Some Surgical Aspects of Atrial Fibrillation

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Some Surgical Aspectsof Atrial Fibrillation

• Vincent A. Gaudiani, MD
• Luis J. Castro, MD
• Audrey L. Fisher, MPH

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The Nature of Surgical InterventionDemands a
Simplified Model of What May Be a Complex Problem
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Conceptual strip of atrium with normal
depolarization
Yellow tissue is repolarized and ready to
conduct. Green tissue is depolarized and cannot
currently conduct.
Initial impulse
Impulse travels
Impulse completes circuit while tissue is still
depolarized
Tissue repolarizes ready for next impulse
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Each macro-reentrant pathway must have a
conduction time sufficiently long to permit
initially depolarized muscle to repolarize before
the depolarizing wavefront returns. This will
depend on the

• Physical length of the pathway
• Conductance of the pathway

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Macro-reentrant pathways
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Macro-reentrant pathways
Initial impulse
Yellow tissue is repolarized and ready to
conduct. Green tissue is depolarized and cannot
currently conduct.
Impulse travels farther in long circuit and at
slwoer speed in slow circuit. Both of these
circuits allow for tissue to repolarize by the
time the impulse completes the circuit.
Circuit complete normal circuit tissue is still
depolarized and unable to conduct again. The
time delay in long and slow circuits creates
tissue that is repolarized by the time the
circuit is complete, and the impulse can be
conducted again and again.
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Cox and his colleagues demonstrated that atrial
fibrillation may be seen as the result of the
interaction of a finite number of macro-reentrant
pathwaysANDthat each pathway correlated with an
anatomic feature of the atria.
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Cox reasoned that surgical interdiction of each
of these pathways would preclude sustained atrial
fibrillation.
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The likely Anatomic Pathways are around the right
atrium
Right Atrial Appendage
Atrial Septum
Tricuspid Valve
Venae Cavae
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The likely Anatomic Pathways are around the left
atrium
Atrial Septum
Left Atrial Appendage
Pulmonary Veins
Mitral Valve
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Surprisingly, other research has shown that
atrial fibrillation is frequently initiated
within the cuff of tissue comprised by the
pulmonary veins and the local atrial tissue
around them.- Perhaps 70-80 of atrial
fibrillation can be prevented solely by isolating
this tissue from the rest of the atrium.
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Optimum Therapy of AF demands

• Ablation of AF
• Restoration of AV Synchrony
• Restoration of AV Transport

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Optimum therapy corrects the clinical problems
associated with AF

• Atrial thrombus formation
• Decreased cardiac efficiency
• Palpitations
• Need for anticoagulation

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Surgical incisions in the right atrium

• Excise right atrial appendage
• Extend from right atrial appendage totricuspid
  valve
• SVC to IVC straight line incision
• Extend from caval incision to tricuspid

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Surgical incisions in the left atrium
Left atriotomy
Encircle pulmonary veins (epv)

• Excise left atrial appendage
• Extend from appendage to epv
• Extend from mitral annulus to epv
• Cut atrial septum through fossa ovalis

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The Cox/Maze III operation restores AV synchrony
and transport in gt 70-80 of patients by
isolating the pulmonary vein cuff and placing
surgical incisions through each of the major
macro-reentrant circuits.Every segment of the
atria, except the pulmonary vein cuff, remains in
electrical contact with the SA node.
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Maze Results I

• From October 1997 through December 2003 we
  performed 162 Maze operations as follows
• Maze Only 11
• Maze and Mitral Valve Only 74
• Maze and Any Other 77

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Maze Results II

• In the entire series of 162 cases, there were
  three operative mortalities (1.9). These
  occurred in high-risk patients. There have not
  been any deaths in reasonable or low risk
  patients.

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Maze Results III

• We follow up with our Maze patients on an annual
  basis. Our follow up of August 2003 included 133
  patients from between three months to over five
  years out from the time of operation. The
  percentage of patients in normal rhythm at 2003
  follow up was
• Maze Only 91 (10/11)
• Maze and Mitral Valve Only 92 (55/60)
• Maze and Any Other 89 (55/62)

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Conclusion

• The Cox/Maze procedure is an effective
  treatment for atrial fibrillation for some
  patients who require cardiac operations.