Mid-term follow-up by speckle tracking and cardiac MRI of children post-transcatheter closure of large atrial septal defects

This is a case-control study of our experience of mid-term follow-up of 40 children who had a transcatheter closure of very large atrial septal defects group (1). All cases had an atrial septal defect device size more than 1.5 times their weight, a ratio considered a contraindication for trans catheter closure (TCC) in some previous reports. The aim of this study is to report the outcomes and mid-term follow-up of transcatheter closure of large atrial septal defects using two-dimensional conventional echocardiography, tissue Doppler imaging, and four-dimensional speckle tracking imaging, and as such to compare results of same echocardiographic examination of age-matched control group of 40 healthy children group (2). Cardiac MRI was performed on cases group (1) only to detect right ventricle and left ventricle volumes and function and early signs of complications. There was no difference between cases and matched healthy controls in terms of the assessment of left ventricle and right ventricle by two-dimensional echocardiography, tissue Doppler imaging, and four-dimensional speckle tracking imaging. Similarly, there was no statistically significant difference between four-dimensional echocardiography and cardiac MRI in their respective assessment of both left ventricle and right ventricle volumes and function. We also detected no complications by echo or by cardiac MRI after a median follow-up period of 2 years and recorded a complete remodelling of right ventricle volumes in all children studied. This points to the safety and efficiency of transcatheter closure of large atrial septal defects in children on mid-term follow-up.

Assessment of Nit-Occlud atrial septal defect occluder device healing process using micro-computed tomography imaging

After percutaneous implantation of a cardiac occluder, a complex healing process leads to the device coverage within several months. An incomplete device coverage increases the risk of device related complications such as thrombosis or endocarditis. We aimed to assess the device coverage process of atrial septal defect (ASD) occluders in a chronic sheep model using micro-computed tomography (micro-CT). After percutaneous creation of an ASD, 8 ewes were implanted with a 16-mm Nit-Occlud ASD-R occluder (PFM medical, Cologne, Germany) and were followed for 1 month (N = 3) and 3 months (N = 5). After heart explant, the device coverage was assessed using micro-CT (resolution of 41.7 μm) and was compared to histological analysis. The micro-CT image reconstruction was performed in 2D and 3D allowing measurement of the coverage thickness and surface for each device. Macroscopic assessment of devices showed that the coverage was complete for the left-side disk in all cases. Yet incomplete coverage of the right-side disk was observed in 5 of the 8 cases. 2D and 3D micro-CT analysis allowed an accurate evaluation of device coverage of each disk and was overall well correlated to histology sections. Surface calculation from micro-CT images of the 8 cases showed that the median surface of coverage was 93±8% for the left-side disk and 55±31% for the right-side disk. The assessment of tissue reactions, including endothelialisation, after implantation of an ASD occluder can rely on in vitro micro-CT analysis. The translation to clinical practice is challenging but the potential for individual follow-up is shown, to avoid thrombotic or infective complications.

Assessment of the healing process after percutaneous implantation of a cardiovascular device: a systematic review

The healing process, occurring after intra-cardiac and intra-vascular device implantation, starts with fibrin condensation and attraction of inflammatory cells, followed by the formation of fibrous tissue that slowly covers the device. The duration of this process is variable and may be incomplete, which can lead to thrombus formation, dislodgement of the device or stenosis. To better understand this process and the neotissue formation, animal models were developed: small (rats and rabbits) and large (sheep, pigs, dogs and baboons) animal models for intra-vascular device implantation; sheep and pigs for intra-cardiac device implantation. After intra-vascular and intra-cardiac device implantation in these animal models, in vitro techniques, i.e. histology, which is the gold standard and scanning electron microscopy, were used to assess the device coverage, characterize the cell constitution and detect complications such as thrombosis. In humans, optical coherence tomography and intra-vascular ultrasounds are both invasive modalities used after stent implantation to assess the structure of the vessels, atheroma plaque and complications. Non-invasive techniques (computed tomography and magnetic resonance imaging) are in development in humans and animal models for tissue characterization (fibrosis), device remodeling evaluation and device implantation complications (thrombosis and stenosis). This review aims to (1) present the experimental models used to study this process on cardiac devices; (2) focus on the in vitro techniques and invasive modalities used currently in humans for intra-vascular and intra-cardiac devices and (3) assess the future developments of non-invasive techniques in animal models and humans for intra-cardiac devices.

Never drop your guard down after atrial septal defect closure: a case report

Background

Percutaneous atrial septal defect (ASD) closure carries a not negligible burden of complications, such as the erosion of cardiac structures surrounding the device. Complications related to erosion are rare and often occur during the first 6 months after implantation.

Case summary

A 40-year-old female patient underwent percutaneous ASD closure in 2006. After 12 years of uneventful follow-up, in March 2018, a device dislodgement causing atrial shunting was incidentally discovered and was attributed to device-induced atrial septal erosion. The patient successfully underwent surgical removal of the device and correction of the interatrial defect.

Discussion

Our purpose is to underline the importance of staged long-term imaging follow-up, even many years after a successful procedure and to highlight the possible risk factors leading to this worrisome condition. In addition, we sought to underline the possible risks associated with deficient aortic rim and explain pros and cons of different approaches.