this presentation starts with the description of atrial fibrillation and goes on to describe the basis of it's surgical cure, viz. The Maze procedure. I then describe the technical aspects of Maze 1,2,3,4...

1. Surgery for Atrial
Fibrillation
Abhijit Joshi
NH

2. basic mechanisms
• concept of refractory period
• a faster source will eventually re-organise cardiac
excitation
• what is re-entry?
• what are ectopic foci? what is macro and micro re-entry?

3. • so now we know why:
• ectopic foci/fibrosis foci cause re-entry
• effect of chamber dilatation on macro re-entry

4. 3 atrial tachycardias
• focal ectopic tachycardia: no re-entry
• atrial flutter : single wavefront
• atrial fibrillation : multiple (at least 2) wavefronts : multiple
simultaneous irregular re entry circuits - undefined
number of spatiotemporally varying wavelets and colli-
sions

6. AF maintaining substrate
• AF begets AF
Structural remodeling (atrial
enlargement and fibrosis, most
typically affecting the left atrium
[LA]), produces relatively fixed
reentry substrates
Progressive atrial dilation creates
longer conduction pathways for
reentry. Tissue fibrosis slows
conduction, makes conduction
more heterogeneous, and creates
conduction barriers that favor re
entry

9. 3 problems in AF
(1) palpitations, which cause the patient discomfort and anxiety;
(2) loss of synchronous atrioventricular contraction, which
compromises cardiac haemodynamics, resulting in varying
degrees of ventricular dysfunction; and
(3) stasis of blood flow thromboembolism and stroke
contrast this with atrial flutter

10. flutter has an atrial kick
regular atrial systoles, evidenced by a waves in the JVP

11. remodelling in AF
• electrical remodelling : reduction in atrial effective
refractory periods, increased spatial heterogeneity of
refractoriness, and conduction slowing.
• structural remodelling : atrial dilatation, myocyte
hypertrophy, sarcomere loss, glycogen accumulation,
mitochondrial abnormalities, and the development of
atrial fibrosis. Atrial fibrosis is thought to be a fundamental
component of AF sustenance
• fibrosis promotes AF and AF promotes Fibrosis : AF
begets AF

13. hence AF needs..
• a trigger : usually a premature depolarization or runs of
focal ectopic depolarizations
• a macro re-entry circuit
• surgery for AF is directed at alteration of geometry and
anatomy needed to support AF.

14. • “ Fortunately, the macro-reentrant circuits that we had
mapped in both dogs and patients were physically
relatively large, that is, more than 5 to 6 cm in diameter
in the left atrium and much larger than that in the right
atrium. Therefore, atrial incisions placed no more than 5
to 6 cm apart should theoretically prevent the
development of macro-reentrant circuits anywhere in the
atria. It was clear that if macro-reentrant circuits could not
develop in the atria, then the atria could not fibrillate. The
dilemma was how to place enough lesions on the atria to
preclude the development of atrial macro-reentry
(fibrillation) and leave behind an atrium that could be
activated by the sinus node and still contract effectively.”
- James Cox

15. if the atrium cannot develop macro re-entry circuits then it cannot fibrillate, because
that’s what a-fib is by definition.

16. initial surgeries
• 1980 : James Cox - left atrial isolation -
• electrical isolation of the LA, after recognition that most
triggers are from the LA
• advantages : controlled the ventricular rate, alleviated
palpitations, Right atrial kick was present and surprisingly
increased LA preload because of this significantly improved
haemodynamics
• drawback : LA still fibrillated, thromboembolism risk
continued
• eventually abandoned

17. • Catheter Ablation of the Atrioventricular Node–His Bundle
Complex. 1982 - Scheinman
• only alleviated palpitations and anxiety
• necessitated pacemaker
• no improvement in haemodynamics
• thromboembolism persists
• 1985, Giraudon’s corridor procedure: isolated a strip of atrial septum
harboring both the sinoatrial node and the atrioventricular node, thereby
allowing the sinoatrial node to drive the ventricles. This procedure
corrected the irregular heart beat associated with AF, but both atria
either remained in fibrillation or developed their own asynchronous
intrinsic rhythm because they were isolated from the septal “corridor.”
• except for the requirement of a pacemaker, it suffered all the drawbacks
of Scheinman’s catheter ablation of the Bundle.

18. • to cure AF, what was needed is to have lesions close
enough to prevent macro re entry lesions to develop, at
the same time maintain the pathway for conduction from
SA node to AV node.

19. James Cox …
That question was answered one Saturday afternoon while I
was studying some of the Boineau–Schuessler experimental
maps of atrial fibrillation in my office at Barnes Hospital. To
better visualize the relationship between atrial anatomy and
atrial electrophysiology, a rectangle was drawn to represent
the entire mass of both atria 2-dimensionally.

20. • “While studying this 2-dimensional representation of the atria
with the superimposed electrophysiology of atrial fibrillation, I
suddenly realized that everything necessary to abolish atrial
fibrillation, while leaving the atrial activation and contraction
intact afterward, could be accomplished by creating a pattern of
lesions in the atria that was essentially that of a simple maze.
The lesions could be placed close enough to prevent atrial
macro-reentry, and if placed in a maze pattern, the SA node
could serve as the site of entry of electrical activity into the atria
and the AV node as its site of exit from the atria. One contiguous
“true route” of conduction would be left intact between the
entrance and exit sites, and multiple “blind alleys” off this main
conduction route would allow activation of all of the atrial
myocardium, thereby preserving atrial contractility (Figure 1, D).
One entrance, one exit, one true route between the two and
multiple blind alleys … the pattern and principle of a maze.”

23. Maze 1
• compromised the
normal sinus
tachycardia response
• LA conduction delayed
• both these :
“chronotropic
incompetence”
• high rate of pacemaker
implantation

25. Bachmann’s bundle allows almost simultaneous activation of the 2 atria
Maze 1 led to LA activation delay to the extent that LA was activated when the impulse
had reached the LV

27. Maze 2
• required SVC transection and was too difficult
• abandoned soon

29. Maze 3

30. Operation is performed via median sternotomy. Cannulae for venous uptake are placed in superior
vena cava and through the low right atrium into inferior vena cava. Small venous cannulae (24F) and
vacuum-assisted venous return are employed. Cardiopulmonary bypass is established, and
tourniquets are tight- ened around venae cavae. First incision divides right atrial appendage and
extends obliquely to midpoint of right atrial free wall. Medially, incision extends to atrioven- tricular
groove. Longitudinal incision is made from superior to inferior vena cava along crista terminalis. Lower
2 cm of inci- sion is closed with a continuous suture of 4-0 polypropylene to prevent tearing during
retraction. Vertical incision is made from point of closure to atrioventricular groove

31. Vertical incision is extended to tricuspid valve anulus in area of posterior leaflet
(2-o’clock position, surgeon’s view), working on endocardial surface of atrium
cutting through the entire atrial wall. Residual myocardial fibers are ablated by
applying a 3-mm cryolesion (−70°C for 2 minutes) at tricuspid anulus. This
portion of incision is closed with 4-0 polypropyl- ene suture.

32. Incision of medial aspect of right atrial
appendage is continued into atrial groove
to tricuspid valve anulus (10- o’clock
position, surgeon’s view) by dis- secting
on endocardial surface. A cryolesion is
placed at anulus of tricuspid valve to
ablate residual myocardial fibers. This
portion of incision is closed with 4-0
poly- propylene suture.

33. Aorta is occluded. Coronary sinus is cannulated, and cold
cardioplegic solution is administered to achieve total
electromechanical arrest. Left atrium is opened on right side
behind interatrial groove and in front of pulmonary veins.
Incision is extended superiorly and inferiorly. Atrial septum is
divided at level of right superior pulmonary vein. This incision
is curved inferiorly to divide the membrane of fossa ovalis.

34. Atrial septum is
retracted anteriorly.
Pulmonary vein
encircling incision is
developed, working
within left atrium by
extending incision
across back wall of
atrium above and
below left pulmonary
veins.

35. Heart is retracted inferiorly and to the right to expose left atrial
appendage on external surface of heart. Two ori- entation
sutures of 3-0 polypropylene are placed through left pulmonary
vein encircling incision at level of left superior and left inferior
pulmonary veins. Encircling incision is completed between
orientation sutures (dashed line). Left atrial appendage is
excised at its base. Atrial wall between atrial appendage and
encircling incision is divided (dashed line).

36. Orientation sutures are tied, then used to close left atrium between them.
Separate suture of 3-0 polypropylene is used to close bridge to and base of left
atrial appendage.

37. Exposure returns to interior of left atrium. Orientation sutures are passed inside
left atrium and used to close encircling incision superiorly to midpoint and
inferiorly for about 2 cm of posterior wall of left atrium. Vertical incision is
developed between encircling incision and mitral valve anulus. Incision is
through entire left atrial wall into epicardial fat in atrioventricular groove,
exposing coronary sinus. A cryolesion is made on exterior surface of coronary
sinus, using a 15-mm cryoprobe applied for 3 minutes. After 1 minute, a 3-mm
cryoprobe is placed on mitral valve anulus and a 2-minute cryolesion is made.
Vertical incision is closed with 4-0 polypropylene. Mitral valve repair or

38. Pulmonary vein encircling incision is closed to pulmonary veins on right side.
Retraction is switched to right atrium, allowing all but final centimeter of
encircling incision to be closed. Left ventricular venting catheter is placed
through separate incision in right superior pulmonary vein.

41. ONCE AGAIN !

42. Maze 4

44. Hassaiguerre et al - 1998, NEJM
• studied 45 patients with frequent
episodes of atrial fibrillation
refractory to drug therapy.
• The spontaneous initiation of atrial
fibrillation was mapped with the use
of multielectrode catheters
• Three foci were in the right atrium, 1
in the posterior left atrium, and 65
(94 percent) in the pulmonary
veins (31 in the left superior, 17 in
the right superior, 11 in the left
inferior, and 6 in the right inferior
pulmonary vein).
• laid down the basis for PVI

45. • RA is the trigger source in 15%
• also, addressing only the RA, frequent post procedure
flutter is there

47. Energy sources for ablation

49. Thank You