20. Biatrial Cox-Maze Ablation for Atrial Fibrillation

Abhishek K. Kashyap, MD and Bruce M. Toporoff, MD
Loma Linda University Medical Center, Loma Linda, CA, USA
This chapter is a revision and update of that included in the previous edition of the TSRA Operative Dictations in
Cardiothoracic Surgery written by Mark J. Kearns, MD and Jamil Bashir, MD.

Essential Operative Steps

  1. Bluntly dissect the right pulmonary veins
  2. Insert the bipolar radiofrequency clamp device around the right pulmonary veins and perform ablation on CPB with a
    beating heart
  3. Perform at least 4 ablations in “doublets”, repositioning the clamp after each doublet
  4. Bluntly dissect the left pulmonary veins
  5. Divide the ligament of Marshall with cautery, opening the space superiorly around the left pulmonary veins
  6. Use the bipolar radiofrequency clamp device to ablate the left pulmonary veins in similar fashion with at least 2 “doublets”
  7. Place antegrade and retrograde cardioplegia cannulas, apply the crossclamp, and arrest the heart
  8. Standard left atrial incision in Waterston’s groove
  9. Use the clamp device to create adjoining ablation lines between the superior and inferior veins, respectively, with a single
    doublet (the heart is empty during this doublet ablation)
  10. Left atrial appendage amputation
  11. Use the clamp device to ablate between the amputation site and left superior pulmonary vein
  12. Place the cryoprobe from the inferior aspect of the atriotomy to the mitral annulus at P2 and perform cryoablation
  13. Pull back the retrograde cannula and perform epicardial cryoablation in the same area crossing the coronary sinus
  14. Close the left atrium in the standard fashion after completing any concomitant mitral valve procedure as necessary
  15. Close the left atrial appendage with an appropriately sized clip or, alternatively, close it with suture at the base with a
    double layered running suture
  16. Make 3-4cm right atrial incision
  17. Use the bipolar radiofrequency clamp to ablate from the atriotomy to the right atrial appendage using a single doublet
  18. Use the bipolar radiofrequency clamp to ablate from the atriotomy to both the inferior and superior vena cava using a
    single doublet with care taken to avoid the sinus node during SVC ablation
  19. Place the cryoablation probe through atrial incision to create an ablation line connecting the incision to the cavotricuspid
    isthmus at 2 o’clock position (above the antero-posterior commissure)
  20. Close the right atriotomy

Potential Complications and Pitfalls

  1. Friable atrial tissue, prone to injury
  2. Injury to pulmonary arteries and veins: this can be avoided with careful blunt dissection. If isolation of left sided veins is
    difficult with a beating heart, it can be done more safely with the heart arrested. A pericardial patch repair may be required
    for large injuries
  3. Hemorrhage
  4. Biatrial Maze frequently results in sinus bradycardia: this is managed with routine placement of epicardial atrial temporary
    pacing wires in addition to ventricular wires
  5. Injury to conduction tissue and need for permanent pacemaker: this can be managed with placement of temporary
    epicardial pacing wires; many patients will recover rhythm without need for a permanent pacemaker
  6. Prolonged CPB and crossclamp times
  7. Failure to achieve lesion transmurality: can be avoided by following manufacturer recommendations for both the clamp
    device and cryoablation probe; the patient may need repeated ablations to achieve transmurality
  8. Procedural failure

Template Dictation
Preoperative Diagnosis: [INDICATION: e.g. symptomatic AF, undergoing other cardiac operations; asymptomatic AF,
undergoing other cardiac operations and where the ablation can be performed with minimal additional risk]
Postoperative Diagnosis: Same (with appropriate adjustments)
Procedure(s) Performed: [BLANK] and surgical AF ablation [DETAILS: e.g. cardiac incisions, energy source(s) used,
extent of lesion sets employed, whether testing for exit block was performed, and additional CPB and crossclamp times required
for the ablation]
Attending Surgeon: [BLANK]
Secondary Surgeon: [BLANK]
Assistants: [BLANK]
Anesthesia: [BLANK]
Indication(s) for Procedure: [AGE] year old [SEX] with [DURATION] history of [COMPLAINTS: symptoms accounted
for by condition [BLANK], in addition to symptom burden associated with AF]. In addition to preoperative investigations for

condition [BLANK], include details regarding the type of AF (paroxysmal or persistent), and any past interventions used to
treat it (pharmacologic, cardioversion, and/or electrophysiology ablation attempts).
Description of the Procedure: [DETAILS of preparation for procedure [BLANK] (the primary cardiac surgical
indication)]. With the arterial and bicaval cannulation sutures in place, heparin [UNITS] was administered intravenously for
a target ACT >480 seconds. The patient remained in [RHYTHM] and the absence of left atrial thrombus was confirmed by
TEE [for the patient in AF at the time of surgery, document whether they were converted to normal sinus rhythm for the
purpose of testing for exit block]. The aorta and both cavae were cannulated in standard fashion. The superior and inferior
vena cavae were freed circumferentially and ensnared with umbilical tapes just distal to both caval cannulation sites.
Cardiopulmonary bypass was then instituted at normothermia.
The right superior and inferior pulmonary veins were dissected circumferentially to allow the passage of a bipolar
radiofrequency clamp device [MANUFACTURER]. The jaws of the clamp were closed around both right-sided veins, and
ablation carried out as indicated by [MANUFACTURER]. The clamp was removed and cleaned with saline-soaked gauze.
Next, the left superior and inferior pulmonary veins were identified and dissected circumferentially, and the Ligament of
Marshall was divided. The ablation clamp was carefully positioned around both veins, closed, and ablation was performed as
previously described. [Document whether exit block at the pulmonary veins was tested for, to ensure completeness of the
The antegrade and retrograde cardioplegia cannulas were placed. Cardiopulmonary bypass flows were reduced, and the
ascending aorta was clamped prior to the resumption of full flow. Cold blood cardioplegia [VOLUME] was administered
down the antegrade cannula to achieve complete electro-mechanical cardiac arrest. [PER SURGEONS PREFERENCE:
Retrograde cardioplegia was administered]. Both caval tapes were then snared.
A standard left atrial incision was performed next, and the bipolar clamp device was used to create two adjoining ablation lines
across the superior and inferior pulmonary veins, respectively. The left atrial appendage was identified and amputated. The
bipolar radiofrequency clamp device was introduced through the appendectomy and oriented towards the left superior
pulmonary vein. The clamp was closed, and a line of ablation was created joining the left atrial appendage base with the left
superior pulmonary vein.
A cryoablation probe was used to create the mitral isthmus lesion down to the mitral annulus both endocardially and
epicardially, crossing the coronary sinus. The site of left atrial appendage amputation was then closed in two layers using 5-0
prolene suture. [ALTERNATIVELY: The left atrial appendage was ligated using an epicardial atrial appendage clip]. The
left atrium was then closed in the standard fashion (unless a mitral valve procedure is indicated).
A 3-4cm transverse right atriotomy was performed and the bipolar clamp was used for an ablation line towards the right atrial
appendage. The bipolar clamp was then used to ablate the posterior atrial tissue on to the superior and inferior vena cavae
taking care to avoid the sinoatrial node on the superior vena cava ablation. The cryoablation device was inserted and ablation
was utilized to join the anterior aspect of the right atriotomy with the tricuspid annulus above its antero-posterior commissure
and the cavo tricuspid isthmus was ablated. The right atrium was then closed in the routine fashion.
[DETAILS of the remainder of the cardiac operation (procedure [BLANK]), including: closure of cardiac incisions, rewarming, deairing, weaning from cardiopulmonary bypass, heparin reversal and hemostasis, drains left in situ, atrial and
ventricular pacing wires, sternal and soft tissue closure, and details regarding patient stability and level of pharmacologic
support at the end of the case].
Instrument, sponge, and needle counts were correct. The patient was transferred to the cardiac surgical intensive care unit in
stable condition.
Dr. [BLANK] was present and scrubbed for [BLANK] elements of the case.

Multiple Choice Question(s)

1.Which of the following variables is a predictor of failure following a Cox-Maze?
A. Age
B. Duration of atrial fibrillation
C. Left atrial size
D. Failure to complete box lesion set
E. Early postoperative atrial tachyarrhythmias
F. B and D
G. C, D and E
H. All of the above
Answer: G. Multivariable analysis of 280 patients who underwent a Cox-Maze IV was conducted by Damiano et al. and
demonstrated increasing left atrial size, failure to anatomically isolate the entire posterior left atrium, and early atrial
tachyarrhythmias as the only significant risk factors for late recurrence of atrial fibrillation. Interestingly, duration of
preoperative atrial fibrillation was not shown on multivariable analysis to be significant, despite previous studies demonstrating
this to be a significant variable in late recurrence following Cox-Maze III procedures. Sex, age, EF, failed catheter ablation,
type of atrial fibrillation, NYHA class, and postoperative pacemaker implantation were not found to be associated with late
failure on univariate analysis.

2.In patients with known atrial fibrillation, what is the approximate rate of concomitant ablation during aortic valve
replacement in North America?

A. 10%

B. 30%

C. 50%

D. 70%

Answer B.

  1. In patients with known atrial fibrillation, what is the approximate rate of concomitant ablation during coronary artery
    bypass grafting in North America?
    A. 15%
    B. 25%
    C. 35%
    D. 45%
    Answer B.
    Explanation for Questions 2 and 3. Despite a growing number of patients who are now being treated for atrial fibrillation
    concurrent to other cardiac surgery procedures, a large number of patients are left untreated. According to a retrospective
    review of the Society for Thoracic Surgeons National Cardiac Database, 52% of patients undergoing mitral valve surgery, 28%
    of patients undergoing aortic valve surgery and 24% of patients undergoing coronary artery bypass grafting have a concomitant
    ablation for atrial fibrillation. Overall up to 60% of patients with atrial fibrillation are left untreated.

Damiano, R. J., Jr, Schwartz, F. H., Bailey, M. S., Maniar, H. S., Munfakh, N. A., Moon, M. R., & Schuessler, R. B. (2011).
The Cox maze IV procedure: predictors of late recurrence. The Journal of Thoracic and Cardiovascular Surgery, 141(1), 113–
Gammie, J. S., Haddad, M., Milford-Beland, S., Welke, K. F., Ferguson, T. B., O’Brien, S. M., Griffith, B. P., & Peterson,
E. D. (2008). Atrial fibrillation correction surgery: Lessons from the Society of Thoracic Surgeons National Cardiac Database.
The Annals of Thoracic Surgery, 85(3), 909–914

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