(Circulation. 1995;92:128-131.)
© 1995 American Heart Association, Inc.
Articles |
Interrupted Aortic Arch
Impact of Subaortic Stenosis on Management and Outcome
From the Divisions of Cardiothoracic Surgery, Cardiology, and Cardiac Anesthesia, the Children's Hospital of Philadelphia (Pa).
Correspondence to Marshall L. Jacobs, MD, The Children's Hospital of Philadelphia, 34th St and Civic Center Blvd, Philadelphia, PA 19104.
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Abstract |
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Abstract Interrupted aortic arch (IAA) is often related developmentally to subaortic obstruction (SAO). When severe, SAO must be addressed in surgical management of IAA. From 1990 to 1993, 25 neonates presented for initial surgical management of IAA complexes. Associated lesions were ventricular septal defect (VSD) with or without atrial septal defect (19 patients), truncus arteriosus (3 patients), tricuspid atresia with transposition of the great arteries (1 patient), aortic atresia with VSD (1 patient), and d-transposition of the great arteries with VSD (1 patient). Overall hospital mortality was 20% (five deaths). One death was related to sepsis and two to sudden hemodynamic decompensation (a 2-kg premature infant after arch repair and VSD closure and a neonate with IAA–truncus arteriosus after arch repair and truncus repair with aortic root replacement). Two deaths were related to low cardiac output in patients with severe subaortic narrowing (<3 mm by two-dimensional echocardiography), which was not addressed surgically. Of 10 additional patients judged preoperatively to have severe SAO, 1 underwent resection of the infundibular septum together with VSD closure and arch reconstruction, and 9 underwent a modification of Norwood's operation with arch reconstruction and proximal pulmonary artery to aortic anastomosis (7 with systemic to pulmonary artery shunts and 2 with right ventricle to pulmonary artery outflow tract reconstruction). One patient died 2 months after surgery of staphylococcal sepsis. All 9 others were discharged well. Subaortic narrowing is a physiologically important element of IAA complexes. When SAO is severe, satisfactory initial palliation can be achieved by a modification of Norwood's operation.
Key Words: aorta • surgery
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Introduction |
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Interrupted aortic arch occurs in association with a wide variety of intracardiac malformations. When two ventricles are present, there is almost always an interventricular communication,1 and frequently there is some degree of obstruction or hypoplasia of the outflow tract of the subaortic ventricle.2 The use of prostaglandin E1 has made it routinely possible to resuscitate and support neonates with interrupted aortic arch complexes in anticipation of surgical therapy.3 Nonetheless, despite marked improvement in the outcome of surgical therapy for a broad spectrum of complex heart malformations in neonates, the operative mortality for repair of interrupted aortic arch complexes remains greater than that associated with many procedures that pose comparable if not more formidable technical challenges to the congenital heart surgeon.
It is generally recognized that hypoplasia of the subaortic outflow tract is a common accompaniment of interruption of the aortic arch. While on a physiological basis nonrelief of systemic ventricular outflow obstruction would be anticipated to impact on the physiology and potentially on survival after surgical management of interrupted aortic arch, controversy exists on what surgical techniques if any should be used to address systemic ventricular outflow tract obstruction and what parameters define a degree of subaortic obstruction that is likely to be poorly tolerated. Among existing clinical investigations, one of the largest and most comprehensive studies of outcome in patients with interrupted aortic arch complexes is the report by Jonas et al4 of the multi-institutional study undertaken by the Congenital Heart Surgeons Society. The analysis of outcomes among this group of 183 neonates with interrupted aortic arch and ventricular septal defect suggested that "procedural risk factors for death after repair were (1) repair without concomitant procedures in patients with other important levels of obstruction in the left heart–aortic complex, (2) a Damus-Kaye-Stansel anastomosis, and (3) subaortic myotomy/myectomy in the face of subaortic narrowing." One is then left with the troublesome inferences that on the one hand failure to address the systemic ventricular outflow tract obstruction is associated with increased operative mortality, while on the other hand surgical modifications designed to relieve or bypass systemic ventricular outflow tract obstruction were also associated with increased operative mortality. While the Congenital Heart Surgeons Society study is unique because of the large size of the patient population, a potential limitation of that report is the incalculable contribution of interinstitutional variability in patient evaluation and management.
In an attempt to assess the importance of subaortic narrowing in patients with interrupted aortic arch complexes and determine the effectiveness of a surgical strategy that would be expected to minimize the influence of subaortic narrowing on postoperative physiology, we undertook this review of a single institution's recent experience with surgical management of neonates with interrupted aortic arch.
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Methods |
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Patients
All newborn infants with a diagnosis of interrupted aortic arch who were managed at the Children's Hospital of Philadelphia between January 1990 and December 1993 constitute the study population. The population consists of 25 patients whose age at surgery ranged from 2 to 73 days. The latter was a premature infant maintained on ventilatory support and prostaglandin infusion at another institution until referral to the Children's Hospital of Philadelphia for surgical management. Patient weight at the time of surgery ranged from 1.9 to 4.7 kg. In all instances, the diagnosis of interrupted aortic arch was made by two-dimensional echocardiography. The majority of patients did not undergo preoperative cardiac catheterization. Interrupted aortic arch was associated with normally related great arteries and single or multiple ventricular septal defects in 19 patients, with persistent truncus arteriosus communis in 3, tricuspid atresia and d-transposition of the great arteries in 1, aortic atresia and malalignment-type ventricular septal defect in 1, and d-transposition of the great arteries and malalignment-type ventricular septal defect in 1.
Echocardiographic Measurements
Assessment of the anatomy
including
echocardiographic measurement of the subaortic region
of the left ventricular outflow tract in patients with
normally related great arteries was made at the time of diagnosis by
one of five attending staff
cardiologists/echocardiographers. As part of this
retrospective study, all available echocardiographic
tapes were reviewed, and measurements of the subaortic region of the
left ventricular outflow tract were made by a single
observer (A.J.C.).
Surgical Methodology
All operative procedures were performed
by two surgeons using
one general scheme of operative management.
Follow-up
The primary source of follow-up information is the
hospital
medical record. The secondary source of follow-up information
is the records of the referring cardiologists. None of the 25
patients have been lost to follow-up.
Results
Echocardiography
Measurements of the
subaortic region of the left
ventricular outflow tract by one observer are summarized in
the Table
for the 19 patients with interrupted aortic
arch and ventricular septal defect. Also listed in the
Table are the anatomic type of the ventricular septal
defect and the nature of the aortic valve (bicuspid or otherwise) when
known. While the vast majority of measurements of the subaortic region
of the left ventricular outflow tract are clustered in the
3 to 5 mm range, there is for most patients some degree of variability
between measurements made using different
echocardiographic windows. Similarly, there were at
times larger differences between these measurements made
retrospectively by one observer and those that were made by a variety
of echocardiographers at the time of initial
assessment.
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Surgical Procedure
Of the 19 patients
with interrupted aortic arch and
ventricular septal defect, 11 underwent
ventricular septal defect closure and anastomosis of the
ascending aorta to the thoracic aorta with augmentation of the
ascending aorta, aortic arch, and thoracic aorta by use of a gusset of
cryopreserved pulmonary artery homograft (Fig 1). In 1 of these
11 patients, the conal septum was
resected to enlarge the subaortic portion of the left
ventricular outflow tract. One patient with interrupted
aortic arch with ventricular septal defect underwent
ventricular septal defect closure and simple primary
anastomosis of the postductal thoracic aorta to the ascending aorta.
Seven patients with interrupted aortic arch and ventricular
septal defect who were believed to have severe subaortic
stenosis underwent a modified Norwood procedure wherein the
transected proximal main pulmonary artery was associated with
the ascending aorta, and the aortic arch was repaired by anastomosis of
the thoracic aorta to the ascending aorta with cryopreserved
pulmonary artery homograft augmentation of the aortic arch (Fig
2). In 5 of these patients, pulmonary blood flow
was provided by a systemic to pulmonary artery shunt, as in the
Norwood procedure as described for hypoplastic left heart
syndrome.5 In the remaining 2 patients, an
interventricular baffle was used to direct left
ventricular outflow through the ventricular
septal defect to the pulmonic valve, and the branch pulmonary
arteries were associated with the right ventricular outflow
tract, resulting in a one-stage biventricular
repair. Two additional patients, one with interrupted aortic arch,
tricuspid atresia, and d-transposition of the great arteries and
one with interrupted aortic arch, aortic atresia, and
malalignment-type ventricular septal defect, underwent
a Norwood stage I procedure. The patient with interrupted aortic arch,
d-transposition of the great arteries, and malalignment-type
ventricular septal defect underwent ventricular
septal defect closure, arterial switch, aortic arch
anastomosis with pulmonary artery homograft gusset
augmentation, and transannular patch reconstruction of the right
ventricular outflow tract. Two of the three patients with
truncus arteriosus and interrupted aortic arch underwent arch
anastomosis with homograft augmentation, ventricular septal
defect closure, and truncus repair with right ventricular
outflow tract reconstruction. One of the two also underwent aortic root
replacement with a cryopreserved aortic homograft and coronary
reimplantation. The third patient with truncus arteriosus and
interrupted aortic arch also had severe truncal valve dysplasia and
regurgitation and underwent orthotopic cardiac and
aortic arch transplantation.
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Outcome of the Initial Procedure
There were five hospital
deaths, for a hospital mortality of
20%. The patient who had undergone repair of truncus arteriosus,
aortic arch repair, and aortic root replacement experienced sudden
hemodynamic decompensation on the third postoperative
day and died. One of the two patients who underwent a Norwood-type
one-stage biventricular repair died as a result of
staphylococcal sepsis 2 months after surgery. Among the 13 patients who
underwent ventricular septal defect closure and aortic arch
repair with or without homograft augmentation, there were three
hospital deaths. The first was a 2-kg, premature infant who experienced
sudden hemodynamic decompensation on the first
postoperative day and died. The other two patients who died remained
ventilator dependent with poor cardiac output and died as a result of
multiple organ dysfunction on postoperative days 10 and 23,
respectively. Analysis of survival in relation to method of
initial repair reveals that among patients with interrupted aortic arch
and ventricular septal defect who underwent arch repair and
ventricular septal defect closure, survival was 77% at 1
month and remained at 77% at 6 and 12 months. For patients who
underwent a Norwood-type repair including association of the
proximal main pulmonary artery with the ascending aorta,
survival was 100% at 1 month and 89% at 6 and 12 months.
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Discussion |
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TopAbstractIntroductionMethods Discussion References |
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The frequency and severity of hypoplasia or stenosis of the subaortic region of the left ventricular outflow tract in association with interrupted aortic arch have been widely recognized and are well documented.2 6 7 It makes sense on a physiological basis to hypothesize that failure to relieve systemic ventricular outflow obstruction at levels proximal to that of the corrected arch interruption could have an important impact on postoperative physiology and survival. We can only speculate whether failure to address physiologically important subaortic stenosis was a factor contributing to the death of 3 of the 13 patients in this series who underwent ventricular septal defect closure and arch repair. One of the three had the smallest subaortic stenotic region of the entire patient population by retrospective echocardiographic measurement.
There remains considerable controversy on the importance of obstruction of the subaortic region in patients with interrupted aortic arch and the most appropriate surgical strategy to deal with it when present.8 9 10 In 1988, Sell and associates11 in Boston reported an improvement in outcome associated with primary one-stage repair of interrupted aortic arch and ventricular septal defect by ventricular septal defect closure and direct aortic anastomosis. They predicted and observed a high incidence of reintervention for left ventricular outflow tract obstruction among survivors but did not suggest any specific alteration of the initial surgical strategy for patients with more than usually severe degrees of subaortic narrowing. Ilbawi et al10 and Bove et al9 independently reported encouraging results in small groups of patients who were believed to have severe subaortic narrowing and were managed by myotomy and myectomy of the left ventricular outflow tract in association with ventricular septal defect closure and arch repair. Yet in the Congenital Heart Surgeons Society study, mortality after an initial procedure including myotomy/myectomy was 47%. A different strategy incorporating an end-to-side proximal main pulmonary artery to aortic anastomosis (referred to in the Congenital Heart Surgeons Society report as a Damus-Kaye-Stansel anastomosis) was reportedly used in that series in a total of 11 patients at a variety of participating centers, with uniformly poor results (mortality, 91%). It is discouraging that in that careful analysis of a large group of patients by the members of the Congenital Heart Surgeons Society, ventricular septal defect closure and arch repair without a concomitant procedure directed at relief of coexisting left heart outflow obstruction was an incremental risk factor for death after repair. Yet at the same time, some strategies directed at subaortic obstruction including myotomy/myectomy and Damus-Kaye-Stansel anastomosis were associated with high rates of operative mortality.
The Norwood operation, which provides rational and satisfactory
initial palliation for hypoplastic left heart syndrome, is equally
applicable to a variety of other heart malformations characterized by
systemic ventricular outflow tract obstruction and ductal
dependency of the systemic circulation.12 Interrupted
aortic arch complexes fall into that category of malformations whose
physiology is dominated by ductal dependency of the systemic
circulation and is usually characterized by a degree of systemic
ventricular outflow tract obstruction. Thus, the Norwood
operation should be associated with predictably satisfactory results in
the initial management of patients with interrupted aortic arch
complexes. Our practice in the last several years has been to use this
operative strategy when the available preoperative and intraoperative
data suggest that a degree of systemic ventricular outflow
tract obstruction is present that could impact negatively on
survival after a more conventional reparative procedure. Such is the
case when the preoperative echocardiographic assessment
suggests a severe degree of narrowing or hypoplasia of the subaortic
region of the left ventricular outflow tract. In such
circumstances, the Norwood operation is performed exactly as for
hypoplastic left heart syndrome, with the only additional feature being
association of the ascending aorta with the descending thoracic aorta
together with homograft arch augmentation, as shown in Fig 1
.
Alternatively, as in two patients in this series, an
interventricular baffle may be used to direct left
ventricular outflow through the ventricular
septal defect to the pulmonic valve which has been associated with the
aortic arch elements and a conduit used to associate the branch
pulmonary arteries with the right ventricle, thus accomplishing
a one-stage biventricular repair. For patients who
undergo the more conventional Norwood operation with systemic to
pulmonary artery shunt, biventricular repair
may later be accomplished, as it is in instances of aortic atresia with
malalignment-type ventricular septal defect.
Alternatively, these patients may be managed by staged reconstruction
culminating in a Fontan operation if mandated, as for example by
hypoplasia of other left heart structures, including the mitral
valve.
In instances in which assessment of the anatomy and morphology of the left ventricular outflow tract is not predictive of a severe degree of left ventricular outflow obstruction, it is our usual practice to accomplish ventricular septal defect closure and association of ascending and descending aortic elements with aortic arch augmentation by use of a gusset of cryopreserved arterial homograft. Minimizing the likelihood of any degree of aortic obstruction from the level of the sinotubular junction through the arch and down to the thoracic aorta may in fact, as suggested by Jonas et al,4 enhance the likelihood of patient survival in the face of a mild to moderate degree of subaortic narrowing. When preoperative studies have suggested the presence of a severe degree of subaortic narrowing, we have been encouraged by the satisfactory results of initial palliation that can be achieved by modification of the Norwood operation.
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References |
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