Postoperative cytotoxic cerebral edema following surgical resection of a giant right atrial aneurysm in an infant: a rare case report

Abstract

This case report describes a rare case of a giant right atrial aneurysm (RAA) in a 7-month-old male infant admitted to Children’s Hospital Affiliated to Zhengzhou University in July 2025. A RAA was detected during a physical examination at 2 months of age with no clinical symptoms present. Follow-up reexamination at 7 months of age revealed progressive enlargement of the RAA, and the infant thus underwent aneurysm resection plus atrial septal defect repair under cardiopulmonary bypass. Postoperative histopathological examination confirmed the diagnosis of RAA. On the second postoperative day, the infant developed neurological complications including lethargy, skew deviation, mild hemiplegia, and focal epilepsy. The hospital immediately implemented a multimodal intervention strategy involving mannitol for dehydration, glucocorticoids for anti-inflammation, antiepileptic medication, and strict fluid management. The infant achieved near-complete recovery of neurological function at discharge on the 21st postoperative day, with significant improvement in brain abnormalities on follow-up at 1 month postoperatively. This case highlights cytotoxic cerebral edema, a rare postoperative neurological complication following RAA resection in children, and emphasizes the importance of early identification and multimodal treatment for such complications, providing valuable clinical evidence for the perioperative management of pediatric cardiac surgery.

Plain Language Summary

Cerebral swelling after heart surgery for a large heart artery bulge in a young baby

We describe a 7-month-old baby who had surgery to fix a large, rare bulge in the wall of the right upper heart chamber. The surgery went well, but two days later the baby became sleepy, had weak movement on one side of the body, and brief seizures. Brain scans showed swelling inside brain cells, a rare complication after heart surgery with a heart-lung bypass machine. We treated the baby with medicines to reduce brain swelling, control seizures, and limit fluid intake. After about three weeks, the baby recovered almost completely and went home. At one-month follow-up, brain swelling was much better, and the baby had no lasting weakness or seizures. This case shows that babies can have rare but serious brain swelling after this type of heart surgery. Close watching and quick, combined treatment can help babies recover well. Doctors should look for early signs of brain problems after infant heart surgery.

Keywords

cardiopulmonary bypass case report cerebral edema infant right atrial wall aneurysm

Introduction

Right atrial aneurysm (RAA) is a rare congenital disorder characterized by outward bulging of the atrial wall due to focal abnormal development of atrial myocardium. Although most cases are asymptomatic, untreated RAAs may lead to severe complications such as atrial fibrillation, thromboembolism, and even sudden cardiac death due to atrial rupture.^1
–3 For symptomatic or progressively enlarging aneurysms, surgical resection is generally recommended in clinical practice, as conservative treatment cannot prevent disease progression and the occurrence of related risks. However, pediatric cardiac surgery under cardiopulmonary bypass (CPB) carries a high risk, which is particularly prominent in infants due to immature organ systems, increased vascular permeability, and high cerebral oxygen demand.^4
–6 Postoperative neurological complications are a major clinical concern in this population, with known etiologies including CPB-related inflammation, ischemia-reperfusion injury, temperature fluctuations, embolic events, and cerebral hypoperfusion.^4,7 At present, reports on cytotoxic cerebral edema complicating RAA resection in infants are rare in domestic and international literature. Therefore, this case has important clinical reference value for pediatric cardiac surgeons and perioperative medical staff and provides new clinical data for the diagnosis and treatment of rare neurological complications after pediatric cardiac surgery.

Case presentation

The reporting of this study conforms to the CARE guidelines for case reports (Supplemental Material).⁸ All patient details have been de-identified to protect patient privacy.

Patient history

A 7-month-old male infant (weight: 8.2 kg) was admitted with a 5-month history of a progressively enlarging RAA detected by echocardiography shortly after birth. Initial chest X-ray revealed a small aneurysm (Figure 1), and conservative management with regular follow-up was advised. During follow-up, chest X-ray showed gradual enlargement of the aneurysm (Figure 2). The patient had no symptoms of respiratory distress, feeding difficulties, or cyanosis. Preoperative echocardiography demonstrated a cystic cavity measuring approximately 38.8 × 24.1 × 30.6 mm³ with multiple access channels to the right atrium, the largest being 2.5 mm in width. A secundum-type atrial septal defect (ASD) of 4.0 mm was also noted. Cardiac computed tomography angiography confirmed these findings, showing a large cystic structure (46.4 × 24.7 × 32.1 mm³) communicating with the right atrium through a 5.6 mm orifice (Figures 3 and 4).

Figure 1.

Initial chest X-ray image showing a small right atrial aneurysm at 2 months of age.

Figure 2.

Follow-up chest X-ray image showing progressive enlargement of the right atrial aneurysm.

Figure 3.

Preoperative cardiac CTA displaying the large cystic aneurysmal structure communicating with the right atrium. Scale: 12 cm, magnification: None.

Figure 4.

Three-dimensional reconstruction of cardiac CTA highlighting the size and extent of the right atrial aneurysm.

Laboratory tests revealed normal hemoglobin (134 g/L), liver function (ALT 24.1 U/L), and renal function (creatinine 16.0 µmol/L). The patient had a history of mild respiratory infections and was born at term after a 1-week premature labor.

Surgical procedure

The patient underwent surgical excision of the RAA and ASD repair under CPB with moderate hypothermia. A right thoracotomy approach through the fourth intercostal space was used. Upon exploration, the right atrium was significantly enlarged, and a large aneurysmal sac measuring approximately 3.5 × 3.5 × 5.0 cm³ was identified. The aneurysmal wall consisted of an outer fibrous layer and an inner muscular layer, separated by a cystic cavity communicating with the right atrium through a 1.0 cm orifice. Two centrally located ASDs, measuring 0.6 and 0.1 cm, were noted and repaired using a 6/0 Prolene continuous suture.

After aneurysm resection, the right atrial wall was reconstructed with continuous suture using 5-0 polypropylene thread. The surgery was uneventful, with a total CPB duration of 40 min and aortic cross-clamp time of 25 min. Intraoperatively, 167 mL of crystalloid fluid and 50 mL of autologous blood were infused, and the urine output was 80 mL. Histopathological examination of the resected tissue (Figure 5, HE staining, magnification ×100) showed that the aneurysm wall was a fibromuscular cystic structure lined with a single layer of flattened epithelium, accompanied by collagen fiber hyperplasia and hyalinization, with scattered elastic fibers and capillaries, consistent with the diagnosis of RAA (Figure 6).

Figure 5.

Histopathological image of the excised right atrial aneurysm: Myocardial fibers are disorganized (blue arrow), collagen fibers are interspersed between muscle bundles (red arrow), with partial hyaline degeneration. Scale: 100 μm, magnification 10×10).

Figure 6.

Postoperative chest X-ray showing a significant reduction in cardiac silhouette following surgical resection of the aneurysm.

Postoperative course

On the second postoperative day (POD), the infant developed lethargy, rightward skew deviation, and mild left-sided hemiplegia (Medical Research Council: muscle strength grade 2). The postoperative neurological symptoms, imaging findings, treatment regimens, and recovery status are summarized in Table 1 (clinical timeline). Magnetic resonance imaging (MRI) was immediately completed, and multimodal comprehensive treatment for cerebral edema and epilepsy was initiated, with the specific regimen as follows:

Table 1.

Clinical timeline of neurological manifestations, diagnosis, treatment, and recovery.

Time point	Neurological manifestations	Examination results	Treatment measures	Recovery status
POD 1	No neurological symptoms	Normal neurological physical examination	Inotropic agents, diuretics, antibiotics, and fluid restriction	Successful extubation, stable vital signs
POD 2	Lethargy, rightward skew deviation, left mild hemiplegia (muscle strength grade 2)	MRI: cytotoxic cerebral edema (bilateral occipital/parietal lobes, periventricular white matter); EEG: focal epilepsy in the occipitoparietal lobe	Mannitol 0.5 g/kg q6h, methylprednisolone 1 mg/kg q12h, phenobarbital loading dose 20 mg/kg + maintenance dose 5 mg/kg qd, strict fluid restriction (80 mL/kg d)	No immediate improvement, stable vital signs
POD 6	Resolution of skew deviation, no clinical epileptic seizures, relief of lethargy	EEG: no epileptiform discharges	Continuous use of mannitol, methylprednisolone, and phenobarbital; addition of oxcarbazepine 5 mg/kg bid	Improvement of mild hemiplegia (muscle strength grade 3)
POD 12	No neurological symptoms at rest, mild left upper limb weakness	MRI: partial resolution of cerebral edema	Methylprednisolone was reduced to 0.75 mg/kg q12h; phenobarbital was switched to oral administration	Improvement of mild hemiplegia, upper limb muscle strength grade 4, lower limb muscle strength grade 4+
POD 21 (discharge)	Near-normal muscle strength (grade 5), no epilepsy, skew deviation, or lethargy	—	Discontinuation of mannitol; methylprednisolone reduced to 0.25 mg/kg q12h (discontinued on POD 14); continuous oral oxcarbazepine 5 mg/kg bid	Basic functional recovery, normal feeding and activity, discharged from the hospital
One-month follow-up	No neurological deficit symptoms, no epileptic seizures	Chest X-ray: marked reduction in cardiac shadow; MRI: basic resolution of cerebral edema in the cortical area, mild residual signal changes in the periventricular area	Oral oxcarbazepine 8 mg/kg bid	Good neurological recovery; neurodevelopmental assessment scheduled at 3/6/12 months postoperatively

bid, twice daily; EEG, electroencephalograph; MRC, Medical Research Council muscle strength grading; MRI, magnetic resonance imaging; POD, postoperative day; q6h, every 6 h; q12h, every 12 h; qd, once daily.

(1) Mannitol (20% injection, 0.5 g/kg intravenous drip, q6h for 5 days) to reduce intracranial pressure;

(2) Methylprednisolone (1 mg/kg intravenous drip, q12h for 7 days, then reduced by 0.25 mg/kg every 2 days until discontinuation on the 14th POD) to alleviate cerebral edema and inflammatory response;

(3) Phenobarbital (loading dose 20 mg/kg intravenous drip, maintenance dose 5 mg/kg qd for 10 days) to control epileptic seizures;

(4) Strict fluid management (80 mL/kg d) to maintain electrolyte balance;

(5) Oxcarbazepine (5 mg/kg bid, initiated on the fifth POD) for long-term prevention of epileptic seizures, with a gradual transition from intravenous phenobarbital to oral antiepileptic drugs.

Discussion

Pathophysiological characteristics and surgical indications of RAA

RAA is a rare congenital cardiac malformation (incidence <0.1% in pediatric cardiac disease).^1
–3 defined by focal myocardial dysplasia and atrial wall bulging. Most asymptomatic lesions are incidentally identified on imaging, with small, non-progressive aneurysms managed conservatively with regular follow-up.¹ However, progressive enlargement evident in this 7-month-old infant represents a key surgical indication, as it correlates with heightened risks of atrial rupture, thromboembolism, arrhythmia, and cardiac insufficiency.^2,3 Despite the absence of clinical symptoms, the infant’s aneurysm showed rapid growth from 2 to 7 months of age, necessitating elective resection to prevent fatal cardiac complications. This case confirms that progressive RAA is an independent surgical indication even in asymptomatic infants, and underscores the importance of close imaging follow-up for incidentally detected aneurysms in children, particularly in infants under 1 year with immature cardiac development.

Pathogenesis of postoperative cytotoxic cerebral edema

Cytotoxic cerebral edema, a rare severe complication of pediatric CPB cardiac surgery, arises from intracellular fluid accumulation due to cerebral metabolic and ion pump dysfunction.^4,7 The infant developed this complication on POD 2, and a systematic assessment was performed to verify potential pathogenic mechanisms.

CPB-related inflammation and ischemia-reperfusion injury

This was the primary suspected mechanism. CPB triggers systemic inflammation via blood-artificial material contact, increasing proinflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6))^9
–11 and inducing vascular and endothelial dysfunction in the immature brain. Ischemia–reperfusion injury further impairs cerebral cells, inhibits Na⁺-K⁺-ATPase (sodium-potassium adenosine triphosphatase), and leads to cytotoxic cerebral edema. Despite 32°C moderate hypothermia for neuroprotection, short-duration CPB (40 min) still caused inflammation and reperfusion injury in the immature brain,⁶ due to an underdeveloped blood–brain barrier and immature immune system.

Embolic events

Microemboli (gas, thrombus, tissue debris) from the aneurysm were a potential secondary factor. Preoperative imaging, intraoperative exploration, and transesophageal echocardiography ruled out intracystic thrombus and gas embolism; brain MRI excluded large-vessel embolism. However, microembolism from aneurysm resection tissue debris could not be fully excluded, possibly exacerbating cerebral damage.

Other potential factors

Stable perioperative hemodynamics (CPB mean arterial pressure 40–50 mmHg; postoperative systolic blood pressure 80–100 mmHg) and no MRI evidence of hypoperfusion injury ruled out severe cerebral hypoperfusion. POD 2 focal epilepsy (electroencephalograph (EEG)-confirmed) was a consequence of edema, and was rapidly controlled to avoid secondary injury. Strict perioperative temperature control (32°C hypothermia with gradual rewarming; postoperative 36.5°C–37.5°C) excluded temperature fluctuations as a major cause.

In summary, CPB-related inflammation and ischemia-reperfusion injury were the primary causes, with aneurysm resection-induced microembolism as a potential secondary trigger. The infant’s immature brain (high vascular permeability, underdeveloped blood–brain barrier, high cerebral metabolic demand)^4,6 was highly susceptible to such injuries, being a key contributor to this complication.

Treatment strategy for postoperative cerebral edema in infants

This case confirms that cytotoxic cerebral edema following pediatric CPB surgery requires timely, multimodal interventions, with core measures including intracranial pressure reduction, anti-inflammation, antiepileptic therapy, strict fluid/hemodynamic management, and continuous neurological monitoring. Mannitol rapidly lowers intracranial pressure to relieve cerebral edema, while methylprednisolone inhibits proinflammatory cytokine release and reduces inflammation and vascular permeability.^4,11 Antiepileptic drugs control seizures to avoid secondary brain injury, and strict fluid management maintains intracranial fluid balance and prevents edema exacerbation. Despite severe initial neurological deficits in this infant, early identification and multimodal treatment achieved near-complete neurological recovery, highlighting the value of prompt recognition and comprehensive therapy for postoperative cerebral edema in infants, as well as the need for individualized treatment plans based on age and condition.

Neurological prognosis and follow-up

This case documents the infant’s short-term neurological prognosis at 1 month postoperatively, with near-complete motor function recovery and significant resolution of cerebral edema on brain MRI. However, long-term neurodevelopmental follow-up is critical for infants with CPB-related neurological complications, as the immature brain may develop delayed deficits (e.g., cognitive/motor impairment, epilepsy)^4,6 even after short-term clinical recovery. This case stresses that long-term neurodevelopmental follow-up should be part of routine postoperative care for such pediatric cardiac surgery patients, with a multidisciplinary team (pediatric cardiologists, neurologists, developmental pediatricians) involved in their management. Regular neurodevelopmental assessments, brain imaging, and EEG monitoring are necessary for timely detection and intervention of potential abnormalities to optimize children’s long-term quality of life.

Literature review of neurological complications in pediatric cardiac surgery

Postoperative neurological complications are major causes of morbidity and mortality in pediatric cardiac surgery, affecting 5%–20% of infants undergoing CPB,^4,6 including cerebral edema, infarction, epilepsy, and neurodevelopmental delay. Key risk factors are young age (<1 year), low body weight, prolonged CPB, deep hypothermic circulatory arrest, and preoperative hemodynamic instability.^4,5,7 Recent studies highlight CPB-related inflammation as a key contributor to these complications,^9
–11 and anti-inflammatory agents (e.g., glucocorticoids, interleukin-1 receptor antagonists) have been trialed for neuroprotection, with inconsistent efficacy in children, possibly due to age, surgical type, and dosage variation.¹¹ Cytotoxic cerebral edema following infant RAA resection is rarely reported, and this case adds novel evidence for such rare post-pediatric cardiac surgery neurological complications, while providing clinical support for multimodal management of this condition in infants.

Study limitations

This case report has the following limitations. First, the follow-up duration is short, and only the short-term neurological and cardiac prognosis at 1 month postoperatively is reported; long-term follow-up of at least 1 year is required to evaluate whether the infant has persistent neurodevelopmental deficits and long-term cardiac function. Second, proinflammatory cytokines such as TNF-α and IL-6 were not detected during the perioperative period, failing to provide objective laboratory evidence for CPB-related inflammation as the main pathogenesis of cerebral edema. Third, this study is a single-center, single-case report with limited generalizability of the results; multicenter case series studies or cohort studies are needed to further clarify the incidence, risk factors, and optimal treatment regimens for this rare complication. Fourth, advanced neuroimaging techniques such as diffusion-weighted imaging and magnetic resonance spectroscopy were not used to further evaluate cerebral edema and neuronal metabolism, failing to obtain more detailed diagnostic information and pathological changes of cerebral cells.

Conclusion

We report a rare case of cytotoxic cerebral edema after giant RAA resection and ASD repair in a 7-month-old infant, a seldom-reported complication in pediatric cardiac surgery. CPB-related inflammation and ischemia–reperfusion injury are the primary pathogenic mechanisms, with infantile immature brains heightening such injury susceptibility. Clinically, enhanced early postoperative neurological monitoring is needed for infants undergoing this surgery; multimodal interventions should be initiated promptly upon the onset of neurological complications. A multidisciplinary team should oversee perioperative and long-term management, with sustained neurodevelopmental follow-up to optimize children’s short- and long-term prognosis. This case adds novel clinical data to pediatric cardiac surgery and offers valuable insights for the early identification, diagnosis, and treatment of rare postoperative neurological complications in infants.

Supplemental Material

sj-pdf-1-tak-10.1177_17539447261453502 – Supplemental material for Postoperative cytotoxic cerebral edema following surgical resection of a giant right atrial aneurysm in an infant: a rare case report

Supplemental material, sj-pdf-1-tak-10.1177_17539447261453502 for Postoperative cytotoxic cerebral edema following surgical resection of a giant right atrial aneurysm in an infant: a rare case report by Hui Yan, Yang Zhou, Kaiyuan Li, Ruiling Feng, Bo Zhai and Zhenliang Chen in Therapeutic Advances in Cardiovascular Disease

Footnotes

Acknowledgements

This manuscript’s Plain Language Summary was generated with AI assistance from Cactus (Editage) and verified by the authors.

Declarations

ORCID iD

Zhenliang Chen

Supplemental material

Supplemental material for this article is available online.

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