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Eur J Cardiothorac Surg 2003;24:21-27
© 2003 Elsevier Science NL
a Department of Pediatric Cardiac Surgery, G. Pasquinucci Hospital, Massa, Italy
b Division of Cardiac Surgery, Policlinico di Careggi, University of Florence, Florence, Italy
c Cardiothoracic Department, St. James Hospital, Dublin, Ireland
Received 8 November 2002; received in revised form 28 February 2003; accepted 4 March 2003.
* Corresponding author. Tel.: +39-0338-985-5782; fax: +39-0573-985-427
e-mail: mbonacchi{at}hotmail.com
| Abstract |
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Key Words: Anomalous origin of the pulmonary artery Pulmonary scintigraphy Restenosis
| 1. Introduction |
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| 2. Patients and methods |
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2.1. Patients' characteristics
The preoperative patients' characteristics are given in Table 1. There were three females and five males. The mean age was 64±81 days (median 35.5) and mean weight was 4.3±1.6 kg (median 3.75). The Waardenburg syndrome was diagnosed in patient 2 and Di George syndrome in patient 8 (Table 1). Patients 1, 3, and 7 presented moderate to severe pulmonary hypertension. Congestive heart failure was present in patients 1, 3, 5, and 7 (Table 1). Three patients presented isolated AOPA. Five patients presented right AOPA and three, left AOPA. In one case, the origin of the left AOPA was from the ipsilateral wall of the descending aorta (Fig. 1A
). In another patient, the origin of the right AOPA was from the contro-posterolateral wall of the ascending aorta (Fig. 1B). The diagnosis was established according to the echocardiographic, angiographic, and operative findings.
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2.2.1. Technique I
Technique I consisted in direct implantation of the AOPA to the MPAT. This technique was employed in patients 3 and 6 presenting left AOPA (Fig. 2A, B
) (Table 1). The left AOPA was identified and encircled with a silastic vascular loop. Then, it was carefully mobilized for a long tract, including the first part of the lobar branches, and temporarily occluded with a tourniquet. The AOPA was detached from the aorta and directly anastomosed to the MPAT with a continuous 6-0 Prolene suture. The anterior half of the suture line was completed with interrupted sutures to allow tissue growth. The aortotomy was sutured primarily or with an autologous pericardial patch.
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2.2.3. Technique III
In patient 5, presenting right AOPA from the contro-posterolateral wall of the ascending aorta and in patient 1, the distance between the right AOPA and MPAT was small enough to permit a direct posterior anastomosis between them, and later, an autologous pericardial patch was employed to enlarge the anterior aspect of the anastomosis.
2.2.4. Technique IV
In all other patients with the right AOPA originating from the right postero-lateral aspect of the ascending aorta, we prolonged the length of the right AOPA using the aortic ring.
2.2.4.1. IVA (single aortic flap technique)
In patients 4 and 7 (Table 1, Fig. 3AC
), the ascending aorta, MPAT, and its branches were mobilized. Then ascending aorta was transected, just above and beneath the origin of the right AOPA. The resulting aortic ring was fashioned into an elongated tube for the pulmonary artery and the far end was connected to the MPAT side-to-end [10]. End-to-end anastomosis of the aorta in front of the right AOPA was performed (Fig. 4 ).
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2.3. Statistical analysis
Group statistics were expressed as mean±SD. The generalized Wilcoxon test was performed for the statistical analysis between groups. Fisher's exact test was used for the non-continuous variables. Significance between data was considered achieved when P<0.05.
| 3. Results |
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Within 1 year after surgery, all patients were alive and underwent cardiac catheterisation. The mean residual gradient for all patients was 14±8 mmHg. The residual gradient in patients undergoing correction according to the technique I was 17±3 mmHg and in patients undergoing implantation of the AOPA according to the techniques III or IV was 9.5±4.6 mmHg (P=0.11). Similarly, the Tc-99m scintigraphy demonstrated that a lower lung perfusion (the lung perfused from the respective AOPA compared with the contralateral lung) in patients undergoing AOPA implantation according to technique I was 59±6(%) and in patients undergoing techniques III or IV 72±4.5(%) (P=0.038).
At follow-up, all patients were alive the mean follow-up was 37.7 months/patient. Patient 2 (Table 1) underwent reoperation at 28 months after the first surgical procedure: the employed graft presented significant stenosis in both anastomotic sites. He underwent graft's replacement employing an 8-mm Goretex graft combined with left pulmonary arterioplasty. All survivors underwent serial echocardiographic examinations during follow-up, demonstrating a progressive regression of the ventricular hypertrophy and dimensions.
We reviewed the age, associated malformations, and surgical procedure undertaken through the literature during the last 30 years, in patients with AOPA from the aorta undergoing repair (Table 2). There were 77 reports of patients with AOPA from the aorta undergoing surgery. Almost 55% of patients were under 6 months of age at operation. Major associated heart defects were identified in 28.7% patients. The most frequently found cardiac malformations was the tetralogy of Fallot or double outlet right ventricle in 12.6% of cases, the aorto-pulmonary window, interrupted aortic arch, and VSD (Table 2). The overall mortality was 12.5% (17 patients). According to the univariate analysis, the associated cardiac malformations resulted to be strong predictors for early postoperative mortality. There were non-significant differences regarding the operation period before 1990, age less than 6 months, employment of synthetic prosthesis for anomalous AOPA reimplantation to the main pulmonary trunk, or the presence of the anomalous origin of the left or right pulmonary artery.
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| 4. Discussion |
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Little is known about the embryogenesis and pathogenesis of this malformation, although an association has been suggested with the CATCH 22 syndrome complex [6,7,18,19], including Di George syndrome [19]. Different authors have reported the important role of the neural crest cells in the development of the third and fourth pharyngeal pouch derivatives as well as the aortic arches and trunco-conal part of the heart [20]. It is plausible that deletions interesting the chromosomic band 22q11 may cause some degree of derangement in the neural crest. Similar defects have recently been described in association with the fetal valproate syndrome [21], another condition linked to disorders of the neural crest cells migration. In our series, one patient presented the Waardenburg syndrome, which is associated with the neural crest-derived melanocyte deficiency. Aru et al. [22] included this anomaly as an aortic arch anomaly complex hypothesizing that a failure of media fusion of the AOPA with the MPAT results in persistence of the aortic sac from which the AOPA originates. In the absence of the left sixth arch, the AOPA may not find connection to the MPAT and consequently, the aortic sac connection persists.
The AOPA may be isolated or associated with other congenital heart defects. Most of the reported cases presented some major associated cardiovascular defect such as tetralogy of Fallot, VSD, and patent ductus arteriosus [4,7]. Surprisingly, we did not observe in any case the association with aorto-pulmonary window, interrupted aortic arch or aortic isthmal hypoplasia [18]. The right aortic arch has been reported in almost 5075% of patients with left AOPA [4,6,8]. Different cases have been reported with isolated malformation [1012], although its incidence is very limited. In our series, there were three cases with isolated malformation. Two of them presented left AOPA and one patient presented right AOPA.
According to some previous studies, the echocardiography is sufficient in recognising the AOPA [6,11]. Complete diagnosis employing echocardioraphy is demonstrated by the presence of two concordant ventricular outflow tracts, absence of the usual MPAT bifurcation pattern and the right or left pulmonary artery arising directly from the aorta with the MPAT continuing with the controlateral pulmonary branch. We believe that this is not always easily demonstrated by echocardiography alone [11]. The third patient in our series, after undergoing echocardiographic examination in another institution was referred with the diagnosis of transposition of the great arteries and patent ductus arteriosus. Cardiac catheterisation showed right AOPA and patent ductus arteriosus arising from the left pulmonary artery. Cardiac catheterisation remains the gold standard diagnostic procedure in such cases and should be indicated preoperatively in all patients.
Most commonly, the surgical correction has been achieved within the first month of age [4,15], although, successful repair has been reported in adults [10,11,17,23]. Fontana et al. [5] found a 30% 1-year survival in a series of 23 cases with AOPA not surgically treated. Successful correction of this anomaly in the first days of life, even in prematures, have been reported [14]. Early repair is preferred to avoid pulmonary hypertension and irreversible pulmonary vascular disease. Serious pulmonary vascular disease has been observed in patients with AOPA as early as the third month of life [24]. Several mechanisms have been postulated for the development of pulmonary vascular disease: high pulmonary blood flow, circulating vasoconstrictor substances, neurogenic crossover from the unprotected lung, and left ventricular failure. In our series, the patient presenting left AOPA from the descending aorta, necessitated catheterisation control due to presence of respiratory symptoms. Moderate restenosis across the anastomotic site was associated with ipsilateral lung hypoperfusion at 99mTc pulmonary scintigraphy. The pulmonary biopsy (at reoperation) demonstrated a HeathEdwards grade-II pulmonary vascular disease of the respective lung.
The origin site of the AOPA is different. Some authors [15] advocate the existence of two forms: a proximal one, the AOPA originates from the ascending aorta close to the valvar plane; and a distal one, the AOPA arises via a patent ductus arteriosus [1]. The third form of presentation is the origin site close to the innominate artery or in extreme cases, the right AOPA may originate from the innominate artery itself [25]. In six of the eight cases in this series, the AOPA originated from the respective proximal postero-lateral part of the ascending aorta. Usually, the origin is from the respective postero-lateral aspect of the ascending aorta [4]. Nevertheless, a more antero-lateral origin of the right AOPA from the ascending aorta was detected in one patient, while an anomalous origin of the right AOPA from the contro-posterolateral wall of the ascending aorta was diagnosed in another case. In another patient, the left AOPA originated from the descending aorta. It is postulated that the ductus arteriosus and the left AOPA develop from the left sixth aortic arch [23]. In our case, we did not find the ductus arteriosus remnant indicating a complete absence of the left sixth aortic arch in this patient.
Different surgical techniques have been employed. The direct anastomosis of the AOPA to the MPAT is most frequently used in the previously described series [4,11,14,15]. End-to-end anastomosis with a synthetic graft [3,15], interposition of a homograft patch [3,4,15], aortic flap [9,12], or interposition of autologous pericardial patch, for increasing the AOPA length, have been successfully employed in specific cases, when direct implantation of the AOPA was not possible. In our experience, we employed four techniques depending on the anatomic characteristics of the malformation. In our hands, the direct implantation was associated with more anastomotic suture tension predisposing to higher risk of dehiscence. Therefore, we preferred this approach, which could easily be performed without extracorporeal circulation, when the distance between the AOPA and MPAT was minimal.
Mortality in our series was 12.5% similar to other reports [4] and the overall mortality in the collected reports (Table 2): the only death occurred at the beginning of our experience with this malformation. This patient presented associated VSD, pulmonary valve stenosis, and congestive heart failure. We believe that a learning curve can explain the improvement in clinical outcome, however, the presence of associated heart defects and preoperative heart failure should be considered as predictors for poor postoperative results. Analysing the 136 reported cases, the associated cardiac malformations resulted to be the main predictor for early postoperative mortality in patients with AOPA.
Occurrence of stenosis at the anastomotic site has been a major problem in some reported series remaining the main late complication [4]. The gradient across the anastomotic site accurately demonstrates the stenosis. The residual gradient seems to be higher and the respective lung less perfused when repair is accomplished according to the direct reimplantation technique than reimplantation using adjunctive autologous material. However, in our analysis, we were not able to demonstrate statistically the benefits that the reimplantation techniques using adjunctive autologous material offer versus the direct reimplantation technique regarding to the residual gradient through the anastomotic site; this due to the very small number of patients. However, the residual gradient through the anastomotic site was twice as high in patients undergoing direct reimplantation technique as in patients undergoing other reimplantation techniques using adjunctive tissue. Probably, the direct reimplantation and synthetic graft interposition fail to gradually accommodate larger volumes with patient's somatic growth, due to growth failure of the anastomotic site. The other techniques (consisting in interposition of autologous tissue for increasing the length and coaptation between the AOPA and MPAT) seems to offer better results in term of late restenosis.
We may conclude that the AOPA from the aorta is a rare but important entity, necessitating a scrupulous preoperative and intraoperative evaluation. Patients presenting this anomaly may undergo correction using various surgical techniques with acceptable results. The techniques employing autologous tissues for enlarging and lengthening the AOPA seems to be associated with less restenosis at the anastomotic site, however, larger series of patients are required to confirm such outcome.
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