Abstract
Background
Critical pulmonary valve stenosis is a rare congenital heart defect that causes cyanosis in the newborn and is characterized by severe narrowing of the right ventricular outflow tract and pulmonary valve, leading to restricted pulmonary blood flow.
First-in-Human/Early Reports Summary
We present the case of a full-term male infant diagnosed with critical pulmonary stenosis with ductal-dependent pulmonary circulation. The patient underwent successful percutaneous pulmonary valvuloplasty and ductal stenting with a new iron-based bioresorbable stent (IBS Angel, Biotyx Medical). Postoperative evaluation was favorable.
Discussion
This combined strategy ensured effective right ventricular decompression and maintenance of pulmonary blood flow.
Novelty
This is to our knowledge the first case in Europe on the use of a bioresorbable stent to maintain ductal patency in critical pulmonary stenosis with dual pulmonary blood supply.
Take-Home Messages
Bioresorbable stents may represent a safe short- to medium-term option in selected neonates with ductal-dependent pulmonary circulation. Early outcomes appear favorable, but longer follow-up is warranted.
Key words: bioresorbable stent, congenital heart disease, ductal-dependent circulation, interventional cardiology, neonate
Graphical Abstract
Pulmonary atresia with intact ventricular septum (PAIVS) and critical pulmonary stenosis are congenital heart diseases with ductal-dependent pulmonary circulation.1, 2, 3 Many patients, especially those with PAIVS, have enormous morphologic diversity of the right ventricle, pulmonary valve, and tricuspid valve.4,5 Such heterogeneity has raised a wide variety of treatment strategies.6 In some cases, a transcatheter approach may be necessary to maintain arterial ductal patency after a successful right ventricular decompression. In clinical practice, coronary stents are used in these newborns. However, the use of drug-eluting stents (DES) is still considered off label in the pediatric population, and their long-term effects are still unknown in small children.
Take-Home Message
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The case highlights new strategies and materials in interventional pediatric cardiology for the treatment of ductal-dependent pulmonary circulation.
Very recently, iron-based bioresorbable stents (BRS) have been available as a promising alternative to conventional metal stents for ductal stenting. These devices are designed to provide temporary scaffolding to maintain ductal patency, gradually degrading over time as the need for ductal patency diminishes or as the patient transitions to definitive surgical repair. Compared with metallic stents, which often require surgical removal or which may interfere with future interventions, BRS offer the advantage of temporary support without leaving permanent foreign material in situ.7
Case Presentation
A full-term male infant, born via spontaneous delivery after an uneventful pregnancy (gestational age: 37 weeks + 4 days, body weight: 3,170 g), developed profound postnatal desaturation unresponsive to hyperoxia. Initial echocardiography showed critical pulmonary valve stenosis, a hypertrophic and bipartite right ventricle with intact interventricular septum, and a patent ductus arteriosus (Figures 1 and 2). Prostaglandin E1 infusion was started, and the newborn was transferred to our center.
Figure 1.
Apical 4-Chamber View Demonstrates a Small Right Ventricle With Severe Tricuspid Regurgitation, Secondary to Severe Pulmonary Stenosis and Elevated Right Ventricular Pressure
Figure 2.
Parasternal Short-Axis View Shows Pulmonary Stenosis, a Mildly Dilated Pulmonary Artery, and Normal Caliber of the Pulmonary Branches
After a multidisciplinary discussion, it was decided to proceed with a percutaneous approach that included pulmonary valvuloplasty and ductal stenting. Cardiac catheterization was performed using 2 femoral accesses (a 5-F femoral vein and a 4-F femoral artery). Angiography showed a hypertrophic right ventricle with very diminutive trabeculated apical portion. The pulmonary valve appeared thickened and dysplastic, with only a tiny antegrade blood flow with a valvular anulus measuring about 5 mm.
Pulmonary valvuloplasty was performed using a Tyshak Mini balloon (7 × 20 mm) (NuMED), with good results; postprocedural angiography showed satisfactory antegrade flow.
Given the marked restrictiveness of the right ventricle, the decision was made to stent the duct with a bioresorbable scaffold. Angiography confirmed the presence of a straight ductus arteriosus, measuring about 2 mm on the pulmonary side and 4 mm on the aortic side (Figure 3).
Figure 3.
Angiography (Lateral Projection) Demonstrates a Patent Ductus Arteriosus of Good Caliber With Mild Distal Narrowing at the Pulmonary End
The duct was assessed with a 0.014-inch guidewire and then crossed with a transvenous right coronary guiding catheter. A premounted iron bioresorbable stent (IBS Angel 3.5 × 15 mm, Biotyx Medical) was then successfully deployed to cover the entire length of the ductus arteriosus to prevent late ductal stenosis (Figures 4 and 5).
Figure 4.
Poststenting Angiography Demonstrates Satisfactory Ductal Caliber
Figure 5.
Postprocedural Echocardiography Demonstrates a Patent Ductal Stent With Preserved Flow
No procedure-related complications occurred. Antiplatelet therapy with aspirin (15 mg) and clopidogrel (0.6 mg) was started.
Postoperatively, the infant remained hemodynamically stable and was extubated the day after. At the first follow-up after 3 months, the baby was doing well, with oxygen saturation 95%. On echocardiography, the stent was patent with good flow, without any apparent sign of restriction (Figure 6).
Figure 6.
3-Month Follow-Up Echocardiography Confirmed Stent Patency Without Evidence of Restenosis
Discussion
Critical pulmonary stenosis may require ductal patency for additional pulmonary blood flow. In some cases, even after an adequate valvuloplasty, the antegrade flow is not sufficient, either because of poor compliance of the right ventricle or because it is not completely formed.
In the current era, a number of coronary platform stents are available to the pediatric interventional cardiologist, including bare metal stents (BMS), DES, and second-generation DES. In a recent study in infants who underwent patent ductus arteriosus stent placement for ductal-dependent pulmonary blood flow, fluoropolymer-coated everolimus-eluting stents offered promise over BMS, with less intimal proliferation, less need for unplanned reinterventions, and similar pulmonary artery growth to BMS.8
However, some concern remains over the potential immunosuppressive effects of DES. In a study of neonates receiving sirolimus-eluting stents, peak sirolimus levels reached immunosuppressive levels, although no clinically significant adverse outcomes were observed.9
BRS are designed to provide temporary scaffolding to maintain vessel patency and then gradually degrade, reducing the possibility of long-term risks of stent-related complications These stents have recently received the European Union compliance mark and are available for ductal use.
In our case, the intrinsic degradability of the stent, with the consequent possibility of spontaneous ductal closure after a few months, could temporarily compensate for the ductal dependency as the right ventricle develops, which could ultimately allow the achievement of a biventricular circulation without any other reinterventions.
In our early experience, the BRS has shown excellent handling, trackability, and delivery profile. The device is radiolucent, with 2 radiopaque platinum markers that allow easy visualization.
In ductal-dependent congenital heart disease with dual-source pulmonary blood flow, BRS can provide a temporary or permanent therapeutic option, or they can serve as a bridge to more definitive future interventions. This procedure represents a short- to medium-term solution for a carefully selected group of patients. In particular, it may be considered in those with potential recovery of right ventricular diastolic function, thereby allowing deferral or avoidance of a more invasive surgical procedure. Moreover, the iron-based alloy of the stent undergoes gradual resorption within approximately 6 months.
As a matter of fact, the iron undergoes a physiological oxidation in the vascular environment, and the degradation products are subsequently internalized by macrophages and processed through the physiological iron metabolism. As this is the same process of iron metabolization from hemoglobin catabolism, it should cause no adverse effects in the short, medium, or long term.
The main concern for the use of the BRS is the shorter duration of palliation owing to rapid neointimal hyperplasia, as seen in pilot studies.10 However it is too early to draw conclusions on this aspect from our experience.
Conclusions
In this report, we present to our knowledge the first case in Europe regarding the use of a BRS to maintain ductal patency in a patient with critical pulmonary stenosis with dual pulmonary blood supply. BRS offer theoretical advantages over traditional metal stents, including the potential to reduce long-term complications such as vessel distortion, as well as noninterference with future surgical or interventional procedures. Despite these promising features, the clinical efficacy and safety of BRS remain to be fully established, especially in the pediatric population. Further validation through larger, prospective studies and continued technological refinement is essential to define their optimal role in the management of ductal-dependent congenital heart disease.
Funding Support and Author Disclosures
This work was supported by the Italian Ministry of Health with Current Research funds. The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
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