Cardiovascular Research 2003 58(3):501-509; doi:10.1016/S0008-6363(03)00350-X
© 2003 by European Society of Cardiology
Copyright © 2003, European Society of Cardiology
New strategies in the surgical treatment of atrial fibrillation
Hauw T Siea,*,
Willem P Beukemab,
Arif Elvanb and
Anand R Ramdat Misierb
aDepartment of Cardiothoracic Surgery, Isala Clinics, Hospital De Weezenlanden, Groot Wezenland 20, 8011 JW Zwolle, The Netherlands
bDepartment of Cardiology, Isala Clinics, Hospital De Weezenlanden, Zwolle, The Netherlands
hauwsie{at}worldonline.nl
* Corresponding author. Tel.: +31-38-424-2866; fax: +31-38-424-3163.
Received 25 November 2002; accepted 18 March 2003
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Abstract
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In patients with longstanding atrial fibrillation surgical correction
of the underlying cardiac abnormality alone will not abolish
the arrhythmia. The Cox's Maze III has proven to be an effective
treatment for atrial fibrillation but because of its complexity
cardiac surgeons are reluctant to expose their patients to the
potential risks of this procedure. Attempts have been made to
simplify the Cox's Maze III procedure by using alternative energy
sources and modifying the pattern of atrial lines of conduction
block. In patients with atrial fibrillation without structural
heart disease Maze surgery may be an option as an ultimate therapeutic
alternative when atrial fibrillation is drug resistant and very
symptomatic. The objective of this article is to outline the
different surgical procedures that have formerly been used in
the treatment of atrial fibrillation and to give an overview
of new and evolving techniques.
KEYWORDS Ablation; Valve disease; Supraventricular arrhythmia
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1 Introduction
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The surgical treatment of drug-refractory atrial fibrillation
was reported for the first time in 1981 by Seally et al.
[1],
who used cryo-ablation to interrupt the His bundle. Since 1982
closed-chest catheter ablation of the His bundle
[2] became
a widely used treatment for drug-refractory atrial fibrillation
(AF). However, these procedures implicate the exclusion of the
physiological cardiac pacemaker to drive the ventricles, the
interruption of atrioventricular synchrony and life-long artificial
pacemaker dependency. During the past decades several other
surgical methods have been developed to treat atrial fibrillation:
the left atrial isolation procedure by Williams et al.
[3],
the Corridor procedure by Guiraudon and co-workers
[4,5] and
last but not least the Maze procedure as advocated by Cox et
al.
[6,7]. All these procedures were designed to treat AF, but
the most effective one seems to be the Maze procedure developed
by Cox et al. Ferguson and Cox
[8] defined the five goals to
treat atrial fibrillation: (1) elimination of atrial fibrillation,
(2) restoration of sinus rhythm, (3) reestablishment of atrioventricular
synchrony, (4) restoration of atrial transport function, (5)
reduction of the risk of thromboembolism. The Maze procedure
claims to attain all these five goals. However, because of the
complexity and extent of the Maze procedure, surgeons are reluctant
to expose their patients to the potential hazards of the Maze
procedure, especially in addition to other complex cardiac procedures.
The objective of the following section is to outline the different
surgical procedures that have formerly been used in the treatment
of atrial fibrillation and to give an overview of new and evolving
techniques.
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2 Left atrial isolation procedure
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Surgical isolation of the left atrium circumvents the interruption
of sinus node activity. This procedure was initially developed
to treat atrial tachycardias originating from the left atrium.
A major drawback of this method is that the underlying arrhythmia,
i.e., atrial tachycardia, flutter or fibrillation continues.
Graffigna et al.
[9] have published data on a group of 100 patients
who underwent concomitant left atrial isolation and mitral valve
surgery. They have shown that in 81% of patients sinus rhythm
was achieved in the early postoperative period. At 2 years follow-up
70% of the patients were still in sinus rhythm. The investigators
applied this procedure because the left atrial isolation procedure
is simple and does not significantly prolong ischemic time interval.
The major disadvantage of this procedure is that the left atrium
remains in fibrillation or becomes electrically silent and the
risk of thromboembolism due to stasis of blood in the left atrium
remains unaltered. All these patients were on long-term anticoagulation.
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3 Corridor procedure
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In 1985, Guiraudon et al.
[10] introduced the Corridor operation
in which a corridor of atrial tissue was isolated in the right
and left atrium to enable electrical activity to propagate from
the sinus node area to the atrio-ventricular (AV) node region.
The Corridor procedure was at that time an alternative to His
bundle ablation and permanent pacemaker implantation. This surgical
method preserves physiological driving of the ventricles, but
atrial transport function is lost. Both atria were isolated
from the corridor and atrial fibrillation associated with increased
thromboembolic risk remained. The early results of the Guiraudon
group showed that seven out of nine patients remained in sinus
rhythm. However, the Corridor operation was associated with
a high incidence of sinus node dysfunction and four out of nine
patients required a pacemaker. In a larger group of patients
(
n = 36), Defauw and co-workers
[5,11] showed that successful
treatment was achieved in 86% of patients. Five patients ultimately
needed His bundle ablation and permanent pacemaker implantation.
Left atrial contractile function was absent in all patients.
There were two strokes in the early postoperative period. Biatrial
enlargement occurred in the majority of patients on echocardiographic
follow-up. The corridor procedure did not restore atrial contractility
and did not eliminate atrial fibrillation nor the risk of thromboembolism.
Long-term anticoagulant therapy was needed after corridor surgery.
The corridor operation has been abandoned after introduction
of the Maze procedure.
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4 Maze procedure
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Atrial fibrillation is not a homogeneous arrhythmia, but represents
a spectrum from focal atrial tachycardia demonstrating atrial
fibrillation on the surface ECG to chronic atrial fibrillation
associated with structural heart disease. Cox et al.
[7] performed
intra-operative mapping studies of pacing induced atrial fibrillation
in patients. They found that atrial fibrillation is based on
randomly migrating wavelets of macroreentry. In 1991, Cox et
al.
[7] described a new surgical procedure for the treatment
of drug-refractory atrial fibrillation. The Maze operation compartmentalizes
both atria to create a labyrynth with blind alleys in which
the amount of atrial myocardium is insufficient to sustain multiple
wavelets of reentry. The electrical impulse propagation is forced
over a surgically determined route (
Fig. 1A) Initially, the
surgical Maze procedure was performed as an isolated cardiac
operation. However, as the experience expanded, it has been
performed concomitantly with other cardiac procedures. The Cox
Maze procedure was designed to prevent reentrant atrial fibrillation,
and several series have confirmed the success of the operation.
As a result, indications have been extended from lone atrial
fibrillation to treatment of atrial fibrillation in patients
having cardiac surgery for associated mitral valve disease and
other structural cardiac abnormalities. Restoration of sinus
rhythm brings symptomatic relief of palpitation and, perhaps
more important restoration of atrial transport function reduces
the risk of thromboembolism. Maze surgery is performed in a
selected group of patients with symptomatic drug-refractory
atrial fibrillation. Cox et al. have shown that in a series
of 178 surgical patients, 58% of them had lone AF and 66% underwent
arrhythmiasurgery only
[12]. The investigators reported a combined
recurrence of atrial flutter and atrial fibrillation of 2% in
the 118 patients who had Maze III surgery during a follow up
of at least 3 months (range 3–63 months). The Maze operation
was associated with impaired sinus node automaticity in 6% of
patients. Jessurun et al. have recently shown that Maze surgery
for lone atrial fibrillation is very effective
[13]. In this
latter study, in 35 of 41 (85%) patients with longstanding drug-refractory
lone atrial fibrillation, sinus rhythm was restored after Maze
operation. After a mean follow-up of 31 months, 95% of the patients
were free of paroxysmal AF and 80% of patients did not need
antiarrhythmic therapy. Death or stroke was not observed in
this study. In two patients (5%), paroxysmal atrial fibrillation
persisted requiring His bundle ablation and pacing. In another
study, Lönnerholm et al.
[14] confirmed the improvement
of health-related quality of life up to 1 year after the Maze
operation for paroxysmal or chronic lone AF, in 48 patients.
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Fig. 1 (A) Maze III procedure: the cephalad to caudad view of the atria (upper diagram) and view of the dorsal aspect of the atria (lower diagram). Black arrows indicate lines of electrical activation; the zigzag lines depicting the surgical incisions and sewing in the atria. (B) Radiofrequency modified Maze procedure. The cephalad to caudad view of the atria (upper diagram) and view of the dorsal aspect of the atria (lower diagram). Black arrows indicate lines of electrical activation; the zigzag lines depicting the surgical incisions and sewing in the atria. The dotted lines depicting the endocardial radiofrequency ablation lines. (C) Radial approach. The cephalad to caudad view of the atria (upper diagram) and view of the dorsal to ventral aspect of the atria (lower diagram). Black arrows indicate lines of electrical activation; the zigzag lines depicting the surgical incisions and sewing in the atria. (D) Bilateral appendage preserving Maze procedure (BAP Maze). The cephalad to caudad view of the atria (upper diagram) and view of the dorsal to ventral aspect of the atria (lower diagram). Black arrows indicate lines of electrical activation; the zigzag lines depicting the surgical incisions and sewing in the atria. See text for details.
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The Maze procedure has been reported as effective in restoring
sinus rhythm and atrial contraction in patients with AF with
and without underlying heart disease. However, restoration of
both sinus rhythm and atrial contraction is apparently different,
and the rate of restoring atrial contraction varies from 21
to 95%
[12–20]. The percentage of patients with restored
atrial contraction seems to differ with the etiology of atrial
fibrillation. More than 90% of the patients with lone atrial
fibrillation or an atrial septal defect had restored atrial
contraction, whereas 21–90% of patients with mitral valve
disease had restored atrial contraction after the Maze procedure.
In the study of Yuda et al.
[16], 50% of the patients resumed
atrial contraction in the early stage (3.1±3.3 months).
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5 Combined Maze procedure and mitral valve surgery
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Approximately 30–40% of patients who undergo mitral valve
surgery have chronic atrial fibrillation before the operation
[17–20] and the majority remains in atrial fibrillation
after the operation. In patients with atrial fibrillation lasting
more than 1 year mitral valve surgery alone does not eliminate
the arrhythmia
[14]. Several authors reported long-term freedom
of atrial fibrillation of 80% in patients undergoing the Maze
procedure in combination with mitral valve surgery
[16–33].
Factors associated with recurrence of atrial fibrillation after
the Maze operation include left atrial dilatation, impaired
left ventricular function and longstanding atrial fibrillation
(atrial fibrillation duration >1 year)
[16–33]. Recently
Jessurun
[23] published the results of a small prospective randomized
study of combined Maze surgery and surgical correction of mitral
valve disease in 35 patients. In the control arm, atrial fibrillation
persisted in >70% of patients after valve surgery. In the
Maze group, sinus rhythm was present at discharge in 56% and
after 12 months of follow-up in 92% of patients. Quality of
life after surgery improved in both control and Maze group without
a significant difference between the two groups.
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6 Impact of Maze surgery on stroke rate
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Persistent atrial fibrillation is an important risk factor for
ischemic stroke
[31–35]. Prevention of thromboembolic
complications, e.g., stroke, should be one of the major goals
in the treatment of atrial fibrillation
[34–39]. The Framingham
data
[38] have shown that the relative risk of stroke is 5.6
in patients with non-rheumatic atrial fibrillation and 17.6
in patients with rheumatic atrial fibrillation. Approximately
20% of ischemic strokes is associated with non-rheumatic atrial
fibrillation. The incidence of atrial fibrillation related stroke
is especially high in the elderly (age >80 years), i.e.,
up to 36% of ischemic strokes in this age group is causally
related to atrial fibrillation
[34–39]. The overall incidence
of stroke in non-rheumatic atrial fibrillation is approximately
5% per year
[34–39].
Recent studies have shown that atrial fibrillation produces a hypercoagulable state. The increased plasma concentrations of fibrin D-dimer and β-thromboglobulin becomes more pronounced with longer episodes of atrial fibrillation [40–43]. Cai et al. [41] have delineated the potential pathophysiological mechanisms for the hypercoagulable state caused by persistent atrial fibrillation. They demonstrated that atrial fibrillation is associated with a marked decrease in the expression of nitric oxide synthase (NOS) and nitric oxide (NO) bioavailability. In addition, expression of plasminogen activator inhibitor 1 was significantly enhanced in the fibrillating atria. These data indicate that sinus rhythm with intact atrial contractile function is important in normal endocardial expression of NOS. It is conceivable that atrial fibrillation-induced reduction of this latter anti-thrombotic enzyme contributes to the increased risk of thromboembolic events.
The Maze procedure involves multiple atrial incisions to prevent the occurrence of atrial fibrillation, reestablish normal sinus rhythm and preserve left and right atrial transport function. Cox and associates have shown that the surgical procedure preserves normal hemodynamics and reduces the risk of thromboembolism [39]. Cox Maze procedure was performed on 306 patients with medically refractory atrial fibrillation, 58 of these patients had a history of stroke or transient ischemic attack prior to surgery. Perioperative stroke was 0.7% (two of 306 patients) and in the 265 patients who were followed for up to 11.5 years after the Maze operation, only one late minor stroke was observed. The transport function of the left atrium was present in 93% of patients and the transport function of the right atrium was present in 98% of patients. Nakajima et al. [44] have compared the conventional Maze surgery with cryo-Maze which is a modification including cryoablation for the isolation of the pulmonary veins. Their study consisted of 220 patients and the actuarial freedom from stroke was 99% with a follow-up duration of 3 years [44]. Maze procedures includes amputation of both atrial appendages and the remaining part of the atria are contracting after surgery in the majority of the patients. In these patients anticoagulation can be discontinued unless there is an underlying thrombotic disorder. In this latter study, Cox and associates, have shown that the Maze procedure is effective in abolishing the risk of thromboembolism associated with atrial fibrillation without the need for anticoagulation. On the other hand, atrial thrombi have been localized in the isolated left posterior left atrium in 9% of heart transplant recipients with sinus rhythm and anticoagulation therapy. As the Maze procedure includes isolation of the left posterior left atrium; it is conceivable that atrial thrombi can occur in these patients. The decision to discontinue anticoagulation therapy after Maze operation should be based on the individual patient characteristics.
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7 New surgical techniques
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Excellent results have been described for the surgical treatment
of chronic atrial fibrillation associated with organic heart
disease at the expense, however, of considerable prolongation
of time required for cardiac arrest and cardiopulmonary bypass
[6–8,12–19]. In an attempt to reduce ischemic time
and to minimize the risk of peri- and postoperative bleeding
associated with the surgical Maze procedure, modifications of
the Maze procedure have been developed. In order to simplify
the surgical technique of the Maze procedure, some investigators
attempted to reduce the number of surgical lines of conduction
block and altered the pattern of atriotomies, e.g., the mini
Maze procedure. Other groups attempted to replace the cutting
technique totally or partially by producing transmural contiguous
lines of conduction block using alternative energy sources,
including the use of cryo-ablation and application of RF energy
alone or in combination with cryo-ablation
[19–30,39,44–54].
Treatment of atrial fibrillation by application of contiguous
RF-induced lesions in the atria is based on the concept of preventing
functional reentrant circuits or eliminate anatomically determined
circuits. The most important and promising modifications of
the Maze procedure are discussed in the following section.
Table 1 summarizes the results of different surgical approaches.
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8 Radiofrequency modified Maze procedure
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Radiofrequency (RF) catheter ablation has become an important
mode of treatment in patients with supraventricular and ventricular
tachycardias
[52–69]. In patients with atrial flutter
or atrial reentrant tachycardias, RF energy is used to create
continuous linear lesions in the atrium, interrupting a critical
part of the reentrant circuit. Recent results of application
of RF catheter ablation to mimic the surgical Maze procedure
in a canine model of AF were encouraging
[60]. Sie et al.
[21,22] performed the radiofrequency modified Maze procedure in 122
patients (
Fig. 1B). The majority (89%) of these patients underwent
the RF modified Maze in combination with multiple cardiac procedures
including mitral valve surgery. The RF energy was applied in
a unipolar mode between the ablation electrode and a cutaneous
dispersive pad. Furthermore, the RF energy was applied using
a cooled tip electrode technique allowing creation of deeper
lesions without the need for cryoablation. All the lesions were
made endocardially and replaced most of the surgical incisions.
The elective cardiac arrest time required to complete the Maze
procedure in their investigation was 10–15 min in contrast
to at least 30 min for the Cox Maze III
[6–8] or the modification
of the Cox Maze III by Kosakai et al.
[26] or the combination
of RF energy and cryoablation to complete the left sided Maze
[28]. Although the complexity of the combined approach carries
potential risks, this is not supported by data from the studies
by Sie and associates. In a recent editorial Grover and Edwards
are reporting similar mortality rates between the Society of
Thoracic Surgeons and the New York State Database, ranging from
5.9% for isolated MV replacement to 13.3% for combined MV replacement
and coronary artery bypass grafting
[70]. Despite the complexity
of the surgical the procedures performed in the patients undergoing
RF modified Maze, the in-hospital mortality rate was comparable
to previous reports on patients who underwent mainly isolated
mitral valve surgery with or without surgery for atrial fibrillation.
The aim of surgery for atrial fibrillation is restoration of sinus rhythm and reestablishment of atrial mechanical function. In the RF modified Maze patients atrial rhythm and atrial contractility were documented in 77% of patients, which is comparable with the results of the surgical Maze III procedure in patients with longstanding atrial fibrillation and structural heart disease [18,19]. Melo and associates [45] performed intra-operative endocardial bilateral isolation of the pulmonary veins in patients with chronic atrial fibrillation and mitral valve disease. Atrial rhythm and contractility was restored in 69% of the patients. Haissaguerre et al. elegantly demonstrated that atrial fibrillation can be triggered by rapid, repetitive foci in the pulmonary veins [62]. From experimental and clinical studies it was demonstrated that atrial fibrillation or atrial flutter can occur in the absence of any electrical input from the pulmonary veins [71]. Atrial fibrillation may be caused by fibrosis and inflammation resulting in slow conduction. Atrial enlargement caused by, e.g., valvular disease helps sustain atrial fibrillation by accommodating more electrical wavelets. Atrial excitable properties are modulated by autonomic tone and various other factors like thyroid dysfunction and myocardial ischemia. The interplay between triggers, substrate and modulating factors can create an arrhythmogenic milieu for the initiation and perpetuation of atrial fibrillation.
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9 The radial approach
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Nitta and co-workers
[72–76] developed the radial incision
approach to provide a more physiological atrial activation sequence
and improve left atrial contractile function (
Fig. 1C). The
classical Maze procedure is associated with insufficient left
atrial mechanical function. This latter may be related to the
isolated posterior left atrium between the pulmonary vein orifices,
delayed activation of isolated atrial compartments and incisions
across atrial arteries. The incisions produced by the radial
approach radiate from the sinus node toward the atrioventricular
annular margins, paralleling atrial activation sequence and
the coronary arteries. Nitta et al. compared the results of
Maze operation (
n = 13) and radial incision approach (
n = 32)
in patients with chronic atrial fibrillation associated with
valvular disease
[76]. They showed that the radial incision
approach was technically easier and the left atrial transport
function after surgery assessed with Doppler echocardiography
was better with the radial approach in comparison with the Maze
procedure. The restoration of sinus rhythm was equivalent (90%
in radial approach and 92% in Maze patients).
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10 Bilateral appendage-preserving Maze procedure
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Maze procedure results in partial restoration of atrial transport
function and impaired secretion of atrial natriuretic peptide
(ANP)
[77]. One of the early complications of the Maze procedure
is fluid retention. Yoshihara et al.
[77] reported that preservation
of the right atrial appendage was effective in improving ANP
secretion and alleviating fluid retention postoperatively. Isobe
et al.
[49] compared bilateral appendage-preserving (BAP) Maze
procedure performed in 46 patients with the Maze III procedure
performed in 40 patients (
Fig. 1D). In both groups in >95%
of the patients sinus rhythm was achieved. In the BAP Maze group
the left atrial ejection fraction measured by transesophageal
echocardiography was close to normal and the atrial natriuretic
peptide secretory reserve was greater compared with the Maze
III patients. These investigators concluded that the BAP Maze
procedure improved atrial transport function and simplified
the Maze operation without decreasing the anti-arrhythmic surgical
efficacy.
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11 The endo/epicardial approach
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Melo et al.
[45] developed the combined endocardial and epicardial
radiofrequency ablation of right and left atria in the treatment
of atrial fibrillation. Although the Maze procedure and its
modifications have proven efficacy, the attendant increase in
operation time and morbidity, these investigators have attempted
to further simplify the surgical treatment of atrial fibrillation.
All Maze surgical incisions were replaced by RF ablation lines.
The ‘cut and sew’ technique is the golden standard
to produce transmural contiguous lines of conduction block.
Nontransmural lesions created by RF ablation, especially in
regions with pectinate muscles, may constitute an important
limitation of this approach. The intraoperative epicardial handling
of the radiofrequency catheter to secure a constant and firm
tissue–electrode surface contact on a beating heart can
be technically difficult. Melo et al. applied intra-operative
RF ablation in 43 patients with chronic atrial fibrillation
undergoing concomitant cardiac procedures. They showed disappointing
results, i.e., only 10 (30%) of the patients had sinus rhythm
with atrial contraction after the operation. Benussi et al.
[58] used the combined epicardial and endocardial left atrial
RF ablation approach in conjunction with mitral valve surgery
in 132 patients with chronic atrial fibrillation. The ablation
was performed with a temperature-controlled, non-irrigated multipolar
radiofrequency catheter. At a mean follow-up of 3 years, 102
of 132 (77%) of the patients had sinus rhythm with echocardiographically
documented atrial contractility. The actuarial freedom of stroke
at 3 years was 98%. No patient required implantation of a permanent
pacemaker. Recently, Raman et al.
[52] showed that after 6 months
follow-up, 23 of 26 patients (95%) undergoing concomitant cardiac
surgery and RF ablation procedure remained in sinus rhythm.
Histological studies demonstrated that 83% of the RF ablation
lines were transmural.
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12 Microwave ablation
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Microwave produces high frequency electromagnetic radiation
causing oscillation of H
2O (water) molecules resulting in kinetic
energy and heat. The advantage of microwave over radiofrequency
ablation is related to the larger volume and depth of lesions
produced by microwave. The probability of transmural lesions
is greater with microwave ablation. In addition microwave does
not cause charring of endocardial surface, which may reduce
the risk of thromboembolism
[78–83]. Knaut et al. reported
a series of 105 patients with chronic atrial fibrillation who
underwent a microwave Maze procedure concomitant to mitral valve
surgery
[79]. The survival rate was 99% (
n = 104). Time needed
to perform the microwave ablations was approximately 13 min.
After a follow-up of 1 year, 58% of their patients were in sinus
rhythm. Maessen et al. published preliminary data on 24 patients
who underwent beating-heart epicardial microwave ablation for
atrial fibrillation without cardiopulmonary bypass support
[83].
The microwave antenna was used to create lines of conduction
block around the right and left pulmonary veins followed by
amputation of the left atrial appendage. All patients received
either sotalol or amiodarone as anti-arrhythmic medication.
At the latest follow-up (duration 3–9 months), 20 of 23
(87%) patients were in sinus rhythm.
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13 Cryothermy
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Cryo-ablation reliably creates transmural lesions by freezing
atrial tissue. The myocardial cells within the frozen block
of tissue become irreversibly damaged. Cryoablation results
in freezing of atrial tissue that undergoes an initial phase
of hemorrhage and inflammation followed by a later phase of
replacement fibrosis. Cryo-ablation has been widely used in
anti-arrhythmia surgery and has been found to be safe and effective.
Potential advantages of cryo-ablation over radiofrequency ablation
includes the ability to perform reversible ice-mapping and stable
adhesion of the cryothermal catheter to the endocardium and
reduced incidence of endocardial thrombus formation at the site
of cryo-ablation. Recently, Timmermans et al. demonstrated that
cryothermy compared with radiofrequency ablation, produces less
pain during application in patients who underwent ablation of
atrial flutter
[84]. Cryo-ablation has become an important component
of the Maze III procedure. Nakajima et al.
[44] demonstrated
in a case-matched study including 220 patients that cryo-ablation
for pulmonary vein isolation reduced the cardiopulmonary and
aortic cross-clamp time significantly with less chest tube drainage.
The actuarial freedom from recurrence of atrial fibrillation
at 3 years was 97% in the cryo-Maze group and 90% in the conventional
Maze group (
P = 0.11).
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14 Summary and conclusions
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In patients with longstanding atrial fibrillation surgical correction
of the underlying cardiac abnormality alone will not abolish
the arrhythmia. The Cox's Maze III has proven to be an effective
treatment for atrial fibrillation but because of its complexity
cardiac surgeons are reluctant to expose their patients to the
potential risks of this procedure. Attempts have been made to
simplify the Cox's Maze III procedure by using alternative energy
sources and modifying the pattern of atrial lines of conduction
block. Several studies have shown that left atrial lesions are
more crucial than right atrial lesions in abolishing atrial
fibrillation. The RF modified Maze based on Cox's Maze III is
a simple and effective alternative to eliminate atrial fibrillation
during cardiac surgery. Alternative energy sources like microwave
are not yet evaluated in large group of patients. Maze or modified
Maze surgery for atrial fibrillation is efficacious for patients
with preoperative atrial fibrillation, who are scheduled for
elective cardiac surgery. Restoration of sinus or atrial rhythm,
absence of spontaneous left atrial echocontrast and documented
left-sided atrial transport by transesophageal Doppler echocardiography
are reasons to consider discontinuation of coumadin during follow-up.
The decision to discontinue anticoagulation is delicate because
atrial thrombi may occur in the isolated left posterior atrial
wall as described in heart transplant patients.
In patients with atrial fibrillation without structural heart disease Maze surgery may be an option as an ultimate therapeutic alternative when atrial fibrillation is drug resistant and very symptomatic. Recent studies have demonstrated that rate control can be considered as a primary treatment modality if rhythm control is ineffective [85,86]. It is conceivable that in the near future, surgery for lone atrial fibrillation will be replaced by percutaneous catheter ablation techniques if the outcome of these methods become comparable with that of Maze surgery. The success rate of pulmonary vein isolation ranges between 60 and 70%, whereas Maze surgery for lone atrial fibrillation has a success rate of more than 90%. Future studies are needed to delineate which type of procedure is the most effective in abolishing atrial fibrillation, elimination of thromboembolic risk and restoration of atrial transport function.
Time for primary review 23 days.
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Abstract
1 Introduction