Proof of Concept: A New Solution for Low-Profile Transcatheter Implantation of Optimus-L Stents in Small Children.

BACKGROUND: There is no stent designed or approved for use in infants. We sought to obtain in vitro and in vivo data on a new concept conceived to implant Optimus-L stents at infant vessel diameters and offer a potential long term stent solution. METHODS: Nineteen Optimus-L stents were mounted on 8 types of angioplasty balloons with diameters 6, 8, and 10 mm with the use of an injection-moulded hand crimper. We evaluated balloon-stent unit (BSU) stability before insertion and advancement through short Terumo introducers with incremental French size and possibility of side-arm contrast injections. Three types of long sheaths were tested. Stents were inflated to balloon nominal diameters and re-expanded to 18 and 23 mm. Stent recoil, foreshortening, and fracture were evaluated. In vivo implantations were performed afterward. RESULTS: In vitro: Medtronic Evercross balloons and modified Terumo Destination sheaths were the best combination: BSUs were inserted in 6 F sheaths with possible injections (for 6 and 8 mm balloons), and 7 F sheaths without injections (for the 10 mm balloon). Retrieving BSUs inside the sheath required 1 additional F-size. Boston Scientific Sterling and Balton Lovix balloons, as well as APT Braidin L guiding sheaths showed unsatisfactory performance. Dilation up to 23 mm was possible, and stent shortening was < 24% at 18 mm and < 37% at 23 mm. Recoil was limited, and no stent fractured. In vivo: Optimus-L stents were used to treat 2 infants with aortic coarctation and 2 children with pulmonary artery stenosis with the use of 8 mm balloons and low-profile access. CONCLUSIONS: Optimus-L stents can be implanted safely in small patients with a low-profile approach. These stents have the potential to achieve adult size while maintaining structural integrity.

SwiftNINJA steerable microcatheter: a new kid on the block for selective catheterization of vascular and valvular congenital lesions.

Background: SwiftNINJA (Merit Medical Systems, USA) is a novel steerable microcatheter intended for coronary and peripheral vascular interventions. We evaluate and report the first use of SwiftNINJA in pediatric catheterization of congenital heart defects (CHDs). Methods: We performed a retrospective clinical data review of children with CHDs in whom SwiftNINJA was used during cardiac catheterization between April 2022 and June 2023. Utility, application, and standard safety were described comprehensively. Results: We identified 19 patients (78.9% males) with a median age of 5.3 months (IQR, 2-13.9), and a median weight of 5.3 kg (IQR, 4-7.7). 36.8% of the catheterizations were transarterial and 78.9% were interventional. SwiftNINJA was applied upfront in 3/19 patients to cannulate precisely the right pulmonary artery and eliminate the risk of dislocating a freshly implanted left pulmonary flow restrictor. In 16/19 patients, SwiftNINJA was applied after a median of 5 (IQR, 5-7) failed catheterization attempts using various combinations of catheters, microcatheters, and wires to cannulate challenging vasculature in seven, engage the lumen of stented vessels in five, cross complex aortic valve stenosis in three, and cross an apical ventricular septal defect in one patient with Damus-Kaye-Stansel repair. After the SwiftNINJA application, catheterization was done from the first attempt in 12/16 patients and from the second attempt in 4/16 patients. The median applied tip angulation was 90 degrees (IQR, 85-95). All procedures were completed successfully. No device malfunction or adverse events occurred. Conclusions: SwiftNINJA is a valuable addition for selective catheterization of challenging vasculatures or valvular anatomies in children with CHDs.

Outcomes of manually modified microvascular plugs to pulmonary flow restrictors in various congenital heart lesions.

Background: The development of microvascular plugs (MVPs) has enabled novel transcatheter deliverable endoluminal pulmonary flow restrictors (PFRs) with the potential to treat newborns and infants with life-threatening congenital heart diseases (CHDs) in a minimally invasive manner. We present our experience to evaluate the efficacy of this concept in controlling pulmonary blood flow in various CHDs. Methods: Retrospective clinical data review of patients with CHD and pulmonary over-circulation who received bilateral PFRs percutaneously. Results: Twenty-eight PFRs (7 MVP-5Q, 12 MVP-7Q, and 9 MVP-9Q) were finally implanted in 14 patients with a median age of 1.6 months (IQR, 0.9-2.3) and a median weight of 3.1 Kg (IQR, 2.7-3.6). Nine patients had large intra-cardiac left-to-right shunts (including 3 with fatal trisomy and palliative programs), 2 had borderline left ventricles, 2 had Taussig-Bing anomaly, and one had a hypoplastic left heart. Four patients had concomitant ductal stenting. Two MVP-5Qs were snare-removed and upsized to MVP-7Q. Patients experienced a significant drop in oxygen saturation and Qp/Qs. All patients were discharged from the ICU after a median of 3.5 days (IQR, 2-5.8) postoperative. Five patients had routine inter-stage catheterization and no device embolization or pulmonary branch distortion was seen. Fourteen (50%) PFRs were surgically explanted uneventfully on a median of 4.3 months (IQR, 1.2-6) post-implantation during biventricular repair in 6 patients and stage-2 palliation in one patient. The latter died 1 month post-operative from severe sepsis. Four patients are scheduled for surgical PFR removal and biventricular repair. Two patients with trisomy 18 died at 1 and 6.8 months post-procedure from non-cardiac causes. One patient with trisomy 13 is alive at 2.7 months post-procedure. Conclusion: It is feasible to bespoke MVPs and implant them as effective PFRs in various CHDs. This approach enables staged left ventricular recruitment, comprehensive stage-2 or biventricular repair with lower risk by postponing surgeries to later infancy. Device explantation is uneventful, and the outcomes afterward are promising.

A word of caution: Early failure of Magmaris® bioresorbable stent after pulmonary artery stenting.

Bioresorbable scaffolds (BRS) have been advocated as the fourth revolution in interventional cardiology medical devices with promising technology to improve the treatment of coronary artery disease with an event-free future. We describe the first reported use and early collapse of the Magmaris® Resorbable Magnesium Scaffold (RMS) stent (BIOTRONIK AG, Switzerland) to relieve left pulmonary artery severe stenosis in a newborn after the Norwood procedure. The stent collapse was detected 2 weeks after implantation and urgently treated with a balloon-expandable stent. This complication raises the alarm about the need to keep implanted RMS under scrutiny. The possibility of faster scaffold resorption in small babies or lack of sufficient radial force of RMS to resist acute vessel recoil has led to ineffective relief of branch pulmonary artery stenosis and failure to enable a safe short-term bridge to Stage II palliation.