The role of stents in the treatment of congenital heart disease: Current status and future perspectives

Pulmonary Artery Stent Implantation

Pulmonary artery stent implantation has become integral in the treatment of pulmonary artery stenosis and is probably the most efficacious therapy for these lesions. Advancements in technology involving stent design and the equipment used for stent delivery have made this procedure much safer and more effective. Strategies to mitigate and successfully treat adverse events related to pulmonary artery stent implantation are reasonably well-established. Pulmonary artery stent implantation remains one of the most complex and technically challenging of congenital cardiac interventions.

Blueprint for a Semi-automated Image Processing Tool to Characterize Stent Features: Application to a Pediatric Growth-Adaptive Stent

The goal of this work was to develop a general blueprint for a semi-automated image processing tool (SIPT) to measure small, complex features of stent prototypes that can replace the current gold standard of manual measurements. The stents were designed using CAD software and manufactured via laser cutting. Stent prototypes were imaged using a Keyence microscope in top and side view orientations. The SIPT algorithm was developed in MATLAB to extract and measure 4 dimensions of the stent (inner and outer diameter, spring bend outer radius, spring bend width). The same dimensions were also manually measured by an experienced metrology technician as a gold standard comparison. We successfully made over 5000 unique measurements across the 4 key dimensions of 15 stents using the SIPT algorithm. Compared to the gold standard manual method, SIPT reduced measurement time by nearly 90% and increased the total number of measurements captured by over 2300%. The two one-sided test and Bland-Altman analysis demonstrated that SIPT achieved equivalency against the manual method of measurement for all 4 dimensions. In summary, we found that our SIPT software could be used to replace manual measurements and provided substantial time savings with consistent accuracy. Overall, this paper presents a generalizable workflow to isolate and measure critical features of stent prototypes that we believe will provide a valuable, cost-effective tool to other medical device designers seeking to rapidly iterate on unique stent designs or other manufactured parts with small and complex structures.

Virtual Planning and Patient-Specific Graft Design for Aortic Repairs

PURPOSE

Patients presenting with coarctation of the aorta (CoA) may also suffer from co-existing transverse arch hypoplasia (TAH). Depending on the risks associated with the surgery and the severity of TAH, clinicians may decide to repair only CoA, and monitor the TAH to see if it improves as the patient grows. While acutely successful, eventually hemodynamics may become suboptimal if TAH is left untreated. The objective of this work aims to develop a patient-specific surgical planning framework for predicting and assessing postoperative outcomes of simple CoA repair and comprehensive repair of CoA and TAH.

METHODS

The surgical planning framework consisted of virtual clamp placement, stenosis resection, and design and optimization of patient-specific aortic grafts that involved geometrical modeling of the graft and computational fluid dynamics (CFD) simulation for evaluating various surgical plans. Time-dependent CFD simulations were performed using Windkessel boundary conditions at the outlets that were obtained from patient-specific non-invasive pressure and flow data to predict hemodynamics before and after the virtual repairs. We applied the proposed framework to investigate optimal repairs for six patients (n = 6) diagnosed with both CoA and TAH. Design optimization was performed by creating a combination of a tubular graft and a waterslide patch to reconstruct the aortic arch. The surfaces of the designed graft were parameterized to optimize the shape.

RESULTS

Peak systolic pressure drop (PSPD) and time-averaged wall shear stress (TAWSS) were used as performance metrics to evaluate surgical outcomes of various graft designs and implantation. The average PSPD improvements were 28% and 44% after the isolated CoA repair and comprehensive repair, respectively. Maximum values of TAWSS were decreased by 60% after CoA repair and further improved by 22% after the comprehensive repair. The oscillatory shear index was calculated and the values were confirmed to be in the normal range after the repairs.

CONCLUSION

The results showed that the comprehensive repair outperforms the simple CoA repair and may be more advantageous in the long term in some patients. We demonstrated that the surgical planning and patient-specific flow simulations could potentially affect the selection and outcomes of aorta repairs.

Failure to post-dilate BeSmooth peripheral stents to adult vessel size diameters during benchside tests

BACKGROUND

Low-profile stent implantation remains a rescue treatment for aortic coarctation and branch pulmonary arteries stenosis in small children. Stent re-expansion to cope with vascular growth remains problematic.

OBJECTIVES

To evaluate ex vivo feasibility and mechanical behaviour of over-dilating BeSmooth peripheral stents (Bentley InnoMed, Germany).

METHODS

Three BeSmooth peripheral stents in diameters of 7, 8, and 10 mm were dilated to nominal pressure and then 13 atm. BeSmooth Ø7 × 23 mm was sequentially post-dilated using 12, 14, and 16 mm high-pressure balloons. BeSmooth Ø10 × 57 mm was post-dilated with a 14 mm balloon and then with a 48 mm bare-metal Optimus XXL stent hand-mounted on a 14 mm balloon (stent-in-stent). BeSmooth Ø8 × 57 mm was directly post-dilated with a 48 mm bare-metal Optimus XXL stent hand-mounted on a 16 mm balloon (stent-in-stent). The stents' diameter and length were measured. Digital inflation pressure was noted. Balloon rupture and stent fracture patterns were closely evaluated.

RESULTS

At 20atm pressure, BeSmooth Ø7 × 23 mm shortened to 2 mm forming a 12 mm diameter solid ring circle and the woven balloon ruptured radially. At 10 atm pressure, BeSmooth Ø10 × 57 mm fractured longitudinally in various dispatched breaking points at a diameter of 13 mm without shortening and ruptured the balloon with multiple pinholes. At 10 atm pressure, BeSmooth Ø8 × 57 mm fractured centrally at three different points at a diameter of 11.5 mm without shortening and the balloon broke radially in half.

CONCLUSIONS

In our benchmark tests, extreme shortening, severe balloon rupture, or unpredictable stent fracture patterns at small balloon diameters limits safe post-dilation of BeSmooth stents beyond 13 mm. BeSmooth stents are not ideal candidates for off-label stent interventions in smaller patients.

Right ventricular outflow tract stenting promotes pulmonary artery development in tetralogy of fallot

Background

Right ventricular outflow tract (RVOT) stenting seems to be suggested as a promising treatment option and an alternative to modified Blalock-Taussig shunt (mBTS) in the initial palliation of patients with Fallot-type lesions in recent years. This study sought to assess the effect of RVOT stenting on the growth of the pulmonary artery (PA) in patients with Tetralogy of Fallot (TOF).

Methods

Retrospective review analyzing 5 patients with Fallot-type congenital heart disease with small pulmonary arteries who underwent palliative with RVOT stenting and 9 patients underwent modified Blalock-Taussig shunt within 9 years period. Differential left PA (LPA) and right PA (RPA) growth was measured by Cardiovascular Computed Tomography Angiography (CTA).

Results

RVOT stenting improved arterial oxygen saturation from median of 60% (interquartile range [IQR]: 37% to 79%) to 95% (87.5% to 97.5%) (p = 0.028). The LPA diameter Z-score improved from -2.843 (-3.51-2.037) to -0.78 (-2.3305-0.19) (p = 0.03), the RPA diameter Z-score improved from median -2.843 (-3.51-2.037) to -0.477 (-1.1145-0.459) (p = 0.002), the Mc Goon ratio increased from median 1 (0.8-1.105) to 1.32 (1.25-1.98) (p = 0.017). There were no procedural complications and all 5 patients have undergone final repair in the RVOT stent group. In the mBTS group, the LPA diameter Z-score improved from -1.494 (-2.242-0.6135) to -0.396 (-1.488-1.228) (p = 0.15), the RPA diameter Z-score improved from median -1.328 (-2.036-0.838) to 0.088 (-0.486-1.223) (p = 0.007), and there were 5 patients occur different complications and 4 patients was not attained the standards of final surgical repair.

Conclusion

RVOT stenting, compared with mBTS, seems to better promote pulmonary artery growth, improve arterial oxygen saturations, and have less procedure complications in patients with TOF who being absolute contraindicated for primary repair due to high risks.

Multicentre experience with Optimus balloon-expandable cobalt-chromium stents in congenital heart disease interventions

OBJECTIVES

To evaluate bare-metal Optimus and polytetrafluoroethylene (PTFE)-covered Optimus-CVS balloon-expandable, cobalt-chromium, hybrid cell-designed stents in congenital heart disease (CHD) interventions.

METHODS

Retrospective multicentre review of patients with CHD receiving Optimus stents. Stent mechanical behaviour, clinical indications and outcomes were assessed.

RESULTS

183 stents (49.2% XXL/15-ZIG, 33.3% XL/12-ZIG, 17.5% L/9-ZIG) were implanted (98.9% success rate, 2.3% serious procedural complication rate) in 170 patients (57.6% men, 64.1% adults), median age 23.6 years (IQR, 15.2-39.2) and weight 63.5 kg (IQR, 47-75.7). Indications were right ventricular outflow tract stand-alone stenting or before revalvulation (62.4%), aortic coarctation treatment (15.3%), Fontan-circuit fenestration closure (12.4%) and miscellaneous (10%). 86/170 (50.6%) patients had PTFE-covered stenting (50% prophylactic). In 86/170 (50.6%) patients with stenotic lesions, median percentage of achieved stent expansion was 93.4% (IQR, 85.5%-97.7%), median gradient decreased from 28 mm Hg (IQR, 19-41) to 5 mm Hg (IQR, 1-9) (p<0.001), median vessel diameters increased from 13 mm (IQR, 7.9-17) to 18.9 mm (IQR, 15.2-22) (p<0.001) and percentage of vessel expansion was 45.2% (IQR, 19.8%-91.3%). In 30/36 (83.3%) patients with graft, median dilation of 2 mm (IQR, 2-5) above nominal diameter was achieved. Median stent shortening was 10.9% (IQR, 6.1-15.1) and was associated only with expansion diameter (OR: 0.66, 95% CI: 0.38 to 0.93). No clinically relevant fracture, stent embolisation or dysfunction occurred on a median follow-up of 9 (IQR, 4-14) months.

CONCLUSIONS

Optimus stents are effective tools for transcatheter treatment of simple and complex CHD. Optimus stents' reliable mechanical behaviour and particular covering design can promote widespread use.

Transcatheter Device Therapy and the Integration of Advanced Imaging in Congenital Heart Disease

Transcatheter device intervention is now offered as first line therapy for many congenital heart defects (CHD) which were traditionally treated with cardiac surgery. While off-label use of devices is common and appropriate, a growing number of devices are now specifically designed and approved for use in CHD. Advanced imaging is now an integral part of interventional procedures including pre-procedure planning, intra-procedural guidance, and post-procedure monitoring. There is robust societal and industrial support for research and development of CHD-specific devices, and the regulatory framework at the national and international level is patient friendly. It is against this backdrop that we review transcatheter implantable devices for CHD, the role and integration of advanced imaging, and explore the current regulatory framework for device approval.

Anatomical variation of the aorta in the West of Scotland - A population with high cardiovascular disease burden. Implications for stent design and deployment

The prevalence and complexity of cardiovascular disease (CVD) in the West of Scotland are high with the aortic arch and abdominal aorta, particularly at increased risk of cardiovascular pathology. Stent deployment can be key in preventing further cardiovascular events, however, current stent design does not account for complex advanced CVD in these areas. This cadaveric study aimed to provide anatomical measurements requested by manufacturers to improve stent design and deployment in this target population. Nine cadavers (six females and three males; age range = 82.7 ± 10.4 years) from the West of Scotland were dissected to expose the aortic arch and abdominal aorta. Digital callipers and protractors were used to collect data on vessel diameters (including taper), branch spacing, angles and presence of collaterals. CVD was present in all cadavers and ranged from mild plaque presence to aortic dissections. One possessed a bovine aortic arch variation. Supra-aortic vessels were approximately equally spaced, but the left common carotid had the most acute branching angle. Angulation of the arch from the coronal plane positively correlated with a deviation of the left subclavian artery (LSA) from the sternal midline (Spearman's coefficient r = 0.82, p = 0.01) which may impact surgical access. The origin of the vertebral artery on the LSA was also highly variable. The diameter of the descending aorta decreased along its length from the aortic hiatus to superior mesenteric by 21 ± 10% indicating a high degree of taper. The artery of Adamkiewicz was present in 33% and additional renal collaterals were present in 22%. 66% had tortuous vessels in the abdominal region. These results highlight the need for more data to aid the refinement of stent-graft design and deployment methods to ensure successful surgical intervention in this population.

A New Solution for Stenting Large Right Ventricular Outflow Tracts Before Transcatheter Pulmonary Valve Replacement

BACKGROUND

Prestenting right ventricular outflow tracts (RVOTs) before transcatheter pulmonary valve replacement (TPVR) is essential. Optimus-XXL (AndraTec GmbH, Koblenz, Germany) is a new extra-large, balloon-expandable cobalt-chrome stent with promising technologies.

METHODS

From June 2020 to November 2020, 15 patients with congenital heart disease, dysfunctional RVOTs and target TPVR diameter ≥ 23 mm received Optimus-XXL stents before proceeding to TPVR using the SAPIEN valve (Edwards Lifesciences, Irvine, CA). Standard safety and outcomes were prospectively assessed.

RESULTS

Patients' median age and weight were 25.8 years (range: 10.5-63.1 years) and 58 kg (range: 43.8-101 kg), respectively. Underlying diagnosis was tetralogy of Fallot (66.7%), and RVOTs were patched (80%). Fifteen bare-metal stents were implanted using femoral (n = 14) and jugular approaches (n = 1). One conduit rupture was immediately controlled with a covered Optimus-XXL. Median stent length was 43 mm (range: 33-57 mm), and median target expansion diameter was 28 mm (range: 23-30 mm). Two procedural incidents occurred during stent delivery and were percutaneously treated. Stent stability was documented during TPVRs immediately performed in 14 patients. Median stent shortening was 13.7%, and median percentage of intended stent expansion was 95.9%. There was no stent fracture on the short-term follow-up (median: 4.5 months).

CONCLUSIONS

We report the first implantations of Optimus-XXL stents in dysfunctional RVOTs with excellent preliminary results. Optimus-XXL should be considered as a valuable adjunct in the armamentarium for routine and complex TPVR procedures.

Can a self-expanding pediatric stent expand with an artery? Relationship of stent design to vascular biology

OBJECTIVES

A large-diameter, intravascular, self-expanding stent system capable of continued expansion during somatic and vascular growth was modeled with finite element analysis (FEA), manufactured and tested in an animal model.

BACKGROUND

Children can quickly outgrow intravascular stents. If a stent could expand after implantation in arteries this would be ideal for use in pediatric patients.

METHODS

Computer-aided design and FEA were used to design and manufacture large-diameter, self-expanding nitinol stents with both high and low chronic outward force (COF). Four distinct stents with similar designs but with variable lengths and strut thicknesses were manufactured. Fourteen of these stents were implanted in the abdominal aortas or iliac arteries of four juvenile swine.

RESULTS

All animals survived without complication to their designated time points of harvest (90 or 180-days), and all stents expanded to greater diameters than the adjacent non-stented artery. Luminal diameter growth was 34-49% and 20-23% for stented and non-stented segments, respectively. Histologic examination revealed variable degrees of the internal elastic lamina and/or medial disruption with a mean injury score ranging from 0.70 ± 0.56 to 1.23 ± 0.21 and low COF stents implanted in smaller arteries having a larger injury score. Inflammatory responses and stenosis formation were minimal and ranged from 0.50 ± 0.71 to 3.00 ± 0.00 and 5.52 ± 1.05% to 14.68 ± 9.12%, respectively. The stent's COF did not correlate with vessel expansion or vascular injury.

CONCLUSIONS

Self-expanding stents can mirror and even exceed somatic growth. Although longer-term testing is needed, it may be possible to custom tailor self-expanding stents to expand after arterial implantation in pediatric patients.

A NEW RING STENT WITH GRADED GEOMETRY FOR TREATING COARCTATION OF CURVED AORTA ARTERIES

Ring stent implantation has been widely used to treat coarctation of the aorta (CoA) as an alternative to surgery. Currently adopted stents with uniform geometry may cause uneven stress distribution and high stress concentration in curved vessels, leading to in-stent restenosis (ISR). Inspired by functional graded material, here we propose a new ring-and-link stent, which has graded geometry in order to achieve a reduced peak stress when deployed in curved arteries. Numerical simulation of a single ring of the graded stent indicated that by varying the circumferential spacing of wave crest, the maximum stress exerted on the artery was reduced by as much as 27.86% in comparison with the uniform one. The effects of stent geometric parameters and artery curvature were also obtained through a parametric study. Finally, a whole stent was studied to verify the design, and a maximum stress reduction by 31.96% was achieved. In summary, the proposed graded ring stent shows great potential in clinical applications to reduce the risk of ISR.

Mechanical properties of low-diameter balloon expandable covered stents

OBJECTIVES

To determine over-dilation potential of commercially available covered stents.

BACKGROUND

Covered stents including the Atrium iCast, Gore VBX, and Lifestream stents (LS) can treat ruptures, dissections, and aneurysms in small vessels. Especially in growing patients, stents often require serial dilations beyond their implant or nominal diameters. Tolerance of serial dilations is clinically important information for interventionalists.

METHODS

Serial dilations of 5-12 mm iCast, VBX, and LS covered stents were performed in 1-2 mm increments (up to 20 mm). With each dilation, foreshortening and recoil were measured, and stent strut and covering integrity were assessed. High-pressure balloons were used to expand the stents until they fractured or could not be further expanded.

RESULTS

The 5-8 mm LS tolerated dilation to 14.5-16 mm. The 10-12 mm LS stents tolerated dilation to 18 mm and fractured on the 20 mm balloon. LS stents foreshortened 35%-45% on average after 8 mm of over-dilation and had 5%-10% recoil on <6 mm over-dilation. All iCast stents tolerated dilation to 12-13 mm and required fracture for dilation to >14 mm. ICast stents foreshortened 19%-29% at maximum dilation, with 3-6% recoil on <2 mm over-dilation, and < 3% thereafter. VBX stents over-dilated to 2.9-4.7 mm above nominal, foreshortening 40%-50% after 4-6 mm of over-dilation before collapsing into a ring. VBX stent recoil was <2.5% on all dilations.

CONCLUSIONS

LS stents had the greatest over-dilation potential. VBX stents had the least recoil but tended to foreshorten significantly 3-4 mm above nominal. Regardless of nominal size, all iCast stents (including the 5 mm) tolerated dilation to a maximum of 12-13 mm.

Serum Sirolimus Levels After Implantation of Third Generation Drug Eluting Cobalt Chromium Coronary Stent in Ductus Arteriosus in Neonates with Duct-Dependent Pulmonary Circulation

Ductal stenting (DS) palliates duct-dependent lesions using coronary stents. Sirolimus-eluting stents have replaced bare-metal stents in coronary interventions. Concerns exist about sirolimus levels in neonates. Therapeutic immunosuppressive sirolimus level is 5-15 ng/ml. After neonatal DS, drug levels were assessed at 24 h, 7 days and monthly thereafter till they were undetectable. Clinical course, ductal patency till their final corrective surgery was analyzed. The exact quantity of sirolimus in each stent was known. Twelve neonates with median age of 5.5 days received sirolimus-eluting stents, one stent in nine and two in the rest. The lesions were pulmonary atresia intact ventricular septum(PAIVS) in four, univentricular lesions with pulmonary atresia in four, biventricular lesions with pulmonary atresia in three and right ventricular rhabdomyoma in one neonate. If single stents up to 22 mm length, 24-h drug levels were less than 5 ng/ml. Even though 24-h levels were above 5 ng/ml in patients with single longer stent or two stents, it reduced to very low levels by seventh day. Two hospital deaths included rhabdomyoma with complete heart block and post-valvotomy cardiac failure for PAIVS. Stent patency after valvotomy for PAIVS exceeded three years. Patency was retained for 8-27 months till their elective corrective surgery in others. Sirolimus levels were acceptable at 24 h in all neonates receiving single stent under 22 mm length. In patients needing two stents, drug levels were in immunosuppressive range at 24 h but reduced rapidly within 7 days. The palliation provided by sirolimus-eluting DS was sufficiently long to provide clinical benefit.

Hot topics in interventional cardiology: Proceedings from the society for cardiovascular angiography and interventions 2020 think tank

The society for cardiovascular angiography and interventions (SCAI) think tank is a collaborative venture that brings together interventional cardiologists, administrative partners, and select members of the cardiovascular industry community for high-level field-wide discussions. The 2020 think tank was organized into four parallel sessions reflective of the field of interventional cardiology: (a) coronary intervention, (b) endovascular medicine, (c) structural heart disease, and (d) congenital heart disease (CHD). Each session was moderated by a senior content expert and co-moderated by a member of SCAI's emerging leader mentorship program. This document presents the proceedings to the wider cardiovascular community in order to enhance participation in this discussion, create additional dialogue from a broader base, and thereby aid SCAI and the industry community in developing specific action items to move these areas forward.

First in man study of a new semi-open cell design Zephyr cobalt-chromium stent in large vessels and conduits

OBJECTIVES

We present a first-in-man clinical use of a new hybrid design stent in stenosed large vessels. Its unique C and S polylinks prevent foreshortening without compromising its strength. Its thin profile permits use of smaller introducer sheaths.

BACKGROUND

Stent angioplasty is widely employed in large vessel and conduit stenosis. These procedures are associated with difficulties due to large stent profiles, stent fractures, foreshortening and recoil. Cobalt chromium stents have high tensile strengths compared to stainless steel stents.

METHODS

A retrospective analysis of feasibility and safety of a new Cobalt chromium stent in large vessels namely aorta, pulmonary arteries and outflow conduits was done from two institutions. Demographic patient details, procedural results, complications and medium term follow-up were analyzed. Stent recoil, foreshortening, fractures were assessed.

RESULTS

Twenty patients including three with aortic coarctations, seven with stenosed conduits and 10 with pulmonary artery stenosis underwent stent angioplasty using 23 stents. Three stents were deployed to expand further a previously implanted stent. Procedure was successful in all patients, lumen increased by 150-300%, gradients reduced in all patients. There was no stent recoil, foreshortening or fractures. There were no complications. At a follow up of 3-27 months, there were no stent related complications and the gradients remained stable.

CONCLUSIONS

The new Zephyr stent was useful in a wide variety of stenotic lesions involving large vessels including those that were previously stented. Lack of stent recoil and foreshortening seems to be an advantage for this new stent that needs validation in larger multicenter studies.

Self-Expandable Stents in Vascular Stenosis of Moderate to Large-Sized Vessels in Congenital Heart Disease: Early and Intermediate-Term Results

Background and Objectives

Vascular stenosis after surgical repair frequently occurs in congenital heart disease. Although conventional balloon dilation is a useful option for stenotic lesions, restenosis may occur. Consequently, balloon expandable stents have been used; however, there are a limited number of balloon expandable stents in our country. Here, we report the early and intermediate-term outcomes of self-expandable stents in vascular stenosis of moderate to large-sized vessels in congenital heart disease.

Methods

Twelve self-expandable stents were implanted in 9 patients between February 2012 and January 2019. The median age and weight were 12 years (range, 4–39 years) and 38 kg (range, 19–69 kg), respectively. The patients were followed-up for a median duration of 43 months (range, 1–83 months) after stent implantation.

Results

Nine self-expandable stents were implanted in the pulmonary artery, 2 stents in the right ventricle to the pulmonary artery conduit, and 1 stent in the coarctation. The narrowest diameter of the stented vessel increased from 5.7±3.2 mm to 12.6±3.4 mm (p<0.05). The mean pressure gradient across the stenotic lesion decreased from 23.0±28.2 mmHg to 3.2±3.6 mmHg (p<0.05). Distal migration of the stent occurred in 1 patient, and significant neointimal ingrowth was noted in 1 patient.

Conclusions

The self-expandable stent may be a useful option to relieve vascular stenosis in moderate to large-sized vessels with acceptable intermediate-term outcomes.

Three-year outcome of everolimus-eluting bioresorbable vascular scaffold versus everolimus-eluting metallic stents: a comprehensive updated meta-analysis of randomized controlled trials

INTRODUCTION

In recent years, everolimus-eluting bioresorbable vascular scaffold stents (EE-BRS) were developed as alternative to everolimus-eluting metallic stents (EES) for coronary artery disease (CAD) treatments. Areas covered: Searches were conducted in MEDLINE, EMBASE, EBSCO, Springer, Ovid, TCTMD, Cardiosource, Clinical Trial Results and the Cochrane Library with combined key words such as bioresorbable vascular scaffold (BVS), everolimus-eluting metallic stents, EES, coronary artery disease, CAD and randomized-Controlled Trials.Finally, 5,474 patients were enrolled for comparison of device-induced thrombosis, ischemia-driven target lesion revascularization (ID-TLR), device-oriented composite endpoints (DOCE), patient-oriented composite endpoints (POCE), and target vessel failure (TVF) between EE-BRS and EES treatments. The primary literature search retrieved 200 records. Expert Opinion: There was no difference regarding DOCEs, POCEs and ID-TLRs for 1 or 2 years, whereas there were significant differences regarding thrombosis between EE-BRS and EES interventions in the 1-year (pooled HR, 2.15, 95%CI: 1.11, 4.18) and 2-year follow-ups (pooled HR, 2.02, 95%CI: 1.08, 3.78), but not in the 3-year follow-up (pooled HR, 1.57, 95%CI: 0.66, 3.75) anymore. The results of this study showed no inferiority of EE-BRS regarding TVF, DOCE, POCE and ID-TLR 1-year and 2-years after interventions, but enhanced risk of thrombosis in the EE-BRS patients, which disappeared in 3-year follow-ups.

Serial Optical Coherence Tomography at Baseline, 7 Days, and 1, 3, 6 and 12 Months After Bioresorbable Scaffold Implantation in a Growing Porcine Model

BACKGROUND

Little is known about serial changes in lumen and device dimensions after bioresorbable scaffold implantation in a growing animal model. Methods and Results: ABSORB (n=14) or bare metal stents (ICROS amg [Abbott Vascular, Santa Clara, CA, USA], Winsen-Luhe, Germany; n=15) were implanted in the coronary arteries of domestic swine (a hybrid of Finnish-Norwegian Landrace swine) weighing 30-35 kg. Angiography and optical coherence tomography (OCT) were performed immediately after implantation and repeated at 7 days, 1, 3, 6 and 12 months after the index procedure. One month after implantation, mean lumen area decreased relative to baseline in both groups (relative area change from baseline, -41.4±15.6% for ABSORB vs. -20.9±18.6% for ICROS) while mean device area decreased only in the ABSORB group (relative area change: -11.1±9.4% vs. +0.14±7.95%, respectively). At 12 months, mean lumen area increased relative to baseline in both groups (relative area change from baseline, +55.6±22.4% vs. +32.3±83.6%, respectively) in accordance with the swine growth weighing up to 260-300 kg. Mean device area in the ICROS group remained stable whereas that in the ABSORB group began to increase between 3 and 6 months along with the vessel growth (relative area change: +107.8±25.7% vs. +0.14±7.95%).

CONCLUSIONS

In the growing porcine model, ABSORB was associated with greater extent of recoil 1 month after implantation compared with ICROS but demonstrated substantial adaptability to vessel growth in late phase.

First-in-man pulmonary artery stenting in children using the Bentley® BeGrow™ stent system for newborns and infants

BACKGROUND

Stent implantation into growing vessels is a common treatment option in infants and children with congenital heart disease (CHD) and corresponding vessel lesions. After stent implantation in small children, repetitive stent redilations are frequently necessary to accommodate for somatic growth. Until now, all available stents have limited final expansion diameters.

MATERIAL AND RESULTS

The new Bentley BeGrow™ stent system for newborns and infants is a L605 cobalt‑chromium, pre-mounted, balloon expandable stent, which is compatible with a 4 French sheath and 0.014 inch guide wire thus allowing implantation in small vessels (4-6 mm). It offers a new, unique stent design that allows post-dilation steps up to Ø11.5 mm. While re-dilating up to Ø11.5 mm this new stent maintains radial force and shows uniform expansion with only minimal foreshortening. Predetermined breaking points allow the stent struts to break in a controlled manner when exceeding a diameter of 11.5 mm. Residual radial force maintains even after stent opening due to spiral arrangement of the predetermined breaking points. The 2 first-in-man pulmonary artery stent implantations in a newborn with univentricular circulation and a toddler with biventricular circulation are reported as part of the currently performed licencing trial (ClinicalTrials.govNCT03287024).

CONCLUSION

The low-profile BeGrow™ stent system offers new treatment options for transcatheter stent implantations in newborns and infants. In our first experience, it can be effectively implanted. Longer follow-up will evaluate multiple, stepwise redilations and controlled stent strut breakage, which have the potential to accommodate for somatic vessel growth and/or subsequent implantation of larger stents.

Stent Angioplasty for Critical Native Aortic Coarctation in Three Infants: Up to 15-Year Follow-Up Without Surgical Intervention and Review of the Literature

Management of neonatal native coarctation is debated till now. Surgical therapy remains an option but may be unwarranted in critically sick infants with complex lesions. Balloon dilatation has been employed but with early re-stenosis. Stent angioplasty has also been used but as a bridge towards definitive surgical therapy. Four critically sick infants with complex coarctation and additional co-morbidity factors underwent primary stent therapy as surgical intervention was denied. One patient had died earlier due to reasons unrelated to the procedure. Three survivors underwent multiple dilatations of primary stents as indicated. One of the three survivors did not require any further dilatation after the age of 5 years and remained stable till the time of reporting. High-pressure Cheatham Platinum stents were implanted inside the primary stents in two infants, who developed re-stenosis due to somatic growth. These stents were further balloon dilated at high atmospheric pressure. Femoral arteries in both of them were blocked but were re-canalized after balloon dilatation in one and stent angioplasty in the other. After a follow-up of about 15 years, all of them have been doing fine with acceptable Doppler gradients. They were normotensive and on no cardiac medications. It can be concluded that, though surgical repair remains a standard of care, stent angioplasty in selected infants with complex lesions is feasible and effective. Multiple dilatations can be performed without added risk of stent migration. Bio-absorbable and growth stents hold a promise for future use in such situations.

Thrombogenic superior vena cava syndrome from long-standing central venous access in a 5-year-old patient treated with balloon-expandable stents

Thrombogenic superior vena cava syndrome is an uncommon, dangerous complication of long-standing central venous catheter use. The increased use of central venous catheters has resulted in more non-malignant cases of superior vena cava syndrome across all age groups. We present a 5-year-old male with superior vena cava syndrome associated with acute onset of severe upper extremity and facial swelling, dyspnea, and a right subclavian central venous catheter malfunction. The patient was ultimately treated with percutaneous stenting of the superior vena cava with balloon-expandable Palmaz stents following unsuccessful angioplasty, catheter-directed thrombolysis, and percutaneous thrombectomy. This case highlights a relatively uncommon complication in children from long-term central venous catheter access and describes an emerging, minimally-invasive therapeutic alternative that allows for preservation of age-appropriate superior vena cava luminal diameter as patients grow.

Stent Therapy for Aortic Coarctation in Children <30 kg: Use of the Low Profile Valeo Stent

To report our experience of coarctation stent therapy in small children weighing less than 30 kg, with the low profile dilatable Valeo stent and review the literature on coarctation stent therapy in this patient population. Coarctation stent implantation was undertaken in 14 consecutive children using the Bard Valeo Stent. Demographic, angiographic, echocardiographic and clinical data were reviewed retrospectively. The median age at the time of procedure was 5.1 (2.6-7.5) years and median weight was 20.8 (14.7-27) kg. There was improvement in median coarctation diameter from 4 (1.3-5.2) to 9.5 (5.8-12.7) mm, p < 0.001; and a reduction in the median peak pressure gradient across the coarctation from 35 (20-49) to 9 (0-15) mmHg, p < 0.001. Median stent recoil was 7.9 (0-20)%. There was one case of access related complication that resolved without sequelae. Follow-up was a median of 15 (3.0-57.2) months. CT angiogram performed at a median time of 3.3 (2.6-10.2) months post procedure showed no aortic wall injury and preserved stent integrity in all cases. Two children underwent re-intervention for stent dilation and further stent implantation due to in-stent stenosis and somatic growth after 3 years. Six of fourteen children remained on a single antihypertensive agent post-intervention at last follow-up. Implantation of the dilatable Valeo stent is a feasible treatment strategy in native or recurrent coarctation in small children, accepting that additional stent implantation may be necessary with somatic growth. Further study is required to determine longer-term stent efficacy and clinical outcome.

Use of the AndraStent XL and XXL for the treatment of coarctation of the aorta in children and adults: immediate and midterm results

AIMS

The aim of this study is to present our experience with a new type of extra-large stent, namely the AndraStent XL/XXL.

METHODS AND RESULTS

AndraStents were implanted in 46 patients, 38 with native coarctation of the aorta (CoA) and eight with recurrent coarctation of the aorta following previous surgery (ReCoA). All patients had arterial hypertension in the upper limbs, absent or weak femoral pulses, and continuous flow in the abdominal aorta on Doppler examination. The median age of patients was 25 years (range from nine to 65). The stents (cobalt-chromium with semi-open cell design) were manually mounted on balloon catheters and delivered through 10 to 14 Fr Mullins sheaths using a conventional femoral approach. All procedures were successful (no stent migration, proper expansion, no aorta dissection/rupture, major bleeding or major vessel injury). The systolic gradient across the aorta decreased from 40.6 mmHg before the procedure to 11.6 mmHg after the procedure (p<0.001). The mean fluoroscopy time was 5.7 minutes. Imaging examinations were scheduled and performed between six and 12 months after the initial procedure in 40 patients (angiography or angio CT or both). Procedural outcome remained favourable during a mean 2.4 years of follow-up. Neither stent fracture nor dislocation was observed in any patient at follow-up. In two patients, small aneurysm formation was observed six and eight months after the procedure -they were treated successfully with subsequent covered stent implantation. Re-dilatation of the implanted stent was performed between four and 26 months in 14 patients.

CONCLUSIONS

Implantation of new large cobalt-chromium stents is a good therapeutic option for the treatment of native and recurrent CoA.

Twenty years of experience with intraoperative pulmonary artery stenting

OBJECTIVES

To describe our 20-year experience with intraoperative pulmonary artery (PA) stent placement and evaluate long-term patient outcomes, specifically the need and risk factors for reintervention.

BACKGROUND

Intraoperative PA stent placement is an alternative to surgical patch arterioplasty and percutaneous angioplasty or stent placement to treat branch PA stenosis.

METHODS

We performed a retrospective review of all intraoperative PA stents placed at our institution from 1994-2013. Patient and stent characteristics and outcome data were collected. Risk factors associated with reintervention were identified using univariate cox regression analysis.

RESULTS

Eighty-one PA stents were placed in 68 patients. The procedural complication rate was 4.4%. During a median follow-up period of 6 years (interquartile range [IQR] 0.9-12.7), 30 patients (44%) underwent reintervention on the stented PA with a median time to first reintervention of 2.6 years (IQR 0.7-4.4 years). The first reintervention was surgical in 30% and catheter-based in 70%. Risk factors for reintervention included age < 18 months (Hazard ratio [HR] 2.97, P = 0.005) and body surface area < 0.47 m² (HR 3.20, P = 0.003) at the time of stent implantation, and the presence of multiple aortopulmonary collaterals in patients with tetralogy of Fallot (HR 4.61, P = 0.003).

CONCLUSIONS

Intraoperative PA stent implantation is a safe and effective alternative to percutaneous stent implantation and offers several advantages, including the ability to implant adult-size stents in small patients while avoiding injury to peripheral vessels, to position stents to facilitate future percutaneous stent redilation, and to access the PAs directly, which eliminates radiation exposure. © 2017 Wiley Periodicals, Inc.

Early and Midterm Results Following Interventional Coarctoplasty: Evaluation of Variables that Can Affect the Results

Background and Objectives

Stent coarctoplasty has been approved as the treatment of choice for adult patients with coarctation of the aorta. We have evaluated the early and midterm clinical and procedural results after interventional coarctoplasty. Also, variables that can affect these results were evaluated.

Subjects and Methods

Gathering clinical, angiographic and procedural data, we evaluated the pre-specified outcomes, including procedural success, complications, the incidence of hypertension after coarctoplasty etc., after the procedure. The effect of pre-specified variables including aortic arch shape, coarctation type and etc. on the procedural result was evaluated.

Results

Between February 2005 through March 2014, 133 stent coarctoplasty procedures were performed. Median age was 23.5 years old (interquartile range [IQR]:19-28), and 105 (71.9%) were male. Nearly all of the patients were undergone stent coarctoplasty, mostly with cheatham platinum (CP) stents. There was no association between aortic arch morphology and acute procedural complications. Balloon length more than 40 mm (p=0.028), aorta diameter at the site of Coarctation larger than 2.35 mm (p=0.008) was associated with higher rate of restenosis during follow-up. Comparison between the prevalence of hypertension (HTN) before and after coarctoplasty showed a significant reduction in the prevalence of HTN (117 [91.4%] vs. 95 [74.2%] p<0.001).

Conclusion

Stent coarctoplasty is a low-risk procedure with favorable early and delayed outcomes. Most mortality is related to the patient's comorbid conditions and not to the procedure.

Revolution of Drug-Eluting Coronary Stents: An Analysis of Market Leaders

Percutaneous coronary intervention with drug-eluting stents (DES) is a well-established and widely-accepted treatment approach in patients with coronary artery disease. Although the underlying principle of DES remains constant for different stents available on the market, certain factors may offer variations with respect to deliverability (ease of placement), efficacy (preventing restenosis), and safety (thrombosis rates). These factors may include the type of drug (sirolimus, everolimus, biolimus, zotarolimus, novolimus, paclitaxel, docetaxel), type of stent platforms (stainless steel, platinum, cobalt-chromium, cobalt-nickel, platinum-chromium), type of polymers (permanent, biodegradable, polymer-free), thickness of stent struts (thick, thin, ultra-thin), type of coating (abluminal, conformal), and type of stent design (open-cell, closed-cell, combination of open-closed cell). In this context, we present a review on characteristic features of several of the most widely used coronary stents worldwide. Furthermore, the advancements of completely biodegradable stents are discussed. In addition, the future directions for the development of creating an ideal or perfect DES are debated.

The Use and Outcomes of Small, Medium and Large Premounted Stents in Pediatric and Congenital Heart Disease

We sought to describe the use and outcomes of small, medium and large premounted stents in patients with congenital heart disease, including incidence of and risk factors for re-intervention and development of in-stent stenosis. Premounted stents offer several advantages over traditional manually crimped bare-metal stents, especially in small patients. There are no data describing the medium-term effectiveness and outcomes of premounted stents in congenital heart disease. We performed a single-center retrospective review of all small, medium and large premounted stents implanted over an 8-year period. Premounted stents were implanted in 71 vessels within 59 patients with a 97 % success rate. Regardless of implantation site, premounted stent implantation resulted in significant improvements in vessel size and pressure gradient (p < 0.0001). Over a median follow-up duration of 3.1 years [interquartile range (IQR) 1.3-5.2], 25 patients (43 %) required re-intervention (18 catheter based, 3 surgical and 4 hybrid) at a median time of 1.4 years (IQR 0.9-3.0) from implant. Factors associated with re-intervention included age ≤1.9 years [hazard ratio (HR) 2.4, p = 0.03], weight ≤11.5 kg (HR 2.5, p = 0.03) and bare-metal premounted stents compared to covered premounted stents (HR 4.2, p = 0.001). In-stent stenosis was diagnosed in 42 % of premounted stents which underwent follow-up angiography. No identified characteristics were associated with in-stent stenosis, including "oversizing" the premounted stent. Small, medium and large premounted stents are effective in treating vascular stenosis in congenital heart disease. Frequent follow-up is required, especially in smaller patients with expected somatic growth, and to evaluate for in-stent stenosis which occurs in nearly half of premounted stents.

The Valeo stent: a pre-mounted, open-cell, large stent for use in small children with CHD

OBJECTIVES

The aim of the present study was to determine the outcomes of using the Valeo stent (Bard Peripheral Vascular, Tempe, Arizona, United States of America) in small children with CHD.

BACKGROUND

Stenting vascular stenoses is safe and effective in adults and older children with CHD but is limited in smaller children. The design of the Valeo stent addresses these limitations but has not been extensively described.

METHODS

Bench testing was conducted to determine the maximum diameter of the stent, foreshortening, and side-cell diameter. A retrospective analysis of Valeo stents implanted between October, 2012 and October, 2014 was performed. Patient profile, pre-implant/post-implant catheterization data, and stent geometry were reviewed.

RESULTS

Bench testing: medium and large Valeo stents can be dilated up to 13 mm and 20 mm diameters, respectively. Side-cells are dilatable up to 12 mm. Valeo stents are of low profile - delivered through 6- or 7-Fr sheaths - and show minimal foreshortening. Retrospective analysis: a total of 81 stents were implanted in 61 patients with CHD. The median weight was 15.3 kg, and the median age was 58.9 months. Stents were implanted in the pulmonary artery, systemic vein, aorta, and pulmonary vein. Overall, mean vessel diameters increased from 4.1 to 7.7 mm (121.7%). There was effective mean gradient reduction: 3.7-0.5 mmHg (63%) in the venous systems, 28.2-12.5 mmHg (63.7%) in the pulmonary arteries, and 17.4-4 mmHg (77.1%) in the aorta. The mean stent foreshortening was 2.5%, and the mean recoil was 5.9%. Side-cells that crossed other vessels were dilated in four cases, and stents were re-mounted onto different-sized balloons in seven cases.

CONCLUSIONS

The features of the Valeo stent, such as low profile, large maximum diameter, open-cell design, minimal foreshortening, and recoil, make it suitable for treating vascular stenoses in small children with CHD.

Bench and initial preclinical results of a novel 8 mm diameter double opposed helical biodegradable stent

BACKGROUND

Metallic endovascular stents are utilized off-label in congenital heart disease. Biodegradable stents (BDS) offer potential advantages in a growing child. We have previously reported double opposed helical (DH) BDS up to 6 mm diameter (DH-6). The objectives are to investigate the bench characteristics of larger 8 mm diameter BDS (DH-8) manufactured with increasing strut thicknesses and the inflammatory profile in a porcine model.

METHODS

DH-8 were manufactured with strut thicknesses 0.10, 0.12, and 0.18 mm and mechanical testing performed. Stents were deployed into the infrarenal descending aorta (DAO) of nine minipigs. At insertion (nonsurvival = 2), 1 week (n = 2), 1 month (n = 2), and 9 months (n = 3) follow-up angiography, intravascular ultrasound and histopathology were performed.

RESULTS

There was superior recoil and collapse pressure with increasing strut thickness, with 0.18 mm having 1.0% elastic recoil and collapse pressure 0.75 Atmospheres. There was good wall apposition at insertion with 5 BDS (4 DH-8 and 1 DH-6) but suboptimal in 4 as the minipigs infrarenal DAO were >8 mm (deployed at iliac bifurcation). Structural integrity was maintained in 8 BDS with 1 DH-8 collapsed at 9 months, secondary to strut damage at insertion. No thrombosis was seen. There was mild inflammation and neointimal proliferation at 1 week and 1 month, but a moderate inflammatory response at 9 months.

CONCLUSIONS

DH-8 with increased strut thickness had acceptable mechanical properties at the cost of an increased inflammatory response. Miniaturization to improve delivery and further investigation on the long-term inflammatory profile of thicker struts, including through degradation, is needed. © 2016 Wiley Periodicals, Inc.

The metamorphosis of vascular stents: passive structures to smart devices

The role of nanotechnology enabled techniques in the evolution of vascular stents.

Metallic zinc exhibits optimal biocompatibility for bioabsorbable endovascular stents

Although corrosion resistant bare metal stents are considered generally effective, their permanent presence in a diseased artery is an increasingly recognized limitation due to the potential for long-term complications. We previously reported that metallic zinc exhibited an ideal biocorrosion rate within murine aortas, thus raising the possibility of zinc as a candidate base material for endovascular stenting applications. This study was undertaken to further assess the arterial biocompatibility of metallic zinc. Metallic zinc wires were punctured and advanced into the rat abdominal aorta lumen for up to 6.5months. This study demonstrated that metallic zinc did not provoke responses that often contribute to restenosis. Low cell densities and neointimal tissue thickness, along with tissue regeneration within the corroding implant, point to optimal biocompatibility of corroding zinc. Furthermore, the lack of progression in neointimal tissue thickness over 6.5months or the presence of smooth muscle cells near the zinc implant suggest that the products of zinc corrosion may suppress the activities of inflammatory and smooth muscle cells.

The role of the new Valeo stent in treating pulmonary artery stenoses in children with complex cardiac malformations: A report of two cases

Case series Patient: -

FINAL DIAGNOSIS

Pulmonary artery stenosis Symptoms: -

MEDICATION

- Clinical Procedure: - Specialty: -

OBJECTIVE

Congenital defects/diseases • Unusual or unexpected effect of treatment.

BACKGROUND

The decision of which stent can be used for treating a congenital heart lesion can be difficult for a pediatric interventional cardiologist. Features of an ideal stent would be to have a low profile to enable small sheaths to be fitted and allow for advancement. It would need to be flexible to negotiate curves of arteries and have sufficient radial strength to prevent recoil of the lesion and vessel. It should have high trackability and wide struts to enable junctional artery flow and prevention of thrombosis and toxic adverse effects from the stent.

CASE REPORTS

Much work is being carried out to design the ideal stent and provide the best treatment for congenital heart lesions. We investigated this matter with the use of the Valeo stent in 2 patients. The Valeo stent is a new premounted stent with several advantages for use in children with complex cardiac conditions. We investigated the Valeo stent's ability to navigate tortuous cardiac anatomy and maintain junctional artery blood flow. In addition, the stents have sufficient radial strength to provide long-term support to the large pulmonary arteries involved.

CONCLUSIONS

The new open-design, premounted, stainless steel Valeo stent has been shown to be useful in treating pulmonary artery stenosis and in young children when catheterization is a less popular choice in comparison to balloon angioplasty. In addition to previous use of Valeo stents in coarctation of the aorta, we have shown the benefits of the stent for pulmonary artery stenosis.

Using the Valeo dilatable stent in coarctation stenting for small children: expanding the inclusion criteria for coarctation stenting?

The application of coarctation stenting has grown in paediatric and adult practice in recent years. Stent and delivery sheath technology has improved; however, we remain technically limited when implanting small calibre stents through small sheaths in small children, which then have the potential to be dilated to adult size as time passes. We describe the first reported use of the Valeo Biliary Pre-mounted Re-dilatable Stent (Edwards Life Sciences, California, USA) in aortic coarctation with 1 year follow-up including cross-sectional imaging. This 14 kg 3-year-old girl presented following an intracerebral haemorrhage secondary to severe systemic hypertension. Despite implantation through a 7-French sheath, this stent can be postdilated up to 20 mm, and therefore provides an important new addition to the interventional armamentarium.

Stent angioplasty to relieve left pulmonary artery obstruction caused by patent ductus arteriosus device occlusion: bipartisan teamwork by two interventional devices

A 7-month-old patient in congestive heart failure due to a moderate sized patent ductus arteriosus (PDA) underwent uncomplicated implantation of an Amplatzer Ductal Occluder (ADO1). Two months after percutaneous device PDA closure, left pulmonary artery (LPA) stenosis was discovered. Rather than spontaneous improvement as reported in previous cases, our patient's LPA stenosis progressed in severity 7 months after ADO1 placement. A catheterization demonstrated a 32 mm Hg peak gradient from her main pulmonary artery to her LPA. She underwent successful stent angioplasty of her LPA with an excellent result and preserved PDA closure. This case demonstrates that stent angioplasty is a feasible an effective method of relieving LPA obstruction caused by a PDA occluder device. Additionally, despite slight deflection by the stent, the ADO1 device continued to provide complete ductal closure. Stent angioplasty should be considered in patients who have LPA stenosis caused by ADO1 occluder device that does not improve over time.