High-resolution imaging for the analysis and reconstruction of 3d microenvironments for regenerative medicine: An application-focused review

The rapid evolution of regenerative medicine and its associated scientific fields, such as tissue engineering, has provided great promise for multiple applications where replacement and regeneration of damaged or lost tissue is required. In order to evaluate and optimise the tissue engineering techniques, visualisation of the material of interest is crucial. This includes monitoring of the cellular behaviour, extracellular matrix composition, scaffold structure, and other crucial ele-ments of biomaterials. Non-invasive visualisation of artificial tissues is important at all stages of development and clinical translation. A variety of preclinical and clinical imaging methods—in-cluding confocal multiphoton microscopy, optical coherence tomography, magnetic resonance imaging (MRI), and computed tomography (CT)—have been used for the evaluation of artificial tis-sues. This review attempts to present the imaging methods available to assess the composition and quality of 3D microenvironments, as well as their integration with human tissues once implanted in the human body. The review provides tissue-specific application examples to demonstrate the applicability of such methods on cardiovascular, musculoskeletal, and neural tissue engineering

Arrhythmogenic cardiomyopathies (ACs): diagnosis, risk stratification and management

Introduction Phenotype is defined as a set of observable characteristics of an individual resulting from the interaction of their genotype with the environment. It differs from ‘disease’ in that it does not reflect the mechanism by which it is produced. In 1982, the term arrhythmogenic right ventricular dysplasia was first used to describe a clinical phenotype characterised by ventricular arrhythmias of left bundle branch block (LBBB) configuration accompanied by right ventricular dilatation, wall motion abnormalities and fibrofatty replacement of the myocardium.1 Arrhythmogenic right ventricular cardiomyopathy (ARVC) became the preferred descriptor when subsequent histopathological analysis revealed that myocyte atrophy as a consequence of progressive cell death occurred after birth.2 3 Initial clinical diagnostic criteria for ARVC were based on descriptions of patients with advanced disease,4 but discovery of its genetic basis, and the phenotyping of large patient cohorts including relatives, revealed a broader disease spectrum in which right ventricle (RV) and left ventricle (LV) can be involved.5 The disease paradigm has expanded further with the recognition of new disease genes causing similar phenotypes. Hence, terms such as left-dominant arrhythmogenic cardiomyopathy, arrhythmic dilated cardiomyopathy or simply arrhythmogenic cardiomyopathy (AC) are increasingly used to describe the clinical phenotype observed in a family of disorders in which frequent ventricular arrhythmia and dysfunction of one or both ventricles are the defining features. In this article, we review this emerging concept with a focus on the genetics and clinical presentation of different forms of AC and a diagnostic approach based on recognition of particular clinical traits (figure 1)

Short-term effects of angiotensin receptor-neprilysin inhibitors on diastolic strain and tissue doppler parameters in heart failure patients with reduced ejection fraction: A pilot trial

OBJECTIVE: Although sacubitril/valsartan has recently shown its long-term benefits on morbidity and mortality in symptomatic patients with chronic heart failure with reduced ejection fraction (HFrEF), its short-term effects on diastolic function remain uncertain. We sought to assess 30-day effects of sacubitril/valsartan on left ventricular (LV) diastolic paremeters determined by speckle tracking and tissue Doppler imaging (STI and TDI respectively) as well as their association with functional capacity change evaluated by peak oxygen uptake (VO2max) in stable patients with symptomatic HFrEF. METHODS: A total of 35 patients (aged 61 ± 9 years) eligible for sacubitril/valsartan underwent a complete two-dimension (2D) echocardiographic study and a cardiopulmonary exercise test at baseline and 30 days after the initiation of therapy. RESULTS: Significant improvements in ratio of trans-mitral inflow early diastolic velocity E to mitral annulus early diastolic velocity E' (ΔΕ//Ε' = -35.9%, p = 0.001), peak early diastolic strain rate SRE (ΔSRE = +22.5%, p = 0.024) and ratio E/SRE (ΔE/SRE = -33.2%, p = 0.025) were observed after 1-month therapy. Compared with baseline, VO2max also increased significantly by 16.7 % (p = 0.001). Baseline E/SRE and ΔE/SRE were the strongest independent predictors of VO2max improvement (beta = -0.43, p = 0.004 and beta = 0.45, p = 0.021 respectively) in the multivariate analysis. CONCLUSION: Sacubitril/valsartan was associated with early improvement in LV diastolic function determined by TDI and 2D STI. Baseline E/SRE was stronger than standard echocardiographic parameters in predicting the early benefit of sacubitril/valsartan therapy

Genetic basis of arrhythmogenic cardiomyopathy

PURPOSE OF REVIEW: To date 16 genes have been associated with arrhythmogenic cardiomyopathy (ACM). Mutations in these genes can lead to a broad spectrum of phenotypic expression ranging from disease affecting predominantly the right or left ventricle, to biventricular subtypes. Understanding the genetic causes of ACM is important in diagnosis and management of the disorder. This review summarizes recent advances in molecular genetics and discusses the application of next-generation sequencing technology in genetic testing in ACM. RECENT FINDINGS: Use of next-generation sequencing methods has resulted in the identification of novel causative variants and genes for ACM. The involvement of filamin C in ACM demonstrates the genetic overlap between ACM and other types of cardiomyopathy. Putative pathogenic variants have been detected in cadherin 2 gene, a protein involved in cell adhesion. Large genomic rearrangements in desmosome genes have been systematically investigated in a cohort of ACM patients. SUMMARY: Recent studies have identified novel causes of ACM providing new insights into the genetic spectrum of the disease and highlighting an overlapping phenotype between ACM and dilated cardiomyopathy. Next-generation sequencing is a useful tool for research and genetic diagnostic screening but interpretation of identified sequence variants requires caution and should be performed in specialized centres

Arrhythmic risk stratification in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable cardiomyopathy characterized by a predominantly arrhythmic presentation. It represents the leading cause of sudden cardiac death (SCD) among athletes and poses a significant morbidity threat in the general population. As a causative treatment for ARVC is still not available, the placement of an implantable cardioverter defibrillator represents the current cornerstone for SCD prevention in this setting. Thanks to international ARVC-dedicated efforts, significant steps have been achieved in recent years towards an individualized, patient-centred risk stratification approach. A novel risk calculator algorithm estimating the 5-year risk of arrhythmias of patients with ARVC has been introduced in clinical practice and subsequently validated. The purpose of this article is to summarize the body of evidence that has allowed the development of this tool and to discuss the best way to implement its use in the care of an individual patient

Arrhythmic Risk Stratification in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an heritable cardiomyopathy characterized by a predominantly arrhythmic presentation. It represents the leading cause of sudden cardiac death (SCD) among athletes and poses a significant morbidity treat in the general population. As a causative treatment for ARVC is still not available, the placement of an implantable cardioverter defibrillator (ICD) represent the current cornerstone for SCD prevention in this setting. Thanks to international ARVC-dedicated efforts, significant steps have been achieved in recent years towards an individualized, patient-centered risk stratification approach. A novel risk calculator algorithm estimating the 5 year risk of arrhythmias of patients with ARVC have been introduced in clinical practice and subsequently validated. The purpose of this article is to summarize the body of evidence that has allowed the development of this tool and to discuss the best way to implement its use in the care of an individual patient

Effect of trimetazidine dihydrochloride therapy on exercise capacity in patients with nonobstructive hypertrophic cardiomyopathy: A randomized clinical trial

Importance: Hypertrophic cardiomyopathy causes limiting symptoms in patients, mediated partly through inefficient myocardial energy use. There is conflicting evidence for therapy with inhibitors of myocardial fatty acid metabolism in patients with nonobstructive hypertrophic cardiomyopathy. Objective: To determine the effect of oral therapy with trimetazidine, a direct inhibitor of fatty acid β-oxidation, on exercise capacity in patients with symptomatic nonobstructive hypertrophic cardiomyopathy. Design, Setting, and Participants: This randomized, placebo-controlled, double-blind clinical trial at The Heart Hospital, University College London Hospitals, London, United Kingdom was performed between May 31, 2012, and September 8, 2014. The trial included 51 drug-refractory symptomatic (New York Heart Association class ≥2) patients aged 24 to 74 years with a maximum left ventricular outflow tract gradient 50 mm Hg or lower and a peak oxygen consumption during exercise of 80% or less predicted value for age and sex. Statistical analysis was performed from March 1, 2016 through July 4, 2018. Interventions: Participants were randomly assigned to trimetazidine, 20 mg, 3 times daily (n = 27) or placebo (n = 24) for 3 months. Main Outcomes and Measures: The primary end point was peak oxygen consumption during upright bicycle ergometry. Secondary end points were 6-minute walk distance, quality of life (Minnesota Living with Heart Failure questionnaire), frequency of ventricular ectopic beats, diastolic function, serum N-terminal pro-brain natriuretic peptide level, and troponin T level. Results: Of 49 participants who received trimetazidine (n = 26) or placebo (n = 23) and completed the study, 34 (70%) were male; the mean (SD) age was 50 (13) years. Trimetazidine therapy did not improve exercise capacity, with patients in the trimetazidine group walking 38.4 m (95% CI, 5.13 to 71.70 m) less than patients in the placebo group at 3 months after adjustment for their baseline walking distance measurements. After adjustment for baseline values, peak oxygen consumption was 1.35 mL/kg per minute lower (95% CI, -2.58 to -0.11 mL/kg per minute; P = .03) in the intervention group after 3 months. Conclusions and Relevance: In symptomatic patients with nonobstructive hypertrophic cardiomyopathy, trimetazidine therapy does not improve exercise capacity. Pharmacologic therapy for this disease remains limited. Trial Registration: ClinicalTrials.gov identifier: NCT01696370

State of the Art Review on Genetics and Precision Medicine in Arrhythmogenic Cardiomyopathy.

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterised by ventricular arrhythmia and an increased risk of sudden cardiac death (SCD). Numerous genetic determinants and phenotypic manifestations have been discovered in ACM, posing a significant clinical challenge. Further to this, wider evaluation of family members has revealed incomplete penetrance and variable expressivity in ACM, suggesting a complex genotype-phenotype relationship. This review details the genetic basis of ACM with specific genotype-phenotype associations, providing the reader with a nuanced perspective of this condition; whilst also proposing a future roadmap to delivering precision medicine-based management in ACM