Introduction
Common arterial trunk usually presents after birth with increasing pulmonary blood flow as pulmonary vascular resistance falls. In the modified Van Praagh classification, the pulmonary arteries typically arise from the arterial trunk above the truncal sinuses. Reference Jacobs1 Rarely, the pulmonary trunk may arise from a truncal valvar sinus, close to a coronary orifice. We describe a neonate in whom this anatomy, combined with dysplasia of the truncal valve, caused severe pulmonary hypoperfusion rather than pulmonary overcirculation.
Case report
A male neonate with prenatal diagnosis of conotruncal malformation was delivered at term. Apgar scores were 4, 6, and 8 at 1, 5, and 10 minutes. Despite high-flow oxygen, arterial oxygen saturation remained near 70%. Echocardiography showed a single overriding arterial trunk, a large ventricular septal defect, a small atrial septal defect, a right aortic arch, and usual coronary origins for this lesion. The truncal valve was tricuspid, dysplastic, and moderately stenotic, with a peak Doppler gradient of 40 mmHg. The infant had dysmorphic features including right cryptorchidism, peripheral hypotonia, a large anterior fontanelle, low-set ears, and micro-retrognathia. Genetic testing identified a variant of uncertain significance in KAT6A, a gene associated with Arboleda-Tham syndrome. Reference Jiang, Yang, Wu, Xiong and Li2
Because profound cyanosis was unexpected, respiratory disease, infection, and high pulmonary vascular resistance were considered. Inhaled nitric oxide and high-flow oxygen did not prevent recurrent desaturation to nearly 50%. CT angiography on day 6 showed the pulmonary trunk arising unusually low from the arterial trunk, close to the left coronary artery (Figure 1). The pulmonary trunk measured 4 mm, the right pulmonary artery 2 mm, and the left pulmonary artery 3 mm. Cardiac catheterisation on day 12 confirmed a low sinus origin of the pulmonary trunk and hypoplastic but confluent pulmonary arteries, with a Nakata index of 75 mm/m2 (Figure 2).
CT angiography. ( a ) Three-dimensional reconstruction in a left posterolateral view showing the low sinus origin of the pulmonary trunk and hypoplastic branches. ( b ) Oblique coronal maximum intensity projection showing the abnormal pulmonary trunk origin from the arterial trunk and hypoplastic pulmonary vascularisation.
Catheter angiography. Angiographic images ( a , b ) confirm the very low abnormal origin of the pulmonary trunk from the arterial trunk.
Staged palliation was chosen. At surgery on day 13, the truncal valve was tricuspid with three dysplastic cauliflower-like cusps and no commissural fusion. The pulmonary trunk orifice arose very low in the antero-left sinus, immediately adjacent to—but distinct from—the left coronary ostium, which occupied a more proximal and superior position within the same sinus. The right coronary artery was dominant. At each systole, the antero-left cusp prolapsed to occlude the pulmonary trunk orifice while the left coronary ostium remained patent throughout (Supplementary Video S1). There was no intraoperative truncal valve regurgitation. The valve was left in situ, given the absence of regurgitation and the risk of manipulation near the left coronary ostium. The pulmonary trunk was detached from the arterial trunk and connected to the right ventricle with a 6-mm polytetrafluoroethylene conduit. Recovery was uncomplicated, and the infant was discharged 16 days later.
At 1 year, pulmonary arterial growth and haemodynamics were favourable. The ventricular and atrial septal defects were closed, and the initial conduit was replaced by a 14-mm Hancock conduit between the right ventricle and pulmonary trunk. Recovery after complete repair was favourable.
Discussion
Severe cyanosis in common arterial trunk should prompt systematic evaluation for an obstructive mechanism. In this case, the diagnosis was not suspected prenatally nor on the initial echocardiogram; it was established by CT angiography, cardiac catheterisation, and surgical inspection.
The anatomic substrate reported here is rare but recognised. Bharati and colleagues found pulmonary arterial origin from a sinus in 1 of 98 type 1 specimens, Reference Bharati, McAllister, Rosenquist, Miller, Tatooles and Lev3 whereas Adachi and colleagues identified sinus-origin pulmonary trunks in 8 of 56 hearts, Reference Adachi, Uemura, McCarthy, Seale and Ho4 establishing that pulmonary orifices can lie unusually low and near coronary ostia.4 The novelty here is the dynamic interaction: the antero-left cusp acted as a systolic barrier to pulmonary flow, making the lesion behave more like pulmonary atresia with ventricular septal defect than like classic common arterial trunk.
Truncal valve morphology was central to surgical strategy. Consistent with the spectrum of neonatal truncal valve dysplasia described by Konstantinov, Reference Konstantinov5 the valve was tricuspid with dysplastic cusps and no regurgitation. Konstantinov et al. have demonstrated that spatial proximity of a coronary ostium and pulmonary orifice within the same sinus can be managed by left coronary artery unroofing during valve repair; Reference Konstantinov, Perrier, Naimo and d’Udekem6 in our case, the absence of regurgitation and the risk associated with manipulation near the left coronary ostium justified leaving the valve in situ and focusing on pulmonary trunk detachment. This contrasts with cases of severe truncal valve insufficiency, where early neonatal repair has been reported with acceptable outcomes. Reference Konstantinov7 Staged palliation was driven primarily by pulmonary arterial hypoplasia and the very low sinus origin of the pulmonary trunk, which limited available tissue for safe reconstruction.
For cyanotic neonates labelled as common arterial trunk, echocardiography should not stop at confirming the common trunk. The pulmonary trunk origin, truncal valve morphology, coronary proximity, and direction of systolic flow into the pulmonary arteries must be analysed carefully. CT and catheter angiography were complementary in this case, clarifying operative risk and supporting a staged strategy.
Conclusion
A sinus-origin pulmonary trunk combined with a dysplastic obstructing cusp converts common arterial trunk into a low-pulmonary-flow lesion. The primary determinants of staged palliation in this case were pulmonary arterial hypoplasia and the anatomically complex proximity of the pulmonary trunk orifice to the left coronary ostium within the antero-left sinus. Systematic assessment of truncal valve morphology and coronary anatomy is essential in all neonates with common arterial trunk presenting atypically.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S1047951126123816.
Acknowledgements
The authors gratefully acknowledge GCS HUGO, AVIESAN, and FHU PRECICARE.
Financial support
A.-E.B. is supported by the French Government as part of the “Investments of the Future” programme managed by the National Research Agency (grant reference ANR-16-IDEX-0007). A.-E.B. is a recipient of an Initiative—Sciences Innovation Territoire Economie—Nantes Excellence Trajectory Junior Talent Chair.
Competing interests
The authors declare none.
Ethical standards
The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national guidelines on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008.
Social media synopsis
A sinus-origin pulmonary trunk and dysplastic truncal valve caused severe neonatal cyanosis in common arterial trunk, successfully managed by staged repair. #PedsCards
