Biology subjects

Martin, C.

Publications and source records attributed to Martin, C..

22 records · Page 2Linked to original sources

bioRxiv2017

Novel Repolarisation Metric Predicts Arrhythmia Origin And Clinical Events In ARVC And Brugada Syndrome

Structured abstractO_ST_ABSBackgroundC_ST_ABSInitiation of re-entrant ventricular tachycardia (VT) involves complex interactions between activation (AT) and repolarization times (RT). The re-entry vulnerability index (RVI) is a recently proposed activation-repolarization metric designed to quantify tissue susceptibility to re-entry.\n\nObjectivesThe study aimed to test the feasibility of an RVI-based algorithm to predict the exit site of VT and occurrence of clinical events.\n\nMethodsPatients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) (n=11), Brugada Syndrome (BrS) (n=13) and focal RV outflow tract VT (n=9) underwent programmed stimulation with unipolar electrograms recorded from a non-contact array. The distance between region of lowest RVI and site of VT breakout (Dmin), and global minimum RVI (RVIG) were computed to assess prediction of site of VT breakout and occurrence of clinical events, respectively.\n\nResultsLowest values of RVI, representing sites of highest susceptibility to re-entry, co-localised with site of VT breakout in ARVC/BrS but not in focal VT and Dmin values were lower in ARVC/BrS. ARVC/BrS patients with inducible VT had lower RVIG than those who were non-inducible or those with focal VT. Patients were followed up for 112 {+/-} 19 months; those with clinical VT events had lower RVIg than those without VT or those with focal VT.\n\nConclusionsThe proposed methodology based on RVI localises the origin of re-entrant but not focal ventricular arrhythmias and predicts clinical events. This index could be applied to target ablation for arrhythmias which are difficult to induce or are haemodynamically unstable and also risk stratify patients for ICD prophylaxis.\n\nAbbreviations list

physiology↗

bioRxiv2017

Improved Outcome And Cost Effectiveness In Ablation Of Persistent Atrial Fibrillation Under General Anaesthetic

AimsOutcome of persistent atrial fibrillation (AF) ablation remains suboptimal. Techniques employed to reduce arrhythmia recurrence rate are more likely to be embraced if cost-effectiveness can be demonstrated. A single-centre observational study assessed whether use of general anaesthesia (GA) in persistent AF ablation improved outcome and was cost-effective.\n\nMethods292 patients undergoing first ablation procedures for persistent AF under conscious sedation or GA were followed. End points were freedom from listing for repeat ablation at 18 months and freedom from recurrence of atrial arrhythmia at one year.\n\nResultsFreedom from atrial arrhythmia was higher in patients who underwent ablation under GA rather than sedation (63.9% vs 42.3%, HR 1.87, 95% CI: 1.23 to 2.86, p = 0.002). Significantly fewer GA patients were listed for repeat procedures (29.2% vs 42.7%, HR 1.62, 95% CI: 1.01 to 2.60, p = 0.044). Despite GA procedures costing slightly more, a saving of {pound}177 can be made per patient in our centre for a maximum of 2 procedures if all persistent AF ablations are performed under GA.\n\nConclusionsIn patients with persistent AF, it is both clinical and economically more effective to perform ablation under GA rather than sedation.\n\nWhats New?O_LIThere is very little known regarding the clinical outcome of catheter ablation of AF under GA compared with sedation; to our knowledge there is one study only in paroxysmal AF and no studies examining cost effectiveness.\nC_LIO_LIThis study shows that in patients with persistent AF, it is both clinical and economically more effective to perform ablation under GA rather than sedation.\nC_LIO_LIThis study leads us to recommend the use of GA for the ablation of persistent AF. As PAF ablation is now increasingly being undertaken by single shot techniques which do not have the same requirements for analgesia and immobility, GA resources may be allocated for persistent AF ablation.\nC_LI

systems biology↗

bioRxiv2017

Ablation Of Complex Fractionated Electrograms Improves Outcome In Long Standing Persistent Atrial Fibrillation

PurposeThere is controversy and sparse data on whether substrate based techniques in addition to pulmonary vein isolation (PVI) confer benefit in the catheter ablation of persistent atrial fibrillation (AF), especially if long standing. We performed an observational study to assess whether substrate based ablation improved freedom from atrial arrhythmia.\n\nMethods286 patients undergoing first ablation procedures for persistent AF with PVI only, PVI plus linear ablation, or PVI plus complex fractionated electrogram (CFAE) and linear ablation were followed. Primary end point was freedom from atrial arrhythmia at one year.\n\nResultsMean duration of pre-procedure time in AF was 28+/-27 months. Freedom from atrial arrhythmia was higher with a PVI+CFAE+lines strategy then for PVI alone (HR 1.56, 95% CI: 1.04-2.34, p=0.032) but was not higher with PVI+lines. Benefit of substrate modification was conferred for pre-procedure times in AF of over 30 months. The occurrence of atrial tachycardia was higher when lines were added to the ablation strategy (HR 0.08, 95% CI: 0.01-0.59, p=0.014). Freedom from atrial arrhythmia at 1 year was higher with lower patient age, use of general anaesthetic (GA), normal or mildly dilated left atrium and decreasing time in AF.\n\nConclusionsIn patients with long standing persistent AF of over 30 months duration, CFAE ablation resulted in improved freedom from atrial arrhythmia. Increased freedom from atrial arrhythmia occurs in patients who are younger and have smaller atria, and with GA procedures. Linear ablation did not improve outcome and resulted in a higher incidence of atrial tachycardia.

systems biology↗

bioRxiv2017

A data-driven model for the assessment of age-dependent patterns of Tuberculosis burden and impact evaluation of novel vaccines.

In the case of tuberculosis (TB), the capabilities of epidemic models to produce quantitatively robust forecasts are limited by multiple hindrances. Among these, understanding the complex relationship between disease epidemiology and populations' age structure has been highlighted as one of the most relevant. TB dynamics depends on age in multiple ways, some of which are traditionally simplified in the literature. That is the case of the heterogeneities in contact intensity among different age-strata that are common to all air-borne diseases, but still typically neglected in the TB case. Furthermore, whilst demographic structures of many countries are rapidly aging, demographic dynamics is pervasively ignored when modeling TB spreading. In this work, we present a TB transmission model that incorporates country-specific demographic prospects and empirical contact data around a data-driven description of TB dynamics. Using our model, we find that the inclusion of demographic dynamics is followed by an increase in the burden levels prospected for the next decades in the areas of the world that are most hit by the disease nowadays. Similarly, we show that considering realistic patterns of contacts among individuals in different age-strata reshapes the transmission patterns reproduced by the models, a result with potential implications for the design of age-focused epidemiological interventions.\n\nSignificance StatementEven though tuberculosis (TB) is acknowledged as a strongly age-dependent disease, it remains unclear how TB epidemics would react, in the following decades, to the generalized aging that human populations are experiencing worldwide. This situation is partly caused by the limitations of current transmission models at describing the relationship between demography and TB transmission. Here, we present a data-driven epidemiological model that, unlike previous approaches, explicitly contemplates relevant aspects of the coupling between agestructure and TB dynamics, such as demographic evolution and contact heterogeneities. Using our model, we identify substantial biases in epidemiological forecasts rooted in an inadequate description of these aspects, both at the level of aggregated incidence and mortality rates and their distribution across age-strata.

epidemiology↗