When the hospital mortality rate is very low, clinical performance is analyzed through surrogate markers of morbidity. An intellectual debate is taking place around general morbidity indicators for congenital cardiac operations [5, 6]. Many agree that the optimal morbidity indicator is a combination of metrics looking at hospital resources and major complications (Lacour-Gayet and associates, 2011, unpublished data). In this context, we analyzed a consecutive series of ASOs with no operative deaths from a single institution, with a stepwise focus on (1) a comparison between simple and complex cases and (2) the operative morbidity burden of ASO.

Weight less than 2.5 kg, which was not a significant risk factor for morbidity in this series, is generally seen as an indicator of patient fragility and increased technical complexity. One report indicated weight was only significant in univariate analysis [2], whereas another group found that weight was independently predictive of hospital and intensive care unit LOS, but not VT or inotropic requirement [15]. A multiinstitutional study of 613 patients found weight was almost identical in survivors and nonsurvivors, postoperatively being only predictive of dialysis [1]. Two patients in our series weighed less than 2 kg, both with TGA and an intact septum. One of these patients (1.9 kg) had a VT of 5 days, peLOS of 8 days, and a morbidity index of 1.125. The other (1.8 kg) required a post-ASO laparotomy for bowel perforation, spent 12 days on a ventilator, and another 51 days in the hospital after, with a morbidity index of 3.125. In the absence of extremely low weight or very adverse anatomic or physiologic risk factors, patient size alone is not a surgical contraindication.

Preoperative enteral feeding and extubation were actively pursued, similar to other reports [7, 15]. One series found preoperative ventilation was associated with high resource utilization postoperatively [15]. The proportions of these interventions in our two groups are comparable. We have no indication to believe that preoperative enteral feeding leads to increased morbidity, and our initial experience suggests that atrial septostomy combined with discontinuation of prostaglandin is beneficial in reducing hospital LOS. We have not studied this formally, however.

The diagnostic and coronary categories (Tables 1 and ​and2)2) reflect our perception of complexity. Although used to define the complex group as noted, neither diagnostic nor coronary patterns emerged as independent predictors of morbidity in this study. Previous work showed that early complete repair for selected cases of DORV, including noncommitted VSD, is possible [8]. Pasquali and colleagues [16] reviewed nine series containing 1,942 patients with mortality recorded by coronary anatomy. Their meta-analysis forms the basis for the complexity classification used here, where a circumflex artery arising from the right (n = 23) was not considered an important risk factor, but double coronary loops, single ostium, and intramural course were.

Collectively, they accounted for 19% of our patients, a prevalence close to that seen by others [2, 15]. We successfully switched these complex patterns, confirming that adverse anatomy is neutralized by careful technique. Others reported a higher mortality with intramural coronaries [17]. Redo sternotomy, multiple VSDs, commissure takedown, or sacrifice of an infundibular artery also did not affect postoperative outcomes, similar to other reports [18]. Accurate coronary transfer is paramount. Liberal use of commissural takedown and sacrifice of an infundibular artery when required is key to obtaining large buttons and undistorted coronary trunks. Any ischemia from the occlusion of an infundibular artery resolves in a few hours in neonates in our experience. Reimplantation of the posterior commissure avoids late pulmonary regurgitation.

The only anatomic conditions emerging as risk factors in this series were aortic arch obstruction and malaligned commissures (Table 3). Arch repair, required in 13 patients (13%), was comparable with other series [1, 3, 15]. Here, these factors were associated with prolonged VT and a higher morbidity index, but not with peLOS. One-stage repair using homograft aortic patch enlargement is our preferred technique [11, 12]; it also allows correcting the aortopulmonary mismatch. In 1 patient with TGA-intact ventricular septum, the diagnosis of associated coarctation was missed preoperatively, requiring an emergency second-stage coarctation repair by thoracotomy.

The antegrade cerebral perfusion technique was uniformly used, avoiding circulatory arrest. In the European multiinstitutional report, arch repair was possibly overshadowed by other factors in a heterogeneous population operated on with different techniques [1]. In single institution reviews, however, arch repair is more likely to be separated in proportion to its contribution to the outcome: Gottlieb and colleagues [18] found in 74 complex ASO patients that a distal transverse arch z score of −2.5 or smaller and circulatory arrest time were important predictors of death.

Commissural malalignment is a feature less well described. In an anatomic study with clinical correlates, its prevalence was 12.5%, close to the 14% observed here [19]. In another 13 patients, with the degree of offsetting divided as major and minor, 8 of 28 ASO patients (29%) had major malalignment, this higher prevalence perhaps relating to ethnic variation. One patient died immediately postoperatively from coronary stretching and ischemia [20]. Realignment of the commissures requires subtle degrees of torsion on the great arteries and, occasionally, a higher coronary implantation. This factor was independently responsible for a higher morbidity index in our patients. It most likely contributed directly to complications in 1 patient who required extracorporeal membrane oxygenation support for 3 days. The only late death occurred in a patient with Taussig-Bing, commissural malalignment, and double-loop coronaries. The postoperative course was satisfactory, but myocardial infarction occurred at home 3 months postoperatively. We attributed this to severely malaligned commissures causing suboptimal relocation of the left coronary.

Accurate technique should not be underestimated. In this series, 82 ASO were performed by the same surgeon. In a rigorous analysis of the interaction between institutional management and surgical experience in four complex procedures (Norwood, pulmonary atresia intact septum, interrupted aortic arch, and ASO) the only procedure in which “experience” had a direct positive effect was ASO [21]. This is partly explained by different patient profiles. A well-performed coronary transfer with a limited CPB time is usually followed by a simple postoperative course in most ASO patients. Conversely, even the most technically accurate Norwood has to navigate the vagaries of more complex postoperative physiology. In terms of length of the operation, we used CPB time to examine its interaction with other variables. A long CPB is a surrogate for technical complexity and causes morbidity through its adverse physiologic effects. It approached statistical significance for peLOS but was not retained in the VT model. These data are consistent with other reports in which CPB time is associated with a higher risk of death or complications [2, 15, 18, 22].

The positive contribution of the comprehensive Aristotle score is confirmed by this study, too. Although still based on subjective probability, the Aristotle score is increasingly used in risk estimates and resource planning [5, 23]. In this analysis it was the main factor independently predictive of postoperative LOS along with CPB time. The Aristotle score was not associated with a high morbidity index in this initial analysis, which is likely in relation to the clustering of complications in our cohort. Similarly, the presence of LV retraining as a morbidity predictor has a similar explanation: the 4 patients who required LV retraining had transposition with an intact ventricular septum and a conspicuous absence of other risk factors. However, 3 of 4 patients experienced notable complications: 2 required chest reopening, and preoperative brain hemorrhage occurred in another. Although the mild neurologic deficit was not exacerbated postoperatively, this was still classified as a major neurologic complication. Delayed sternal closure was used liberally in a fifth of the patients. It contributes to increased VT but otherwise is not predictive of increased peLOS or higher morbidity.

Ventilation time is arguably a better indication of early morbidity compared with intensive care LOS, which is more institutionally dependent. Likewise, peLOS is a better reflection of second-phase morbidity, even if it also depends on institutional protocol. A myriad of complications can be recorded, but a few selected ones can give a concise indication of the patient’s postoperative journey before discharge.

The morbidity index (Lacour-Gayet and associates, 2011, unpublished data) forms a new metric that draws on the Clavien-Dindo classification of surgical complications [24]. It can be assumed that the low mortality rate observed in some centers is not due to an absence of adverse events but to their better recognition and management [25–27]. When applying the failure to rescue principle to this series [27], good survival in presence of 25% major complications translates into a 0% failure to rescue, a new angle for outcome evaluation.

The current study has several limitations. First, the focus was mainly on hospital events. Second, there was some overlap between the comprehensive Aristotle score and a few of the factors analyzed separately. Finally, our data set was too small for studying multiple predictors, and inherently, the regression analysis has low power.