Cryo Maze III Procedure Guide

Designed for easy access. The unique malleability of the Cardioblate® CryoFlex™ probe delivers argon-powered cyroablation for reproducible, transmural lesions. The probe tip can be reshaped by hand to create complete Maze III sets with a single probe.

Cardioblate® CryoFlex™ Surgical Ablation Probe

Overview The surgical cut-and-sew Maze lll procedure is a standard of care for the treatment of atrial fibrillation (AF). Incisions are made in the left and right atria, which form scar tissue. These scars control the abnormal impulses that cause atrial fibrillation and help restore sinus rhythm. In the cryo Maze III procedure, the effect is the same, but the method is different. The surgeon uses an argon cryoablation probe to create scar tissue in the same lesion patterns as the Maze lll cut-and-sew procedure. The use of the argonpowered cryoablation probe reduces the complexity of the procedure, which can increase the likelihood of an optimal outcome. The purpose of this guide is to provide information about the cryo Maze III procedure, using the Cardioblate ® CryoFlex ™ Surgical Ablation System. This procedure involves the use of an argon-powered cryoprobe with a malleable tip, which provides a unique degree of facility in placement and leverage. Following, you will find a basic overview of the cryo Maze III procedure, several advantages of this procedure, and step-by-step instructions for performing the procedure, using the Cardioblate CryoFlex Surgical Ablation System.

Advantage Argon Argon gas is the coldest ablation source commercially available for the surgical treatment of AF. The CryoFlex probe reaches temperatures of approximately -150°C in test freezes.1 During in vitro testing, argon cryoablation achieved deeper lesions than nitrous oxide cryoablation.2 This provides greater confidence that lesions are transmural. Levels of Cell Death3-6 Effective Cryoablation Achieves Necrotic Cell Temperatures Through Targeted Tissue Probe Tip

Cross Section of Tissue Necrosis [≈ -20˚C – -40˚C and colder] Cell destruction is immediate and irreversible Apoptosis [≈ 0˚C – -20˚C ] Cells are damaged and may recover; some cells destroyed Hypothermia [≈ 32˚C – 0˚C ] Cells temporarily stop functioning

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Advantages of Cryo Maze III

Advantages of the Cryo Maze III Procedure While there have been a number of alternate lesion patterns proposed since the creation of the Maze III cut-and-sew procedure, none has been as effective when applied for all types of atrial fibrillation.7 The difference is significant: • It works equally well for all types of reentrant atrial fibrillation. The specific type of atrial fibrillation (ie, paroxysmal, persistent, longstandingpersistent) has no impact on the success rate of the Maze procedure, confirming that the lesion pattern addresses the varied mechanisms in these different groups.8 • Bi-atrial procedures have greater success than left atrial procedures. In a 5,885 patient meta-analysis by Barnett and Ad, patients had better outcomes from bi-atrial procedures than left atrial only.9 • Concomitant and stand-alone Maze procedures have similar results. In long-term follow-up of 198 Maze III procedures, freedom from atrial fibrillation was similar in stand-alone versus concomitant procedures, 95.9% vs 97.5% respectively at 5.4±2.9 years.10 • Surgical Maze procedures are effective in enlarged atria, provided that the atrium is reduced. In a randomized study of 80 atrial fibrillation patients with enlarged left atria (≥60mm), the atrial reduction group had 90% sinus restoration at 12 months, compared to 69% in the control group.11

Clinical Results of Ablation Procedures 97% Concomitant Maze III 10

100

% Freedom from AF

>90% Bi-atrial Surgery with New Energy Sources7

50

92% Stand-alone Maze III 10

60% Left-sided Surgical Procedures7 60% Overall Catheter Ablation 7

28% First-time Catheter Ablation12

0

5

10

15

Years Postoperative

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Advantages of Cryo Maze III

Applicable Clinical Situations: The cryo Maze III procedure is appropriate for treating atrial fibrillation in the following clinical situations: • Concomitant atrial fibrillation procedures performed in conjunction with mitral valve repair or replacement (MVR) via either a right mini-thoracotomy or a median sternotomy. • Concomitant atrial fibrillation procedures performed in conjunction with Coronary Artery Bypass Grafting (CABG) if the surgeon decides that the severity of the atrial fibrillation justifies adding an atriotomy. • Concomitant atrial fibrillation procedures performed in conjunction with aortic valve replacement (AVR) if the surgeon feels the severity of the atrial fibrillation justifies adding an atriotomy. • Stand-alone atrial fibrillation procedures performed via either a right minithoracotomy or a median sternotomy.

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Lesions of the Cryo Maze III Procedure B C

Lesions of Cryo Maze III

A

A Pulmonary Vein Isolation Pulmonary vein isolation (PVI) prevents triggers in and around the pulmonary vein (PV) orifices from inducing atrial fibrillation. Limitations of PVI alone -In a 293-patient study of paroxysmal patients • 68% had triggers located exclusively within the PVs. • 20% had triggers both within and outside of the PVs. • 12% had exclusively non-PV triggers. Therefore, pulmonary vein isolation alone will have limited success.13 Box versus pairs-A clinical study by Damiano et al, demonstrated that a box lesion around all four PVs is associated with a lower failure rate and lower use of postop AARx than isolation of the PVs in pairs.14

B Left Atrial Appendage Lesion The left atrial appendage (LAA) lesion prevents reentrant circuits around the base of the left atrial appendage.15

C Mitral Line and Coronary Sinus Lesion The mitral line and coronary sinus (CS) lesion stop left atrial isthmus-dependent flutter. Benefit of the mitral-CS lesion-Success of left-sided procedures increases by 10% to 20% when the mitral line and coronary sinus lesions are included to block conduction across the left atrial isthmus.7 Importance of ablating the coronary sinus-The coronary sinus itself can conduct cardiac signals.16 Up to 20% of Maze III patients will have atrial fibrillation recurrences, if both the mitral line and the CS lesion are not performed. “The only sure way to interrupt conduction along the coronary sinus is to cryoablate it.”17

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E

Lesions of Cryo Maze III

F D

D Intercaval Lesion The intercaval lesion from the superior vena cava (SVC) to the inferior vena cava (IVC) prevents macro-reentrant circuits from forming around the orifices of the superior and/or inferior vena cava.18

E

Counter Lesion The counter lesion prevents macro-reentrant circuits from forming around the base of the right atrial appendage. Dome lesion-For enlarged atria, this lesion can be extended across the top of the right atrial appendage onto the right atrial lateral wall toward the “T” lesion (leaving a 2-3cm gap).19

F

”T” Lesion Combined with the intercaval line and the counter lesion, the “T” lesion prevents both typical (isthmus-dependent) right atrial flutter and other macroreentrant atrial fibrillation. “T” lesion versus “flutter line”-Although in some procedures, the “T” lesion and intercaval line are sometimes replaced by a cavotricuspid isthmus lesion, also known as a “flutter line”-the flutter line does not reduce the area of the RA to prevent it from sustaining reentrant atrial fibrillation.18

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Key Procedural Steps This is a method of applying the cryo Maze III procedure lesion pattern in the left and right atria using the Cardioblate® CryoFlex™ Argon-powered Surgical Ablation System. This lesion set can be performed as a stand-alone procedure or concomitantly with mitral valve surgery or other cardiac surgical procedures as previously described in the surgical literature.20-23 Note that the following procedure represents one method of placing the lesions of the Maze III procedure; additional methods and access may also be possible.

Cardioblate® CryoFlex™ Probe

Adverse Effects or Complications: Potential adverse events with this device are similar to other cardiac surgery procedures and may include the following: bleeding; re-operation; extension of extracorporeal bypass; heart rhythm disturbances (atrial and/or ventricular); effusion; pericarditis; cardiac tamponade; pleural effusion; mediastinitis; conduction disturbances (SA/AV node); acute ischemic myocardial event; thrombus formation; low cardiac output; stroke; renal, gastrointestinal or respiratory complications; sepsis; adjacent structural damage; and death. • Avoid contact between the cryoablation probe and the phrenic nerve to avoid injury. Perioperative heart rhythm disturbances (atrial and/or ventricular). • Cryoablation involving coronary vessels has been associated with subsequent clinically significant arterial stenosis. It is unknown whether Cryoablation with the Cardioblate CryoFlex Surgical Ablation Probe will have such an effect, but as in all such procedures, care should be taken to minimize unnecessary contact with coronary vessels during Cryoablation.

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Key Procedural Steps

The CryoFlex probe is flexible, so it can be easily shaped to facilitate leverage and placement during the procedure.

Helpful Hints •  Positioning the probe. Placing a rigid or semi-rigid sterile instrument, beneath the tissue to be ablated and lifting may help to facilitate probe positioning and improve tissue contact. •  Setting ablation time. For argon cryolesions performed under cardioplegic arrest or during on-pump normothermic perfusion, apply cryoablation for 120 seconds at full power (at least -100°C). •  Avoiding a bloody field. It is important when placing lesions that the surgeon makes every attempt to keep the field clear and free of blood pooling around the probe. The blood can provide a significant heat sink, especially if the patient’s body temperature is normothermic. •  Removing the probe. During the ablation, the probe will adhere to the tissue. After completing ablation, applying warm saline to the ablation site will aid in removing the probe. •  Performing concomitant procedures. If the cryo Maze III procedure is performed concomitantly with mitral valve surgery, the left atrial lesions should be completed prior to the mitral valve surgery. If performed concomitantly with AVR or CABG, the timing of placement of the left atrial lesions is up to the surgeon. In any case, the right atrial lesions are placed during the rewarming period following release of the aortic cross-clamp. Notes on Additional Lesions

Key Procedural Steps

•  Lateral Right Atrial Lesion. The lateral right atrial lesion of the traditional cut-and-sew Maze III procedure extends from the tip of the right atrial appendage across the lateral wall of the right atrium at an angle perpendicular to the right atriotomy (“T” lesion) always leaving a space of at least 2–3 cm between the end of this lesion and the “T” lesion. If the right atrium is not enlarged, this lesion is unnecessary. If the right atrium is enlarged, this lesion can be added. •  Septal Lesion (at the surgeon’s discretion). The septal lesion of the traditional cut-andsew Maze III procedure is not essential to the efficacy of the procedure. This cut-andsew lesion was originally performed to gain access to the atria, not to prevent atrial fibrillation. This lesion is often omitted from the cryo Maze III procedures; however, if desired, it may be added by creating a cryolesion between the right atrial intercaval line and the standard left atriotomy in Waterston’s Groove. •  Flutter Line (not recommended). An ablation line that extends from the IVC to the tricuspid annulus (cavotricuspid isthmus lesion) is not a part of the traditional cut-andsew Maze III procedure or of the cryo Maze III procedure described herein. The flutter line should never be used in combination with the right atrial lesions of the cryo Maze III procedure since doing so can result in adverse sequelae.

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Operative Technique 1) Left Atrial Access a)

Open the pericardium to expose the heart.

b) Initiate cardiopulmonary bypass, cross-clamp the aorta and institute cardioplegic arrest. c) Place a standard left atriotomy in Waterston’s groove to expose the inside of the left atrium. This incision constitutes approximately one-half of the circumferential lesion necessary to isolate all four pulmonary veins using a box lesion.

2) Mitral Line and Coronary Sinus Lesion In order to attain optimal results, it is essential to attain complete conduction block across the “left atrial isthmus,” i.e., the posterior-inferior left atrial wall between the inferior pulmonary veins and the mitral annulus. This requires two separate lesions: an epicardial coronary sinus lesion and an endocardial lesion across the atrial myocardium, the so-called “mitral line.” Neither the endocardial mitral line nor the epicardial coronary sinus lesion alone will stop conduction across this isthmus. Therefore, it is absolutely essential to perform both lesions. Furthermore, the endocardial mitral line and epicardial coronary sinus lesion must align. a)

Coronary Sinus Lesion i) Lift the lower edge of the left atrium gently with forceps in the region of the lower end of the atriotomy. The coronary sinus can usually be exposed on the epicardial surface of the posterior left atrium by this maneuver.

ii) Place the Cardioblate® CryoFlex™ probe directly on the epicardial surface of the coronary sinus. It is helpful to bend the end of the probe as diagrammed, in order to make it stiffer.

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Operative Technique

Note:

•  If the coronary sinus is obscured from direct viewing by surrounding fat, place the CryoFlex™ probe epicardially across the full thickness of the posterior left atrium between the lower end of the atriotomy and the mitral annulus.

iii) Push against the coronary sinus with the probe to compress it.

iv) Initiate cryothermia to freeze the coronary sinus epicardially while watching for a transmural “iceball” to break through at that site endocardially.

v) Mark the site of endocardial “breakthrough” of the iceball with methylene blue. This will help with aligning the epicardial and endocardial lesions.

b)

Mitral Line

Operative Technique

Place the CryoFlex probe endocardially from the inferior edge of the atriotomy, across the endocardial methylene blue mark, to the mitral annulus and apply cryothermia.

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3) Pulmonary Vein Isolation a) Place the CryoFlex™ probe on the floor of the left atrium, extending from the inferior edge of the left atriotomy to the area between the left pulmonary veins and the left atrial appendage. Apply cryothermia. b) Place the probe on the roof of the left atrium, extending from the superior edge of the left atriotomy and across the previous lesion. Apply cryothermia. Note:

•  Placing a rigid instrument beneath the tissue may facilitate positioning of the probe for pulmonary vein isolation.

•  I f the lesions do not overlap, due to individual patient anatomy, additional lesions may be placed to complete the box lesion.

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4) Left Atrial Appendage Lesion Place the CryoFlex™ probe into the left atrial appendage near the appendage tip. Extend the probe along the atrial wall to a point where it will overlap the pulmonary vein isolation lesion. Apply cryothermia.

5) Complete the Left Atrial Portion of the Surgical Procedure a)

Close the base of the left atrial appendage in two layers.

b) Complete any concomitant mitral valve repair or replacement. c)

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Close the atriotomy and release the aortic cross-clamp.

6) Right Atrial Access (Partial “T” Incision) The location of the atriotomy should be in the lower third of the right atrium extending from the thick tissue of the crista terminalis towards the right atrioventricular groove. This incision forms part of the traditional “T” lesion of the cut-and-sew Maze III procedure.

7) Intercaval Lesion a) Place a sponge over the phrenic nerve adjacent to the inferior vena cava (IVC). Leave this sponge in place for all of the right-sided lesions. b) Place the CryoFlex™ probe epicardially on the right atrium on the thin tissue just anterior to the crista terminalis so that it extends from the superior vena cava (SVC) to the IVC. Apply cryothermia. Note:

•  Use the atriotomy to locate the crista terminalis and the thinner free atrial wall just anterior to it.

•  The SVC end of the intercaval line should be placed posteriorly well behind the anatomic SA node.

•  The IVC end of the intercaval line should be placed anteriorly to avoid injury to the phrenic nerve.

•  Placing a rigid instrument inside the right atrium may facilitate positioning of the epicardial probe. Conversely, the probe can be placed endocardially for creation of the intercaval line in two steps.

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8) Completion of the “T” Lesion Place the CryoFlex™ probe through the right atriotomy and position it against the endocardium under the atrio-ventricular groove down to the tricuspid annulus to complete the “T” lesion. Apply cryothermia. Note:

•  Bending the probe just distal to the insulation may facilitate leverage and placement.

9) Counter Lesion  Bend the CryoFlex probe at a right angle and place it through the right atriotomy. Position it with the proximal end at the level of the tricuspid annulus and the distal tip in the right atrial appendage. Apply cryothermia. Note:

•  Place this lesion well anterior to the site of the His bundle, which is located posterior to the membranous portion of the interatrial septum.

•  To identify the site of the membranous septum, place the left index finger or a clamp between the ascending aorta and the right atrium and pass it to the level of the tricuspid annulus externally. The tip of your finger or of the clamp will be at the membranous septum. The cryolesion should always be anterior to your finger or the clamp.

10) End of Procedure  Close the right atriotomy.

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References 1. Medtronic Data on File. 2. Medtronic in vitro test data on file. Bench test comparison of the performance of Cardioblate CryoFlex argon powered probe to AtriCure Cryo 1 nitrous oxide powered probe on porcine tissue. Results may not be indicative of clinical performance. 3. Baust JG, Gage AA. The molecular basis of cryosurgery. Institute of Biomedical Technology, State University of New York, Binghamton, and School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York, NY, USA; pp.1187-91. 4. Gage A, Baust JM, Baust JG. Experimental cryosurgery investigations in vivo. Journal of Society for Cryobiology 2009. Vol 59: 3; 229–43. 5. Aoyama H, Nakagawa H, Pitha J, et al. Comparison of cryothermia and radiofrequency current in safety and efficacy of catheter ablation within the canine coronary sinus close to the left circumflex coronary artery. J Cardiovasc Electrophysiol 2005: Vol. 16;1218-26. 6. Gage AA, Baust J. Review Mechanisms of Tissue Injury in Cryosurgery. Cryobiology Vol. 37; pp. 171-86. State University of New York, Binghamtom, NY. ©1998 Academic Press. 7. Gillinov AM. Choice of lesion set: Answer from the data. Ann Thorac Surg, 2007; 84:1786-92. 8. Gillinov AM, Sirak J, Blackstone EH, et al. The Cox maze procedure in mitral valve disease: Predictors of recurrent atrial fibrillation. J Thorac Cardiovasc Surg 2005; 130:1653-60. 9. Barnett SD, Ad N. Surgical ablation as treatment for the elimination of atrial fibrillation: A meta-analysis. J Thorac Cardiovasc Surg 2006; 1029-1035. 10. Prasad SM, Maniar HS, Camillo CJ, et al. The Cox maze III procedure for atrial fibrillation: Long-term efficacy in patients undergoing lone versus concomitant procedures. J Thorac Cardiovasc Surg 2003; 126:1822-8. 11. Marui A, Nishina T, Tambara K, et al. A novel atrial volume reduction technique to enhance the Cox maze procedure: Initial results. J Thorac Cardiovasc Surg 2006; 132:1047-53. 12. Cheema A, Vasamreddy CR, Dalal D, et al. Long-term single procedure efficacy of catheter ablation of atrial fibrillation. J Interv Card Electrophysiol 2006; 15:145-155. 13. Lee S, Tai C, Hsieh M, et al. Predictors of nonpulmonary vein ectopic beats initiating paroxysmal atrial fibrillation. J Am Coll Card 2005; 46:1054-9. 14. Voeller RK, Bailey MS, Zierer A, et al. Isolating the entire posterior left atrium improves surgical outcomes after the Cox maze procedure. J Thorac Cardiovasc Surg 2008; 135:870-7. 15. Cox JL, Boineau JP, Schuessler RB, et al. Modification of the maze procedure for atrial flutter and atrial fibrillation. J Thorac Cardiovasc Surg 1995; 110:485-495. 16. Katritsis, DG. Arrhythmogenicity of the coronary sinus. Journal of Indian Pacing and Electrophysiology 2004 (4); 176-184. 17. Cox J, Ad, N. The importance of cryoablation of the coronary sinus during the maze procedure. Semin Thorac Cardiovasc Surg 2000; 12:20-4. 18. Tai and Chen. Electrophysiological mechanisms of atrial flutter. J Chin Med Assoc 2009 Feb; 72(2):60-7. 19. Byrd GD, Prasad SM, Ripplinger CM, et al. Importance of geometry and refractory period in sustaining atrial fibrillation: Testing the critical mass hypothesis. Circulation 2005; 112[suppl I]:I-7-I-13. 20. Doll N, Kiaai BB, Fabricius AM, et al. Intraoperative left atrial ablation (for atrial fibrillation) using a new argon cryocatheter: Early clinical experience. Ann Thorac Surg 2003; 76:1711-5. 21. Gammie JS, Laschinger JC, Brown JM, et al, A multi-institutional experience with the cryomaze procedure, Ann Thorac Surg 2005; 80:876-80. 22. Moten SC, Rodriquez E, Cook RC, et al. New ablation techniques for atrial fibrillation and the minimally invasive cryo-maze procedure in patients with lone atrial fibrillation. Heart Lung Circ. 2007; 16 Suppl 3:S88-93. Epub 2007 Jul 3. 23. Mack CA, Milla F, Ko W, et al. Surgical treatment of atrial fibrillation using argon-based cryoablation during concomitant cardiac procedures. Circulation. 2005; 112[suppl I]: I-1-I-6.

The Cardioblate® CryoFlex™ Surgical Ablation System Indications for Use: Is intended for minimally invasive cardiac surgical procedures, including the treatment of cardiac arrhythmias. The Cardioblate CryoFlex 7 cm, 10 cm and 10-S probes plus the Cardioblate CryoFlex Clamp and Cardioblate CryoFlex Surgical Ablation Console freeze target tissue and block the electrical conduction pathways by creating an inflammatory response and cryonecrosis. Contraindications: The Cardioblate Surgical Ablation Probe is not designed for use inside a beating heart. Adverse Events or Complications: Potential adverse events with this device are similar to other cardiac surgery procedures and may include the following: bleeding; re-operation; extension of extracorporeal bypass; heart rhythm disturbances (atrial and/or ventricular); effusion; pericarditis; cardiac tamponade; pleural effusion; mediastinitis; conduction disturbances (SA/AV node); acute ischemic myocardial event; thrombus formation; low cardiac output; stroke; renal, gastrointestinal or respiratory complications; sepsis; adjacent structural damage; and death. • Avoid contact between the cryoablation probe and the phrenic nerve to avoid injury. Perioperative heart rhythm disturbances (atrial and/or ventricular) • Cryoablation involving coronary vessels has been associated with subsequent clinically significant arterial stenosis. It is unknown whether Cryoablation with the Cardioblate CryoFlex Surgical Ablation Probe will have such an effect, but as in all such procedures, care should be taken to minimize unnecessary contact with coronary vessels during Cryoablation. Cardioblate is a registered trademark and CryoFlex is a trademark of Medtronic, Inc.

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