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Successful embolisation of coronary artery fistulas with the Azur® CX peripheral coil system in three paediatric patients

Published online by Cambridge University Press:  24 February 2025

Emine Gulsah Torun Open the ORCID record for Emine Gulsah Torun [Opens in a new window] ,
Utku Pamuk Open the ORCID record for Utku Pamuk [Opens in a new window] ,
Velihan Çayhan Open the ORCID record for Velihan Çayhan [Opens in a new window]  and
Hazım Alper Gürsu Open the ORCID record for Hazım Alper Gürsu [Opens in a new window]
Emine Gulsah Torun*
Affiliation:
Department of Pediatric Cardiology, University of Health Sciences, Ankara Bilkent City Hospital, Cankaya, Ankara, Turkey
Utku Pamuk
Affiliation:
Department of Pediatric Cardiology, University of Health Sciences, Ankara Bilkent City Hospital, Cankaya, Ankara, Turkey
Velihan Çayhan
Affiliation:
Department of Radiology, University of Health Sciences, Ankara Bilkent City Hospital, Cankaya, Ankara, Turkey
Hazım Alper Gürsu
Affiliation:
Department of Pediatric Cardiology, University of Health Sciences, Ankara Bilkent City Hospital, Cankaya, Ankara, Turkey
*
Corresponding author: E.G.Torun; Email: drgtorun@gmail.com
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Abstract

Coronary artery fistulas are rare cardiac anomalies, often asymptomatic and frequently discovered incidentally during routine cardiac imaging. Transcatheter closure with coil embolisation is increasingly recognised as a preferable alternative to surgical intervention due to its lower complication rates. In this report, we present three paediatric cases in which coronary artery fistulas were successfully embolised using the Azur® CX Peripheral Coil System. This system demonstrates low-profile suitability for occluding highly tortuous vessels in children, enabling controlled coil delivery via a microcatheter. Its hydrogel-coated coils allow for expansion between gaps, making it highly effective as a minimally invasive treatment.

Keywords

coil embolisationcoronary artery fistulatranscatheter closureAzur® CX Peripheral Coilchildren

Information

Type
Brief Report
Information
Cardiology in the Young , Volume 35 , Issue 3 , March 2025 , pp. 645 - 648
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Copyright
© The Author(s), 2025. Published by Cambridge University Press

Introduction

Coronary artery fistulas are abnormal communications between one or more coronary arteries and a heart chamber or great vessel. They can be congenital or acquired. Coronary artery fistulas are rare, occurring in only 0.002% of the general population and visualised in 0.2–0.25% of patients undergoing catheterisation. Reference Dodge-Khatami, Mavroudis and Backer1,Reference Gowda, Vasavada and Khan2 Management options for coronary artery fistulas include surgical ligation or interventional approaches using embolisation coils, occlusion devices such as plugs, or covered coronary stents. Reference Gowda, Vasavada and Khan2,Reference Balanescu, Sangiorgi, Castelvecchio, Medda and Inglese3

In this report, we present three paediatric patients with coronary artery fistulas that were effectively embolised using the low-profile Azur® CX Peripheral Coil System (HydroCoil, Terumo Medical Corporation, Somerset, NJ, USA), highlighting the success of this minimally invasive procedure.

Cases presentation

Case 1

An asymptomatic 16-year-old adolescent presented to the cardiology outpatient clinic for routine evaluation. Physical examination, including cardiac auscultation, was unremarkable. Teleradiography showed mild cardiomegaly, and the resting electrocardiogram was normal. Troponin I and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were within normal limits. Echocardiography revealed left ventricular dilatation, enlargement of the left coronary artery, and shunt flow at the main pulmonary artery. CT angiography confirmed the dilatation of left coronary artery and the presence of a vascular structure consistent with a coronary fistula originating from the left coronary artery and draining into the main pulmonary artery. In addition, the fistula showed focal saccular aneurysmal dilatation in the anterior portion of the pulmonary artery.

The patient was referred to the catheterisation laboratory. A selective left coronary angiogram demonstrated a tortuous fistula between the left coronary artery and the pulmonary artery, accompanied by an aneurysm near the entry into the pulmonary artery (Figure 1 a). A selective right coronary angiogram revealed two fine fistulas, both draining into the aneurysm associated with the coronary artery fistula originating from the left coronary artery. The bilateral communicating fistulas formed an aneurysm before draining into the main pulmonary artery.

Figure 1.

Selective left coronary angiography images of Case 1: (a). A large coronary fistula (black arrow) and an aneurysm (black arrowhead) at presentation. (b). The coil-embolised fistula (white arrowhead).

The anatomical characteristics and dimensions of the coronary arteries and fistulas were assessed through coronary angiography. A 0.014-inch guidewire was advanced through a 4-F Judkins left coronary artery guiding catheter to the proximal origin of the main fistula. A 2.7-F Progreat® microcatheter (Terumo; Somerset, NJ, USA) was positioned within the aneurysm. The aneurysm sac was filled with four coils (one 6 mm × 20 cm, two 4 mm × 13 cm, and one 3 mm × 4 cm Azur® CX peripheral coils, Terumo). A selective coronary angiogram performed 5–10 minutes after embolisation revealed the complete exclusion of the aneurysm (Figure 1 b). During the 17-month follow-up, echocardiography confirmed normalisation of left ventricular dimensions. The patient completed 6 months of oral acetylsalicylic acid therapy (3–5 mg/kg) and remains clinically stable and asymptomatic without medication.

Case 2

A 16-year-old asymptomatic adolescent attended a routine evaluation at the cardiology outpatient clinic. Physical examination revealed a systolic murmur graded 2/6. Cardiac enzymes and NT-proBNP were within normal limits. Echocardiography showed left ventricular dilatation and left coronary artery enlargement, with evidence of shunt flow at the main pulmonary artery. Cardiac catheterisation was scheduled for percutaneous coronary artery fistula occlusion. Coronary angiography revealed a coronary fistula originating from the left main coronary artery and draining into the pulmonary artery (Figure 2 a). The left coronary arterial ostium was entered with a 4-F JL4 catheter, through which a 2.7-F Progreat® microcatheter (Terumo; Somerset, NJ, USA) and 0.014-inch guidewire were positioned within the fistula. A 3 mm/4 cm Azur CX coil was used to occlude the coronary artery fistula. A selective coronary angiogram performed 5–10 minutes after embolisation showed the complete closure of the fistula and revealed a previously undetected, thin coronary fistula (Figure 2 b). During the patient’s 15-month follow-up, left ventricular dimensions returned to normal. The patient completed a 6-month course of oral acetylsalicylic acid therapy (3–5 mg/kg) and was regularly monitored with echocardiography, clinical evaluations, and electrocardiography. The patient remains in a clinically stable and asymptomatic condition without medication.

Figure 2.

Selective left coronary angiography images of Case 2. (a). A coronary fistula (black arrow) at presentation. (b). The coil-embolised first fistula (black arrow) and a second, thin coronary fistula (white arrow).

Case 3

A six-year-old girl, followed up in our paediatric cardiology clinic for the past year, had a diagnosis of a coronary fistula between the right atrium and the right coronary artery. At her most recent visit, findings included right coronary artery dilation (Z-score: 5.2) and right heart chamber enlargement, prompting the decision for fistula closure.

The patient was referred to the catheterisation laboratory, where a selective right coronary angiogram confirmed the presence of a coronary fistula originating from the right coronary artery and draining into the right atrium (Figure 3 a). The anatomical characteristics and dimensions of the coronary arteries and fistula were evaluated through coronary angiography. A 0.014-inch guidewire was advanced through a 4-F Judkins right coronary artery guiding catheter to the proximal origin of the fistula. A 2.7-F Progreat® microcatheter (Terumo; Somerset, NJ, USA) was positioned within the fistula.

Figure 3.

Angiography images of Case 3. (a). Aortic root angiography (left anterior oblique view at 30°) image showing a coronary artery fistula (white arrowhead) from a dilated right coronary artery (black arrow) to the right atrium. (b). Selective right coronary angiography image showing the coil-embolised fistula (white arrow).

The fistula was successfully embolised using one 3×8 mm and one 4×13 mm Azur® CX peripheral coils (Terumo). A selective coronary angiogram performed 5–10 minutes after the procedure confirmed the complete closure of the fistula (Figure 3 b). The patient has been followed for 4 months post-procedure and remained clinically stable and asymptomatic. Echocardiography revealed a reduction in the dimensions of the right heart chambers. The patient was administered oral acetylsalicylic acid therapy (3–5 mg/kg) for 6 months as part of the post-procedural management plan.

Discussion

Coronary artery fistulas exhibit a heterogeneous range of morphological configurations and clinical presentations. Most adult patients with coronary artery fistula are asymptomatic. Reference Gowda, Vasavada and Khan2,Reference Balanescu, Sangiorgi, Castelvecchio, Medda and Inglese3 In contrast, a higher proportion of paediatric patients experience symptoms. Reference Wang, Hsieh, Shen and Lin4 The clinical presentation is influenced by the severity of the left-to-right shunt. Progressive enlargement of the fistula and an increase in the left-to-right shunting can lead to pulmonary hypertension, congestive heart failure, or myocardial ischaemia. Reference Gowda, Vasavada and Khan2,Reference Wang, Hsieh, Shen and Lin4

The primary indications for closure are clinical symptoms, particularly heart failure and myocardial ischaemia. In asymptomatic patients with high-flow shunts, closure is recommended to prevent symptoms or complications, especially in the paediatric population. Reference Gowda, Vasavada and Khan2–Reference Wang, Hsieh, Shen and Lin4

The management of coronary artery fistulas includes surgical ligation and interventional approaches, such as covered coronary stent grafts or coil embolisation. Reference Gowda, Vasavada and Khan2,Reference Balanescu, Sangiorgi, Castelvecchio, Medda and Inglese3,Reference Armsby, Keane, Sherwood, Forbess, Perry and Lock5 Transcatheter closure has been shown to be safe and effective, supporting its use for closing clinically significant coronary artery fistulas in childhood. The choice of approach depends on the fistula’s anatomy, any associated defects, and the experience of the interventional cardiologist and surgeons. Reference Balanescu, Sangiorgi, Castelvecchio, Medda and Inglese3,Reference Loureiro, Ewert and Eicken7

The Azur® CX Peripheral Coil System (HydroCoil, Terumo Medical Corporation, Somerset, NJ, USA) combines a hydrogel-coated platinum coil in a 3D spherical shape with a screwless, proprietary delivery system, offering several advantages over traditional stainless steel pushable coils. This coil is available in a detachable delivery format with wire diameters of 0.018 and 0.035 inches and features loops of variable diameters (2–20 mm) and lengths (2–40 cm). Its smaller first loop facilitates the placement of the coil within tortuous anatomies. Unlike the previous version, the Azur® CX coil does not require pre-delivery hydration to enhance its softness profile, and it can be repositioned up to 30 minutes after delivery. The system is compatible with the Progreat® microcatheter (Terumo; Somerset, NJ, USA), allowing precise coaxial placement and positioning of the coil in fistulas through a 4-F catheter. Another significant advantage is that these coils are detached using the Azur Detachment Controller, which enables precise placement with minimal movement. Additionally, the hydrogel-coated platinum coil structure does not produce significant artefacts on magnetic resonance imaging, which is particularly beneficial for patients requiring lifelong monitoring. Reference Goldstein, Aiyagari, Bocks and Armstrong6,Reference Loureiro, Ewert and Eicken7

Compared to other peripheral coils of similar size, the Azur® CX Peripheral Coil offers greater volume and packing density per unit length. This design advantage arises from cross-sectional coverage that allows hydrogel-assisted expansion into gaps, creating a solid core coil that enhances volume filling. Thus, the Azur® CX Peripheral Coil can potentially reduce the number of coils required for small vessel embolisation procedures. Moreover, these coils exhibit a lower midterm recanalization rate than fibred coils. Reference Goldstein, Aiyagari, Bocks and Armstrong6–Reference Fohlen, Namur, Ghegediban, Laurent, Wassef and Pelage8

In this report, we presented the successful use of the Azur® CX Peripheral Coil, which is rarely used in children, for coronary artery fistula closure in three paediatric patients. Due to its advantages, such as a smaller delivery profile, enhanced delivery control, and improved volumetric filling of vessels, this coil can be considered safe and effective for managing coronary artery fistulas. However, further studies with larger patient cohorts are necessary to validate these findings, establish a more comprehensive safety profile, and provide a detailed comparison of the Azur® CX system with other closure devices commonly used in the management of coronary artery fistulas.

Competing interests

The authors declare none.

References

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Figure 0

Figure 1. Selective left coronary angiography images of Case 1: (a). A large coronary fistula (black arrow) and an aneurysm (black arrowhead) at presentation. (b). The coil-embolised fistula (white arrowhead).

Figure 1

Figure 2. Selective left coronary angiography images of Case 2. (a). A coronary fistula (black arrow) at presentation. (b). The coil-embolised first fistula (black arrow) and a second, thin coronary fistula (white arrow).

Figure 2

Figure 3. Angiography images of Case 3. (a). Aortic root angiography (left anterior oblique view at 30°) image showing a coronary artery fistula (white arrowhead) from a dilated right coronary artery (black arrow) to the right atrium. (b). Selective right coronary angiography image showing the coil-embolised fistula (white arrow).