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Archives of cardiovascular diseases
Volume 103, n° 11-12
pages 579-584 (novembre 2010)
Doi : 10.1016/j.acvd.2010.10.005
Received : 6 August 2010 ;  accepted : 7 October 2010
Very early correction of anomalous left coronary artery from the pulmonary artery improves intensive care management
Les anomalies d’implantation de la coronaire gauche sur l’artère pulmonaire corrigées très tôt ont une réanimation postchirurgicale plus simple
 

Laurent Bonnemains a, , b , Virginie Lambert b, Anne Moulin-Zinch a, Dany Youssef a, Alain Serraf b
a Service de cardiologie infantile, CHU Nancy-Brabois, rue du Morvan, 54500 Vandœuvre-lès-Nancy, France 
b Centre chirurgical Marie-Lannelongue, Le Plessis Robinson, France 

Corresponding author. Fax: +33 3 83 15 45 63.
Summary
Background

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) can sometimes be diagnosed very early in newborns and thus be corrected surgically before any myocardial ischaemia occurs.

Aim

To evaluate the influence of this very early surgery on intensive care management and long-term outcome.

Methods

All children operated on for ALCAPA before the age of 1 year between 1995 and 2010 were considered. Those operated on before the onset of ischaemia (group B) were compared with a matched group of children of similar weight who were operated on by the same surgeon on a close surgery date (group A).

Results

We obtained a homogenous population of 13 children (eight in group A; five in group B) with no significant weight difference between groups. The surgical technique and peroperative variables were similar in both groups. There was one death in each group. The group B death was due to postoperative occurrence of global myocardial infarction despite correct surgical reparation. Mechanical ventilation duration, inotropic support duration, intensive care duration and long-term complications were lower in group B.

Conclusion

Very early ALCAPA surgical correction before occurrence of ischaemia must be encouraged whenever possible because it simplifies intensive care management and prevents persistent mitral regurgitation, but it does not reduce peroperative risk.

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Résumé
Contexte

Il est parfois possible de dépister une coronaire gauche naissant anormalement du tronc pulmonaire (Alcapa) à un très jeune âge et donc de corriger chirurgicalement cette anomalie avant la survenue de l’ischémie.

Objectif

Évaluer l’influence d’une telle chirurgie précoce sur la réanimation et le devenir à long terme.

Méthodes

Tous les enfants opérés d’une Alcapa avant l’âge d’un an entre 1995 et 2010 dans nos deux centres ont été inclus. Ceux opérés avant l’ischémie constituée (groupe B) ont été comparés à un groupe témoin (groupe A) appareillé sur le poids, la date opératoire et le chirurgien.

Résultats

Nous avons constitué une population homogène de 13 patients (huit dans le groupe A et cinq dans le groupe B). Le poids, la technique chirurgicale et les paramètres peropératoires étaient similaires dans les deux groupes. Il y a eu un mort dans chaque groupe. Le décès du groupe B a été imputé à la survenue d’un infarctus massif au décours immédiat de la chirurgie malgré une réparation correcte. Pour autant, la durée de ventilation, du support inotrope et du séjour en réanimation ainsi que les complications à long terme ont été moins importantes dans le groupe B.

Conclusion

La réparation très précoce des Alcapa avant constitution de l’infarctus doit être choisie dès que possible car la réanimation s’en trouve simplifiée et les régurgitations mitrales persistantes moins fréquentes. Cependant, ce choix ne diminue pas le risque opératoire.

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Keywords : Anomalous origin of the left coronary artery from the pulmonary artery, Timing of surgery, Myocardial ischaemia, Intensive care management, Outcome

Mots clés : Origine anormale de la coronaire gauche naissant de l’artère pulmonaire, Quand opérer, Infarctus du myocarde, Réanimation, Devenir

Abbreviations : ALCAPAAnomalous, ECG


Background

ALCAPA is a rare but well-known cause of paediatric myocardial ischaemia. The global incidence of ALCAPA is close to 1 in 300,000 living births [1], even if some regional studies report much higher figures [2]. Newborns are usually asymptomatic in the first month of life, but congestive cardiac failure occurs 90% of the time between the second month and the first year, when a decrease in pulmonary artery pressure results in lower left coronary pressure [1]. The anomaly must be corrected by surgery, in order to improve left coronary artery perfusion. Reimplantation into the aortic root is the most efficient technique [3, 4]. However, postsurgery intensive care management can be very hazardous in this setting of myocardial ischaemia and stunning phenomenon. Some children are diagnosed by chance at a very early stage, before the onset of ventricular dysfunction, and thus can benefit from surgery before the occurrence of myocardial infarction. The option to undertake very early surgery could be considered obvious and safe, but our experience shows that surgery can trigger a massive myocardial infarction, leading to very complex intensive care management. Therefore, we designed this retrospective study in our centres to compare the influence of presurgical myocardial ischaemia on the short- and long-term outcomes of surgical ALCAPA correction.

Methods
Patients

The cardiovascular surgery databases in our centres were reviewed for all patients with a diagnosis of ALCAPA corrected during their first year of life, from January 1995 to July 2010. Diagnoses associating ALCAPA with other complex heart defects were excluded. Fifty-eight patients were identified whose median age at surgery was 130 days. Within this population, we identified a group of five children without any electrical or biological sign of constituted ischaemia on the day of surgery (hereafter called group B=surgery before ischaemia). The selection criteria were: absence of significant Q waves, and normal troponin, creatine phosphokinase and MB isoform plasma concentrations, if available. We sought to match every child in group B to two other children operated on after the onset of ischaemia, using three criteria: same surgeon, similar weight at surgery (weight difference <1kg) and close surgery date (children operated on within 1 year). Two group B children could only be matched to one child. We therefore included eight children in this second group (hereafter called group A=surgery after the onset of ischaemia). Therefore, the study population consisted of 13 children who underwent direct reimplantation of the anomalous left coronary artery into the ascending aorta.

Data

The clinical records were reviewed to document presentation, preoperative state and postoperative course. The following data were retrieved: age at diagnosis; preoperative state (age at surgery; weight; clinical status assessed by the Ross classification [class I–IV] [5]; mitral regurgitation assessed by echocardiography (classified as none, mild, moderate or severe); left ventricular function evaluated by the shortening fraction in TM mode; ECG anomalies in the anterior and lateral zones (classified as none, ST depression or negative T wave, ST elevation or Q wave); and troponin plasma concentration if available); peroperative or postoperative course (surgeon identity; extracorporeal circulation duration; circulatory assistance duration; cardioplegia (blood or crystalloid); delayed sternal closure; mechanical ventilation duration; inotropic support duration; intensive care duration; long-term complications (none, mitral regurgitation, ejection fraction alteration or death); and follow-up duration).

Statistical analysis

Continuous variables were compared by the non-parametric Mann–Whitney U test adapted for small groups [6]. Two categorical variables were analysed by Fisher’s exact test and multicategorical variables by a unilateral two-sample Kolmogorov-Smirnov test for small samples of different sizes. A value of p <0.05 was considered to be of statistical significance.

Results
Diagnosis and preoperative state

Of the 13 patients, eight had come to attention because of signs of heart failure (group A), whereas five (group B) were diagnosed at the median age of 10 days before any symptoms of heart failure. In two of the five children in group B, initial echocardiography was performed to check aortic coarctation (reduced femoral pulses in one and antenatal ventricular imbalance in the other). In two other children in this group, echocardiography was performed to look for associated cardiac malformation after neonatal surgical correction of oesophageal atresia and omphalocele. The fifth child was diagnosed because of global anterolateral ST elevation (ECG justified by antenatal tachycardia).

The children’s characteristics and their preoperative states are presented in Table 1. Our population sex ratio was four males to nine females. There was no weight difference between groups. Among the collected data, only age at surgery, clinical status (Ross class), lateral anomalies in ECG, troponin plasma concentrations and echographic criteria differed between groups A and B.

Surgery and intensive care management

Each child was operated on using the same operative technique, consisting of direct reimplantation of the anomalous left coronary artery into the ascending aorta after median sternotomy. The patients were placed on cardiopulmonary bypass with anterograde perfusion in the anomalous coronary, promoted by snaring the pulmonary artery branches. Five operations were performed in mild hypothermia with cold crystalloid cardioplegia and eight in normothermia with warm blood cardioplegia. Cardioplegic solutions were periodically infused into the aortic root as well as into the left coronary ostium once the pulmonary trunk was opened. Concomitant mitral surgery was not undertaken. Peroperative and intensive care variables are presented in Table 2. Peroperative variables did not differ between groups A and B. In particular, duration of extracorporeal circulation, type of cardioplegia and use of immediate postoperative assistance or delayed sternal closure were similar between groups.

Duration of ventilation and of intensive care hospitalization, and time before echographic ejection fraction normalization were significantly lower in group B: the median stay in the intensive care unit was 13 days for group A vs 6 days for group B (p =0.003) and the median durations of ventilatory support and inotropic support were 11 days and 13 days for group A vs 5 and 3.5 days for group B, respectively (p =0.012 and 0.003, respectively). Sternal closure delay seemed to be lower in group B (p =0.10).

Outcome

Two postoperative deaths occurred, one in each group. Both were low weight girls (2610g and 2680g) who died in 1999. Both surgeries were performed with cold crystalloid cardioplegia. The child in group A died during surgery for untractable low cardiac output syndrome after 353minutes of extracorporeal circulation, whereas the child in group B died 5 days after surgical reparation despite extracorporeal assistance. This second baby underwent an autopsy, showing an extended left ventricular infarction despite good permeability of the reimplanted left coronary artery (a 1.5mm bougie could be inserted into the anterior interventricular branch of the left coronary artery along half of its length).

The 11 surviving children were still alive in 2010, with a median follow-up duration of 7 years; 86% of group A survivors had persistent mitral regurgitation 1 year after surgery vs 25% in group B (p =0.05). Short- and long-term outcomes are presented in Table 2.

Discussion

ALCAPA detection is possible at a very early stage of life before any constituted myocardial ischaemia. This study emphasizes that very early surgery is possible for these children, even if this surgical process remains dangerous because use of anaesthesia and extracorporeal circulation with aorta cross clamping can easily unbalance such a precarious situation and induce peroperative myocardial injury. Nonetheless, postoperative management is much simpler for those children with shorter durations of ventilation, inotropic support and intensive care hospitalization. Long-term outcome is also improved with less persistent mitral regurgitation and with much shorter delays before normalization of left ventricular ejection fraction.

To ensure that the population studied was not biased, we checked our observations against previously reported ALCAPA population-based studies and found them to be in line with these previous results. Of course, our children were younger and hence of lower weight because of our chosen criterion. However, group A left ventricular shortening fraction before surgery (18%) stayed within the 17–20% interval previously described [7, 8]. The group A population had standard rates of mild and severe heart failure (mild, 62%; severe, 37%), close to those reported by Caspi et al. (mild, 70%; severe, 30%) [7]. The preoperative moderate or severe mitral regurgitation rate of 62% was also close to the rate observed in other studies (Ben Ali et al., 48%; Michielon et al., 77%; Caspi et al., 100%) [4, 7, 8]. The ECG Q wave frequency in the aVL lead in group A was higher than the rate reported by Chiu et al. (100% vs 85%, respectively) [9]; this may be due to the younger age of our children whose coronary arterial collateral networks were certainly less developed. Our population sex ratio is quite low compared with other studies (0.33) but this is of no consequence to the purpose of the study.

The operative technique used is quite similar to other studies except, perhaps, the fact that some surgeons chose to use warm blood cardioplegia from the year 2000, which was not standard practice at this time. This explains the small numbers of cold crystalloid cardioplegia in our population. For example, cold blood cardioplegia was used by Caspi et al. (New Orleans) until 2005 and by Amanullah et al. (Newcastle upon Tyne) until 2007, while Lange et al. (Munich) reported cold crystalloid cardioplegia until 2002 [1, 7, 10]. The latest studies (since 2007) tend to recommend warm blood cardioplegia [4, 11, 12]. Within our population, we could find no significant influence of preoperative myocardial ischaemia level on peroperative behaviour. The rates of delayed sternal closure were quite similar in groups A and B, and higher than the 40% reported by Alsoufi et al. (Riyadh) [11]. Indeed, our centre tends to promote the preventive use of delayed sternal closure, which allows much more secure immediate postsurgical management. Our team has probably been influenced by the postoperative death in 1999 of one child from group B.

The group A death rate (12%) was very close to that reported by other teams in recent studies (Ben Ali et al., 10%; Lange et al., 14%; Michielon et al., 16%) [4, 8, 10]. The group B death rate is a little higher (20%), but this is due to the very small number of children in this group. Different hypotheses have been formulated concerning the cause of this acute persurgical myocardial infarction: no myocardial protection defect was identified in 1999 during surgery, but the use of cold crystalloid cardioplegia may be considered non-optimal nowadays; the myocardium, although non-necrotic before surgery, was probably ischaemic and “hibernating”, and surgery probably caused a massive ischaemia-reperfusion syndrome. Indeed, this unexpected death encouraged us to adopt very cautious peroperative and intensive care strategies. Early-diagnosed ALCAPA patients are potential candidates for peroperative acute myocardial ischaemia, the management of which is hazardous. This particular risk might be lowered by the use of repeated warm blood cardioplegia.

Comparison of the groups also poses the question of the mitral regurgitation mechanism. Indeed, both groups had similar rates of mitral regurgitation before surgery but there was a trend (p =0.08) towards lower regurgitation in group B after surgery. This could be due, as suggested by Blot-Souletie et al., to a dual regurgitation mechanism. In group B, mitral regurgitation was probably due to regional myocardial dysfunction and dyssynchrony, which recovered soon after surgery, whereas in group A the higher ischaemia level probably induced restrictive motion of the anterolateral papillary muscle, recovery of which is reputed to be slower and incomplete [13].

One of the challenges of a study such as this is the unavoidable small sample size. Considering the rarity of the situation we chose to analyse, it was impossible to gather a large group of patients. Thus, the Chi2 test was unsuitable because the contingency table expected values were<5 and the Student’s t test was unsuitable because the normality hypothesis of the distribution cannot be inferred with small samples. Hopefully, accurate conclusions may be drawn with small samples. Indeed, we chose special versions of two classical tests (the Mann-Whitney U test and the Kolmogorov-Smirnov test) designed for small samples [6]. Another possible solution would have been to use the randomization test (or permutation test). Of course, two categorical variables may always be compared by Fisher’s exact test, which does not rely on any sample size hypothesis.

Another limitation of this retrospective study was the long time span needed to gather the five group B cases. Indeed, 15 years separated the first and last cases. During this period, echocardiography improved considerably and several more reliable techniques became available for assessing left ventricular function (tissue Doppler imaging, two-dimensional strain, three-dimensional echography, etc.) [13]. We recorded and used the shortening fraction in TM mode because it was the only variable for which data were available during the entire period.

Conclusion

Early surgery (with direct reimplantation of the anomalous left coronary artery) must be preferred whenever ALCAPA is diagnosed, regardless of ischaemia level. This surgery is still associated with a relatively high risk of severe complication, with a death rate close to 10%. These data suggest that practice of this surgery very early before any myocardial infarction does indeed guarantee a shorter duration of intensive care management but does not lower peroperative risk.

Conflict of interest statement

None.

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