Biodisk: a new device for closure of patent foramen ovale: a feasibility study in swine

Progress of biodegradable polymer application in cardiac occluders

Cardiac septal defect is the most prevalent congenital heart disease and is typically treated with open-heart surgery under cardiopulmonary bypass. Since the 1990s, with the advancement of interventional techniques and minimally invasive transthoracic closure techniques, cardiac occluder implantation represented by the Amplazter products has been the preferred treatment option. Currently, most occlusion devices used in clinical settings are primarily composed of Nitinol as the skeleton. Nevertheless, long-term follow-up studies have revealed various complications related to metal skeletons, including hemolysis, thrombus, metal allergy, cardiac erosion, and even severe atrioventricular block. Thus, occlusion devices made of biodegradable materials have become the focus of research. Over the past two decades, several bioabsorbable cardiac occluders for ventricular septal defect and atrial septal defect have been designed and trialed on animals or humans. This review summarizes the research progress of bioabsorbable cardiac occluders, the advantages and disadvantages of different biodegradable polymers used to fabricate occluders, and discusses future research directions concerning the structures and materials of bioabsorbable cardiac occluders.

The Future of Paediatric Heart Interventions: Where Will We Be in 2030?

Purpose of Review

Cardiac catheterization therapies to treat or palliate infants, children and adults with congenital heart disease have developed rapidly worldwide in both technical innovation and device development in the previous three decades. By reviewing of current status of novel or development of devices and techniques, we will discuss what is likely to happen in paediatric heart intervention in the next decade.

Recent Findings

Recently, biodegradable stents and devices, transcatheter pulmonary valve implantation for the native right ventricle outflow tract and MRI-guided interventions have been progressing rapidly with good immediate to early results. These are expected to be introduced and spread in the next decade although there are still challenges to overcome.

Summary

The future of paediatric heart intervention is very promising with rapid development of technological progress.

Initial experiences with a novel biodegradable device for percutaneous closure of atrial septal defects: From preclinical study to first-in-human experience

Objective

To evaluate the feasibility, safety, and effectiveness of a novel, absorbable atrial septal defect (ASD) closure device made of poly‐l‐lactic acid (PLLA) in a swine model of ASD and for the first time in humans.

Methods

A preclinical safety study was conducted using a swine model of ASD. In a clinical setting, five pediatric patients underwent ASD closure with the PLLA device with fluoroscopic and transthoracic echocardiography guidance. The procedural results and clinical outcomes at 1 day, 30 days, 3 months, and 6 months after closure were analyzed.

Results

The 24‐ and 36‐month follow‐up results of the preclinical study demonstrated that the PLLA device exhibited good endothelialization and degradability in the swine model. In the clinical study, successful device implantation was achieved in all five patients (median age, 3.6 years; range, 3.1–6.5 years). The mean defect size was (13.6 ± 2.7) mm. Follow‐up at 30 days, 3 months, and 6 months was completed in all five cases. The complete defect closure rates with no residual shunt at 30 days, 3 months, and 6 months follow‐up were 60% (3/5), 80% (4/5), and 80% (4/5), respectively. No device dislodgement, significant aortic valve or mitral valve regurgitation, new onset cardiac arrhythmia, or other adverse events were reported.

Conclusion

The study results demonstrated that it is feasible to implant the PLLA device for closure of small to medium sized ASDs without significant residual shunts or severe adverse events in humans. The PLLA device exhibited good endothelialization and degradability in the swine model at 24 and 36 months. Further studies to evaluate long‐term safety and effectiveness with the device in a large cohort of patients are warranted.

Study of biodegradable occluder of atrial septal defect in a porcine model

Objective

To evaluate the safety and feasibility of a modified poly(l‐lactic acid) (PLLA) atrial septal defect (ASD) occluder.

Methods

Forty‐five piglets were divided into two groups: an experimental group (n = 27) and a control group (n = 18). The experimental group underwent percutaneous implantation of a modified PLLA ASD device while the control group underwent percutaneous implantation of a widely used metal ASD device. X‐ray imaging, transthoracic echocardiography (TTE), electrocardiogram (ECG), histopathology and electron microscopic examination were performed at 7 days, 1, 3, 6, and 12 months after implantation.

Results

Twenty‐seven experimental piglets and 18 control piglets were all successfully implanted with modified biodegradable and metal ASD devices, respectively. While both devices exhibited very good occluding effects, the modified PLLA ASD devices were completely endothelialized at 3 months after implantation, and the endothelialization appeared to be more complete compared to the control group. Degradation of the PLLA devices was noted at 12 months follow‐up with no loss of integrity at the atrial septum.

Conclusion

This animal model with implanting of the occluders was effective and not associated with complications. The modified PLLA ASD devices are more controllable and practical than our previous devices. The implanted devices demonstrated good endothelialization and degradability in short and moderate term follow‐up. Long‐term studies are now underway to further evaluate the biodegradability of this novel device.

A Novel-Design Poly-L-Lactic Acid Biodegradable Device for Closure of Atrial Septal Defect: Long-Term Results in Swine

Objectives: The aim of this study is to evaluate the long-term effectiveness and safety of a self-expandable, double-disk biodegradable device made of poly-L-lactic acid (PLLA) for closure of atrial septal defects (ASDs) in swine. Methods: ASDs were created by transseptal needle puncture followed by balloon dilatation in 20 piglets. The experimental group comprised 18 animals, while the remaining 2 animals were used as controls. Effectiveness and safety were evaluated by rectal temperature, leukocyte count, chest radiography, electrocardiogram, transthoracic echocardiography (TTE), intracardiac echocardiography (ICE), and histologic studies. Animals were followed up at 1, 3, 6, and 12 months. Results: An ASD model was successfully created in 19 animals; 1 piglet died during the procedure. The ASD diameters that were created ranged from 5 to 6.4 mm. Devices were successfully implanted in 17 animals. No animal died during the follow-up studies. Rectal temperatures and electrocardiograms were normal at follow-up, while leukocyte counts transiently increased from 1 to 6 months. Radiography, TTE, ICE, and macroscopic studies demonstrated that PLLA occluders were positioned well, with no shifting, mural thrombus formation, or atrioventricular valve insufficiency. Histologic evaluations showed that PLLA devices were partially degraded in the follow-up study. Conclusions: ASD closure with the novel PLLA biodegradable device is safe and effective. Longer-term studies are needed to evaluate long-term biodegradability.

Double BioDisk: a new bioprosthetic device for transcatheter closure of atrial septal defects - a feasibility study in adult sheep

BACKGROUND

To evaluate the long-term effectiveness and safety of a new Double BioDisk (DBD) device for closure of atrial septal defect (ASD). MATERIALS AND METHODS.: ASD was created with transeptal needle (TS) followed by balloon dilatation in 12 sheep weighing 40.1 to 64 kg (mean 55.2 ± 7.1). The ASD diameters were measured after creation and two weeks later before DBD implantation. The DBDs consists of two nitinol rings 18 to 28 mm in diameter connected with small cannulas and covered with a porcine small intestinal submucosa (SIS). They were implanted via a 10 Fr sheath. DBD effectiveness was evaluated by angiocardiography and by intra-cardiac echogram (ICE) with Doppler studies. Two animals were acute, two were followed for 6 weeks, three for 3 months, three for 6 months and two for 12 months.

RESULTS

TS punctures were successful in 10 sheep. In two sheep ASD was created by existing PFO dilation. The ASD size ranged from 13-15 mm (mean 14.1± 0.73 mm) after initial balloon dilation and from 9-13 mm (mean 10.06 ± 1.37 mm) after two weeks. In all animals none of the successfully implanted DBDs spontaneously embolized on release or on follow up. ICE demonstrated no shunting around the DBDs during follows ups. Macroscopic and histologic evaluation of the 6, 12, 24 and 52 weeks animals showed that DBDs were well incorporated in the atrial septum with complete shunt closure. The SIS showed progressive remodeling with the host cells, including endothelization of the DBD devices.

CONCLUSIONS

ASD closure with the Double BioDisk is safe and effective in adult sheep.

Infrahepatic caudal/inferior vena cava interruption with azygos/hemiazygos continuation. Vascular anomaly in swine

Background

Swine are commonly used as a model to study congenital cardiovascular defects that occur in humans and these models have been both spontaneous and experimentally induced. Ventricular septal defect, patent ductus arteriosus, and atrial septal defect (ASD) are examples of experimentally induced models. Absence of caudal/inferior vena cava (CVC/IVC) with azygos/hemiazygos continuation is an uncommon vascular anomaly.

Case report

The vascular anomaly presented in this case report was an incidental finding on a pig that was evaluated for experimental percutaneous atrial septal defect creation and its closure using a percutaneous femoral vein approach. Absence of CVC/IVC was confirmed by venography and necropsy.

Conclusions

To the best of the investigators knowledge, this is the first report of absence of CVC/IVC with azygos/hemiazygos continuation in the swine.