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Journal of the American College of Cardiology
© 2006 by the American College of Cardiology Foundation
Published by Elsevier Inc.
EDITORIAL COMMENT
Aortic Regurgitation
After Arterial Switch Operation*
Pedro J. del Nido, MD, FACC,†
Marcy L. Schwartz, MD‡
Boston, Massachusetts
In the early 1980s, Jatene developed the arterial switch
operation (ASO), which soon became the preferred surgery
for d-loop transposition of the great arteries (TGA). This
operation includes translocation of the pulmonary artery and
aorta above the sinuses, often with a Lecompte maneuver
(bringing the pulmonary artery anterior to the aorta) and
coronary reimplantation into the neo-aortic sinuses. Although the complications inherent in the previous atrial
switch procedures were avoided, and the left ventricle could
remain the systemic ventricle, other post-operative complications following ASO have been encountered. With increased surgical experience, the initial problems seen with
coronary transfer are now rare. Unusual coronary patterns,
once considered to be a risk factor for survival, have been
found more recently not to affect outcome (1). Supravalvar
pulmonary stenosis at the reanastomosis site or branch
pulmonary stenosis due to tension has been observed. At
short- and longer-term follow-up, neo-aortic root dilation
and neo-aortic regurgitation (AR) are relatively common,
infrequently leading to reoperation.
See page 2057
In this issue of the Journal, Losay et al. (2) report the
incidence and risk factors of aortic regurgitation in a very
large cohort of 1,156 patients at long-term follow-up after
ASO. Although aortic regurgitation is relatively common,
approximately 15% at a mean follow-up of 76 months and
up to 30% by 15 years, the majority of patients had only
trivial or mild regurgitation, and higher degrees of regurgitation (2.1%) and AR requiring reoperation (1.4%) were
rare. Furthermore, the authors also report that although
the prevalence of AR increases over time following ASO,
the degree of AR may actually decrease during follow-up.
Since trivial or mild native pulmonary regurgitation can be
considered to be normal, the relevant issue may not be the
overall incidence of AR, but instead the incidence and risk
factors of significant AR necessitating close follow-up and
*Editorials published in the Journal of the American College of Cardiology reflect the
views of the authors and do not necessarily represent the views of JACC or the
American College of Cardiology.
From the †Department of Cardiac Surgery, Department of Surgery, and the
‡Department of Cardiology, Department of Pediatrics, Children’s Hospital, Harvard
Medical School, Boston, Massachusetts.
Vol. 47, No. 10, 2006
ISSN 0735-1097/06/$32.00
doi:10.1016/j.jacc.2006.02.026
sometimes aortic valve repair or replacement. As acknowledged by the authors, a limitation of this study is that AR
quantification was not defined or standardized among the
several institutions providing follow-up assessment and
classification.
The authors of this study found that by univariate
analysis, AR of all degrees was associated with pre-operative
aorta-pulmonary artery size discrepancy, pulmonary artery
band placement, aortic arch obstruction, and older age at
ASO. By multivariate analysis, risk factors for AR were
regurgitation at hospital discharge after ASO and complex
TGA, defined as presence of a surgical ventricular septal
defect (VSD) or Taussig-Bing anomaly. In the present
study, risk factors for more significant AR and/or for aortic
valve surgery were not reported. From their findings, the
authors of this study speculate that AR is related to high
pressure and flow in the pulmonary artery before ASO.
Surgical technique, sometimes including VSD repair, may
also be a risk factor.
Other potential explanations for AR after ASO should be
considered. Several studies have also shown that pulmonary
artery banding before ASO is related to the development of
AR (3–5). In a recent study, the only risk factor for at least
moderate AR by multivariate analysis was age ⬎1 year at
ASO, which was closely related to VSD repair at the time
of ASO and a previous pulmonary artery band (6). In that
study, it was not possible to distinguish which was the most
important risk factor because of the high covariance of these
variables, and VSD repair at the time of ASO was the only
independent risk factor for subsequent neo-aortic valve or
root repair. In one study, AR was not as commonly seen
when the indication for pre-operative pulmonary artery
band was to restrict pulmonary blood flow as when following a two-stage ASO. This suggested that the etiology of
AR was not only pulmonary artery distortion, but possibly
also the rapid rise in pressure encountered by an unprepared
pulmonary valve (4). Risk factors for AR have been reported
to overlap with those of aortic root dilation. A correlation
between degree of AR and aortic root dilation has been
described, but significant overlap was seen between groups
(6). Measurement of aortic root dimension was not performed in the present study, and therefore the role of root
dilation in the development of AR was not investigated.
Looking more closely at the time of onset and rate of
progression of significant regurgitation in the series by
Losay et al. (2), a familiar pattern is discernable. Excluding
the group that had AR shortly after ASO, there is a gradual
decline in the number that are free from AR and reintervention over the 10 to 15 years of follow-up. This curve is
remarkably similar to the experience with the Ross operation, where the pulmonary root is inserted into the left
ventricular outflow as a root replacement. With late
follow-up of the Ross procedure in children and young
2064
del Nido and Schwartz
Editorial Comment
adults now exceeding 10 years, the incidence of aortic root
dilatation (Z-score ⬎3) is very high (90% in some series),
and freedom from aortic valve regurgitation and need for
reoperation falls to approximately 70% by 10 years (7,8).
Reoperation for AR was less common in the series described
by Losay et al. (2); however, the rise in the late hazard
function is similar to the Ross experience.
The causes of AR after ASO are clearly multi-factorial,
possibly including tissue characteristics of the native pulmonary wall and valve, as well as pre-operative and operative
risk factors. Histologic examination of the pulmonary root
has shown important differences compared to the aorta with
respect to elastin layer and smooth muscle actin, even in
transposition (9). Although long-term results of the ASO
are encouraging, long-term surveillance for aortic root
dilatation and AR remains necessary.
Reprint requests and correspondence: Dr. Pedro J. del Nido,
Department of Cardiac Surgery, Children’s Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115. E-mail: Pedro.
[email protected].
JACC Vol. 47, No. 10, 2006
May 16, 2006:2063–4
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