Abstract
Purpose:
We retrospectively analyzed the effect of coil type on the number of coils used and the procedure time in pre-Fontan coil embolization of collateral arteries.
Material and Methods:
Twelve patients with congenital heart disease underwent coil embolization before Fontan surgery between 2010 and 2021. They were divided into 2 groups. Group A comprised 6 patients who underwent coil embolization before the introduction of longer microcoils (≥30 cm) and group B comprised 6 patients who underwent embolization after the introduction of the microcoils. The primary endpoints (number of coils used, embolized area per patient and the internal thoracic artery, and procedure time) were compared between the 2 groups.
Results:
The number of coils used per patient and internal thoracic artery (groups A vs. B: 36.5 vs. 18; p = 0.036, 11.7 vs 7.4; p = 0.047) and the procedure time (247 vs 180 minutes; p = 0.002) were significantly smaller in group B than in group A. The embolized area per internal thoracic artery was significantly larger in group B than in group A (45 vs. 93.5; p < 0.001). All patients underwent Fontan surgery at a mean of 24 days after embolization. Fontan circulation was established in nine of 12 patients. There were no major complications in either group.
Conclusions:
In pre-Fontan coil embolization, a combination of longer microcoils (≥30 cm) may help reduce the number of coils used and the procedure time, which may decrease the health care cost and radiation exposure.
Keywords: cyanotic single ventricular disease, microcoil, pre-Fontan coil embolization, procedure time
Introduction
In patients with cyanotic single ventricular disease, multiple collateral arteries may develop between the aortic branches and the pulmonary arteries before Fontan surgery [1]. These arteries can lead to volume overload and increased pulmonary arterial and venous pressures in the Glenn and Fontan circulation. Several reports have linked these collateral arteries to postoperative chest drainage duration, ventilatory management, and hospital stay [2-4]. Therefore, coil embolization of these collateral arteries may be performed prior to Fontan surgery.
The collateral arteries requiring coil embolization are often numerous and extensive, necessitating many coils and resulting in extended procedure times and increased health care costs. Although various types of coils exist, no studies have investigated the impact of coil type on the number of coils used or procedure duration for pre-Fontan embolization.
We conducted a retrospective study on patients who underwent coil embolization before Fontan surgery at our hospital to compare the number of coils implanted and procedure times before and after the introduction of longer microcoils (≥30 cm), such as the POD packing coil (Medico's Hirata, Tokyo, Japan) and the i-ED coil Infini ExtraSoft/Soft (Kaneka, Tokyo, Japan).
Material and Methods
Patients
This retrospective study included 12 patients with congenital heart disease who underwent pre-Fontan coil embolization of collateral arteries between the aortic branches and pulmonary arteries from April 2010 to November 2021. At our hospital, coil embolization was performed in patients with prominent collateral arteries identified on preoperative angiography. The mean age of the patients was 2 years 3 months ± 4.7 months (range, 1 year 7 months to 2 years 11 months). The mean height was 83.1 ± 3.9 cm (range, 79.0-92.4 cm) and the mean weight was 10.8 ± 1.2 kg (range, 9.3-13.5 kg). Five patients had a single right ventricle, 3 had tricuspid atresia, 2 had pure pulmonary atresia with an intact ventricular septum, one had a double-inlet left ventricle, and one had a double-outlet right ventricle (Table 1).
Table 1.
Patient Background Information.
| Case | Diagnosis | Age | Sex | Height (cm) | Weight (kg) |
|---|---|---|---|---|---|
| 1 | TA | 2y11m | Female | 83.0 | 10.0 |
| 2 | SRV | 1y7m | Male | 80.5 | 11.6 |
| 3 | DORV | 2y2m | Male | 79.0 | 9.5 |
| 4 | DILV | 2y6m | Male | 86.9 | 10.9 |
| 5 | SRV | 2y | Male | 79.8 | 9.3 |
| 6 | SRV | 2y5m | Male | 84.2 | 10.8 |
| 7 | SRV | 2y1m | Female | 83.5 | 12.0 |
| 8 | PA/IVS | 1y11m | Male | 80.4 | 10.5 |
| 9 | SRV | 2y5m | Male | 82.7 | 11.4 |
| 10 | TA | 2y4m | Female | 85.8 | 10.2 |
| 11 | TA | 1y9m | Male | 79.0 | 9.3 |
| 12 | PA/IVS | 2y10m | Male | 92.4 | 13.5 |
DILV: double-inlet left ventricle; DORV: double-outlet right ventricle; PA/IVS: pulmonary atresia with intact ventricular septum; SRV: single right ventricle; TA: tricuspid atresia
Coil embolization
All procedures were performed under general anesthesia. A 4 Fr sheath (Medikit, Tokyo, Japan) was inserted into the right femoral artery. A 4 Fr IMA catheter (Medikit) or a multi-purpose catheter (Terumo, Tokyo, Japan) and a 1.8-2.6 Fr microcatheter were used for coil embolization of the right and left internal thoracic arteries (ITAs), right and left thyrocervical arteries, right and left thoracoacromial arteries, left lateral thoracic artery, and right and left bronchial arteries. Patients were divided into 2 groups depending on the timing of the procedure and coils used. Group A comprised 6 patients who underwent coil embolization with a Guglielmi Detachable Coil (0.010 or 0.015 inches, 4-10 cm; Stryker, Tokyo, Japan) and/or Target Detachable Coil (0.010 inches, 4-20 cm; Stryker) between April 2010 and January 2015. Group B comprised 6 patients who underwent embolization with Target XL/XXL coils (0.014/0.017 inch, 3-30 cm; Stryker) combined with POD packing coils (0.020 inches, 15-60 cm) and/or i-ED COIL Infini ExtraSoft/Soft coils (0.014 inches, 15-50 cm), between January 2020 and November 2021. Angiography was performed using an Integris BH5000 (Philips, Amsterdam, Netherlands) until May 2011, an Allura Xper FD10C (Philips) from June 2011 to March 2014, and an Allura Clarity FD 20 OR (Philips) from April 2014. All embolization procedures were performed by the same main operator with over 20 years of experience.
Evaluations
The primary endpoints were the number of coils used per patient, the embolized area per patient, the number of coils used per ITA, the embolized area per ITA, and the procedure time required for coil embolization in both groups. The area of the embolization zone (a) (Fig. 1A) and the square area with one side of the outer diameter of a 4 Fr catheter (b) (Fig. 1B) were measured on the frontal X-ray image after embolization, and the embolized area was calculated as a/b. The areas were measured using Adobe Photoshop 2024 (25.6.0) (Adobe Inc., San Jose, CA). Secondary endpoints were the establishment of Fontan circulation, complications, and final outcomes. Complications were graded according to the Common Terminology Criteria for Adverse Events version 5.0.
Figure 1.
Calculation of the embolized area. We traced the embolized area (a) (outlined by dotted lines) in A and set the square area (b) (one side of the square represents the outer diameter of a 4 Fr catheter) in B. The embolized area was calculated as a/b.
Statistical analyses
For continuous variables, normality was considered, and the means and medians were compared using Student's t-test or Wilcoxon's rank sum test, respectively. Nominal variables were compared using Fisher's exact test. P values of < 0.05 were considered statistically significant. Statistical analyses were performed using JMP Pro 14.1.0 (SAS Institute Inc., Cary, NC, USA).
Results
In all 12 patients, microcoils were implanted in the target arteries, and there was no evidence of coil migration or unraveling. Fig. 2 and 3 show a representative patient from groups A and B, respectively. The results of the primary endpoints are provided in Table 2. In group A vs. group B, the median (range) number of coils required for embolization per patient was 36.5 (28.3-46.8) vs. 18 (12.3-22), and the embolized area per patient was 130 (52-163.4) vs. 212 (154.3-251.5). The mean (± standard deviation), number of coils per ITA was 11.7 (±6.4) vs. 7.4 (±2.8), and the embolized area per ITA was 45 (±8.1) vs. 93.5 (±7.8). The procedure time was 247 (235-360) vs. 180 (170-210) minutes. The number of coils used per patient (p = 0.036), the number of coils used per ITA (p = 0.047), and the procedure time (p = 0.002) were significantly lower in group B than in group A. The embolized area per patient did not differ between the 2 groups (p = 0.065). The embolized area per ITA was significantly greater in group B than in group A (p < 0.001) (Fig. 4).
Figure 2.
Pre-Fontan embolization in a boy (1 year 7 months old) with a single right ventricle (patient 2 in group A). (a, b) Arteriography of both subclavian arteries showed numerous collateral vessels from both internal thoracic and thyrocervical arteries (arrowheads). (c) Fluoroscopic image obtained after embolization showing 38 Guglielmi detachable coils inserted into the collateral arteries. The procedure time was 240 minutes.
Figure 3.
Pre-Fontan embolization in a girl (2 years 4 months old) with tricuspid atresia (patient 10 in group B). (a, b) Arteriography of both subclavian arteries showed numerous collateral vessels from both internal thoracic and thyrocervical arteries (arrowheads). (c) Fluoroscopic image after embolization showing 21 microcoils (15 Target XL and XXL coils, 6 POD packing coils) inserted into the collateral arteries. The procedure time was 180 min.
XL: extra large; XXL: double extra large
Table 2.
Results for Individual Patients.
| Group | Case | Coil Type | Length of Coils Used (cm) | Per Patient | Per ITA (Right/Left) | Procedure Time (min) | |||
|---|---|---|---|---|---|---|---|---|---|
| No. of Coils | Embolized Area | No. of Coils | Embolized Area | ||||||
| A | 1 | GDC | 6–8 | 11 | 53 | −/6 | −/27 | 255 | |
| 2 | GDC | 4–12 | 38 | 226 | 14/12 | 107/63 | 240 | ||
| 3 | GDC | 4–20 | 49 | 143 | 19/11 | 44/49 | 360 | ||
| 4 | GDC | 6–10 | 46 | 136 | 8/20 | 20/87 | 240 | ||
| 5 | TDC | 6–20 | 34 | 49 | 2/22 | 5/42 | 220 | ||
| 6 | TDC | 4–20 | 35 | 124 | 6/9 | 25/26 | 360 | ||
| B | 7 | Target XL, XXL POD | 6–60 | 15 | 184 | 9/6 | 94/90 | 140 | |
| 8 | Target XL POD | 3–60 | 7 | 240 | 5/2 | 123/117 | 210 | ||
| 9 | Target XL POD | 6–60 | 14 | 165 | 6/8 | 92/73 | 180 | ||
| 10 | Target XL POD | 6–45 | 21 | 122 | 5/8 | 63/59 | 180 | ||
| 11 | Target XL i-ED ES/S | 6–50 | 21 | 268 | 8/10 | 80/102 | 210 | ||
| 12 | Target XL i-ED ES | 6–30 | 25 | 246 | 9/13 | 93/136 | 180 | ||
–: not embolized; GDC: Guglielmi detachable coil; POD: POD packing coil; i-ED ES/S: i-ED COIL Infini 0.014 inch Extrasoft/Soft; TDC: target detachable coil; XL: extra large; XXL: double extra large
Figure 4.
Comparison of total number of coils per patient (a), embolized area per patient (b), number of coils per ITA (c), embolized area per ITA (d), and procedure time (e).
ITA: internal thoracic artery; n.s.: not significant
All patients underwent Fontan surgery after a mean of 24 ± 16 days. Fontan circulation was successfully established in 9 out of 12 patients (5 in group A, 4 in group B). Although one patient (group B) had a minor cerebral infarct equivalent to grade 2, her mild right hemiparesis disappeared 1 week after embolization. Seven patients (3 in group A, 4 in group B) had grade 1 fever (38.0-39.0°C), and 2 patients (one in group A, one in group B) had grade 2 fever (39.0-40.0°C). There were no grade ≥3 complications. No significant differences were found between the 2 groups in terms of the establishment of Fontan circulation or the frequency of the respective complications (Table 3).
Table 3.
Complications, Establishment of Fontan Circulation, and Final Outcomes of Individual Patients.
| Patient | Complications | Time between embolization and surgery (days) | Establishment of Fontan circulation | Final outcomes |
|---|---|---|---|---|
| 1 | − | 8 | ○ | Alive (16 y), short stature (lower limit of normal), precocious puberty |
| 2 | Fever (grade 2) | 31 | ○ | Alive (15 y) |
| 3 | Fever (grade 1) | 18 | ○ | Alive (15 y) |
| 4 | Fever (grade 2) | 11 | ○ | Alive (13 y) |
| 5 | Fever (grade 1) | 8 | ○ | Deceased (7 y)a |
| 6 | Fever (grade 1) | 8 | × | Deceased (2 y)b |
| 7 | Fever (grade 1) | 64 | ○ | Alive (6 y) |
| 8 | Fever (grade 1) | 22 | ○ | Alive (5 y) |
| 9 | Fever (grade 1) | 22 | × | Deceased (2 y)b |
| 10 | Minor cerebral infarct (grade 2) | 43 | ×c | Alive (5 y) |
| 11 | None | 22 | ○ | Alive (4 y) |
| 12 | Fever (grade 1) | 36 | ○ | Alive (5 y) |
−: no data; ○: Fontan circulation was established; ×: Fontan circulation was not established
aDue to liver failure and rupture of esophageal varices.
bAfter Fontan operation.
cTake-down from Fontan to Glenn circulation.
Discussion
The development of collateral arteries between the aortic branches and the pulmonary arteries is caused by decreased blood oxygen saturation and pulmonary blood flow, postoperative adhesions, and inflammation. A possible underlying mediator could be vascular endothelial growth factor [5, 6]. Some animal studies have shown that collateral arteries develop when pulmonary blood flow is reduced, but these collaterals decrease when the pulmonary blood flow is restored to normal [7, 8]. In patients with cyanotic single ventricle disease, collateral arteries often develop from the branches of the subclavian arteries between Glenn and Fontan surgeries. Because the ITA is a long, thick branch of the subclavian artery, embolization of this artery requires many microcoils. Some insurance companies place an upper limit on the number of coils to be used during embolization, and excessive coils may not be covered by insurance regardless of their necessity. Therefore, it is important to reduce the number of coils used during embolization. In the present study, the number of coils used per patient and per ITA was significantly lower in group B than in group A, and the embolized area per ITA was significantly larger in group B than in group A. Notably, there was no difference between the 2 groups regarding the establishment of Fontan circulation. POD packing coils and i-ED microcoils (both ≥30 cm) may therefore be useful for the embolization of long vessels such as the ITA. For a given coil type, the cost of the coil does not change with its length. Therefore, performing the procedure using longer microcoils (≥30 cm) may help reduce the number of coils required, and thus reduce the cost.
Children with severe congenital heart disease need to undergo cardiac catheterization and interventional treatment as early as the neonatal period. In recent years, advances in medical technology have allowed for interventional procedures for patients with congenital heart disease that could previously only be treated by surgery. It is estimated that about 7% of all cardiovascular angiographic procedures are performed on children aged 0-15 years [9]. Children are 2 to 3 times more sensitive to the stochastic effects of radiation than adults [10]. Furthermore, the relationship between effective dose and the Kerma-area product (KAP; International Commission on Radiological Protection [ICRP]) varies considerably with age. Even for the same KAP value, age produces an approximately 10-fold difference in the effective dose [11]. Children have a longer potential predicted lifespan than adults and therefore have more time to develop radiation-related sequelae. Compared with diagnostic catheterization, interventional treatments tend to involve higher radiation doses due to longer fluoroscopy times and more frequent cine imaging [12]. In addition, because the thyroid and mammary glands are included in the irradiated field in children, these organs are exposed to radiation during each fluoroscopy. Therefore, it is important to optimize radiation protection based on the ALARA principle (As Low As Reasonably Achievable; ICRP) [13]. In the present study, the procedure time was significantly shorter in group B than in group A. The use of longer microcoils (≥30 cm) reduced the procedure time by a median of approximately 60 minutes. Shorter procedure times may reduce the burden of radiation exposure on the patients, doctors, and medical staff.
A minor cerebral infarct was observed in one patient in group B. Patients with cyanosis tend to become polycythemic, and their blood viscosity may increase. The use of contrast media further increases blood viscosity and may cause cerebral thrombosis [14, 15]. Thrombosis can also occur during embolization of collateral arteries originating from the subclavian artery due to their small size in the target vessel. It is important to flush the catheter frequently to remove any air or thrombi, to reduce the procedure time, and to perform the procedure under adequate heparinization. We also observed transient fever after embolization in 9 out of 12 patients. It has been suggested that fever after coil embolization is related to the inflammatory process/cascade as well as the absorption of heat associated with the procedure [16, 17]. Prolonged fever can complicate the response, including systemic management, and may lead to the postponement of surgery or emergency investigation to determine the source of the fever. Therefore, detailed systemic observation is important because it may be difficult to differentiate fever from infection. In this study, we found no significant difference in the frequency of complications between the 2 groups, and the safety of the procedure was comparable between the 2 groups, regardless of the type of coil.
This study has 5 limitations. First, this retrospective study was conducted at a single center, and the number of patients is small. Therefore, prospective studies will be needed in the future. Second, the choice of coils and embolization methods varies between operators. However, the main operator was the same for all 12 patients. Therefore, we believe that there was little influence from different operators. Third, because the fluoroscopic time and exposure radiation dose were unavailable in group A, it was not possible to compare these factors between the 2 groups. Fourth, the embolized area was calculated using the frontal view alone, which means the area in the tangential direction may be underestimated. Fifth, improvements in equipment and devices over time, other than coils, were not considered.
Conclusion
In pre-Fontan coil embolization, a combination of longer microcoils (≥30 cm) may help reduce the number of coils used, procedure time, healthcare costs, and radiation exposure.
Conflict of Interest
None
Author Contribution
All authors contributed to the study conception and design. Masae Deguchi and Tetsuo Sonomura conceived and designed this study. Masae Deguchi analyzed the date and drafted the manuscript. Tetsuo Sonomura, Hirotatsu Sato, Atsufumi Kamisako, Nobuyuki Kakimoto, Takayuki Suzuki, Tomohiro Suenaga, Takashi Takeuchi, Hiroyuki Suzuki, Daisuke Tokuhara, Kodai Fukuda, Nobuyuki Higashino, Akira Ikoma, Hiroki Minamiguchi performed the procedures and provided medical care to patients. Tetsuo Sonomura supervised the project. All authors read and approved the final manuscript.
IRB
This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Research Ethics Committee of Wakayama Medical University on 17 June 2024 (approval number 4186).
Informed Consent
As this was a retrospective study, informed consent to participate and publish was obtained in the form of an opt-out on the website.
Past Presentation
This study has been presented at CIRSE 2024 (an e-poster).
Disclaimer
Tetsuo Sonomura is one of the Editorial Board members of Interventional Radiology. This author was not involved in the peer-review or decision-making process for this paper.
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