Short and Long-term Consequences/results of Covered Stents in Children for the Management of Complex Coarctation of the Aorta

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Short and Long-term Consequences/results of Covered Stents in Children for the Management of Complex Coarctation of the Aorta

https://doi.org/10.21203/rs.3.rs-1434571/v1

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Background: The use of covered stents in cases of complex coarctation of the Aorta is now increasing. However, its long-term benefits for children, adolescents and young adults remain unclear. We assessed the long-term results of covered stents in children with complex coarctation of the Aorta.

Methods: Forty-seven children with complex coarctation of the Aorta treated with covered stents were retrospectively assessed. The patients were followed up for 6 to 12 months to evaluate the long-term outcome.

Results: The most common indications for using covered stent were long segment coarctation of the Aorta plus hypoplasia of the aortic arch (23.4%) followed by coarctation of the Aorta with PDA (23.4%) and interrupted aortic arch (19.1%). A single stent was used in 87.2%, two and three covered stents were used in 10.6% and 2.1%, respectively. During follow-up, short-term procedural complications were detected in 25.5% included isolated residual coarctation of the Aorta in 25.0%, followed by residual coarctation of the Aorta plus closure of the left subclavian artery in 16.6%. Short-term complications were femoral artery dissection (8.3%), femoral artery thrombosis (8.3%), stent dislocation and closure of left subclavian artery (8.3%), residual COA and closure of left subclavian artery (16.6%), residual COA (25%), endoleak (8.3%), endoleak and pseudoaneurysm (8.3%), endoteliaztion (8.3%) and retroperitoneal hematoma (8.3%). In long-term following-up, 10.6% showed significant complications including endoleak, residual hypertension, and residual coarctation. Overall, 25.6% underwent re-dilation successfully.

Conclusion: The covered stent can be used as an effective and uncomplicated treatment in children with complex coarctation of the Aorta.

coarctation of the Aorta

stent

outcome

child

Congenital heart disease occurs during fetal growth and development in the uterus and can be triggered by both genetic and environmental factors. About 8 to 11 per 1000 live births are affected by these abnormalities that with or without treatment may lead to the death of the child depending on the severity of the abnormality (in 1 case per 1000 live births) [1–3]. Today, in 47–85% of cases, children with congenital heart disease survive into adulthood [4–6]. In mild cases, conservative treatment in the choice managerial approach is considered, however in severe cases; surgical or interventional management may be necessary [7–9].

Coarctation of the Aorta refers to stenosis of the proximal aortic region with an increase in systemic blood pressure and a systolic pressure difference greater than or equal to 20 mmHg between the upper and lower limbs [10]. Coarctation of the Aorta is the fifth most common congenital heart disease in children accounting for 5–9% of congenital heart defects. After neonatal age, many patients remain asymptomatic, and the disease is detected in routine examinations of upper extremity BP monitoring and absence or weak pulse of the lower extremities [11]. In most patients, the stenosis occurs in the area of the isthmus of the Aorta, and the ratio of the diameter of the stenosis to the diameter of the Aorta at the level of the diaphragm (CoA-index) is less than 60% [12]. In the isolated type (discrete), the length of the stenosis is less than or equal to 5 mm, if this distance is longer, it is determined as long segment stenosis [13]. If not corrected with surgery or intervention, 90% of patients die before the age of 50 and 50% before the age of 10, most often due to heart failure or other complications (i.e. intracranial bleeding). Surgical procedures used to treat aortic coarctation include nowadays as standard an extended end-to end anastomosis, but also repair with a Dacron patch, simple end-to-end anastomosis, Goretex patch aortoplasty, and repair with a left subclavian artery flap are reported [14].

The use of stents is now an established method in the treatment of congenital heart diseases, including aortic coarctation, which is the treatment of choice of these patients whenever suitable. Based on new guidelines, it has largely replaced traditional methods such as surgery [15]. In cases of complex aortic coarctation, a covered stent is used to increase the safety of the procedure. Complex coarctation of aorta includes long-segment coarctation along with aortic arch hypoplasia, pseudoaneurysm or aortic arch aneurysm (post balloon angioplasty or previous surgery), previous history of stenting and breaking the previous stent, aortic dissection that occurred during or before the procedure; aortic coarctation associated with Turner and Marfan syndrome, previous history of surgery in which the Goretex patch was used to repair the coarctation and aortic coarctation associated with patent ductus arteriosus [16]. Today, the use of covered stents in the mentioned cases of complex aortic coarctation is increasing [17], but the long term results, especially in children, are not known. Therefore, due to the importance of the issue, we aimed to assess the short and long-term therapeutic results of applying covered stents in children suffering from complex aortic coarctation.

In total, 47 consecutive children suffering complex coarctation of the aorta that underwent treatment by covered stents were retrospectively assessed. Patients who had another congenital heart disease with COA at the same time except for PDA or cases that could not be followed up were excluded from the study. To conduct this study, after receiving the code of ethics, demographic and clinical information of patients were extracted by reviewing the hospital recorded files from 2009 to 2020 and recorded in the designed study checklist. The information extracted were demographics, medical and interventional history (previously using stent or scheduling surgical repairing), the type and number of covered stents used, the length and diameter of the stent used, and stenting indications. Short term effects of stent implantation, the probable short-term complications including femoral artery dissection or thrombosis, stent dislocation plus the closure of the left subclavian artery, residual coarctation of Aorta, endoleak, pseudoaneurysm, endothelialization, or retroperitoneal hematoma were assessed and recorded. To determine the sources of such complications, the patients were assessed by physical exam, transthoracic echocardiography (TTE) and CT angiography. The patients were also followed up for 6 to 12 months to assess the long-term, post covered stenting outcomes, including femoral artery dissection, femoral artery thrombosis, stent dislocation, closure of left subclavian artery, Residual coarctation, endoleak, pseudoaneurysm, endoteliazation and peritoneal hematoma.

For statistical analysis, results were presented as mean ± standard deviation (SD) for quantitative variables and were summarized by frequency (percentage) for categorical variables. Continuous variables were compared using t-test or Mann-Whitney test whenever the data did not appear to have normal distribution or when the assumption of equal variances was violated across the study groups. The multivariable logistic regression model was used to assess the main determinants of procedural outcome. P values of ≤ 0.05 were considered statistically significant. For the statistical analysis, the statistical software SPSS version 23.0 for windows (IBM, Armonk, New York) was used.

In total, 47 patients (mean age of 14.5 ± 4.4 years, male gender 68.1%) were included in the study. The baseline characteristics of study subjects are summarized in Table 1. Thirty-four patients were hypertensive, and 40.4% had evidence of bicuspid aortic valve. Regarding previous procedural interventions, 23.4% had a history of balloon angioplasty, and 8.5% had a history of surgical COA repair with the use of a LSCA flapp in one patient, end to end anastomosis of the coarctation plus PDA closure in two patients. Moreover, 25.5% had a history of bare stent implantation using Genesis stent in 12.8% and CP stent in 12.8%. The characteristics related to the stents used are shown in Table 2. Regarding the number of covered stents used, one, two and three covered stents were used for 87.2%, 10.6% and 2.1% of patients, respectively. The most common indications for using covered stent were long segment coarctation of the aorta plus hypoplasia of the aortic arch (23.4%) followed by coarctation of the aorta with a PDA (23.4%) and interrupted aortic arch (19.1%).

Table 1

Baseline characteristics of study population (n = 47)
Male gender, %	32 (68.1)
Mean age, year	14.5 ± 4.4
Mean body mass index, kg/m²	18.0 ± 5.6
History of hypertension, %	34 (72.3)
Bicuspid aortic valve, %	19 (40.4)
History of balloon angioplasty, %	11 (23.4)
History of surgery, %	4 (8.5)
History of bare stent implantation, %	12 (25.5)

Table 2

Characteristics related to covered stents
Number of covered stents used
One stent	41 (87.2%)
Covered CP	17 (41.5)
Bently	24 (58.5)
Two stents	5 (10.6)
Covered CP	1 (20.0)
Bently	4 (80.0)
Three stents	1 (2.1)
Covered CP	1 (100)
Size and diameters of the stents, mm
First stent (n = 47)
Diameter	13.7 ± 2.2
Length	41.2 ± 7.6
Second stent (n = 6)
Diameter	13.6 ± 2.6
Length	47.5 ± 6.6
Third stent (n = 1)
Diameter	16.0
Length	39.0
Indications for stenting
Long segment CoA + hypoplasia of aortic arch	11 (23.4)
Stent fracture	4 (8.5)
Pseudoaneurysm	5 (10.6)
CoA with PDA	11 (23.4)
IAA	9 (19.1)
Stent fracture + pseudoaneurysm	3 (6.4)
Stent fracture + CoA with PDA	1 (2.1)
Pseudoaneurysm + hypoplasia of aortic arch + long segment CoA	2 (4.3)
Interrupted aortic arch (IAA) + pseudoaneurysm	1 (2.1)

Short-term post stenting complications with covered stents were detected in 25.5%. The most prevalent of such complications (Table 3) included isolated residual coarctation of the aorta in 25.0%, followed by residual coarctation of the Aorta plus closure of the left subclavian artery in 16.6%. After stenting, the patients underwent echocardiography again for more accurate evaluations, and according to the symptoms, five patients underwent CT angiography. Based on the results of CT angiography, four patients were non-significant residual coarctation of the aorta who received drug treatment (I do not believe this. The relevance is due to residual gradient under exercise. Very likely the CoA Index was < 80% - and so redilatation would be necessary – please check!). Also, out of 5 patients who underwent CT angiography, only one patient's CT results were abnormal that the patient had endoleak and was finally repaired with surgery. In other cases, all results were normal, indicating successful stenting with no related lesions. The mean peak coarctation of aorta gradient in the studied patients with normal ejection fraction, before implantation of the stent, was 25.5 ± 50.9 mmHg (with a minimum of 0 mm Hg and a maximum of 120 mm Hg), which decreased significantly after implantation of the stent to 7.0 ± 5.1 mmHg ranged 0 to 35 mmHg. Also, the mean aortic diameter before stent implantation was 3.0 ± 1.7 mm (range 0 to 7 mm), which increased to 13.8 ± 2.2 mm (ranged 12 to 20mm) after stent implantation. One patient who had two long stents at the transverse aortic arch with complete occlusion of the left subclavian artery was treated with stent fenestration via LSCA access successfully. Five patients also had additional syndromes (including Turner Syndrome, Williams Syndrome, Goldenhaar Syndrome, Mid Aotic Syndrome and Dandy-Walker Syndrome). In these patients, coarctation treatment was successful; the complications however in the patients with underlying syndromes were higher than in the other patients. Vascular complications of the access consisted of one minor transient dissection of the femoral artery in one patient, and one femoral artery thrombosis that was treated with medical therapy (alteplase).

Table 3

Short-term outcome of covered stents implantation
Femoral artery dissection	1 (8.3)
Femoral artery thrombosis	1 (8.3)
Stent dislocation + closure of the left subclavian artery	1 (8.3)
Residual CoA + closure of the left subclavian artery	2 (16.6)
Residual CoA	3 (25)
Endoleak	1 (8.3)
Endo leak + pseudoaneurysm	1 (8.3)
Endothelization	1 (8.3)
Peritoneal hematoma	1 (8.3)

In long-term following-up, overall, five patients (10.6%) did reveal complications. In this regard, one patient suffered from an endoleak that was closed with surgery, one patient suffered from residual hypertension that was managed medically, and three patients from residual coarctation of the Aorta that were managed medically (2 patients) and surgical COA repairing (one patient). Long-term death was reported in none of the subjects. Also, 12 patients (25.6%) underwent re-dilation.

The use of stents, especially its expandable types, which can be increased in size to adulthood after implantation with re-radiation, is now a standardized method in the treatment of congenital heart diseases, including coarctation. It has revolutionized the treatment of these patients and largely replaces traditional methods [14, 15]. Bekin et al. report the use of stents to reduce the risk of neointimal hyperplasia and restenosis by creating a protective wall against the elasticity of the vessel and also creating a uniform framework for endothelial growth [18]; however, the various dimensions of these benefits remain unknown. One of the questions we still face is whether the stent is the best treatment for primary coarctation (without prior intervention). In studies that have been performed to compare the consequences of stenting and balloon angioplasty in the treatment of primary coarctation, stenting has been suggested as the preferred and choice treatment [19]. In our study, out of 47 patients, with covered stenting were assessed. Meanwhile stenting has been recommended as treatment of choice in current guidelines in children after neonatal age and childhood whenever anatomically suitable.

After stenting, all of the patients presented here underwent transthoracic echocardiography during short and long term fallow up for more accurate evaluations. According to the symptoms, all patients had normal ejection fraction, only five patients that had abnormal echocardiography data that consisted of increased systolic velocity without a diastolic component, these patients underwent CT angiography. The results of CT angiography showed that four patients had non-significant. Residual coarctation of the Aorta who ultimately received drug treatment. Also, out of 5 patients who underwent CT angiography, only one patient's CT results was shown to be abnormal that the patient had endoleak and was finally repaired with surgery. In all other cases, all results were normal, indicating successfully covered stenting with no significant lesion. In our study, at long follow-up of patients, 12 patients required redilatation, all of which were successfully managed, leading to reducing peak COA gradient significantly.

Few reports are available that address the use of covered stents as a primary treatment for coarctation rather than for aneurysm formation; however, the same studies have emphasized the effectiveness and low complication of this method in pediatric patients. Subsequently, Ewert et al. [20] reported their successful experience in treating long segment coarctations in four adult patients by the implantation of covered stents while in our study 11 patient with long segment COA and hypoplasia of aortic arch underwent covered stent implantation successfully. In their long-term follow-up, the stents were redilated, and one stent fractured, requiring the implantation of a second stent. Qureshi et al. [21] reported the implantation of covered CP stents in patients with native CoA, leading to a reduction of gradients and increasing aortic diameter with no encountering complications. This is similar to our results that nine patients with interrupted aortic arch treated with a covered stent. A larger experience was reported by Ewert et al. [20] that among 60 stents implanted and in long-term following-up, one covered stent fractured at six months, requiring the implantation of an additional covered stent. In another study on Brazilian patients suffering coarctation, nine patients received covered stents. In their study, although the procedure was successful in all subjects, the development of aneurysms was detected in two patients and a small aneurysm requiring conservative management in another patient. During follow-up, all patients had either reduced the dose or suspended the use of antihypertensive drugs [22]. In the study presented by Tzifa et al [23] on complex CoA, both a significant reduction in systolic gradients across the CoA and an improvement in the diameter of the CoA site was shortly revealed. During long-term follow-up, all stents were visualized either with CT or MRI and showed adequate patency and correct position. In our study 12 patients need covered stent redilation after a few years that was caused by an increased body weight due to growth. Thus, although studies on the usefulness of covered stents in cases of complex coarctation are few, these studies emphasize the low complication of this technique even in the long run.

In conclusion, a comparison of the above studies and the findings of our study indicate that the covered stent can be used as an effective treatment in cases of coarctation of the aorta. There are however a significant rate of complication that has to be weighed against the risk of redo surgery. What distinguish the use of covered stents in children are the characteristics of covered stents compared to uncovered stents. One of the biggest limitations of using covered stents compared to uncovered stents is the need to use larger arterial sheets, especially in small and underweight children, which can lead to important problems such as serious trauma to accesses. The second feature that limits the use of covered stents in children is the limitation in opening and expanding the volume and length of stents after children grow to adjust an optimal result according to the CoA index achieved. What children need after a few years is the ability to expand the stent with a larger balloon. Therefore, the capability of covered stents, especially in cases of complex coarctation in children, should be further investigated.

ACKNOWLEDGEMENT

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

The study was ethically approved by the Iran University of Medical Sciences.

Informed consent was obtained from all individuals included in this study.

Authors state no conflict of interest.

HM and HG designed the study planning, FR and YK collected the data, NAH analyzed the data and MM drafted the paper. All authors have accepted responsibility for the entire content of this manuscript and approved its submission

The authors would thanks all the subjects participated in the project

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No competing interests reported.

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Short and Long-term Consequences/results of Covered Stents in Children for the Management of Complex Coarctation of the Aorta

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