Introduction
An aortopulmonary window is an abnormal communication between the ascending aorta and the main pulmonary artery, despite the presence of two separate semilunar valves arising from distinct ventricular outflow tracts.Reference Talwar, Sharma, Datt, Choudhary and Airan1 It is a rare CHD, accounting for approximately 0.2–0.6% of all congenital cardiac malformations.Reference Kutsche and Van Mierop2 Although aortopulmonary window can occur as an isolated anomaly, up to 50% of cases are associated with other cardiovascular abnormalities. The most frequent associated lesions involve the aortic arch, particularly interrupted aortic arch or coarctation of the aorta. Less commonly, aortopulmonary window may coexist with ventricular septal defects, tetralogy of Fallot, or transposition of the great arteries.Reference Barnes, Mitchell and Tweddell3
Aortopulmonary window was first described by Elliotson in 1830,Reference Elliotson4 and in 1978, Mori et al. Reference Mori, Ando, Takao, Ishikawa and Imai5 proposed the classification still most widely used, based on the anatomical location of the defect. Aortopulmonary window is therefore categorised into:
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Type I: proximal defect just above the semilunar valves;
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Type II: distal defect near the bifurcation of the pulmonary artery;
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Type III: extensive defect involving the entire main pulmonary artery from just above the valves to the bifurcation and proximal right pulmonary artery.
Most patients present early with significant symptoms of congestive heart failure—typically NYHA class II—or pulmonary hypertension. Tachypnoea, recurrent lower respiratory tract infections, and cardiomegaly on chest radiography are common findings.Reference Talwar, Sharma, Datt, Choudhary and Airan1
Criss-cross heart is an exceedingly rare congenital malformation, accounting for fewer than 0.1% of all CHDs.Reference Duncan, Wong and Freedom6 It is characterised by abnormal twisting of the ventricular mass, resulting in crossed atrioventricular connections and nonparallel systemic and pulmonary flows without intracardiac mixing. Criss-cross heart is frequently associated with other structural cardiac abnormalities, which pose significant diagnostic challenges even for experienced specialists.Reference Ren, Ma and Li7,Reference Liang, Kong, Liu, Ji, Zhang and Wang8
Despite the well-established association of both aortopulmonary window and criss-cross heart with other congenital anomalies, the coexistence of these two defects is extraordinarily rare. This combination markedly increases diagnostic and therapeutic complexity, given the need to manage both the abnormal aortopulmonary communication and the atypical spatial orientation and connectivity of the cardiac chambers.
Case report
A full-term female neonate (Apgar 8/8, birth weight 3195g) underwent fetal echocardiography, which suggested an aortopulmonary window. Postnatal echocardiography revealed: situs solitus; mesocardia with leftward apex; discordant atrioventricular connection; concordant ventriculoarterial connection; patent foramen ovale (4 mm) with right-to-left shunting; dilated right-sided chambers; left-sided tricuspid valve with mild regurgitation; right-sided mitral valve with mild regurgitation; normally positioned semilunar valves; left aortic arch with apparent interruption after the brachiocephalic artery; and an aortopulmonary window measuring 6.5 mm with right-to-left flow and no obstruction. The patient was transferred to a tertiary cardiac centre.
Repeat echocardiography showed: situs solitus; levocardia; persistent left superior cavel vein draining into a dilated coronary sinus; biventricular concordant atrioventricular connection with two distinct atrioventricular valves; concordant ventriculoarterial connection; rotational abnormality of the ventricular mass compatible with criss-cross heart; inferior sinus venosus atrial septal defect (8.6 mm); markedly dilated right-sided chambers; significant right ventricular hypertrophy with mild systolic dysfunction; thickened semilunar valves; aortopulmonary window measuring 10 mm; dilated pulmonary trunk (13 mm); and no evidence of interrupted aortic arch.
CT confirmed these findings and revealed a large type III aortopulmonary window measuring 19 × 16 mm (Figure 1). Three-dimensional reconstructions allowed a more comprehensive visualisation of the defect and its spatial relationship with the right pulmonary artery branches, the aortic arch branches, and the descending aorta, which was useful for surgical planning (Figure 2). Final diagnosis included criss-cross heart with concordant atrioventricular and ventriculoarterial connections, a large aortopulmonary window, and absence of interrupted aortic arch.
Large APW, confirmed as type III by computed tomography angiography. Furthermore, Aorta seemed free of obstructions throughout its course, with a side of the crisscross heart also visible.
3D reconstruction of the type III APW, also showing some of the right pulmonary artery branches, Aortic Arch branches and Descending Aorta.
At 17 days of life, surgical correction of the extensive aortopulmonary window was performed, involving reconstruction from the ascending aorta to the proximal descending aorta. The immediate postoperative period was complicated by severe acute heart failure and low cardiac output syndrome refractory to conventional therapy, necessitating initiation of extracorporeal membrane oxygenation. After nine days, extracorporeal membrane oxygenation was discontinued following haemodynamic stabilisation. Follow-up echocardiography demonstrated moderate right-sided dilation, thickened pulmonary valve without significant gradient, absence of residual lesions, and good biventricular systolic function.
Discussion
This case highlights three central clinical elements: (1) the prenatal diagnosis of an aortopulmonary window, later confirmed and classified as a large type III defect; (2) the identification of criss-cross heart, an exceptionally rare congenital anomaly; and (3) the need for early neonatal surgical intervention due to the anatomical complexity and risk of rapid clinical deterioration. Despite technically successful repair, the patient required extracorporeal membrane oxygenation for severe postoperative haemodynamic instability—reflecting the high intrinsic risk associated with such complex anatomy.
Prenatal diagnosis, as in this case, is crucial for early and optimised perinatal management. Fetal echocardiography has shown increasing sensitivity for complex congenital defects and allows pre-delivery planning.Reference Gonçalves, Simões and Lopes9 However, complete anatomical characterisation—particularly in the presence of multiple malformations—may require complementary imaging such as cardiac CT angiography or MRI.Reference Rajan, Krishnamurthy and Gupta10
Surgery remains the definitive treatment for aortopulmonary window and should ideally be performed within the first weeks of life to prevent the development of irreversible pulmonary vascular disease.Reference Backer, Mignosa and Franco11 Surgical technique depends on the defect’s type and extent and may include patch closure or aortic reconstruction. In this case, early repair was essential due to the large type III aortopulmonary window, although postoperative instability required advanced circulatory support. Extracorporeal membrane oxygenation, while reserved for life-threatening postoperative complications, has demonstrated utility in neonatal recovery following complex congenital cardiac surgery.Reference Larsen, Pedersen and Johansen12
From a prognostic standpoint, isolated aortopulmonary window repaired early generally has favourable outcomes, with survival rates exceeding 80% in specialised centres.Reference Ilbas, Kiran and Sari13 However, when associated with multiple anomalies—as with criss-cross heart—surgical risk increases substantially. Long-term follow-up is essential to monitor ventricular function, arrhythmia risk, and the potential need for reinterventions.
The rarity of the association between aortopulmonary window and criss-cross heart underscores the importance of detailed case reporting. Such documentation expands the existing knowledge base and supports the development of more standardised diagnostic and therapeutic approaches for complex congenital malformations.
Conclusion
The coexistence of an aortopulmonary window and criss-cross heart, as demonstrated in this case, highlights the intricate cardiac anatomy and significant haemodynamic repercussions inherent to exceptionally rare CHDs.Reference Anderson, Baker and Murphy14 Prenatal diagnosis, complemented by detailed postnatal imaging, was critical for defining the anatomical substrate and guiding management.Reference Gonçalves, Simões and Lopes9,Reference Rajan, Krishnamurthy and Gupta10 Nevertheless, complete elucidation of the atrioventricular and ventriculoarterial relationships and ventricular rotation remained challenging until after birth.Reference Ren, Ma and Li7,Reference Liang, Kong, Liu, Ji, Zhang and Wang8
Early surgical repair was mandatory to prevent progressive pulmonary vascular disease and biventricular dysfunction.Reference Backer, Mignosa and Franco11 The postoperative course, marked by severe haemodynamic instability, emphasised the high risk associated with this anatomical spectrum. Extracorporeal membrane oxygenation—traditionally reserved for extreme cases—was vital for achieving survival, reinforcing the need for access to advanced circulatory support in centres managing complex congenital heart conditions.Reference Larsen, Pedersen and Johansen12
Given the extreme rarity of this association and the short follow-up duration, broader prognostic conclusions are limited. Long-term outcomes—including ventricular function, arrhythmia risk, and reintervention rates—remain to be determined. Multicentre registries and international collaborative studies may help establish more robust evidence-based strategies for patients with this uncommon combination of anomalies.Reference Yu, Kim and Choi15
In summary, this case expands current knowledge on the coexistence of aortopulmonary window and criss-cross heart, emphasising the importance of prenatal diagnosis, timely surgical intervention, and specialised postoperative care.Reference Talwar, Sharma, Datt, Choudhary and Airan1,Reference Ilbas, Kiran and Sari13 Each documented case adds valuable insight to the limited literature and reinforces the need for integrated management involving fetal cardiology, paediatric cardiac surgery, and advanced intensive care.
