Ann Thorac Surg 2009;87:1495-1499. doi:10.1016/j.athoracsur.2009.02.043
© 2009 The Society of Thoracic Surgeons
Original Articles: Pediatric Cardiac
Common Arterial Trunk With Atrioventricular Septal Defect: New Observations Pertinent to Repair
Iki Adachi, MDa,
Siew Yen Ho, PhD, FRCPatha,*,
Margot M. Bartelings, MD, PhDb,
Karen P. McCarthy, BSa,
Anna Seale, MDc,
Hideki Uemura, MD, FRCSd
a Cardiac Morphology Unit, National Heart and Lung Institute, Imperial College London, London, United Kingdom
b Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
c Department of Pediatric Cardiology, Royal Brompton and Harefield NHS Trust, London, United Kingdom
d Department of Cardiothoracic Surgery, Royal Brompton and Harefield NHS Trust, London, United Kingdom
Accepted for publication February 18, 2009.
* Address correspondence to Dr Ho, Cardiac Morphology Unit, National Heart and Lung Institute, Imperial College London, Guy Scadding Building, Dovehouse St, London, SW3 6LY, United Kingdom (Email: yen.ho{at}imperial.ac.uk).
Presented at the Poster Session of the Forty-fifth Annual Meeting of The Society of Thoracic Surgeons, San Francisco, CA, Jan 26–28, 2009.
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Abstract
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Background: The coexistence of abnormalities in both atrioventricular and ventriculoarterial junctions occasionally represents a formidable challenge to the surgeon. The association of common arterial trunk with atrioventricular septal defect is such an example. To date, only two reports have described successful operative outcome. This paucity of success might reflect the anatomical complexity that could prevent favorable results.
Methods: We reviewed six specimens with common arterial trunk and atrioventricular septal defect, focusing on how to establish a nonobstructed connection between the left ventricle and the truncal valve.
Results: In all cases, the common trunk arose exclusively from the right ventricle, and the only exit from the left ventricle was the ventricular component of the septal deficiency. In particular, the preferential route was limited to a space below the superior bridging leaflet that did not have any tendinous cords inserting onto the ventricular crest, in contrast to the inferior bridging leaflets that were always tethered to the crest with many short cords. Accordingly, the size of potential left ventricular outflow depended on the shape of the anterosuperior margin of the ventricular crest below the superior bridging leaflet. The potential outflow was narrower than the truncal valvar area in all hearts but one having extensive anterosuperior excavation of the ventricular crest, suggesting the necessity of septal enlargement had anatomical repair been attempted during life.
Conclusions: Owing to the unique ventriculoarterial connection, the surgeon, considering anatomical repair, needs to pay attention to the anterosuperior margin of the ventricular scoop, which determines the adequacy of left ventricular outflow size.
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Introduction
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The surgical management of common arterial trunk and atrioventricular septal defect (AVSD) as an isolated lesion has improved steadily, leading to a remarkable decrease in operative mortality in recent years [1–3]. Nevertheless, a combination of the two anomalies, albeit rare, still represents a significant surgical challenge. Only two reports have described favorable outcomes after surgical repair of this lesion [4, 5], and many more cases were reported in autopsy studies [6–14]. The cardiac anatomy of these two lesions have been well investigated previously, but only as separate entities [6, 15–21]. We therefore investigated hearts with this particular combination of anomalies with the aim to identify morphologic features that could complicate anatomical repair.
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Material and Methods
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This study has been approved by our Institutional Ethics Committee. From the cardiac specimen archives of the Royal Brompton Hospital, United Kingdom, and Leiden University Medical Center, Netherlands, we identified 6 hearts with common arterial trunk in the setting of a biventricular atrioventricular connection through a common atrioventricular valve; 4 had the usual atrial arrangement (situs solitus), and the other 2 had isomeric arrangement of the right atrial appendages. Although 4 hearts (3 with usual atrial arrangement and 1 with right isomerism) had more or less balanced ventricles and were deemed suitable for biventricular repair in view of ventricular cavity size, the right heart was dominant in the remaining 2 (namely, unbalanced AVSD). Although the latter 2 hearts would not have been suitable for anatomical repair, we opted to include these specimens for reference. We carried out morphologic investigations on these specimens, particularly focusing on how to establish a nonobstructed connection between the left ventricle and the truncal valve as a key component of anatomical repair.
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Results
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Ventriculoarterial Junction
Among 4 hearts with the usual atrial arrangement, 2 had the pulmonary trunk arising from the common arterial trunk (so-called type 1 according to the Collet and Edward classification [20]), whereas the other 2 had separate and adjacent pulmonary orifices (type 2). By contrast, both hearts with right isomerism had separate and remote pulmonary orifices (type 3). In 2 hearts, the pulmonary orifice was located immediately above the sinotubular junction and left aspect of the circumference of the common trunk. Apart from 1 heart in which the aortic arch had been removed, the aortic arch was left-sided and not obstructed in the remaining. All the hearts had a two-coronary arterial system, and there were no major branches that crossed right ventricular outlet where a ventriculotomy would be made during surgical repair. The most striking finding was that all 6 hearts had the common trunk originating exclusively from the right ventricle, irrespective of the mode of pulmonary origin (Table 1).
Atrioventricular Junction
All the hearts had a common atrioventricular junction guarded by a basically five-leaflet configured atrioventricular valve. In 5 hearts, the superior bridging leaflet extended well into the right ventricle, resulting in a diminutive anterosuperior leaflet. In the remaining heart, the superior bridging leaflet was less extensive, and there were two separate papillary muscles supporting a well-developed anterosuperior leaflet. In all 6 hearts, the superior bridging leaflet did not have any tendinous cords (chordae tendinae) inserting onto the crest of the ventricular septum and could be lifted upward freely toward the level of the atrioventricular junction, restrained only by cordal attachments to papillary muscles in the ventricles. In 1 of the 6 hearts, however, the tip of the leaflet was attached directly to the crest, but the leaflet body was still free from the septum. By contrast, the inferior bridging leaflet was always, albeit to greater or lesser degree, tethered to the ventricular crest with many short cords. In particular, the inferior leaflet was almost adherent to the septal surface, leading to minimal potential for shunting below the inferior leaflet in 1 heart. In another heart, both bridging leaflets were completely attached to the underside of the atrial septum, resulting in intracardiac shunting being only at the ventricular level. In this particular heart, the anticipated location of the atrioventricular node was less displaced inferoposteriorly from the apex of the triangle of Koch [19].
All the hearts had an additional atrial communication at the floor of the oval fossa. In 1 heart, there were no pulmonary veins entering the left atrial chamber, which consisted of little more than a normal appendage. On the contrary, the right atrium was grossly dilated and received a large inferior caval vein and a right superior caval vein of normal size, suggesting the presence of an infracardiac type of totally anomalous pulmonary venous connection, but this could not be confirmed on the isolated heart specimen. This heart was also associated with a persistent left superior caval vein that drained into the coronary sinus. In both hearts with right atrial isomerism, the pulmonary veins were connected to the left-sided atrium. The pulmonary veins were narrow in 1 of them. Although obstruction in the pulmonary venous pathway is likely in this heart, there is no clinical information available to confirm this.
Pathway From Left Ventricle to Truncal Valve
Because of the exclusive commitment of the truncal valve to the right ventricle, the only exit from the left ventricle was a ventricular component of the septal deficiency in all 6 hearts. More specifically, the preferential pathway was limited to a space between the underside of the superior bridging leaflet and the anterosuperior margin of the ventricular scoop, owing to tethering of the inferior bridging leaflet onto the ventricular crest (Fig 1). Fibrous continuity was observed between the truncal valve and superior bridging leaflets in all but 1 heart in which valvar discontinuity was due to persistence of the ventricular infundibular fold (Fig 2, right upper panel). Among the 4 hearts with balanced or nearly balanced ventricles, 1 heart with slightly smaller left ventricle showed a minimal excavation of the anterosuperior border of the ventricular crest (Fig 2, left upper panel). Consequently, the potential exit of the left ventricle was unequivocally small in this heart. By contrast, another heart with a reasonable left ventricular size had an extensive excavation of the ventricular scoop, yielding a much wider space below the bridging leaflet (Fig 2, left lower panel). In the remaining 2 hearts, the degree of excavation was moderate (Fig 2, right upper panel). Even in these 2 hearts, however, the potential pathway for the left ventricular outflow appeared to be smaller than the area of the truncal valve.
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Fig 1. (Left) In hearts with a common arterial trunk exclusively arising from the right ventricle (RV), the only potential pathway to connect the left ventricle (LV) and the truncal valve is the ventricular component of the atrioventricular septal defect, particularly the space between the superior bridging leaflet (SBL) and the anterosuperior margin of the septal deficiency. The block arrows indicate the pathway of blood flow. (Right) Concordant connection of the aortic valve in the setting of a common atrioventricular junction is shown for comparison. (A = aortic annulus; IBL = inferior bridging leaflet; T = truncal annulus.)
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Fig 2. Photographs of three representative specimens with common arterial trunk and atrioventricular septal defect. All photographs were taken from the right ventricular side to illustrate the truncal valve and its relation to the superior bridging leaflet (SBL) and a ventricular scoop (indicated by a red dotted line). All three hearts had the truncal valve arising exclusively from the right ventricle, and the preferential route from the left ventricle is a space between the superior bridging leaflet and the anterosuperior margin of the ventricular scoop. The size of this space is variable, depending on the degree of anterosuperior excavation of the ventricular scoop. In the heart shown in the right upper panel, there is a persistence of the ventricular infundibular fold (VIF), creating discontinuity between the truncal valve and the superior bridging leaflet.
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In 2 hearts with unbalanced ventricles, the anterosuperior border of the ventricular septal deficiency was barely excavated in the one and moderately extended in the other. The heart with a minimal excavation was associated with an extremely small cavity of the rudimentary left ventricle.
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Comment
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Today, the operative outcomes of congenital heart diseases are dramatically improved, owing to the synergistic effect of technical advances and better understanding of surgical anatomy. There still remain some lesions—for example, common arterial trunk associated with AVSD—that represent significant surgical challenges. Other types of malformations such as tetralogy of Fallot associated with AVSD can be repaired with acceptable risks [22, 23]. Rarity itself might in part be an explanation for dismal surgical outcome. The most striking finding in our study is that the common arterial trunk arose exclusively from the right ventricle in all the hearts examined. This finding is in marked contrast to the observation that the common trunk is usually committed, more or less, to both ventricles in the setting of normal separate and discrete atrioventricular junctions [6, 15, 16]. As far as we are aware, there have been 13 articles describing a total of 21 cases of common arterial trunk in the setting of common atrioventricular junction; autopsy cases in 17 [6–14], surgical cases in 3 [4, 5, 24], and a prenatal case (diagnosis was verified subsequently after birth) [25]. Among these cases, the truncal origin from the right ventricle was confirmed with direct inspection and specified in 4 cases [5, 7, 14]; in a further case, the right ventricular origin was evident on the figures provided [12]. We consider the combination of common arterial trunk and AVSD as a heart in which the normal embryologic process of septation failed at both atrioventricular and ventriculoarterial junctions, and there was arrest of the normal backward and leftward shift of the arterial portion. Consequently, we could anticipate the truncal valve to be connected to the right ventricle in the majority of hearts with this combination of lesions.
In this particular setting of ventriculoarterial connection, it may be difficult to connect the left ventricle to the truncal valve for anatomical repair. Although the whole ventricular component of the septal deficiency, theoretically, could serve as the exit from the left ventricle, it is the space between the ventricular surface of the superior bridging leaflet and the anterosuperior margin of the ventricular scoop that composes of the "preferential" or even "sole" pathway from the left ventricle (Figs 1, 2). That is because, in all the cases in our series, the space below the inferior bridging leaflet is more or less obliterated, leaving little potential to be a pathway of intraventricular tunneling. In other words, the relationship between the ventricular surface of the superior bridging leaflet and the anterosuperior margin of the ventricular scoop is the major determinant of the size of the left ventricular outflow tract. If this space is inadequate or obstructed, such a heart may not cope with life. That this space is the sole exit is supported by the lack of any report of common arterial trunk or double-outlet right ventricle associated with the so-called "partial" AVSD or "ostium primum atrial septal defect," in which the bridging leaflets are completely attached to the ventricular crest, thereby occluding the left ventricular outlet. Interestingly, all the hearts but 1 in our series had a ventricular crest free from the superior bridging leaflet, while the inferior leaflet was always tethered to the septum to some degree, as described above. Even in the exceptional case, only a tip of the superior bridging leaflet was directly attached to the septal crest, and a major part of the leaflet was free from any cordal insertion.
The presence of a freely mobile superior bridging leaflet may not result in a nonobstructive outlet for the left ventricle after anatomical repair. Rather, the degree of anterosuperior excavation of a ventricular scoop is also of critical importance (Fig 2). Among 6 hearts in our series, only 1 heart had extensive excavation and, hence, adequate space. In the remaining 5, the potential pathway was smaller than the truncal valvar area. This finding suggests that an anterosuperior enlargement of the ventricular septum would be required should anatomical repair have been attempted during life. That can be accomplished without jeopardy to the atrioventricular conduction system in hearts with right-hand ventricular topology. Conte and colleagues [5] described in their case report that it was particularly difficult to understand the anatomy and how to connect the left ventricle to the truncal valve. Nevertheless, they accomplished anatomical repair by placing an intracardiac tunnel after resecting the ventricular septum to avoid systemic obstruction. During 6 months of follow-up, there was no evidence of left ventricular outflow obstruction, either clinically or echocardiographically.
One of the limitations of the current study is the small number of cases in our series. To overcome this, we reviewed the literature for descriptions of other cases. The lack of physiologic data is another limitation. In addition, we were unable to provide any quantitative data to support our hypothesis that the left ventricular outflow tract would be obstructive if the anterosuperior border of the ventricular crest is not well excavated. That is because the measurement of "potential area" is quite difficult. Nevertheless, we hope our study will stimulate further clinical investigations into this rare but potentially repairable malformation.
In conclusion, in our cases of common arterial trunk associated with AVSD, the common trunk always arose exclusively from the right ventricle. Because of this ventriculoarterial relationship, the main exit from the left ventricle was the space between the superior bridging leaflet and the anterosuperior border of a ventricular scoop. When trying to achieve anatomical repair, the surgeon needs to confirm this space is wide enough to accommodate blood flow from the left ventricle, with a careful consideration of possible need for an anterosuperior enlargement of the ventricular septum.
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Acknowledgments
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This study is supported by the Francis Fontan Prize of the European Association of Cardio-Thoracic Surgery awarded to Iki Adachi and by a grant from the Uehara Memorial Foundation. The Cardiac Morphology Unit receives funding from the Royal Brompton and Harefield Hospital Charitable Fund. The authors appreciate Ms Manveer Sroya and Ms Carina Lim for their technical and secretarial assistance.
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Abstract
Introduction
