Human Coxsackie- and adenovirus receptor is a putative target of neutrophil elastase-mediated shedding.

BACKGROUND: During viral-induced myocarditis, immune cells migrate towards the site of infection and secrete proteases, which in turn can act as sheddases by cleaving extracellular domains of transmembrane proteins. We were interested in the shedding of the Coxsackie- and adenovirus receptor (CAR) that acts as an entry receptor for both eponymous viruses, which cause myocarditis. CAR shedding by secreted immune proteases could result in a favourable outcome of myocarditis as CAR's extracellular domain would be removed from the cardiomyocytes' surface leading to decreased susceptibility to ongoing viral infections. METHODS AND RESULTS: In this work, matrix metalloproteinases and serine proteinases were screened for their proteolytic activity towards human CAR. Whereas matrix metalloproteinases, proteinase 3, and cathepsin G did not cleave human recombinant CAR or only within long incubation times, neutrophil elastase showed a distinct cleavage pattern of CAR's extracellular domain that was time- and dose-dependent. Neutrophil elastase cleaves CAR at its membrane-proximal immunoglobulin domain as we determined by nanoLC-MS/MS. Furthermore, neutrophil elastase treatment of cells reduced CAR surface levels as seen by flow cytometry and immunofluorescence microscopy. CONCLUSIONS: With this study, we show that CAR might be a target for shedding by neutrophil elastase.

Multi-parametric speckle tracking analyses to characterize cardiac amyloidosis: a comparative study of systolic left ventricular longitudinal myocardial mechanics.

Cardiac amyloidosis (CAM), the most common cardiac storage disease is associated with significant changes in left-ventricular (LV) morphology and function. To gain particular insights into LV systolic longitudinal myocardial mechanics we investigated seven parameters derived by speckle-tracking-echocardiography (STE) in patients with confirmed CAM (n = 59). The results were compared with those of individuals with healthy heart (n = 150) and another primary myocardial disease with also thickened myocardium and severe diastolic and systolic LV-dysfunction (symptomatic LV-non-compaction-cardiomyopathy, LV-NC, n = 30). In addition to standard echocardiographical measures, the STE-derived data were evaluated and documented utilizing polar-diagrams to obtain overviews of longitudinal myocardial mechanics of the entire LV. Compared with healthy individuals, patients with CAM and LV-NC showed significantly reduced LV-ejection-fraction (EF), global longitudinal systolic peak-strain, strain-rate, and displacement. Pre-systolic stretch-index, post-systolic index, and the EF/global peak-longitudinal-strain-ratio (EF/S) were increased. In contrast to healthy-hearts and the LV-NC group only patients with CAM demonstrated significantly reduced time-to-peak systolic longitudinal strain and time-to-peak strain-rate. Although the level of the segmental values in longitudinal mechanics was significantly different between the groups, comparable intraventricular baso-apical parameter-gradients were found for systolic longitudinal peak-strain and strain-rate, pre-systolic-stretch-index, post-systolic-index, and peak systolic displacement. Compared to ATTR-amyloidosis (ATTR-CAM), patients with AL-amyloidosis (AL-CAM) demonstrated significantly lower end-diastolic and end-systolic LV-volumes, LV-mass-indices, relative apical strain, time-to-peak systolic longitudinal strain, and time-to-peak longitudinal strain-rate. CAM and LV-NC demonstrated altered myocardial mechanics with significantly different STE-derived echocardiographical parameters. ATTR-amyloidosis and AL-amyloidosis had at least significantly different time-to-peak strain, time-to-peak strain-rate and relative apical sparing values.

Systolic longitudinal global and segmental myocardial mechanics in symptomatic isolated left ventricular non-compaction cardiomyopathy.

BACKGROUND: Left ventricular (LV) non-compaction cardiomyopathy (LV-NC) is rare, and data of segmental myocardial mechanics are largely lacking. We investigated myocardial longitudinal mechanics in adults with symptomatic LV-NC (n = 30) versus individuals with healthy hearts (n = 150). The contribution of compacted and non-compacted myocardial layer to systolic LV function has to be determined. METHODS: Seven parameters derived from speckle tracking echocardiography were evaluated and documented utilizing polar-diagrams to obtain overviews of myocardial mechanics of the entire LV. RESULTS: According to embryonal myocardial development, non-compacted myocardium was mostly located in mid-ventricular and apical segments of the free LV wall. LV ejection fraction was reduced in LV-NC (34 ± 15%, healthy 63 ± 5%, P < .0001). The compact wall layer in LV-NC demonstrated increasing systolic radial thickness (diastolic 5.6 ± 1.4, systolic 6.5 ± 1.4mm, P = .016), whereas the non-compacted layer remained unchanged or tended to decrease in thickness (diastolic 17.6 ± 5.3, systolic 16.0 ± 4.6mm, P = .22). Compared with heart-healthy individuals in LV-NC peak systolic longitudinal strain (healthy -21.1% vs. LV-NC -8.8, P < .0001), peak systolic longitudinal strain-rate (-1.23%/s vs. -0.64, P < .0001), and peak longitudinal displacement (12.1 vs. 5.6 mm, P < .0001) were reduced, while pre-systolic stretch index (1.31% vs. 3.2%, P < .0001) and post-systolic index (2.5% vs. 15.9%, P < .0001) increased. Time-to-peak longitudinal strain (371 vs. 389 ms, P = .065) and time-to-peak longitudinal strain rate (181 vs. 200 ms, P = .0677) did not differ significantly. In LV-NC, there were no significant differences between analyses using an interpolated endocardial border along the edges of the recesses and the endocardial edge of the compact wall layer. Hence, LV function appeared to depend only on the thin compact wall layer. CONCLUSION: In LV-NC, myocardial efficiency is severely diminished compared with healthy controls and LV function seemed to depend mainly on the compact myocardial wall layer.

Naturally occurring variants in the transmembrane and cytoplasmic domains of the human Coxsackie- and adenovirus receptor have no impact on virus internalisation.

The Coxsackie- and adenovirus receptor (CAR) mediates homophilic cell-cell contacts and susceptibility to both human pathogenic viruses through its membrane-distal immunoglobulin domain. In the present study, we screened five missense variants of the human CAR gene for their influence on adenovector or Coxsackievirus entry into Chinese hamster ovary cells. The CAR variants facilitated virus internalisation to a similar extent as wild type CAR. This underlines CAR's presumed invariance and essential physiological role in embryogenesis.

Fabry disease: Detection of Alu-mediated exon duplication by NGS.

Monogenetic diseases can be analyzed routinely by targeted DNA sequencing. If causative variants are not found, complementary methods like RNA sequencing or analysis of copy number variations by multiplex ligation-dependent probe amplification have to be considered. In the latter, especially exonic duplications or deletions can be detected, but the precise sites of mutations remain unclear. As we demonstrate in this casuistic report of Fabry disease, next-generation sequencing (NGS) of a long-range PCR product can identify the recombination site directly and illuminate the underlying molecular mechanism.

Molecular autopsy of sudden unexplained deaths reveals genetic predispositions for cardiac diseases among young forensic cases.

AIMS: Coronary artery disease accounts for the majority of sudden cardiac deaths (SCD) in the older population whereas cardiomyopathies and arrhythmogenic abnormalities predominate in younger SCD victims (<35 years) with a significant genetic component. The elucidation of the pathogenetic cause of death might be relevant for the prevention of further deaths within affected families. Aim of this study was to determine the portion of underlying genetic heart diseases among unexplained putative SCD cases from a large German forensic department. METHODS AND RESULTS: We included 10 forensic cases of sudden unexplained death (SUD) victims aged 19-40 years, who died by SCD due to forensic autopsy. DNA was analysed by next generation panel sequencing of 174 candidate genes for channelopathies and cardiomyopathies. Cardiological examinations, genetic counselling, and subsequent genetic testing were offered to all affected families. We identified within 1 year 10 cases of SUD among 172 forensic cases. Evidence for a genetic disposition was found in 8 of 10 (80%) cases, with pathogenic mutations in 3 and variants of uncertain significance in 5 of SCD cases. Subsequent selective screening of family members revealed two additional mutation carriers. CONCLUSION: The study provides strong evidence that molecular genetics improves the post mortem diagnosis of fatal genetic heart diseases among SUD victims. Molecular genetics should be integrated in forensic and pathological routine practice.

Effect of lovastatin on coxsackievirus B3 infection in human endothelial cells.

OBJECTIVE: The coxsackie and adenovirus receptor (CAR) mediates the entry of coxsackievirus B (CVB) and adenovirus into host cells and is, therefore, a key determinant for the molecular pathogenesis of viral diseases such as myocarditis. The aim was to investigate the influence of HMG-CoA reductase inhibitor lovastatin on CAR expression in endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVECs) were exposed to different concentrations of lovastatin (0.05-5 µmol/l) for up to 48 h. Alterations in CAR expression were examined by quantitative real-time PCR (qRT-PCR) and flow cytometry. In addition, after treatment with 1 µmol/l lovastatin for 48 h, HUVECs were infected for 8 h with CVB3 and virus replication was detected by qRT-PCR using viral-specific TaqMan probes. RESULTS: We found that lovastatin decreases CAR mRNA expression by up to 80% (p < 0.01) and CAR protein expression by up to 19% (p < 0.01), in a concentration-dependent manner. Moreover, virus replication of CVB3 was significantly inhibited after lovastatin treatment (p < 0.05). The signaling mechanism of CAR down-regulation by lovastatin depends on the Rac1/Cdc42 pathway. CONCLUSION: This study shows for the first time that lovastatin reduces the expression of CAR and subsequently the replication of CVB3 in HUVECs.

CMR-based right ventricular strain analysis in cardiac amyloidosis and its potential as a supportive diagnostic feature.

Background: Right ventricular (RV) strain has provided valuable prognostic information for patients with cardiac amyloidosis (CA). However, the extent to which RV strain and strain rate can differentiate CA is not yet clinically established. CA underdiagnosis delays treatment strategies and exacerbates patient prognosis. Aims: Evaluation of cardiac magnetic resonance (CMR) quantified RV global and regional strain of CA and HCM patients along with CA subtypes. Methods: CMR feature tracking attained longitudinal, radial and circumferential global and regional strain in 47 control subjects (CTRL), 43 CA-, 20 hypertrophic cardiomyopathy- (HCM) patients. CA patients were subdivided in 21 transthyretin-related amyloidosis (ATTR) and 20 acquired immunoglobulin light chain (AL) patients. Strain data and baseline clinical parameters were statistically analysed with respect to diagnostic performance and discriminatory power between the different clinical entities. Results: Effective differentiation of CA from HCM patients was achieved utilizing global longitudinal (GLS: 16.5 ± 3.9% vs. -21.3 ± 6.7%, p = 0.032), radial (GRS: 11.7 ± 5.3% vs. 16.5 ± 7.1%, p < 0.001) and circumferential (GCS: -7.6 ± 4.0% vs. -9.4 ± 4.4%, p = 0.015) right ventricular strain. Highest strain-based hypertrophic phenotype differentiation was attained using GRS (AUC = 0.86). Binomial regression found right ventricular ejection fraction (RV-EF) (p = 0.017) to be a significant predictor of CA-HCM differentiation. CA subtypes had comparable cardiac strains. Conclusion: CMR-derived RV global strains and various regional longitudinal strains provide discriminative radiological features for CA-HCM differentiation. However, in terms of feasibility, cine-derived RV-EF quantification may suffice for efficient differential diagnostic support.

Rapid detection of genetic variants in hypertrophic cardiomyopathy by custom DNA resequencing array in clinical practice.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease (1/500) and the most common cause of sudden cardiac death in young people. Pathogenic mutation detection of HCM is having a growing impact on the medical management of patients and their families. However, the remarkable genetic and allelic heterogeneity makes molecular analysis by conventional methods very time-consuming, expensive and difficult to realise in a routine diagnostic molecular laboratory. METHOD AND RESULTS: The authors used their custom DNA resequencing array which interrogates all possible single-nucleotide variants on both strands of all exons (n=160), splice sites and 5'-untranslated region of 12 HCM genes (27 000 nucleotides). The results for 122 unrelated patients with HCM are presented. Thirty-three known or novel potentially pathogenic heterozygous single-nucleotide variants were identified in 38 patients (31%) in genes MYH7, MYBPC3, TNNT2, TNNI3, TPM1, MYL3 and ACTC1. CONCLUSIONS: Although next-generation sequencing will replace all large-scale sequencing platforms for inherited cardiac disorders in the near future, this HCM resequencing array is currently the most rapid, cost-effective and reasonably efficient technology for first-tier mutation screening of HCM in clinical practice. Because of its design, the array is also an appropriate tool for initial screening of other inherited forms of cardiomyopathy.

When dystrophia meets ischaemia: a case report on cardiac involvement of myotonic dystrophy type 2 and successful arrhythmia elimination after catheter ablation.

BACKGROUND: This case reviews the cardiac involvement of myotonic dystrophy type 2 in terms of ventricular arrhythmias (VAs) and individual myocardial scar formation as target for catheter ablation. CASE SUMMARY: A 62-year-old woman with myotonic dystrophy type 2 and a severely reduced left ventricular ejection fraction (25%) presented with recurrent episodes of VAs and consecutive implantable cardioverter-defibrillator therapies. The patient already underwent two VA ablation attempts focusing on an ischaemia-related arrhythmia substrate in the left ventricle. The patient was scheduled for repeat ablation after the progression of coronary artery disease was ruled out. Interestingly bipolar voltage as well as activation mapping revealed an arrhythmia substrate along with the basal and inferior aspects of the right ventricle (RV). Catheter ablation of this scarred area in the RV resulted in specific termination of the VAs. Due to end-stage heart failure, key heart transplant criteria were met. The patient was evaluated for heart transplantation and added to the waiting list. Hitherto, no further VAs were documented during follow-up. DISCUSSION: As these patients present with specific dystrophia-related arrhythmia substrates, we propose pre-procedural visualization of dystrophy-associated arrhythmia substrates using cardiac magnetic resonance imaging allowing for personalized ablation approaches in these patients.

Cardiovascular Magnetic Resonance Imaging-Based Right Atrial Strain Analysis of Cardiac Amyloidosis.

Background: Cardiac amyloidosis (CA) manifests in a hypertrophic phenotype with a poor prognosis, making differentiation from hypertrophic cardiomyopathy (HCM) challenging and delaying early treatment. The extent to which magnetic resonance imaging (MRI) quantifies the right atrial strain (RAS) and strain rate (RASR), providing valuable diagnostic information, is not yet clinically established. Aims: This study assesses diagnostic differences in the longitudinal RAS and RASR between CA and HCM patients, control subjects (CTRL) and CA subtypes in addition to the impact of atrial fibrillation (AF) on the right atrial function in CA patients. The RAS and RASR of tricuspid regurgitation (TR) patients are used to assess the potential for diagnostic overlap. Methods: RAS and RASR quantification was conducted via MRI feature-tracking for biopsy-confirmed CA patients with subtypes identified. Strain parameters were compared for CTRL, HCM and TR patients. Post hoc testing identified intergroup differences. Results: In total, 41 CA patients were compared to 47 CTRL, 20 HCM and 31 TR patients. Reservoir (R), conduit and booster RAS and RASRs allow for significant differentiation (p < 0.001) between CA and HCM patients (R: 10.6 ± 14.3% vs. R: 33.5 ± 16.3%) and CTRL (R: 44.6 ± 15.7%). Booster and reservoir RAS and RASRs qualified as reliable diagnostic tests (AUC > 0.8). CA patients with AF, in contrast to sinus rhythm, demonstrated a significantly impaired reservoir RAS and RASR and booster RASR. The discriminative power of RAS for CA vs. TR was insufficient (R: 10.6% ± 14.3% vs. 7.0% ± 6.0%, p = 0.069). Differentiation between 21 transthyretin and 20 light-chain amyloidosis subtypes was not achievable (R: 0.7% ± 1.0% vs. 0.7% ± 1.0%, p = 0.827). Conclusion: The MRI-derived RAS and RASR are impaired in CA patients and may support noninvasive differentiation between CA, HCM and CTRL.

Magnetic-Resonance-Imaging-Based Left Atrial Strain and Left Atrial Strain Rate as Diagnostic Parameters in Cardiac Amyloidosis.

Aims: The present study aims to evaluate magnetic-resonance-imaging (MRI)-assessed left atrial strain (LAS) and left atrial strain rate (LASR) as potential parameters for the diagnosis of cardiac amyloidosis (CA), the distinction of clinical subtypes and differentiation from other cardiomyopathies. Methods and results: LAS and LASR were assessed by MRI feature tracking in patients with biopsy-proven CA. LAS and LASR of patients with CA were compared to healthy subjects and patients with hypertrophic cardiomyopathy. LAS and LASR were also analyzed concerning differences between patients with transthyretin (ATTR) and light chain amyloidosis (AL). A total of 44 patients with biopsy-proven CA, 19 patients with hypertrophic cardiomyopathy and 24 healthy subjects were included. In 22 CA patients (50%), histological examination identified ATTR as CA subtype and AL in the remaining patients. No significant difference was observed for reservoir, conduit or booster LAS in patients with AL or ATTR. Reservoir LAS, conduit LAS and booster LAS were significantly reduced in patients with CA and HCM as compared to healthy subjects (p < 0.001). Reservoir LAS and booster LAS were significantly reduced in CA as compared to HCM patients (p < 0.001). A linear correlation was observed between LA global reservoir strain and LA-EF (p < 0.001, r = 0.5), conduit strain and global longitudinal LV strain (p < 0.001, r = 0.5), global booster strain rate and LA-EF (p < 0.001, r = 0.6) and between global booster strain rate and LA area at LVED (p < 0.0001, 0.5). Conclusions: LAS and LASR are severely impaired in patients with CA. The MRI-based assessment of LAS and LASR might allow non-invasive diagnosis and categorization of CA and its distinct differentiation from other hypertrophic phenotypes.

In vitro modeling of ryanodine receptor 2 dysfunction using human induced pluripotent stem cells.

BACKGROUND/AIMS: Induced pluripotent stem (iPS) cells generated from accessible adult cells of patients with genetic diseases open unprecedented opportunities for exploring the pathophysiology of human diseases in vitro. Catecholaminergic polymorphic ventricular tachycardia type 1 (CPVT1) is an inherited cardiac disorder that is caused by mutations in the cardiac ryanodine receptor type 2 gene (RYR2) and is characterized by stress-induced ventricular arrhythmia that can lead to sudden cardiac death in young individuals. The aim of this study was to generate iPS cells from a patient with CPVT1 and determine whether iPS cell-derived cardiomyocytes carrying patient specific RYR2 mutation recapitulate the disease phenotype in vitro. METHODS: iPS cells were derived from dermal fibroblasts of healthy donors and a patient with CPVT1 carrying the novel heterozygous autosomal dominant mutation p.F2483I in the RYR2. Functional properties of iPS cell derived-cardiomyocytes were analyzed by using whole-cell current and voltage clamp and calcium imaging techniques. RESULTS: Patch-clamp recordings revealed arrhythmias and delayed afterdepolarizations (DADs) after catecholaminergic stimulation of CPVT1-iPS cell-derived cardiomyocytes. Calcium imaging studies showed that, compared to healthy cardiomyocytes, CPVT1-cardiomyocytes exhibit higher amplitudes and longer durations of spontaneous Ca(2+) release events at basal state. In addition, in CPVT1-cardiomyocytes the Ca(2+)-induced Ca(2+)-release events continued after repolarization and were abolished by increasing the cytosolic cAMP levels with forskolin. CONCLUSION: This study demonstrates the suitability of iPS cells in modeling RYR2-related cardiac disorders in vitro and opens new opportunities for investigating the disease mechanism in vitro, developing new drugs, predicting their toxicity, and optimizing current treatment strategies.

Antiviral effect of Bosentan and Valsartan during coxsackievirus B3 infection of human endothelial cells.

In viral myocarditis, adeno- and enteroviruses have most commonly been implicated as causes of infection. Both viruses require the human coxsackie-adenovirus receptor (CAR) to infect the myocardium. Due to its crucial role for viral entry, CAR-downregulation may lead to novel approaches for treatment for viral myocarditis. In this study, we report on pharmaceutical drug influences on CAR levels in human umbilical vein endothelial cells (HUVEC) and cervical carcinoma cells (HeLa) detected by immunoblotting, quantitative real time-PCR and cellular susceptibility to the cardiotropic coxsackie-B3 virus strain Nancy (CVB3). Our results indicate, for the first time, a dose-dependent CAR mRNA and protein downregulation upon Valsartan and Bosentan treatment. Most interestingly, drug-induced CAR diminution significantly reduced the viral load in CVB3-infected HUVEC. In order to assess the regulatory effects of both drugs in detail, we knocked down their protein targets, the G-protein coupled receptors angiotensin-II type-1 receptor (AT(1)R) and endothelin-1 type-A and -B receptors (ET(A)R/ET(B)R) in HUVEC. Receptor-specific gene silencing indicates that CAR gene expression is regulated by agonistic and antagonistic binding to ET(B)R, but not ET(A)R. In addition, neither stimulation nor inhibition of AT(1)R seemed to be involved in CAR gene regulatory processes. Our study indicates that Valsartan and Bosentan protected human endothelial cells from CVB3-infection. Therefore, besides their well-known anti-hypertensive effects these drugs may also protect the myocardium and other tissues from coxsackie- and adenoviral infection.

Fulminant Myocarditis Managed by Extracorporeal Life Support (Impella® CP): A Rare Case.

BACKGROUND: Treating myocarditis can be difficult, as clear criteria for diagnosis and management are lacking for heterogeneous clinical presentations. CASE DESCRIPTION: We report a case of a 49-year-old female who presented with cardiogenic shock and subsequent cardiac arrest. Extracorporeal life support was instituted, and after eight days with Impella CP the patient recovered and at six months presented with normal cardiac function. CONCLUSION: Fulminant myocarditis remains a challenging disease in daily clinical practice, not only for diagnosis, but also for treatment. With this report we emphasize that myocardial failure due to fulminant myocarditis may be reversible if treated with extracorporeal life support, which thus plays an important and life-saving role.

[Homozygous hypercholesterolemia - new therapeutic options in cases with complete lack of LDL- receptor]. / Familiäre homozygote Hypercholesterinämie.

Homozygous hypercholesterolemia is an extremely rare genetic disorder caused by mutations in the LDL receptor gene or occasionally by mutations in other genes like proprotein convertase subtilisin / kexin 9 (PCSK9). Gold standard of homozygous hypercholesterolemia therapy is apheresis, accompanied by high-dose statin and ezetimibe therapy. The cholesterol-lowering effect can be supported by new agents like inhibitors of microsomal triglyceride transfer protein (lomitapide), or by enhancing LDL catabolism through inhibition of the PCSK9 activity. We present the case of a young woman with homozygous hyperlipidemia due to a mutation c.1200 C> A(p.Tyr400*) in the LDLR gene that introduces a stop-codon at amino acid position 400. This truncated LDLR cannot mediate a membrane-bound uptake of LDL cholesterol. A combined therapy including simvastatin, ezetimibe and apheresis did not lead to satisfactory LDL levels. By adding lomitapide, a dramatic receptor-independent reduction of LDL was achieved.

Generation of human induced pluripotent stem cell line from a patient with a long QT syndrome type 2.

We report here the generation of human iPS cell line UKKi009-A from dermal fibroblasts of a patient carrying heterozygous mutation c.3035-3045delTCCCTCGATGC, p.Leu1012Pro (fs*55) in KCNH2 gene leading to long QT syndrome type 2 (LQT2). We used the Sleeping Beauty transposon-based plasmids expressing OSKM along with microRNAs 307/367 to reprogram the fibroblasts. The iPS cells possess pluripotent stem cell characteristics and differentiate to cell lineages of all three germ layers. This cell line can serve as a source for in vitro modeling of LQT2. This cell line is distributed by the European Collection of Authenticated Cell Cultures (ECACC).

Determining the role of fibrosis in hypertrophic cardiomyopathy.

Fibroblast activity within the heart may be considered a basically constructive process. Hyperactivity of fibroblasts, however, may result in the accumulation of extracellular matrix proteins with adverse effects on cardiac structure and function including electrical instability and increased risk of arrhythmogenic cardiac death. The detection of cardiac fibrosis by dedicated imaging techniques, mainly gadolinium-enhanced MRI, holds promise to refine patient management in a variety of cardiac conditions. This review aims to summarize the current knowledge regarding fibrosis in hypertrophic cardiomyopathy.

The disease-specific phenotype in cardiomyocytes derived from induced pluripotent stem cells of two long QT syndrome type 3 patients.

Long QT syndromes (LQTS) are heritable diseases characterized by prolongation of the QT interval on an electrocardiogram, which often leads to syncope and sudden cardiac death. Here we report the generation of induced pluripotent stems (iPS) cells from two patients with LQTS type 3 carrying a different point mutation in a sodium channel Nav1.5 (p.V240M and p.R535Q) and functional characterization of cardiomyocytes (CM) derived from them. The iPS cells exhibited all characteristic properties of pluripotent stem cells, maintained the disease-specific mutation and readily differentiated to CM. The duration of action potentials at 50% and 90% repolarization was longer in LQTS-3 CM as compared to control CM but this difference did not reach statistical significance due to high variations among cells. Sodium current recordings demonstrated longer time to peak and longer time to 90% of inactivation of the Na(+) channel in the LQTS-3 CM. This hints at a defective Na(+) channel caused by deficiency in open-state inactivation of the Na(+) channel that is characteristic of LQTS-3. These analyses suggest that the effect of channel mutation in the diseased CM is demonstrated in vitro and that the iPS cell-derived CM can serve as a model system for studying the pathophysiology of LQTS-3, toxicity testing and design of novel therapeutics. However, further improvements in the model are still required to reduce cell-to-cell and cell line-to-cell line variability.

The diagnosis and treatment of hypertrophic cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the most common hereditary disease of the heart. METHODS: In this article, we summarize the current state of the diagnosis and treatment of HCM on the basis of a selective review of recent publications with relevance to clinical practice. RESULTS: Several hundred mutations in more than 27 genes, most of which encode sarcomeric structures, are associated with the HCM phenotype. Thus, HCM can be thought of as a sarcomeric disease, with myocardial fiber disarray as its histological hallmark. There are two types of HCM, a more common, obstructive type (HOCM, 70%) and a less common, non-obstructive type (HNCM; in all cases of HCM, testing should be performed to detect outflow obstruction at rest and/or on provocation, and to thereby determine whether HOCM or HNCM is present. The symptoms of HCM include dyspnea, angina pectoris, palpitations, dizziness, and occasionally syncope. Because sudden cardiac death is the most serious complication of HCM, particularly in young and asymptomatic patients, it follows that correct diagnosis, followed by risk stratification of patients with regard to the need for prophylactic implantation of an implantable cardiac defibrillator (ICD), can be of life-saving importance. The pharmacotherapy of symptomatic HNCM consists of the treatment of heart failure with a normal ejection fraction (HFNEF). In HOCM, the patient's symptoms and the obstructive gradient are the guide to treatment with beta-blockers or verapamil. For patients with drug-resistant disease, surgical myectomy and percutaneous septal ablation are now standard treatments. CONCLUSION: A near-normal life expectancy and a highly satisfactory quality of life are now realistic treatment goals for patients with HCM.