Novel Echocardiographic Biomarkers in the Management of Atrial Fibrillation

Purpose of Review: Atrial fibrillation (AF) is the most common arrhythmia in adults. The number of patients with AF is anticipated to increase annually, mainly due to the aging population alongside improved arrhythmia detection. AF is associated with a significantly elevated risk of hospitalization, stroke, thromboembolism, heart failure, and all-cause mortality. Echocardiography is one of the key components of routine assessment and management of AF. Therefore, the aim of this review is to briefly summarize current knowledge on “novel” echocardiographic parameters that may be of value in the management of AF patients. Recent Findings: Novel echocardiographic biomarkers and their clinical application related to the management of AF have been taken into consideration. Both standard parameters such as atrial size and volume but also novels like atrial strain and tissue Doppler techniques have been analyzed. Summary: A number of novel echocardiographic parameters have been proven to enable early detection of left atrial dysfunction along with increased diagnosis accuracy. This concerns particularly experienced echocardiographers. Hence, these techniques might improve the prediction of stroke and thromboembolic events among AF patients and need to be further developed and disseminated. Nonetheless, even the standard imaging parameters could be of significant value and should not be discontinued in everyday clinical practice. © 2019, The Author(s)

Increased frequency rate and alteration of If current in iPSC-derived atrial fibrillation human cardiomyocytes.

Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide. The mechanisms underlying AF are not fully understood, but multiple pathophysiological pathways have been suggested. On the contrary, the well-established AF risk factors include male sex, advancing age, diabetes, hypertension, heart failure, myocardial infarction, and valvular heart disease. Nevertheless, much of the AF risk variability remains unexplained, leading investigators to look for novel and genetic risk factors. Since 1940, a number of reports have described rare inherited AF disorders mainly associated with cardiac channel mutations. Recently several GWAS studies have shown the association of AF with peculiar chromosomal loci, and, nowadays, parental AF is considered as one of the main risk factor in offspring. We started characterizing a family where three siblings suffered a common persistent AF. The consanguinity, the variability in risk factors, and the young age of onset of AF in these patients (from 44 to 52 years old) strongly suggested a genetic basis for this form of arrhythmia. Since an extensive single candidate gene analysis, comprising several known AF-associated genes, did not reveal any mutation, we approached the entire exome analysis to identify other sequence abnormalities. Preliminary results show that the three siblings are carrying two different single nucleotide mutations in cellular filaments. These mutations, further confirmed by Sanger sequence analysis, are absent in the rest of the family and have not been described in human exome sequence databases. In parallel, we built the cellular-based human in vitro AF model, starting from patients-derived primary cultures of dermal fibroblasts. These cells were transduced with Yamanaka’s factors OCT4, KLF4, SOX2 and c-MYC, using two different systems: either a mix of retroviruses each of them carrying a single gene, or a single lentiviral particle carrying an omni-comprehensive polycistronic RNA. Colonies of pluripotent stem cells (iPSC) were generated using both systems, but the lentiviral infection showed a higher reprogramming efficiency. Nevertheless, karyotype analysis of five independent clones showed a common chromosomal translocation (t17;19) that was absent in fibroblast primary culture, as well as in retroviral infected iPS clones. Following the assessment of pluripotency, we have differentiated AF-derived iPSC into cardiomyocytes (CMs) by a standard differentiation protocol through embryoid bodies formation. The presence of beating cells allowed us to identify and to isolate clusters of CMs whose electrophysiological properties have been analyzed. Cellular spontaneous action potentials were recorded revealing different traces and frequencies in AF-derived CMs versus the normal counterpart. Moreover, after single CM isolation, we measured funny current (If), strongly related to pacemaker activity. We found that the activation of HCN channels in AF-derived CMs is reached before the normal counterpart, thus suggesting a higher cellular excitability. In conclusion we obtained iPSC-derived human CMs that, as shown, represent a valuable and reliable model of AF. We are presently using our model to understand the link between the identified mutations and the recorded functional alterations. Using this tool we will ultimately be able to identify novel therapeutic targets for this form of cardiac arrhythmia

Spinning Disk Reactor technique for the synthesis of nanometric sulfur powder for lithium batteries

Le prestazioni delle batterie zolfo/litio sono strettamente legate alla morfologia dello zolfo nanostrutturato. Nel corso degli anni diversi metodi sono stati analizzati per la produzione di nanoparticelle di zolfo; tra questi, il metodo della microemulsione è uno dei piùimportanti per la sua flessibilità e l'eccellente controllo delle dimensioni delle particelle. Tuttavia, la microemulsione è molto complessa e richiede la creazione di un sistema costituito da olio, acqua e vari tensioattivi, insieme con la fase contenente il precursore. Uno dei maggiori svantaggi della microemulsione è la sua scarsa scalabilità, unitamente alla difficoltà di separazione e purificazione delle particelle. Inoltre, questo metodo impiega una grande quantità di tensioattivi e si rivela antieconomico. Utilizzando differenti condizioni fluidodinamiche è, invece, possibile sintetizzare nanoparticelle monodisperse di zolfo attraverso lo Spinning Disk Reactor che già da qualche tempo è utilizzato nella sintesi di nanoparticelle. In questo lavoro è stato eseguito un confronto sulle caratteristiche morfologiche e sulle proprietà elettrochimiche di elettrodi a base di zolfo colloidale ottenuti in laboratorio mediante precipitazione chimica tradizionale in soluzione acquosa e via Spinning Disc Reactor, con cui grazie a diverse condizioni fluidodinamiche, è possibile ottenere zolfo monodisperso di dimensioni nanometriche e con prestazioni elettrochimiche superiori, quando usato come materiale attivo nelle batterie al litio

Atrial fibrillation modeling with iPSC derived cardiomyocyte

Atrial fibrillation (AF) is the most frequently diagnosed cardiac arrhythmia and is associated with an increased risk of stroke because of the potential for thrombus formation in atrial blood. AF has traditionally been described as a multifactorial sporadic disease; however recently, genome-wide association studies have led to the identification of multiple loci, encoding ion channels, transcription factors, and signaling molecules, that confer increased susceptibility to this type of arrhythmia. Hence in vitro AF models to identify the genetic basis, to examine cell differentiation, to characterize interactions of cells belonging to cardiovascular lineage, are urgently needed in order to improve the comprehension of the pathophysiological basis of AF. We began to characterize three siblings with a history of persistent AF, who were scheduled to undergo surgical ablation following failed pharmacological treatment. The young age of onset of loneAF in the three siblings indicates a strong genetic basis for this form of arrhythmia. Initially using a candidate gene approach, the genomic DNA of one of the three patients has been analyzed but no relevant sequence variations have been identified in genes previously involved with monogenic AF (KCNQ1,KCNH2, KCNE1, KCNE2, and SCN5A). Therefore we are now in process of genetically characterize the family by screening several genes through gene-chip and exons sequencing analysis. In order to provide a valuable experimental platform to model AF disease, primary cultures of dermal fibroblasts were established from all patients. From these skin fibroblasts we started to generate induced pluripotent stem cells (iPSC) by retroviral infection of OCT4, KLF4, SOX2 and c-MYC factors. We have characterized the pluripotency state of our colonies evaluating colony morphology, alkaline phosphatase staining, expression of pluripotency associated transcription factors (OCT4, SOX2, NANOG, REX1), surface markers (SSEA3, SSEA4, TRA1-60, TRA1-81), and silencing of retroviral transgenes. Following the assessment of pluripotency, we have differentiated AF-derived iPSC into cardiomyocytes (CMs) by a standard differentiation protocol through embryoid bodies formation. The presence of beating cells allowed us to identify and isolate CMs. We were able to record action potentials (APs) with different waveforms from AF-derived CMs versus a normal counterpart. These results, although very preliminary, are extremely encouraging because they suggest that the differences we observed in electrophysiology, borne by the iPSC derived CMs, maybe really due to genetic alterations, thus making the study of both genomic and transcriptomic signatures of these patients of primary importance in the comprehension of the biological basis of AF

Generation and characterization of human cardiomyocytes derived from pluripotent stem cells

In vitro development has been widely studied using murine ESCs (mESCs), whose differentiation procedure in culture implies the initial leukemia inhibitory factor (LIF) removal and the formation of cellular aggregates using the “hanging drop” method. These three dimensional (3D) structures, called embryoid bodies (EBs), replicate in vitro the different stages of murine embryonic development. Around differentiation day (dd) 8, clusters of spontaneously beating cells appear in culture; these cells express several transcriptional and structural cardiac markers and were therefore classified generically as cardiomyocytes. Since their isolation, human ESCs have shown different culturing needs from the murine counterpart, and their behavior revealed also minor differentiation plasticity. Cardiac differentiation is the most glaring example of this statement: only a modest proportion of EBs derived from either hESC or hiPSC contains contracting cells. This occurrence leads to the setup of different methods aimed to increase cardiac differentiation during in vitro development of pluripotent stem cells. While some of these procedures retain an initial 3D EB formation, others start from a confluent monolayer. However, CMs differentiated in vitro vary considerably from cells isolated from a mature human heart, because of the absence of humoral factors and organized mechanical and electrical stress. In general, many of the features of hPSC-CMs are reminiscent of normal fetal cells. hPSC-CMs are spontaneously beating cells co-expressing atrial-, ventricular-, and nodal- markers, with unorganized sarcomeres, immature mitochondria, and an expression profile different from adult CMs. The CMs that arise during early hESC or hiPSC in vitro differentiation exhibit spontaneous AP, with a relatively depolarized resting membrane potential, probably due to the temporary absence of the inward rectifier potassium current. The expression of the ion channels and, consequently, the ionic currents will undergo developmental maturation over time, as assessed by modifications in current density and property. hPSC-CMs immaturity is also reflected in their excitation–contraction machinery, lacking clear T-tubuli, disorganized sarcomeric striations, and immature Ca2+ handling. Then the possibility to obtain human CMs in a culture dish is a powerful technique that will allow identification of new drugs in pharmacological studies as well as the identification of new causative genes in modeling genetic pathologies. Nevertheless, newly differentiated human CMs show a low degree of maturation that must be considered and, eventually, overcome by physical, mechanical or cultural stimuli

Framing the multifaceted nature of design thinking in addressing different innovation purposes

Scholars and practitioners acknowledge the role of design, and specifically design thinking, as a driver of innovation and change. Design thinking is gaining attention in the business community beyond the traditional product innovation realm and is increasingly promoted as an engine for the creation of novel user experiences, new businesses, strategic transformation, organizational and cultural change. Is it reasonable to assume that the same set of practices fits such a broad range of applications equally well? This study addresses how design thinking applications are differently framed when addressing diverse innovation purposes. Specifically, we compare two purposes: innovation of solutions, encompassing traditional product and service development projects, and innovation of direction, encompassing strategic and organizational renewal projects. Based on data collected from 146 design thinking projects conducted by European consulting firms we investigate the relationships between the design thinking practices adopted and the value generated by the projects. We then analyze how these relationships vary depending on the purpose of the innovation project, namely whether focused on innovating solutions or direction. The results show that different purposes indeed call for different practices. In projects aimed at innovating solutions, market value is positively related to capturing current user needs and envisioning future society. Conversely, in projects aimed at innovating direction, market value is positively related to challenging current assumptions

iPS technology as a tool to investigate atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmic disorder in adults, characterized by rapid and irregular activation of the atria and loss of coordinated contraction thus resulting in reduced ventricular filling and blood stasis in the atria, and finally leading to heart failure and thromboembolic stroke. AF has traditionally been described as a multifactorial sporadic disease; however some hints about AF hereditability have recently been issued from epidemiological and population-based GWAS. Therefore in vitro AF models to identify the genetic basis and to characterize interactions of cells belonging to cardiovascular lineage are urgently needed. We began to characterize a familial group with continuous AF who were scheduled to undergo surgical ablation following failed pharmacological treatment. Screening for mutation of the most common genes associated to AF (KCNQ1, KCNH2, KCNE1, KCNE2, and SCN5A) did not show any modification. We are now in process of sequencing some other putative candidate (MiRP1, CAV3, and HCN4), but a more extensive analysis needs to be carried out. In order to provide a platform to model AF disease, primary cultures of dermal fibroblasts were established from all individuals. Cells were induced to pluripotency by retroviral infection with the classical set of factors OSKM. Then, 2-4 independent clones per individual of AF-specific induced pluripotent stem cells (iPSC) were isolated. We have begun to characterize their pluripotency by morphology and growth dynamics, alkaline phosphatase staining, expression of pluripotency associated transcription factors (OCT4, SOX2, NANOG, REX1), surface markers (SSEA3, SSEA4, TRA1-60, TRA1-81), and silencing of retroviral transgenes. Following the assessment of pluripotency, we aim to differentiate AF-derived iPSC into cells of the cardiovascular lineage, such as cardiomyocytes and endothelial cells. We believe that the model we are developing will help us in clarifying the molecular basis of AF

Evaluation of pacemaker dependence in patients on ablate and pace therapy for atrial fibrillation

Aims: In patients with atrial fibrillation (AF) and uncontrolled ventricular rate, radiofrequency (RF) ablation of the atrioventricular (AV) node and pacemaker (PM) implantation (ablate and pace) is a valid therapeutic approach, especially in elderly patients. The aim of our study was to evaluate the PM dependence and the incidence of correlated clinical phenomena in a patients population with AV block induced by RF ablation of the AV junction. Methods and results: One-hundred and sixty-three patients (71 men; mean age 71 +/- 8 years) who had undergone ablate and pace therapy were evaluated. The patients underwent assessment of quality of life, impairment of consciousness, stroke/transient ischaemic attack (TIA), hospitalizations for heart failure, episodes of palpitations, and instrumental evaluation of PM dependence during PM inhibition (absence of escape rhythm; asystolic pause >5 s; escape rhythm <30 bpm after rhythm stabilization). Correlation between instrumentally evaluated PM dependence and clinical history was analysed. Hundred and thirty-two patients were evaluated after a mean follow-up period of 36 months [31 subjects (19%) died before the evaluation]; 55 patients (42%) were classified as PM-dependent: 38 (69%) complained of disturbances (19 dizziness, 15 pre-syncope, 4 syncope); 77 patients (58%) were considered non-PM-dependent: symptoms (dizziness, flush) were reported by only 3 (4%). No significant differences emerged between PM-dependent and non-PM-dependent patients with regard to episodes of pre-syncope, syncope, stroke/TIA, hospitalizations for heart failure, and quality of life. Conclusion: This study confirms that ablate and pace is an effective and safe approach in subjects with chronic or recurrent AF and uncontrolled ventricular rat