Discussion

The early onset and progressive course of pulmonary hypertension in patients with anomalous origin of one pulmonary artery from the ascending aorta significantly influences surgical outcomes. Therefore, managing patients diagnosed during adolescence or adulthood presents notable clinical challenges. In such cases, segmental pulmonary hypertension may already be well-established, necessitating meticulous evaluation of operability and long-term prognosis. ^{Reference Gupta, Choubey, Kumar, Patel and Airan5} Beyond anatomical confirmation of anomalous origin of the right pulmonary artery from the ascending aorta, the most critical and complex aspect in late-presenting cases is accurately assessing the severity and reversibility of pulmonary vascular disease.

Echocardiography is a highly sensitive but low-specificity modality for evaluating pulmonary hypertension, particularly in CHD. Cross-sectional imaging techniques, such as CT and cardiac MRI, provide detailed anatomical and functional information and are essential for diagnosis and longitudinal follow-up. Despite these advances, right heart catheterisation remains the gold standard for assessing pulmonary artery pressures and calculating pulmonary vascular resistance. However, in patients with anomalous origin of the right pulmonary artery from the ascending aorta, the atypical vascular anatomy poses significant challenges in interpreting invasive haemodynamic data, particularly concerning operability and reversibility assessment. ^{Reference Urbina-Vazquez, del Lopez-Rodríguez and Ortega-Silva6}

Lung biopsy is not routinely employed in the assessment of pulmonary hypertension due to its invasive nature, limited diagnostic yield, and potential for complications. However, in certain cases—particularly when operability remains uncertain and non-invasive tests are inconclusive—it can serve as a useful adjunct in surgical decision-making. In our patient, a biopsy was conducted to better understand the degree of pulmonary vascular disease. In this case, histological findings indicated Stage II–III disease, supporting the decision to proceed with surgical repair. A similar approach was described by Zhao et al., who reported on two adolescents with anomalous origin of the right pulmonary artery from the ascending aorta (aged 14 and 17 years), in whom lung biopsy revealed Stage II and Stage III pulmonary vascular disease. Both patients successfully underwent surgical correction, and no signs of pulmonary hypertension were observed during 9- and 8-year follow-ups, respectively. ^{Reference Zhao, Si, Wang, Chen, Yan and Chen7}

The normalisation of mean postoperative PA pressure can be explained using Ohm’s law and the formula for resistances in parallel:

$${1 \over PVR_{total} } = {1 \over PVR_{RPA} } + {1 \over PVR_{LPA} } $$

Despite high preoperative resistance in the right pulmonary artery, the low resistance and compliant vascular bed of the left pulmonary artery lowers the total pulmonary vascular resistance, resulting in normalisation of overall PA pressures. This supports the notion that high unilateral PA pressure alone should not be considered an absolute contraindication to surgery. ^{Reference Gupta, Choubey, Kumar, Patel and Airan5}

In patients with anomalous origin of the right pulmonary artery from the ascending aorta, both invasive haemodynamic assessment and lung biopsy carry procedural risks and may not always yield definitive information regarding operability. Therefore, a less invasive yet functionally informative approach was considered in this case. While 2D phase-contrast cardiac MRI has been validated for evaluating pulmonary haemodynamics in CHD, to the best of our knowledge, no prior studies have utilised cardiac MRI to assess pulmonary vasoreactivity in cases of segmental pulmonary arterial hypertension, such as anomalous origin of the right pulmonary artery from the ascending aorta. ^{Reference Körperich, Gieseke and Barth8} In this patient, serial 2D phase-contrast cardiac MRI measurements performed during inhaled iloprost administration revealed a 42% increase in flow through the anomalous right pulmonary artery, suggesting preserved pulmonary vascular reactivity. This non-invasive result provided supportive evidence toward operability and justified proceeding with lung biopsy. The biopsy subsequently confirmed Stage II–III disease, allowing for surgical intervention to be undertaken with a favourable risk–benefit profile.

In the surgical management of anomalous origin of the right pulmonary artery from the ascending aorta, Armer et al. first reported in 1961 that the anomalous pulmonary artery could be connected to the main pulmonary artery using a Dacron interposition graft. Subsequently, in 1967, Kirkpatrick et al. demonstrated that direct anastomosis was also feasible, eliminating the need for synthetic grafts. Today, direct implantation is the preferred technique, particularly in isolated anomalous origin of the right pulmonary artery from the ascending aorta cases diagnosed during infancy. ^{Reference Jiang, Zhang and Hu9}

In patients for whom direct anatomical repair is not feasible—typically due to delayed diagnosis and advanced pulmonary vascular disease—alternative approaches such as pneumonectomy or single-lung transplantation may be considered. In a case reported by Nikolaidis et al., a 41-year-old patient with anomalous origin of the right pulmonary artery from the ascending aorta presented with recurrent haemoptysis and was deemed unsuitable for definitive surgical correction due to high-operative risk. As a palliative measure, pulmonary artery banding was performed. During a two-year follow-up period, no recurrence of haemoptysis was observed. ^{Reference Nikolaidis, Velissaris and Haw10}

The operation was carried out using a mini-sternotomy approach. This method provided adequate exposure for direct implantation while reducing surgical trauma. To our knowledge, this is one of the very few reports describing the use of a minimally invasive technique for late-presenting AORPA. The favourable postoperative outcome further supports the potential feasibility and safety of this approach in carefully selected patients.