Ductus arteriosus aneurysm in neonates

Abstract

This article aims to comprehensively investigate the epidemiology, pathophysiology, diagnostic methods, therapeutic strategies, and prognosis of Ductus Arteriosus Aneurysm (DAA) in neonates, and to analyze the clinical management highlights through specific case studies. DAA is a rare congenital cardiovascular anomaly that can present with subtle symptoms or be misdiagnosed as common neonatal infections. This paper presents a case study of a 22-day-old male neonate diagnosed with a DAA complicated by left pulmonary artery and bronchial compression, which led to respiratory distress and persistent fever failure to respond to conventional anti-infective treatment. The diagnostic process, clinical management, and the outcome of surgical intervention are discussed, with a review of the relevant literature on the pathophysiology, diagnostic criteria, and management strategies for DAA in neonates. This case emphasizes the need for careful differential diagnosis in neonates presenting with persistent fever and respiratory symptoms, particularly when infection markers are elevated but infection etiology remains unclear.

Introduction

Ductus arteriosus aneurysm (DAA) is a rare but significant congenital heart anomaly characterized by abnormal dilation of the ductus arteriosus, and is typically diagnosed in late fetal life or early neonatal period. Although it is considered a rare condition, recent studies suggest that its incidence may be higher than previously thought, with estimates ranging from 1.5 to 8.8% in neonates [1]. Despite these findings, DAA remains underdiagnosed for several reasons. Most DAAs are asymptomatic and often discovered incidentally during routine echocardiography. The diagnosis of DAA relies heavily on imaging techniques such as echocardiography, additionally, the variable morphologic features of DAAs can occasionally result in perplexing imaging appearances, leading to misdiagnosis. There is no universally accepted definition or diagnostic criteria for DAA. Different studies use varying cutoff values for the diameter or length of the ductus arteriosus to diagnose DAA, which can lead to underdiagnosis. Many DAAs spontaneously regress without causing any complications, leading to the possibility that they may not be detected during the brief period they exist. The majority of the literature on DAA consists of case reports or retrospective data, which may miss asymptomatic or mild cases that do not come to clinical attention. This condition, although oftentimes asymptomatic, can be life-threatening when it results in compression of adjacent vascular or bronchial structures [2]. The clinical manifestation of DAA in neonates varies, and early diagnosis is crucial to prevent catastrophic outcomes such as rupture or thrombosis [3, 4]. This study describes a neonate with DAA complicated by significant compression of the left pulmonary artery and mainstem bronchus, which resulted in refractory respiratory symptoms and fever despite anti-infective therapy. The diagnostic workup and the management methods are discussed in detail. The neonate’s patients consented to the study protocol approved by the research ethics committee at Hubei Provincial Women and Child Health Hospital [2023]IEC027.

Case presentation

Patient overview

A 22-day-old male neonate was admitted to our institution with a chief complaint of fever for the past six hours. His history indicated a spontaneous onset of fever (38.1 °C) without identifiable precipitating factors. The infant exhibited poor response to external stimuli, although he continued to feed normally and had no abnormal bowel movements. Laboratory studies showed elevated white blood cell count (WBC: 26.21 × 10^9/L) and C-reactive protein (CRP: 82.82 mg/L), suggestive of an inflammatory or infectious process.

Medical and family history

The neonate was born at 41 weeks of gestation via vaginal delivery, with a birth weight of 3.5 kg. There were no complications during pregnancy, and the Apgar scores were 9 and 10 at 1 and 5 min, respectively. His parents were healthy, with no known genetic or metabolic disorders in the family. The infant had received recommended vaccinations, including hepatitis B and Bacillus Calmette-Guérin (BCG).

Physical examination

On examination, the infant appeared ill and lethargic. Vital signs included: temperature = 38.1 °C, blood pressure = 70/40 mmHg, respiratory rate = 46 breaths per minute, and heart rate = 151 beats per minute. Physical examination revealed soft fontanel, normal pupil reflexes, and no signs of cyanosis or respiratory distress such as subcostal retractions. Auscultation revealed coarse breath sounds with no adventitious noise in the lung, and regular heart rate with no murmurs. The abdominal examination was normal, with the liver palpated 1.5 cm below the right costal margin.

Initial diagnosis

Given the initial clinical findings, neonatal sepsis was suspected, and empirical broad-spectrum antibiotics were initiated. However, the infant’s condition did not improve despite treatment, and respiratory distress appeared in progress. Further diagnostic work-up, including laboratory results and imaging studies, was pursued.

Diagnostic workup

Laboratory results

A second set of blood tests revealed a WBC count of 20.59 × 10^9/L, CRP > 200 mg/L, and a predominance of neutrophils. The procalcitonin level was measured at 0.02ug/L. Blood and urine cultures as well as tests for common respiratory viruses were all negative, ruling out bacterial and viral infections. A comprehensive immunological panel, including TORCH screening and fungal cultures, was also negative, further suggesting that infection was not the primary etiology.

Imaging studies

The initial chest X-ray showed vague and coarse lung markings with scattered patchy opacities (Fig. 1). A repeat X-ray five days later showed worsening lung findings, including enlarged thymic shadow (Fig. 2). Echocardiography showed an interatrial septal shunt flow signal measuring 0.4 cm in the midportion of the atrial septum, along with a rapid heart rate. Chest Computed tomography (CT) demonstrated significant compression of the left pulmonary artery and bronchial narrowing due to a mass-like structure in the mediastinum (Fig. 3).

Fig. 1.

Chest X-ray on admission

Fig. 2.

Chest X-ray repeated on day 5 of admission

Fig. 3.

Chest CT on day 7 of admission

A subsequent Computed Tomography Angiography (CTA) identified a large pseudoaneurysm originating from the aortic end of the ductus arteriosus, which compressed both the left mainstem bronchus and left pulmonary artery, resulting in collapse of the left lung (Fig. 4).

Fig. 4.

CTA on day 10 of admission

Diagnosis

The combination of imaging findings, clinical presentation, and absence of infection collectively led to a diagnosis of DAA complicated by left pulmonary artery and bronchial compression.

Management and treatment

Surgical intervention

The neonate was transferred to a cardiovascular surgical unit for further management. Given the risk of rupture and the significant compression of vital structures, surgery was recommended. The surgery was indeed performed on cardiopulmonary bypass (CPB). The ductus arteriosus aneurysm was successfully resected, and the patent foramen ovale was closed to prevent further complications such as paradoxical embolism, hypoxemia and increased risk of stroke.

Postoperative recovery

Post-surgery, the neonate exhibited gradual improvement in respiratory status, and his fever subsided following the surgical correction. He was closely monitored for potential complications, including respiratory infections or thrombosis. Eventually, he fully recovered with no long-term sequelae.

Discussion

DAA is a rare congenital vascular anomaly characterized by localized dilation or aneurysm because of the failure of the ductus arteriosus to close properly after birth [5]. Normal ductus arteriosus closure occurs in two steps. The first step involves constriction of the media smooth muscle, inducing ischemic hypoxia in the duct wall. Subsequently, intimal cushions protrude into the lumen and thicken the ductal wall via connective and elastic tissue proliferation. In some cases, the aortic end can remain open as an aortic ampulla after the pulmonary end has become occluded and ligamentous. Partial disruption of the normal closure process, with only partial closure of the duct, may predispose to DAA formation. The possible mechanisms of DAA is likely multifactorial, involving partial disruption of the normal ductal closure process, mechanical factors related to in utero curvature and postnatal pressure exposure(such as Marfan, Ehlers-Danlos, Loeys-Dietz, and Larsen syndromes), hormonal influences, and potential associations with connective tissue disorders, infective causes, and protein S deficiency [6–8]. Further research is warranted to elucidate the precise mechanisms underlying this condition.

Clinical manifestations and diagnosis

In neonates, DAA may manifest nonspecific symptoms such as fever, respiratory distress, or failure to thrive [9], which could result in delay in imaging studies that are essential for diagnosing DAA [10]. CT or Magnetic resonance imaging (MRI) is indicated when the diagnosis is in doubt or there is suspicion of associated complications, such as thromboembolism, infection, compression or erosion of adjacent structures, or aneurysm rupture [11]. In this case under investigation, the absence of infection despite elevated inflammatory markers and chest CT findings showing a pseudoaneurysm at the aortic end of the ductus arteriosus that compressed the left pulmonary artery and mainstem bronchus affirmed the definitive diagnosis. The reasons for the failure to detect patent ductus arteriosus (PDA) by echocardiography screening may include the following: First, a large PDA may compress the trachea, and with the interference of lung air, it is difficult to detect when probing from the left side of the pulmonary artery. Second, the shunt volume through the PDA may not be significant. Antenatal diagnosis has improved, leading to better parental awareness and more timely and appropriate intervention [12, 13].

Treatment strategies

While many DAAs resolve spontaneously, those that cause significant compression of adjacent structures, such as the trachea, bronchus, or pulmonary artery, leading to symptoms including respiratory distress, stridor, or feeding difficulties, may require surgical intervention [14, 15]. Previous studies suggested the use of surgical resection to prevent complications such as thrombus formation, thromboembolism, or rupture [3, 4] for DAAs that persist beyond the neonatal period (two months). In cases where DAA is associated with other intracardiac defects, surgical correction may be performed simultaneously. In this studied case, the patient underwent successful surgical resection of the aneurysm, which resulted in relief of compression and a complete recovery. The surgical approach involved median sternotomy or lateral thoracotomy, and in some adult cases, completed with assistance of femorofemoral bypass [16].

Prognosis

The prognosis for neonates with DAA varies; however most cases have a favorable outcome with a high likelihood of spontaneous resolution, particularly when the aneurysm is small in size. Nevertheless, complications such as thromboembolism, compression of surrounding structures, or spontaneous rupture can arise, necessitating close monitoring and potential surgical intervention [4, 15]. Regular echocardiographic follow-up is recommended to monitor the size and behavior of the aneurysm. Surgical intervention may be considered if the aneurysm persists beyond 2 months, shows signs of growth, or is associated with complications [3].

Conclusion

Ductus arteriosus aneurysm is a rare but severe condition that can present with nonspecific symptoms in neonates, often mimicking infections or other common neonatal diseases. Imaging provides a way for early recognition of DAA and therefore enables timely intervention to prevent the associated life-threatening complications. The reported case highlights the importance of considering DAA in the differential diagnosis of neonates with unexplained fever and respiratory distress. Basic imaging such as a chest radiogram can provide initial clues, but echocardiography or advanced imaging is often necessary for a definitive diagnosis. Further investigation of the pathophysiology and management of DAA in neonates is needed to refine treatment protocols and improve patient outcomes.

Abbreviations

DAA

Ductus arteriosus aneurysm

WBC

White blood cell count

CRP

C-reactive protein

BCG

Bacillus Calmette-Guérin

CT

Computed tomography

CTA

Computed tomography angiography

CPB

Cardiopulmonary bypass

MRI

Magnetic resonance imaging

Authors’ contributions

Qianqian Zhou drafted and revised the manuscript, Daicheng Han and Shiwen Xia participated in the clinical evaluation and revised the manuscript. All authors reviewed the manuscript.

Funding

This work was supported by the Public Health Leading Talents Training Program of Hubei Province(No. 1020013003).

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

This study was approved by the hospital ethics committee [2023]IEC027.

Informed consent was obtained from the parents prior to the inclusion in the study.

Consent for publication

Written, informed consent was obtained from the parents.

Competing interests

The authors declare no competing interests.