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| {{Interventions infobox |
| | #REDIRECT: [[Atrial fibrillation surgical ablation]] |
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| ICD9 = 37.33 |
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| {{SI}}
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| {{CMG}}
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| '''Associate Editor-In-Chief:''' {{CZ}}
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| ==Overview==
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| The '''maze procedure''' is a collection of [[cardiac surgery]] procedures intended to cure [[atrial fibrillation]] (AF), a common disturbance of heart rhythm. Recently, various methods of minimally invasive maze procedures have been developed; these procedures are collectively named '''minimaze''' - "mini" versions of the original maze surgery.
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| ==The Cox maze procedure==
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| James Cox, MD, and associates developed the "maze" or "Cox maze" procedure, an "open-heart" [[cardiac surgery]] procedure intended to eliminate [[atrial fibrillation]], and performed the first one in 1987.<ref name="Cox 1991">{{cite journal | author = Cox J, Schuessler R, D'Agostino H, Stone C, Chang B, Cain M, Corr P, Boineau J | title = The surgical treatment of atrial fibrillation. III. Development of a definitive surgical procedure. | journal = J Thorac Cardiovasc Surg | volume = 101 | issue = 4 | pages = 569-83 | year = 1991 | id = PMID 2008095}}</ref> “Maze” refers to the series of incisions arranged in a maze-like pattern in the [[atria]]. The intention was to eliminate [[AF]] by using incisional scars to block abnormal electrical circuits (atrial macroreentry) that [[AF]] requires. This required an extensive series of [[endocardial]] (from the inside of the heart) incisions through both atria, a median sternotomy (vertical incision through the breastbone) and cardiopulmonary bypass (heart-lung machine; [[extracorporeal circulation]]). A series of improvements were made, culminating in 1992 in the Cox maze III procedure, which is now considered to be the "gold standard” for effective surgical cure of [[AF]]. It was quite successful in eliminating [[AF]], but had drawbacks as well.<ref name="Prasad 2003">{{cite journal | author = Prasad S, Maniar H, Camillo C, Schuessler R, Boineau J, Sundt T, Cox J, Damiano R | title = The Cox maze III procedure for atrial fibrillation: long-term efficacy in patients undergoing lone versus concomitant procedures. | journal = J Thorac Cardiovasc Surg | volume = 126 | issue = 6 | pages = 1822-8 | year = 2003 | id = PMID 14688693}}</ref> The Cox maze III is sometimes referred to as the “Traditional maze”, the “cut and sew maze”, or simply the "maze".
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| Efforts have since been made to equal the success of the Cox maze III while reducing surgical complexity and likelihood of complications. During the late 1990s, operations similar to the Cox maze, but with fewer [[atrial]] incisions, led to the use of the terms "minimaze", "mini maze" and “mini-maze”,<ref name="Szalaya 1999">{{cite journal | author = Szalay Z, Skwara W, Pitschner H, Faude I, Klövekorn W, Bauer E | title = Midterm results after the mini-maze procedure. | journal = Eur J Cardiothorac Surg | volume = 16 | issue = 3 | pages = 306-11 | year = 1999 | id = PMID 10554849}}</ref> although these were still major operations.
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| A primary goal has been to perform a curative, "maze-like" procedure ''epicardially'' (from the outside of the heart), so that it could be performed on a normally beating heart, without cardiopulmonary bypass. Until recently this was not thought possible; as recently as 2004, Dr. Cox defined the mini-maze as requiring an [[endocardial]] approach:
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| <blockquote>“In summary, it would appear that placing the following lesions can cure most patients with [[atrial fibrillation]] of either type: [[pulmonary vein]] encircling incision, left atrial isthmus lesion with its attendant coronary sinus lesion, and the right [[atrial]] isthmus lesion. We call this pattern of [[atrial]] lesions the “mini-maze Procedure” ... None of the present energy sources—including cryotherapy, unipolar radiofrequency, irrigated radiofrequency, bipolar radiofrequency, microwave, and laser energy—are capable of creating the left atrial isthmus lesion from the epicardial surface, because of the necessity of penetrating through the circumflex [[coronary artery]] to reach the left atrial wall near the posterior [[mitral]] annulus. Therefore, the mini-maze Procedure cannot be performed epicardially by means of any presently available energy source.”<ref name="Cox 2004">{{cite journal | author = Cox J | title = The role of surgical intervention in the management of atrial fibrillation. | journal = Tex Heart Inst J | volume = 31 | issue = 3 | pages = 257-65 | year = 2004 | id = PMID 15562846}}</ref></blockquote>
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| ==Minimally invasive epicardial surgical procedures for AF ('''minimaze''')==
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| Although Dr. Cox's 2004 definition specifically excludes an epicardial approach to eliminate [[AF]], he and others pursued this important goal, and the meaning of the term changed as successful epicardial procedures were developed. In 2002 Saltman performed a completely [[endoscopic]] surgical [[ablation]] of [[AF]]<ref name="Saltman 2003"/> and subsequently published their results in 14 patients.<ref name="Salenger 2004">{{cite journal | author = Salenger R, Lahey S, Saltman A | title = The completely endoscopic treatment of atrial fibrillation: report on the first 14 patients with early results. | journal = Heart Surg Forum | volume = 7 | issue = 6 | pages = E555-8 | year = 2004 | id = PMID 15769685}}</ref> These were performed epicardially, on the beating heart, ''without cardiopulmonary bypass or median sternotomy''. Their method came to be known as the minimaze or microwave minimaze procedure, because microwave energy was used to make the lesions that had previously been performed by the surgeon's scalpel.
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| Shortly thereafter, Randall K. Wolf, MD and others developed a procedure using radiofrequency energy rather than microwave, and different, slightly larger incisions. In 2005, he published his results in the first 27 patients.<ref name="Wolf 2005">{{cite journal | author = Wolf R, Schneeberger E, Osterday R, Miller D, Merrill W, Flege J, Gillinov A | title = Video-assisted bilateral pulmonary vein isolation and left atrial appendage exclusion for atrial fibrillation. | journal = J Thorac Cardiovasc Surg | volume = 130 | issue = 3 | pages = 797-802 | year = 2005 | id = PMID 16153931}}</ref> This came to be known as the Wolf minimaze procedure.
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| Today, the terms “minimaze”, "mini-maze", and "mini maze" are still sometimes used to describe open heart procedures requiring cardiopulmonary bypass and median sternotomy, but are more commonly they refer to minimally invasive, epicardial procedures not requiring cardiopulmonary bypass, such as those developed by Saltman, Wolf, and others. These procedures are characterized by:
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| <blockquote>1. No median sternotomy incision; instead, an [[endoscope]] and/or “mini-thoracotomy” incisions between the ribs are used.<br>2. No cardiopulmonary bypass; instead, these procedures are performed on the normally beating heart.<br>3. Few or no actual incisions into the heart itself. The "maze" lesions are made ''epicardially'' by using radiofrequency, microwave, or [[ultrasonic]] energy, or by [[cryosurgery]].<br>4. The part of the left [[Atrium (heart)|atrium]] in which most clots form (the “appendage”) is usually removed, in an effort to reduce the long-term likelihood of [[stroke]].
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| </blockquote>
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| ===Microwave minimaze===
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| '''Completely Endoscopic Microwave Ablation of Atrial Fibrillation on the Beating Heart Using Bilateral Thoracoscopy:''' The microwave minimaze requires three 5 mm to 1cm incisions on each side of the chest for the surgical tools and the [[endoscope]]. The [[pericardium]] is entered, and two sterile rubber tubes are threaded behind the heart, in the transverse and oblique sinuses. These tubes are joined together, then used to guide the flexible microwave antenna energy source through the sinuses behind the heart, to position it for [[ablation]]. Energy is delivered and the [[atrial]] tissue heated and destroyed in a series of steps as the microwave antenna is withdrawn behind the heart. The lesions form a "box-like" pattern around all four [[pulmonary veins]] behind the heart. The left atrial appendage is usually removed.<ref name="Saltman 2003">{{cite journal | author = Saltman A, Rosenthal L, Francalancia N, Lahey S | title = A completely endoscopic approach to microwave ablation for atrial fibrillation. | journal = Heart Surg Forum | volume = 6 | issue = 3 | pages = E38-41 | year = 2003 | id = PMID 12821436}}</ref><ref name="Salenger 2004"/> A [http://www.ctsnet.org/sections/clinicalresources/adultcardiac/expert_tech-11.html very thorough description of the procedure] is available.
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| ===Wolf minimaze===
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| '''Video-assisted Bilateral Epicardial Bipolar Radiofrequency Pulmonary Vein Isolation and Left Atrial Appendage Excision:''' The Wolf minimaze requires one 5cm and two 1cm incisions on each side of the chest. These incisions allow the surgeon to maneuver the tools, view areas through an [[endoscope]], and to see the heart directly. The right side of the left [[Atrium (heart)|atrium]] is exposed first. A clamp-like tool is positioned on the left [[Atrium (heart)|atrium]] near the right [[pulmonary veins]], and the [[atrial]] tissue is heated between the jaws of the clamp, cauterizing the area. The clamp is removed. The [[autonomic]] nerves (ganglionated plexi) that may cause [[AF]]<ref name="Coumel 1994">{{cite journal | author = Coumel P | title = Paroxysmal atrial fibrillation: a disorder of autonomic tone? | journal = Eur Heart J | volume = 15 Suppl A | issue = | pages = 9-16 | year = | id = PMID 8070496}}</ref> may be eliminated as well. Subsequently the left side of the chest is entered. The ligament of Marshall (a vestigial structure with marked [[autonomic]] activity) is removed. The clamp is subsequently positioned on the left [[Atrium (heart)|atrium]] near the left [[pulmonary veins]] for [[ablation]]. Direct testing to demonstrate complete electrical isolation of the [[pulmonary veins]], and that the ganglionated plexi are no longer active, may be performed.<ref name="Wolf 2005"/>
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| ===High Intensity Focused Ultrasound (HIFU) minimaze===
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| '''Surgical ablation of atrial fibrillation with off-pump, epicardial, [[high-intensity focused ultrasound]]:''' Although the HIFU minimaze is performed epicardially, on the normally beating heart, it is also usually performed in conjunction with other [[cardiac surgery]], and so would not be minimally invasive in those cases. An [[ultrasonic]] device is positioned epicardially, on the left [[Atrium (heart)|atrium]], around the [[pulmonary veins]], and intense acoustic energy is directed at the [[Atrium (heart)|atrium]] to destroy tissue in the appropriate regions near the [[pulmonary veins]].<ref name="Ninet 2005">{{cite journal | author = Ninet J, Roques X, Seitelberger R, Deville C, Pomar J, Robin J, Jegaden O, Wellens F, Wolner E, Vedrinne C, Gottardi R, Orrit J, Billes M, Hoffmann D, Cox J, Champsaur G | title = Surgical ablation of atrial fibrillation with off-pump, epicardial, high-intensity focused ultrasound: results of a multicenter trial. | journal = J Thorac Cardiovasc Surg | volume = 130 | issue = 3 | pages = 803-9 | year = 2005 | id = PMID 16153932}}</ref>
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| ==Mechanism of Elimination of Atrial Fibrillation==
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| The mechanism by which [[AF]] is eliminated by curative procedures such as the maze, minimaze, or [[catheter ablation]] is controversial. All successful methods destroy tissue in the areas of the left [[Atrium (heart)|atrium]] near the junction of the [[pulmonary veins]], hence these regions are thought to be important. A concept gaining support is that paroxysmal [[AF]] is mediated in part by the [[autonomic nervous system ]]<ref name="Coumel 1994">{{cite journal | author = Coumel P | title = Paroxysmal atrial fibrillation: a disorder of autonomic tone? | journal = Eur Heart J | volume = 15 Suppl A | issue = | pages = 9-16 | year = | id = PMID 8070496}}</ref> and that the intrinsic cardiac nervous system, which is located in these regions, plays an important role.<ref name="Scherlag 2006">{{cite journal | author = Scherlag B, Po S | title = The intrinsic cardiac nervous system and atrial fibrillation. | journal = Curr Opin Cardiol | volume = 21 | issue = 1 | pages = 51-4 | year = 2006 | id = PMID 16355030}}</ref> Supporting this is the finding that targeting these autonomic sites improves the likelihood of successful elimination of [[AF]] by [[catheter ablation]].<ref name="Pappone 2004">{{cite journal | author = Pappone C, Santinelli V, Manguso F, Vicedomini G, Gugliotta F, Augello G, Mazzone P, Tortoriello V, Landoni G, Zangrillo A, Lang C, Tomita T, Mesas C, Mastella E, Alfieri O | title = Pulmonary vein denervation enhances long-term benefit after circumferential ablation for paroxysmal atrial fibrillation. | journal = Circulation | volume = 109 | issue = 3 | pages = 327-34 | year = 2004 | id = PMID 14707026}}</ref><ref name="Scherlag 2005">{{cite journal | author = Scherlag B, Nakagawa H, Jackman W, Yamanashi W, Patterson E, Po S, Lazzara R | title = Electrical stimulation to identify neural elements on the heart: their role in atrial fibrillation. | journal = J Interv Card Electrophysiol | volume = 13 Suppl 1 | issue = | pages = 37-42 | year = 2005 | id = PMID 16133854}}</ref>
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| ==Patient Selection==
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| The minimaze procedures are alternatives to [[catheter ablation]] of [[AF]], and the patient selection criteria are similar. Patients are considered for minimaze procedures if they have moderate or severe symptoms and have failed medical therapy; asymptomatic patients are generally not considered. Those most likely to have a good outcome have paroxysmal (intermittent) [[AF]], and have a heart that is relatively normal. Those with severely enlarged [[atria]], marked [[cardiomyopathy]], or severely leaking [[heart valves]] are less likely to have a successful result; these procedures are generally not recommended for such patients. Previous [[cardiac surgery]] provides technical challenges due to scarring on the outside of the heart, but does not always preclude minimaze surgery.
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| ==Surgical Results==
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| Long-term success of the minimaze procedures awaits a consensus. Attaining a consensus is hindered by several problems; perhaps the most important of these is incomplete or inconsistent post-procedure follow-up to determine if [[atrial fibrillation]] has recurred.<ref name="Prasad 2003"/> It has been clearly demonstrated that longer or more intensive follow-up identifies much more recurrent [[atrial fibrillation]],<ref name="Israel 2004">{{cite journal | author = Israel C, Grönefeld G, Ehrlich J, Li Y, Hohnloser S | title = Long-term risk of recurrent atrial fibrillation as documented by an implantable monitoring device: implications for optimal patient care. | journal = J Am Coll Cardiol | volume = 43 | issue = 1 | pages = 47-52 | year = 2004 | id = PMID 14715182}}</ref> hence a procedure with more careful follow-up will appear to be less successful. In addition, procedures continue to evolve rapidly, so long follow-up data do not accurately reflect current procedural methods. For more recent minimaze procedures, only relatively small and preliminary reports are available. A new metric ([http://www.minimaze.org/curativeprocedures.htm#SPRAS "Single Procedure Risk Adjusted Success"]) has been proposed in an attempt to control for some of these inconsistencies, but it has not been widely accepted. With those caveats in mind, it can be said that reported short-term success rates range from 67% to 91%.<ref name="Salenger 2004"/><ref name="Wolf 2005"/><ref name="Ninet 2005"/>
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| ==References==
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| {{reflist|2}}
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| '''A more complete current listing of minimaze references can be obtained by [http://google.ctsnet.org/search?q=mini+maze&x=0&y=0&site=default_collection&client=default_frontend&proxystylesheet=default_frontend&output=xml_no_dtd this search] at the [[Cardiothoracic Surgery Network]]'''
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| ==External links==
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| * [http://www.afibfacts.com/Treatment_Options_for_Atrial_Fibrillation/Surgical_Ablation_for_Atrial_Fibrillation/ Surgical Treatments for Atrial Fibrillation]
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| * [http://cardiacsurgery.ctsnetbooks.org/cgi/content/full/2/2003/1271 Surgical Treatment of Supraventricular Tachyarrhythmias] in ''Cardiac Surgery in the Adult''
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| * [http://cardiacsurgery.ctsnetbooks.org/cgi/content/full/2/2003/1253 Cardiologic Interventional Therapy for Atrial and Ventricular Arrhythmias] in ''Cardiac Surgery in the Adult''
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| {{Cardiac surgery}}
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