Contact-force monitoring increases accuracy of right ventricular voltage mapping avoiding “false scar” detection in patients with no evidence of structural heart disease

Purpose: Electroanatomical mapping (EAM) could increase cardiac magnetic resonance imaging (CMR) sensitivity in detecting ventricular scar. Possible bias may be scar over-estimation due to inadequate tissue contact. Aim of the study is to evaluate contact-force monitoring influence during EAM, in patients with idiopathic right ventricular arrhythmias. Methods: 20 pts (13 M; 43 ± 12 y) with idiopathic right ventricular outflow tract (RVOT) arrhythmias and no structural abnormalities were submitted to Smarttouch catheter Carto3 EAM. Native maps included points collected without considering contact-force. EAM scar was defined as area ≥1 cm2 including at least 3 adjacent points with signal amplitude (bipolar <0.5 mV, unipolar 3,5 mV), surrounded by low-voltage border zone. EAM were re-evaluated offline, removing points collected with contact force <5 g. Finally, contact force-corrected maps were compared to the native ones. Results: An EAM was created for each patient (345 ± 85 points). After removing poor contact points, a mean of 149 ± 60 points was collected. The percentage of false scar, collected during contact force blinded mapping compared to total volume, was 6.0 ± 5.2% for bipolar scar and 7.1 ± 5.9% for unipolar scar, respectively. No EAM scar was present after poor contact points removal. Right ventricular areas analysis revealed a greater number of points with contact force < 5 g acquired in free wall, where reduced mean bipolar and unipolar voltage were recorded. Conclusions: To date this is the first work conducted on structurally normal hearts in which contact-force significantly increases EAM accuracy, avoiding “false scar” related to non-adequate contact between catheter and tissue

An overview of NMR-based metabolomics to identify secondary plant compounds involved in host plant resistance

Secondary metabolites provide a potential source for the generation of host plant resistance and development of biopesticides. This is especially important in view of the rapid and vast spread of agricultural and horticultural pests worldwide. Multiple pests control tactics in the framework of an integrated pest management (IPM) programme are necessary. One important strategy of IPM is the use of chemical host plant resistance. Up to now the study of chemical host plant resistance has, for technical reasons, been restricted to the identification of single compounds applying specific chemical analyses adapted to the compound in question. In biological processes however, usually more than one compound is involved. Metabolomics allows the simultaneous detection of a wide range of compounds, providing an immediate image of the metabolome of a plant. One of the most universally used metabolomic approaches comprises nuclear magnetic resonance spectroscopy (NMR). It has been NMR which has been applied as a proof of principle to show that metabolomics can constitute a major advancement in the study of host plant resistance. Here we give an overview on the application of NMR to identify candidate compounds for host plant resistance. We focus on host plant resistance to western flower thrips (Frankliniella occidentalis) which has been used as a model for different plant species

Arrhythmias in Patients with Implantable Devices

Pacemakers, cardioverter/defibrillators, and implantable loop recorders with their continuously improved diagnostic capabilities offer detailed information that can help interpreting a cardiac arrhythmia in implanted patients. Nevertheless, in some cases, analysis of the electrical signals stored in the device memory may not be easy. An accurate knowledge of the company-specific software and the meaning of the different markers used are necessary to correctly interpret the arrhythmia or diagnose an inappropriate device intervention due to under- or oversensing. This new technology does not replace the \u201cold\u201d surface electrocardiogram but supplements it to improve arrhythmia diagnosis

Tailoring the ablative strategy for atrial fibrillation. A state-of-the-art review

In spite of technological progress and the improving skills of operators, atrial fibrillation (AF) ablation results appear to date to be at a plateau. In any case, the superiority of ablation over pharmacological therapy in terms of effectiveness, reduction of hospitalizations, and improvement has been well demonstrated in recent randomized trials. Triggers, substrate, and modulating factors (elements of Coumel's triangle) play different roles in paroxysmal and persistent AF, so induction and perpetuation mechanisms of arrhythmia may be different in each patient. Although effective ablative strategies are available for the treatment of paroxysmal AF triggers and persistent AF substrates, an adequate clinical evaluation of the patient is crucial in order to increase the chances of success. Recognizing triggers allows not only performing an effective ablation but also to avoid unnecessary lesions and at the same time reducing the risk of complications. AF beginning and triggers could be recorded by 12-lead ECG, continuous Holter monitoring, or implantable devices. In case of an unsuccessful noninvasive evaluation, nonpulmonary vein triggers should be investigated with an electrophysiological study. Persistent AF needs more effort to perform an accurate substrate characterization. Among the many methods proposed, recently the use of high-density mapping and multipolar catheters seems of particular benefit in order to clarify the arrhythmia mechanisms. Surgical and hybrid techniques allow to treat regions such as the posterior wall or Bachmann's bundle, which is fundamental for an ablative strategy that goes beyond just pulmonary vein isolation. Too often, patients are referred to electrophysiology laboratories without adequate preprocedural screening and planning in order to submit them to a standard "ready-made"procedure. The accurate search for triggers in paroxysmal AF and the correct recognition of the link between a possible underlying heart disease and the substrate in persistent AF could allow us to tailor the interventional approach in order to overcome the current plateau, increasing ablative procedure success and minimizing complications

Managing athletes with palpitations of unknown origin with an external loop recorder. A cohort study

BACKGROUND: Palpitations in athletes are usually benign, but the presence of major cardiac arrhythmias should be ruled out despite the infrequent appraisal of symptoms. External loop recorders (ELR) are promising to identify arrhythmias in these circumstances, but experiences in athletes are lacking. We aimed to investigate the feasibility and diagnostic yield of an ELR in athletes with unexplained palpitations in a cohort study. METHODS: One hundred twenty-two consecutive subjects (61 athletes and 61 sedentary controls) with sporadic palpitations and inconclusive diagnosis were enrolled and equipped with an ELR. Findings were categorized as major and minor arrhythmic findings, non-arrhythmic findings or negative monitoring. RESULTS: Long-term ELR monitoring was feasible in all subjects, with median duration of 12 (11; 15) days. Major arrhythmic events during palpitations were found in 9 (14.8%) athletes: 7 experienced sustained paroxysmal supraventricular tachycardia, and 2 had non sustained ventricular tachycardia. Minor arrhythmic events (premature supraventricular or ventricular beats) were observed in 13 athletes (21.3%). Nonarrhythmic findings (i.e., sinus rhythm or sinus tachycardia) were recorded in 28 athletes (45.9%), whereas 11 (18%) had negative monitoring. In the sedentary group, arrhythmic events were similar for types and frequency to athletes. The diagnostic yield of loop monitoring was 82.8% in the overall population and 82.0% in the athlete's group. CONCLUSIONS: In the management of an athlete symptomatic with unexplained palpitations after 24-hour ECG monitoring and stress test, ELR is an efficient tool to identify major arrhythmic events, which can be present in up to 10% of symptomatic athletes during practice and competition

Use of Fluorescent Probes to Determine Molecular Architecture in Phase Separating Epoxy Systems

A novel route for morphological characterization of phase separating toughener and cross-linker for epoxy matrices has been investigated using fluorescence spectroscopy. Phase behavior of the individual components is determined by attaching different fluorescent probes to the toughener and cross-linker. In contrast to other techniques such as transmission eletron microscopy (TEM), this method allows resolution between similar components in which selective staining cannot be achieved