Introduction
Middle aortic syndrome is a rare vascular condition characterised by segmental or diffuse stenosis of the distal thoracic aorta and/or proximal abdominal aorta, frequently accompanied by varying degrees of renal and/or visceral artery involvement. Reference Wang, Dong, Li, Zou and Jiang1 Middle aortic syndrome may result from genetic disorders (e.g., neurofibromatosis type 1, Williams syndrome, Alagille syndrome), acquired causes such as inflammatory conditions like Takayasu arteritis, or idiopathic causes. As an important aetiological factor of paediatric hypertension, middle aortic syndrome requires early recognition to enable accurate diagnosis and timely therapeutic intervention—an approach that not only optimises hypertension management but also mitigates the risk of associated complications. Reference Musajee, Gasparini, Stewart, Karunanithy, Sinha and Sallam2
Herein, we present a case of middle aortic syndrome, with a focus on its clinical progression, diagnostic challenges, and surgical management strategies.
Patient’s background
We report the case of a 9-year-old boy (height: 132 cm; weight: 27 kg) who was found to have hypertension during a routine school health examination. A notable 40 mmHg blood pressure gradient was detected between the patient’s upper and lower extremities. In the supine and resting state, the non-invasive blood pressure of the left upper limb was measured as 148/98 mmHg, and that of the left lower limb as 108/79 mmHg, with an ankle-brachial index of 0.73.
Case presentation
The significant blood pressure discrepancy between the upper and lower extremities strongly suggested the possibility of aortic coarctation. Subsequent evaluations at our institution, including echocardiography, computed tomography angiography, and magnetic resonance angiography, confirmed the final diagnosis of middle aortic syndrome in this child.
Computed tomography angiography demonstrated severe stenosis of the distal thoracic aorta (Figure 1a). The stenotic segment measured 16 mm in length, with a minimum diameter of approximately 3 mm, localised at the T9 vertebral level. Concomitant findings included marked dilatation of the ascending aorta (32.7 mm), a 2.7 mm patent foramen ovale, and left ventricular hypertrophy with a wall thickness of 14.4 mm.
Computed tomography angiography (CTA) images. (a) Preoperative CTA showing a long segment of severe stenosis in the distal thoracic aorta. ( b) Postoperative CTA demonstrating patency of the reconstructed descending aorta. The white arrow indicates the lesion site.
Ultrasonographic assessment revealed vascular dysfunction, characterised by the absence of triphasic waveforms in bilateral femoral arteries, reduced flow velocities, and decreased resistance indices (RI: 0.54). Other renal parenchymal abnormalities were also identified, including left hydronephrosis, right renal pelvis separation, and reduced blood flow velocities in bilateral renal arteries (right renal resistance index: 0.32; left renal resistance index: 0.35), while renal function was normal.
Cranial magnetic resonance angiography detected an embryonic right posterior cerebral artery. Clinical and laboratory workups to rule out secondary hypertension aetiologies—including primary aldosteronism, pheochromocytoma, Cushing’s syndrome, and hypothyroidism—yielded negative results. The patient had a history of Guillain-Barré syndrome at 18 months of age, which resolved fully with medical treatment. His maternal grandparents had hypertension that was well-managed with antihypertensive medications. Whole-exome sequencing of the patient and his parents did not identify any pathogenic genetic variants.
The patient was initially treated with amlodipine; however, the antihypertensive effect was suboptimal. Following a comprehensive multidisciplinary evaluation, surgical intervention was deemed necessary to correct the vascular stenosis. A left posterolateral thoracotomy was performed via the sixth intercostal space, without cardiopulmonary bypass. Careful dissection revealed a long-segment stenosis of the descending thoracic aorta (Figure 2). Collateral vessels were ligated and transected, and regional hypothermia was implemented to protect thoracoabdominal organs.
Intraoperative direct view. A long-segment stenosis of the descending thoracic aorta is visible, with the white arrow pointing to the most stenotic site.
Under direct visualisation, temporary aortic clamping was applied proximal and distal to the stenotic segment. Approximately 3 cm of vascular tissue was excised, and aortic reconstruction was performed using a 14 mm Intergard Knitted vascular graft (Maquet, Getinge Group). The total aortic cross-clamp time was 42 minutes, within the safe threshold for preventing organ ischaemia in surgery. Following revascularization, the patient’s invasive blood pressure measured 103/66 mmHg in the upper limbs and 97/62 mmHg in the lower limbs, with an ankle-brachial index of 0.94.
For postoperative antithrombotic management, oral aspirin (75 mg, once daily) was started 24 hours after surgery and continued for six months. The postoperative course was uneventful, with no surgical complications observed. Histopathological examination of the resected vascular tissue revealed abnormal wall architecture, including luminal stenosis, prominent intimal thickening, loss of the normal lamellar structure, and minimal inflammatory cell infiltration within the adventitia (Figure 3).
Histopathological H&E staining of the stenotic segment. Examination revealed abnormal aortic wall architecture, including luminal stenosis, prominent intimal thickening, loss of the normal lamellar structure, and minimal inflammatory cell infiltration within the adventitia.
Six-month postoperative follow-up
Echocardiography showed patency of the prosthetic graft, with peak velocities of 1.5 m/s at the proximal anastomosis of the descending aortic arch, 1.0 m/s within the graft, and 1.4 m/s at the distal anastomosis. Computed tomography angiography confirmed overall patency of the descending aorta (Figure 1b), with sagittal measurements of 15.4 mm for the graft and 11.1 mm at both the proximal and distal anastomoses. The patient received aspirin (75 mg, qd) for six months postoperatively and no antihypertensive therapy. Blood pressure remained well controlled, with non-invasive supine measurements of 107/68 mmHg in the left upper limb and 122/63 mmHg in the left lower limb, yielding an ankle-brachial index of 1.14.
Discussion
Middle aortic syndrome may be caused by genetic factors (e.g., neurofibromatosis type 1, Williams syndrome, or Alagille syndrome), acquired factors (e.g., inflammatory aetiologies like Takayasu arteritis), or idiopathic aetiologies. In paediatric and adolescent patients, 7–36% of middle aortic syndrome cases are associated with underlying genetic disorders. Reference Vigneshwaran, Rajinikanth and Seeralar3 Middle aortic syndrome is commonly classified anatomically according to the location of aortic narrowing and is divided into four subtypes: (1) suprarenal (29%–60% of cases), (2) intrarenal, (3) infrarenal, and (4) suprarenal-to-infrarenal. Reference Rumman, Nickel and Matsuda-Abedini4 The presented case herein is a suprarenal-type middle aortic syndrome, with no anatomical abnormalities detected in either renal or visceral arteries. Furthermore, genetic testing revealed no pathogenic mutations, and there was no relevant family history of genetic disorders. Histopathological examination of the stenotic vessel excluded arteritis, as no significant inflammatory cell infiltration was observed in the adventitia, supporting the likelihood of an idiopathic aetiology in this patient.
Pure medical management often fails to adequately control blood pressure in patients with middle aortic syndrome. Therapeutic interventions for middle aortic syndrome include stent angioplasty or surgical vascular reconstruction, with surgical timing determined by the severity of hypertension, the extent of end-organ damage, and the potential for further vascular growth. Surgical complications (e.g., graft stenosis, bleeding, thrombosis, deterioration of biological conduits) occur in approximately 9% of cases, with a mortality rate ranging from 2.9% to 4%. Reference Che, Xiong and Jiang5,Reference Lőrinczy, Benkő and Fazekas6 Given the patient’s age, height, weight, and the length of vascular stenosis, coupled with the lack of appropriately sized vascular stents available at our institution and considerations for the patient’s long-term vascular development, stent angioplasty may not be suitable for this patient. Detailed interpretation of computed tomography angiography images was performed to assess whether the collateral vessels around the upper and lower margins of the stenotic segment functioned as nutrient vessels to the spinal cord or other vital organs. Intraoperatively, continuous tracing and confirmation of these collateral vessels were performed during the anatomical dissection of the stenotic aorta. Following a comprehensive evaluation, the stenotic vascular segment was confirmed to lack branches supplying vital organs, rendering complete resection feasible; thus, surgical replacement with a synthetic vascular graft was selected for this patient. The procedure was performed via a left sixth intercostal thoracotomy without extracorporeal circulation, an approach intended to minimise surgical trauma. During aortic cross-clamping, local ice packs were applied for spinal cord and visceral protection, and renal oxygenation was continuously monitored using near-infrared spectroscopy. Vascular reconstruction was accomplished using a 14 mm Intergard knitted vascular graft—an option that sufficiently meets the patient’s physiological needs during the transition to adulthood. Currently, there is a paucity of large-scale clinical studies comparing vascular graft material selection, particularly in the paediatric aortic disease population. As such, each institution must select a relatively appropriate vascular substitute for paediatric patients based on its own resources and clinical circumstances.
Conclusion
Middle aortic syndrome is a rare yet clinically significant cause of hypertension in children and young adults. Early recognition is critical for accurate diagnosis and timely intervention, as prompt treatment can optimise hypertension management and minimise end-organ damage. Following comprehensive evaluation, prosthetic graft replacement emerges as an effective therapeutic option for paediatric patients with suprarenal-type middle aortic syndrome.
Data availability statement
The authors will supply the relevant data in response to reasonable requests.
Acknowledgements
Not applicable.
Author contributions
All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Yiqing Pu and Hangyan Zhao. The first draft of the manuscript was written by all authors, who commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Financial support
The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.
Competing interests
The authors have no relevant financial or non-financial interests to disclose.
Ethical standard
The Research Ethics Committee of The Children’s Hospital, Zhejiang University School of Medicine, formally waived review in accordance with institutional policy. This manuscript reports a single clinical case using de-identified information and involves no experimental intervention. Written informed consent for publication of the clinical details and accompanying images was obtained from the patient’s legal guardian.
