Minimaze procedure

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Minimaze procedure
ICD-9-CM37.33

The mini-maze procedures are cardiac surgery procedures intended to cure atrial fibrillation (AF), a common disturbance of heart rhythm. They are procedures derived from the original maze procedure developed by James Cox, MD.

The origin of the mini-maze procedures: The Cox maze procedure

Main article: Cox maze procedure

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.[2] The Cox maze III is sometimes referred to as the "Traditional maze", the "cut and sew maze", or simply the "maze".[citation needed
]

Minimally invasive epicardial surgical procedures for AF (minimaze)

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",[3]
although these were still major operations.

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:[citation needed
]

"In summary, it would appear that placing the following lesions can cure most patients with

mitral annulus. Therefore, the mini-maze procedure cannot be performed epicardially by means of any presently available energy source."[4]

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

microwave energy
was used to make the lesions that had previously been performed by the surgeon's scalpel.

Shortly thereafter,

radiofrequency energy rather than microwave, and different, slightly larger incisions. In 2005, he published his results in the first 27 patients.[7] This came to be known as the Wolf minimaze procedure.[citation needed
]

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 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:

  1. No median sternotomy incision; instead, an endoscope and/or "mini-thoracotomy" incisions between the ribs are used.
  2. No cardiopulmonary bypass; instead, these procedures are performed on the normally beating heart.
  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
    .
  4. The part of the left atrium in which most clots form (the "appendage") is usually removed, in an effort to reduce the long-term likelihood of stroke.

Microwave minimaze

Completely Endoscopic Microwave Ablation of Atrial Fibrillation on the Beating Heart Using Bilateral Thoracoscopy: The microwave minimaze requires three 5 mm to 1 cm incisions on each side of the chest for the surgical tools and the

pulmonary veins behind the heart. The left atrial appendage is usually removed.[5][6]

Wolf minimaze

Video-assisted Bilateral Epicardial Bipolar Radiofrequency Pulmonary Vein Isolation and Left Atrial Appendage Excision: The Wolf minimaze requires one 5 cm and two 1 cm incisions on each side of the chest. These incisions allow the surgeon to maneuver the tools, view areas through an

pulmonary veins, and that the ganglionated plexi are no longer active, may be performed.[7]

High Intensity Focused Ultrasound (HIFU) minimaze

Surgical ablation of atrial fibrillation with off-pump, epicardial,

pulmonary veins.[9]

Mechanism of elimination of atrial fibrillation

The mechanism by which AF is eliminated by curative procedures such as the maze, minimaze, or

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[8] and that the intrinsic cardiac nervous system, which is located in these regions, plays an important role.[10] Supporting this is the finding that targeting these autonomic sites improves the likelihood of successful elimination of AF by catheter ablation.[11][12]

Patient selection

The minimaze procedures are alternatives to

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.[citation needed
]

Surgical results

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, although many reasons have been considered.[14] It has been clearly demonstrated that longer or more intensive follow-up identifies much more recurrent atrial fibrillation,[15] 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. With those caveats in mind, it can be said that reported short-term freedom from atrial fibrillation following the radiofrequency ("Wolf") procedure ranges from 67% to 91% [6][7][9] with longer-term results in a similar range, but limited primarily to patients with paroxysmal atrial fibrillation.[16][17]

References

  1. PMID 2008095
    .
  2. PMID 14688693
    .
  3. PMID 10554849
    .
  4. PMID 15562846
    .
  5. ^
    PMID 12821436
    .
  6. ^
    PMID 15769685
    .
  7. ^
    PMID 16153931
    .
  8. ^
    PMID 8070496
    .
  9. ^
    PMID 16153932
    .
  10. S2CID 34469546
    .
  11. PMID 14707026
    .
  12. S2CID 19856445
    .
  13. PMID 21632865.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  14. PMID 17556213
    .
  15. PMID 14715182
    .
  16. S2CID 13944757
    .
  17. PMID 18154774
    .

External links
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