Introduction
Aortic atresia is a rare finding in live births and is clinically often seen in the setting of hypoplastic left heart syndrome. However, aortic atresia may be found outside of hypoplastic left heart syndrome, and even in these instances, these patients will often have hypoplastic left ventricles although with a ventricular septal defect. In some instances, the left ventricle can be of good size and a biventricular repair can be successfully done. While aortic atresia may be present in the setting of other congenital malformations of the heart, it has not previously been described with superior-inferior, or so-called “criss-cross,” ventricles. Reference Jacobs, Franklin and Beland1,Reference Jacobs, Franklin and Beland2
Presented here is a case of a patient with aortic atresia, superior-inferior ventricles, a ventricular septal defect, overriding pulmonary trunk, and coarctation of the aorta. Also presented is a collation of data from other hearts described as having aortic atresia outside of hypoplastic left heart syndrome.
Case report
A baby boy of Honduran descent was born at 39 weeks gestational age with a birth weight of 2,970 g to a then G2P1 mother. Fetal care was delayed until 34 weeks at which point the fetus was noted to have a congenitally malformed heart, consisting of common arterial trunk, rightward apex, and concern for interruption of the aortic arch. There was a maternal history of hypertension but no maternal infectious concerns.
After birth, the APGAR score was four and eight at one and five minutes, respectively. Due to poor respiratory effort, noninvasive continuous positive airway pressure was initiated in the first few minutes of life with improvement in respiratory status. He was eventually weaned to high-flow nasal cannula which he remained on.
Postnatal echocardiography demonstrated usual arranged atriums, concordant atrioventricular connections, right-handed ventricular topology with a superior morphologic right ventricle and inferior morphologic left ventricle, a large outlet ventricular septal defect, aortic atresia with a hypoplastic ascending aorta from which the coronary arteries arose in usual fashion, a pulmonary trunk that overrode the right ventricle.
Initially, the postnatal echocardiographic findings were interpreted as being consistent with usually arranged atriums with an atrial septal defect, concordant atrioventricular connections, right-handed ventricular topology with a superior morphologic right ventricle and inferior morphologic left ventricle, a large outlet ventricular septal defect, common arterial trunk with posteriorly arising branch pulmonary arteries arising from separate orifices, and coronary arteries arising from the brachiocephalic trunk. There was also a persistent left superior caval vein that drained into the coronary sinus. Figure 1 is an apical echocardiographic image demonstrating the superior-inferior ventricular relationship and the concordant atrioventricular connections.
Figure 1. Echocardiography from an apical four-chamber view demonstrating the relationship of the ventricles as well as the ventricular septal defect and the pulmonary outflow.
CT was obtained and confirmed the findings of the echocardiogram. Figure 2 is a three-dimensional computed tomographic reconstruction demonstrating the heart how it lies in the chest cavity. The image demonstrates the superior-inferior ventricular relationship and demonstrates how the pulmonary trunk arises from the heart. Figures 3 and 4 are three-dimensional computed tomographic reconstructions demonstrating the anatomy of the ascending aorta, the head and neck vessels, the pulmonary trunk, and the branch pulmonary arteries.
Figure 2. Three-dimensional CT reconstruction demonstrating how the heart lies in the thorax and demonstrates the relationships of the ventricles and the pulmonary artery.
Figure 3. Three-dimensional CT reconstruction demonstration of the pulmonary artery, aorta, and branch pulmonary arteries in an anterior-posterior projection.
Figure 4. Three-dimensional CT reconstruction demonstrating the pulmonary artery, aorta, and branch pulmonary arteries from a left anterior oblique projection.
As the diagnosis was further clarified to represent aortic atresia and not common arterial trunk, there was concern for ductal tissue being present in the aortic arch with interruption of the aorta. There was also narrowing seen by subsequent echocardiography in the aortic arch, and prostaglandin was started with resolution of this narrowing. Prostaglandin was continued until surgical repair which occurred at day of life 6.
Surgical repair consisted of aortic septal defect closure, a Damus-Kaye-Stansel anastomosis and reconstruction of the aorta (Norwood-like reconstruction), baffling of the ventricular closure septal to the native pulmonary artery (neo-aorta), closure of the atrial septal defect, and right ventricle to pulmonary artery conduit placement using a 10 mm femoral vein homograft. The reassuring preoperative condition of the patient, the lack of other comorbidities, the lack of extracardiac findings, the comfort of the local surgeons, and previous experience led to a decision to proceed with a single-stage approach.
The child had a relatively uneventful postoperative course and was extubated within the first five postoperative days and was discharged home three weeks after his operation.
Literature review
A total of 35 reports, including the current case, of aortic atresia with a normally sized left ventricle were found. Reference Black, Smallhorn and Freedom3–Reference Li, Li and Chen25 Note, these were the only reports in which data for each case could be collected at a patient level. Cohort-level data were not included. The first documented case was in 1970. Of these patients, 13 (59%) were male, 2 (6%) had a genetic anomaly, and only 2 (6%) had an extracardiac anomaly documented. Of the cases listed, 7 (20%) were either presented as cases of common arterial trunk or were documented as initially being thought to be consistent with common arterial trunk (Table 1).
Table 1. Table summarising findings of all described cases of aortic atresia with normal-sized left ventricle
The systemic venous connections were usual in most cases and in the 2 patients in whom there was an abnormality; both patients had bilateral superior caval veins with the left superior caval vein draining into the coronary sinus. The atrial arrangement was usual in all patients, and most (96%) of hearts had concordant atrioventricular connections. Ventricular topology was right-handed in all cases, and the apex was leftward pointing in all but a single heart. A ventricular septal defect was present in most (97%) hearts. The ventriculo-arterial connections were double outlet in most (63%) hearts, followed by concordant in 34% of hearts. The hearts with double outlet ventriculo-arterial connections had the pulmonary trunk overriding the ventricular septal defect. The mitral valve was normal in 94% of hearts. The ascending aorta was hypoplastic in all hearts. Coarctation of the aorta was present in 40% of hearts and interruption of the aortic arch in 23%. Abnormal head and neck vessel anatomy was present in 26% of patients. The coronary arteries had usual course in 91% of patients (Table 1).
Additional cardiac findings were noted in some of the previously reported hearts including superior-inferior (“criss-cross”) ventricles, aorta to right ventricle tunnel, aortopulmonary window, coronary artery to pulmonary artery fistula, and left ventricle to coronary artery fistula (Table 1).
Of these documented patients, 66% underwent an intervention with 74% of these having a biventricular repair done as the initial intervention. The median age of initial intervention was 7 days. For those who did not have a biventricular repair as their initial intervention, some underwent aortic arch reconstruction with right ventricle to pulmonary artery conduit placement without ventricular septal defect closure, branch pulmonary artery band placement with systemic to pulmonary artery shunt placement, branch pulmonary artery band placement with a left ventricle to aorta conduit placement, and branch pulmonary artery band placement with ductal stenting.
Eventually, 78% of patients who underwent intervention eventually got a biventricular repair. Biventricular repair occurred at a median age of 10 days. Biventricular repair strategies most frequently consisted of aortic arch reconstruction with right ventricle to pulmonary artery conduit placement and ventricular septal defect closure. Interestingly, 3 patients underwent a left ventricle to aorta conduit placement and a ventricular septal defect closure.
In a mean follow-up duration of 1 year, 65% were still alive. Those who died tended to have died early in life, within the first week. Additionally, the mortality numbers here are skewed by the fact that some of the cases are from case series of specimens which can only be obtained once the patient has died. Additionally, the mortality was generally in patients reported prior to the year 2000.
Discussion
The current case highlights a few important points. Firstly, the case highlights that aortic atresia with a large ventricular septal defect may be misclassified as common arterial trunk with coronary arteries arising from a head and neck vessel. This cannot be possible, by definition, as common arterial trunk is defined as a single trunk from which the coronary arteries, branch pulmonary arteries, and aorta arise. If any of these do not arise from the outflow, then it is not a common arterial trunk. It is also developmentally difficult to explain how a vessel could arise from the head and neck vessels to then give rise to the right and left coronary arteries. Developmentally, it is now well established that the coronary arteries arise from the epicardial tissues that form from the pro-epicardial organ which is located within the inferior atrioventricular groove. Cells migrate from the organ and begin to propagate on the epicardial surface of the heart. Under the influence of several genes, epicardial cells transform to mesenchymal cells and ultimately form the smooth musculature of the coronary arteries. These developing coronary arteries then grow into the aortic root rather than fusing with channels that originate from the aortic root themselves. Reference Anderson, Chiu, Spicer and Hlavacek26 Keeping this in mind it is difficult to explain how the coronary arteries could arise from the head and neck vessels which find their origin from the pharyngeal arteries in processes entirely separate from that of the development of the coronary arteries.
This vessel is interpreted as being a coronary artery arising from the head and neck vessels in cases such as the one described here in fact the hypoplastic ascending aorta. This is an important distinction because it does have clinical implications in addition to the aforementioned developmental implications. If the diagnosis is truly aortic atresia, then there is likely an area of ductal tissue that is facilitating flow to the descending aorta, particularly if there is concurrent coarctation or interruption of the aorta. A patient with such anatomy will likely require prostaglandin as exemplified by the current case.
The current case, as well as the previously described cases, also highlight the success of a single-stage biventricular repair consisting of closure of the ventricular septal defect, creation of right ventricle to pulmonary artery continuity. Although the specifics of how this is achieved may differ from patient to patient the same effect is achieved.
In the setting of aortic atresia with normal-sized left ventricle, the defect is generally an outlet defect where it is found in the limbs of the septomarginal trabeculation. The defect may have exclusively muscular borders but more often than not has some borders that are fibrous. This is important to note as there is no muscular bar protecting the conduction system that will run infero-posteriorly to the defect. Additionally, there may often be coarctation or interruption of the aortic arch likely secondary to decreased flow in parts of the transverse aortic arch due to aortic atresia.
This case series represents the largest collation of data on hearts with aortic atresia and a normal-sized left ventricle. It highlights important clinical associations and highlights the importance of prompt and precise diagnosis. Additionally, the case series highlights that survival has improved vastly over the years and that an early single-stage Yasui repair can be with low mortality.
While these data are additive to the literature they are not without limitations. The data come from a previously unreported case and then the remainder of published cases, thus allowing for publication bias. Additionally, extremely granular data could not be extracted for many cases in terms of specific anatomic details such as the borders of the ventricular septal defect.
Conclusion
Aortic atresia with a normal-sized left ventricle is often associated with an outlet ventricular septal defect with pulmonary override and coarctation or interruption of the aorta. This entity can be confused for common arterial trunk although this can be easily dismissed if the coronary arteries do not arise from the single outlet. Single-stage biventricular repair can be successfully achieved in the current era.
