• Nitrous oxide-based cryoprobe
• 2min at -60°C reliably produces a transmural
lesion that can be confirmed visually
• Tissue architecture is preserved, leaving a smooth
endocardial surface
• No flexible probe till now
Transmurality & Damaging Effect
• Discontinuous line allow AF breakthrough or
potentiate development of atrial flutter
• Ensured transmurality : cut and sew,
endocardial cryothermy, bipolar RF by
measuring changes in tissue impedence
• Unipolar RF, epicardial cryothermy on a
beating heart do not guarantee transmural
lesions
• Esophageal injury has been reported
• Thermal energy application should be avoided
in thin, frail patients with delicate tissues
Results of Partial Mazes
 Approximately 80% of patients restored
sinus rhythm
 Minor variations in incision pattern and
cryolesions do not influence the results
 Occurrence of atrial flutter is 5-10%
Results of Radiofrequency Ablations
 Most series : mitral valve surgery + RF
 70-80% of successful ablation
 Up to 60% of perioperative AF
 30-40% of AF at discharge, but many return
to sinus rhythm over 3 months
 Atrial transport function in 80-100% who
return to sinus rhythm
Results of Microwave Ablations
Long-term results are unavailable; microwave
catheter has only recently become available for
intraoperative treatment of AF
Among 10 patients. who had mitral valve
operations + MW of the pulmonary veins, 6 in
NSR, 3 in AF, 1 under pacing at discharge
Approximately 80% of patients can be cured of
AF
Energy Sources for Ablation
Type
Endocardial Epicardial Flexible
application application probe
Assess
No char
transmural
Rapid
Radiofreq.
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Microwave
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Cryothermy
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* Radiofrequency energy may be delivered in unipolar or bipolar fashion
Surgical Option for Atrial Fibrillation
• Left atrial incisions of Cox-Maze III procedure
Surgical Option for Atrial Fibrillation
• Left atrial part of standard Cox-Maze procedure
Cox-Maze Procedure
• A; Cox maze III procedure
• B; Kosakai maze procedure
• C; Cryomaze procedure
Modifications of Maze Procedure
* Right & left atrium seen
from behind(A) & inside(B)
* Crossed lines;
modified atriotomies
* Dotted area; cryoablation
* Thick lines; SA node artery
* Right, left, posterior sinus node
arteries
Modifications of Cox-Maze III
• A; Modified procedure
• B; Incision lines & impulse propagation
after modified procedure
Modifications of Cox-Maze III
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A ; conventional Cox-Maze
B & C ; modification(usual & large atrium)
Crossed lines ; surgical atriotomies
Thick black lines ; cryoablation
Radiofrequency Modified Maze
• A; Lines of electrical activation
• B; Zigzag lines depicting incision in the atria
• C; Dotted lines depicting endocardial ablation
Radiofrequency Maze Procedure
Right-sided Saline Irrigated
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A ; RA appendage excised
B ; Vertical incision
C ; Second longitudinal incision in RA
D ; Ablation line is created between cannulation
Radiofrequency Maze-Berlin Modification
• The incisions & sutures of the standard maze technique
are replaced by radiofrequency ablation lines(dashed
lines)
Radiofrequency Maze-Berlin Modification
• Dashed lines show position of radiofrequency maze lines of Berlin
modification in comparison to the standard maze lines
AF Surgery Simplified with Cryoablation
To Improve LA Function(I)
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Redundant, enlarged LA resected
i; incision to atrioventricular groove, j; cryoablation of coronary sinus
AF Surgery Simplified with Cryoablation
To Improve LA Function(II)
• A; Anterior view of posterior left atrial wall
• B; Posterior view of left & right heart
• Cryoablation indicated by dotted lines
Bilateral Appendage-Preserving Maze
• A; Diagram of BAP-Maze procedure
• B; Impulse propagation pattern
• C; Diagram of Maze III
Radial Approach for Atrial Fibrillation
• Small circle indicates SA node, & shaded area indicates the
isolated portion of the atrium
• Arrows indicate the activation wavefront from the SA node,
radiating toward the annular margins
Radial Approach for Atrial Fibrillation
• Thick lines ; surgical incisions
• Solid area ; atria surgically isolated or excised
• Dashed lines ; Bachmann’s bundle between appendage, septum,
and crista terminalis
• Arrows ; activation sequence
Radial Approach for Atrial Fibrillation
Maze procedure. Radial approach
MVR with Maze III
• A & B ; Left side incisions
MVR with Maze III
• Right side incisions, Maze III procedure
MVR with Maze III
Reduction Plasty with Maze
Reduction Plasty with Maze
Atrial Endocardial Maps after Maze
• The shaded area denotes electrically isolated region