NEXN Gene in Cardiomyopathies and Sudden Cardiac Deaths: Prevalence, Phenotypic Expression, and Prognosis.

BACKGROUND: Few clinical data are available on NEXN mutation carriers, and the gene's involvement in cardiomyopathies or sudden death has not been fully established. Our objectives were to assess the prevalence of putative pathogenic variants in NEXN and to describe the phenotype and prognosis of patients carrying the variants. METHODS: DNA samples from consecutive patients with cardiomyopathy or sudden cardiac death/sudden infant death syndrome/idiopathic ventricular fibrillation were sequenced with a custom panel of genes. Index cases carrying at least one putative pathogenic variant in the NEXN gene were selected. RESULTS: Of the 9516 index patients sequenced, 31 were carriers of a putative pathogenic variant in NEXN only, including 2 with double variants and 29 with a single variant. Of the 29 unrelated probands with a single variant (16 males; median age at diagnosis, 32.0 [26.0-49.0] years), 21 presented with dilated cardiomyopathy (prevalence, 0.33%), and 3 presented with hypertrophic cardiomyopathy (prevalence, 0.14%). Three patients had idiopathic ventricular fibrillation, and there were 2 cases of sudden infant death syndrome (prevalence, 0.46%). For patients with dilated cardiomyopathy, the median left ventricle ejection fraction was 37.5% (26.25-50.0) at diagnosis and improved with treatment in 13 (61.9%). Over a median follow-up period of 6.0 years, we recorded 3 severe arrhythmic events and 2 severe hemodynamic events. CONCLUSIONS: Putative pathogenic NEXN variants were mainly associated with dilated cardiomyopathy; in these individuals, the prognosis appeared to be relatively good. However, severe and early onset phenotypes were also observed-especially in patients with double NEXN variants. We also detected NEXN variants in patients with hypertrophic cardiomyopathy and sudden infant death syndrome/idiopathic ventricular fibrillation, although a causal link could not be established.

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.

Nit-Occlud atrial septal defect occluder device: Histological characterisation of the healing process.

We describe the healing process following transcatheter implantation of the Nit-Occlud ASD-R occluder (PFM medical, Cologne, Germany) for atrial septal defect closure in a sheep model with histological confirmation of neotissue formation covering the device.

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.

Postoperative assessment of left ventricular function by two-dimensional strain (speckle tracking) after paediatric cardiac surgery.

BACKGROUND: Left ventricular (LV) dysfunction may complicate paediatric cardiac surgery with cardiopulmonary bypass, notably after long aortic cross-clamping (ACC). Assessment of occult myocardial injury by conventional echocardiographic variables may be difficult in the postoperative period. AIMS: To evaluate the feasibility of two-dimensional (2D) strain in the postoperative period, and to assess the effect of ACC duration on this variable. METHODS: Thirty-three paediatric patients (age<18years) with congenital heart disease undergoing cardiac surgery with cardiopulmonary bypass were included in this prospective single-centre study. Daily echocardiography was performed from the day before surgery to the fifth postoperative day. LV ejection fraction and LV 2D strain were measured. The cohort was divided into three groups according to ACC duration (group 1:<30minutes; group 2: 30-80minutes; group 3:>80minutes). RESULTS: Mean age and weight were 4.2±2.5years and 15.1±5.2kg, respectively. Feasibilities of longitudinal, circumferential and radial strains were good, and quite similar to conventional variables. Compared with conventional variables, intra- and interobserver agreements regarding 2D strain were better (r=0.916, P<0.001 and r=0.855, P<0.001 for longitudinal strain versus r=0.156, P=0.54 and r=0.064, P=0.80 for LV ejection fraction by Simpson's method). Postoperative evolution of longitudinal and circumferential strains was significantly different between the three groups (P<0.001), whereas there was no difference using conventional variables. CONCLUSION: Postoperative LV 2D strain is a feasible and reproducible method. Strain measurements seem to indicate correlation with ACC duration.

Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management.

UNLABELLED: Atrioventricular block is classified as congenital if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental passage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive cardiac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe permanent cardiac pacing in almost all patients, including those with structural heart abnormalities. CONCLUSION: Early diagnosis and appropriate management are critical in many cases in order to prevent sudden death, and this review critically assesses our current understanding of the pathogenetic mechanisms, clinical course, and optimal management of congenital and childhood AV block. WHAT IS KNOWN: • Prevalence of congenital heart block of 1 per 15,000 to 20,000 live births. AV block is defined as congenital if diagnosed in utero, at birth, or within the first month of life, whereas childhood AV block is diagnosed between the first month and the 18th year of life. As a result of several different etiologies, congenital and childhood atrioventricular block may occur in an entirely structurally normal heart or in association with concomitant congenital heart disease. Cardiac pacing is indicated in symptomatic patients and has several prophylactic indications in asymptomatic patients to prevent sudden death. • Autoimmune, congenital AV block is associated with a high neonatal mortality rate and development of dilated cardiomyopathy in 5 to 30 % cases. What is New: • Several genes including SCN5A have been implicated in autosomal dominant forms of familial progressive cardiac conduction disorders. • Leadless pacemaker technology and gene therapy for biological pacing are promising research fields. In utero percutaneous pacing appears to be at high risk and needs further development before it can be adopted into routine clinical practice. Cardiac resynchronization therapy is of proven value in case of pacing-induced cardiomyopathy.

Cone reconstruction for Ebstein's anomaly: Patient outcomes, biventricular function, and cardiopulmonary exercise capacity.

OBJECTIVE: Cone reconstruction is advocated to treat severe tricuspid valve (TV) regurgitation associated with Ebstein's anomaly. Data on postoperative clinical status, ventricular adaptation, and objective cardiopulmonary testing are lacking in these patients. METHODS: The clinical characteristics, echocardiography, magnetic resonance imaging, and exercise data from 27 consecutive cone reconstructions, undertaken from 2009 to 2013, were retrospectively compared between preoperative baseline and follow-up. RESULTS: There were no deaths. The cone TV functioned well in all but 1 patient with late dehiscence of inferior annuloplasty sutures that were subsequently repaired. Four patients required pacemaker insertion (3 for new complete heart block). At median follow-up of 2.7 ± 1.5 years, tricuspid regurgitation was reduced in all patients, without causing stenosis. Global left ventricle function remained unchanged (pre-operative fraction 60% ± 4% vs postoperative fraction 61% ± 3%; P = .96). MRI showed enhanced forward pulmonary flow (pre 26 ± 1 mL/beat vs post 36 ± 10 mL/beat; P < .005) and increased left ventricle filling (body surface area-indexed left ventricle end-diastolic volume pre 49 ± 14 mL/m(2) vs post 60 ± 14 mL/m(2); P < .005). New York Heart Association functional class improved (pre 2.5 ± 0.6 vs post 1.3 ± 0.6; P < .0001) and there was significant improvement in peak oxygen uptake (pre 54% ± 18% vs post 66% ± 22%; P = .02). CONCLUSIONS: Cone reconstruction of TV offers an effective repair in patients with severe regurgitation associated with Ebstein's anomaly. The patients' clinical status improved with better left ventricle filling and objective exercise capacity. The durability of repair, and mechanisms by which the ventricles adapt to the new loading conditions, need longer-term study.

Cardiogenic shock due to acute tramadol intoxication.

Tramadol is a common analgesic, widely prescribed because of its efficiency and safety. We report the case of a 7-year-old child admitted in cardiac intensive care unit for cardiogenic shock due to tramadol intoxication. Without any past history, the child was admitted at emergency room for generalised convulsion, followed by respiratory distress. Cardiogenic shock was suspected after clinical examination and chest X-ray and confirmed by transthoracic echocardiography showing low left ventricular ejection fraction (<30 %) with pulmonary hypertension. No evidence of cardiac infarction or myocarditis was found. Tramadol intoxication was suspected because of empty tramadol tablets found near the child and later confirmed by toxicologic analysis showing high blood concentration of tramadol (>1 mg/L) and O-desmethyltramadol (>1.5 mg/L). Hemodynamic support by inotropic drug infusion and diuretics was necessary. Left ventricular function normalised after 2 days of treatment allowing drug infusion weaning. Cardiac magnetic resonance imaging performed 3 days after admission confirmed normal left ventricular ejection fraction and volumes without evidence of late gadolinium enhancement. Cardiogenic shock due to tramadol intoxication is rare but exists. Negative inotropic effect of high doses of tramadol has been suspected. Quick recovery is possible.

Tetralogy of Fallot with coarctation of the aorta: a newly recognised developmental and anatomic syndrome.

Tetralogy of Fallot and coarctation of the aorta is an exceptional association. We report here four cases of infants referred for tetralogy of Fallot with or without pulmonary atresia associated with aortic coarctation from 1974 to 2013. All had a right aortic arch, and the coarctation was abnormally situated between the right common carotid and the right subclavian arteries. In all, two infants had an abnormal left subclavian artery and one child had DiGeorge syndrome. All underwent staged surgical repair of the left and right-sided obstructions. A review of the literature shows two types of coarctation in this context. In left aortic arch, coarctation is situated distal to the left subclavian artery. In right aortic arch, coarctation is distal to the right common carotid artery, mirror-image of interrupted left aortic arch type B, associated with anomalies of the branches of the aorta, and should be considered a complex anomaly of aortic arches in the setting of an outflow tract defect due to abnormal migration of cardiac neural crest cells. Screening for this unusual association is critical in the initial assessment of all patients with tetralogy of Fallot.