Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 66
Filtrar
1.
Heart Lung Circ ; 2020 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-32418874

RESUMO

In the context of the current global COVID-19 pandemic, this Consensus Statement provides current recommendations for patients with, or at risk of developing, genetic heart disease, and for their health care management and service provision in Australia and New Zealand. Apart from general recommendations, there are specific recommendations for the following conditions: cardiomyopathy, Brugada syndrome (including in children), long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). Other recommendations are relevant to patient self-care and primary health care.

2.
Heart Rhythm ; 2020 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-32229296

RESUMO

BACKGROUND: New Zealand has a multiethnic population and a national cardiac inherited disease registry (Cardiac Inherited Disease Registry New Zealand [CIDRNZ]). Ancestry is reflected in the spectrum and prevalence of genetic variants in long QT syndrome (LQTS). OBJECTIVE: The purpose of this study was to study the genetic testing yield and mutation spectrum of CIDRNZ LQTS probands stratified by self-identified ethnicity. METHODS: A 15-year retrospective review of clinical CIDRNZ LQTS probands with a Schwartz score of ≥2 who had undergone genetic testing was performed. RESULTS: Of the 264 included LQTS probands, 160 (61%) reported as European, 79 (30%) NZ Maori and Pacific peoples (Polynesian), and 25 (9%) Other ethnicities, with comparable clinical characteristics across ethnic groups (cardiac events in 72%; age at presentation 28±19 years; corrected QT interval 512±55 ms). Despite comparable testing (5.3±1.4 LQTS genes), a class III-V LQTS variant was identified in 35% of Polynesian probands as compared with 63% of European and 72% of Other probands (P<.0001). Among variant-positive CIDRNZ LQTS probands (n=148), Polynesians were more likely to have non-missense variants (57% vs 39% and 25% in probands of European and Other ethnicity, respectively; P=.005) as well as LQT1-3 variants not reported elsewhere (71% vs European 22% and Other 28%; P<.0001). Variants found in multiple probands were more likely to be shared within the same ethnic group; P<.01). CONCLUSION: Genetic testing of Polynesian LQTS probands has a lower diagnostic yield, despite comparable testing and clinical disease severity. Rare LQTS variants are more common in Polynesian LQTS probands. These data emphasize the importance of increasing the knowledge of genetic variation in the Polynesian population.

3.
Intern Med J ; 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32043731

RESUMO

BACKGROUND: Catheter ablation has rapidly become an integral part of the management of many arrhythmias. AIMS: This paper provides a history of clinical cardiac electrophysiology (EP) in New Zealand (NZ) and analysis of recent trends in EP procedures and catheter ablations across NZ, which has not previously been reported. METHODS: EP case type and volume were obtained from the EP databases from each of the four public and four private EP centres in NZ from 1st January 2014 to 31st December 2018. Procedure rates were expressed as per million population. RESULTS: A total of 7695 EP cases were performed, including 5929 (77%) in the public sector. Atrial fibrillation (AF) ablation was the most common procedure at 29%. EP procedure rates increased by 21% (to 353 per million in 2018), predominantly due to AF ablation rates increasing by 46%. Ventricular tachycardia ablation rates increased by 41% but only comprised 8% of procedures. There was a striking difference in the growth of EP procedure rates in the public compared to the private sector (4% vs 106%), as well as considerable differences in EP procedure and AF ablation rates across the public EP centres. NZ had lower ablation rates compared to countries with similar healthcare expenditure. CONCLUSION: There has been a substantial increase in EP procedure and AF ablation rates in NZ and international trends suggest this growth will continue. However, there is considerable variation in procedure rates and growth trends between EP centres, highlighting inequities in access within the country. This article is protected by copyright. All rights reserved.

4.
PLoS Comput Biol ; 16(2): e1007678, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32097431

RESUMO

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and is a major cause of stroke and morbidity. Recent genome-wide association studies have shown that paired-like homeodomain transcription factor 2 (Pitx2) to be strongly associated with AF. However, the mechanisms underlying Pitx2 modulated arrhythmogenesis and variable effectiveness of antiarrhythmic drugs (AADs) in patients in the presence or absence of impaired Pitx2 expression remain unclear. We have developed multi-scale computer models, ranging from a single cell to tissue level, to mimic control and Pitx2-knockout atria by incorporating recent experimental data on Pitx2-induced electrical and structural remodeling in humans, as well as the effects of AADs. The key findings of this study are twofold. We have demonstrated that shortened action potential duration, slow conduction and triggered activity occur due to electrical and structural remodelling under Pitx2 deficiency conditions. Notably, the elevated function of calcium transport ATPase increases sarcoplasmic reticulum Ca2+ concentration, thereby enhancing susceptibility to triggered activity. Furthermore, heterogeneity is further elevated due to Pitx2 deficiency: 1) Electrical heterogeneity between left and right atria increases; and 2) Increased fibrosis and decreased cell-cell coupling due to structural remodelling slow electrical propagation and provide obstacles to attract re-entry, facilitating the initiation of re-entrant circuits. Secondly, our study suggests that flecainide has antiarrhythmic effects on AF due to impaired Pitx2 by preventing spontaneous calcium release and increasing wavelength. Furthermore, our study suggests that Na+ channel effects alone are insufficient to explain the efficacy of flecainide. Our study may provide the mechanisms underlying Pitx2-induced AF and possible explanation behind the AAD effects of flecainide in patients with Pitx2 deficiency.


Assuntos
Fibrilação Atrial/metabolismo , Simulação por Computador , Proteínas de Homeodomínio/metabolismo , Fatores de Transcrição/metabolismo , Potenciais de Ação , Animais , Antiarrítmicos/farmacologia , Fibrilação Atrial/genética , Remodelamento Atrial , Cálcio/metabolismo , Eletrofisiologia , Retículo Endoplasmático/metabolismo , Fibrose , Flecainida/farmacologia , Regulação da Expressão Gênica , Estudo de Associação Genômica Ampla , Átrios do Coração/fisiopatologia , Proteínas de Homeodomínio/genética , Humanos , Cinética , Camundongos , Camundongos Knockout , Fenótipo , Canal de Liberação de Cálcio do Receptor de Rianodina/farmacologia , Retículo Sarcoplasmático/metabolismo , Sódio/metabolismo , Fatores de Transcrição/genética
5.
Artigo em Inglês | MEDLINE | ID: mdl-31960345

RESUMO

The 2015 HRS/EHRA/APHRS/SOLAECE Expert Consensus Statement on Optimal Implantable Cardioverter-Defibrillator Programming and Testing provided guidance on bradycardia programming, tachycardia detection, tachycardia therapy, and defibrillation testing for implantable cardioverter-defibrillator (ICD) patient treatment. The 32 recommendations represented the consensus opinion of the writing group, graded by Class of Recommendation and Level of Evidence. In addition, Appendix B provided manufacturer-specific translations of these recommendations into clinical practice consistent with the recommendations within the parent document. In some instances, programming guided by quality evidence gained from studies performed in devices from some manufacturers was translated such that this programming was approximated in another manufacturer's ICD programming settings. The authors found that the data, although not formally tested, were strong, consistent, and generalizable beyond the specific manufacturer and model of ICD. As expected, because these recommendations represented strategic choices to balance risks, there have been reports in which adverse outcomes were documented with ICDs programmed to Appendix B recommendations. The recommendations have been reviewed and updated to minimize such adverse events. Notably, patients who do not receive unnecessary ICD therapy are not aware of being spared potential harm, whereas patients in whom their ICD failed to treat life-threatening arrhythmias have their event recorded in detail. The revised recommendations employ the principle that the randomized trials and large registry data should guide programming more than anecdotal evidence. These recommendations should not replace the opinion of the treating physician who has considered the patient's clinical status and desired outcome via a shared clinical decision-making process.

6.
Heart Rhythm ; 17(1): e220-e228, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31103461

RESUMO

The 2015 HRS/EHRA/APHRS/SOLAECE Expert Consensus Statement on Optimal Implantable Cardioverter-Defibrillator Programming and Testing provided guidance on bradycardia programming, tachycardia detection, tachycardia therapy, and defibrillation testing for implantable cardioverter-defibrillator (ICD) patient treatment. The 32 recommendations represented the consensus opinion of the writing group, graded by Class of Recommendation and Level of Evidence. In addition, Appendix B provided manufacturer-specific translations of these recommendations into clinical practice consistent with the recommendations within the parent document. In some instances, programming guided by quality evidence gained from studies performed in devices from some manufacturers was translated such that this programming was approximated in another manufacturer's ICD programming settings. The authors found that the data, although not formally tested, were strong, consistent, and generalizable beyond the specific manufacturer and model of ICD. As expected, because these recommendations represented strategic choices to balance risks, there have been reports in which adverse outcomes were documented with ICDs programmed to Appendix B recommendations. The recommendations have been reviewed and updated to minimize such adverse events. Notably, patients who do not receive unnecessary ICD therapy are not aware of being spared potential harm, whereas patients in whom their ICD failed to treat life-threatening arrhythmias have their event recorded in detail. The revised recommendations employ the principle that the randomized trials and large registry data should guide programming more than anecdotal evidence. These recommendations should not replace the opinion of the treating physician who has considered the patient's clinical status and desired outcome via a shared clinical decision-making process.

7.
Am J Physiol Endocrinol Metab ; 318(2): E164-E172, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31821041

RESUMO

Epicardial adipose tissue (EAT) deposition has a strong clinical association with atrial arrhythmias; however, whether a direct functional interaction exists between EAT and the myocardium to induce atrial arrhythmias is unknown. Therefore, we aimed to determine whether human EAT can be an acute trigger for arrhythmias in human atrial myocardium. Human trabeculae were obtained from right atrial appendages of patients who have had cardiac surgery (n = 89). The propensity of spontaneous contractions (SCs) in the trabeculae (proxy for arrhythmias) was determined under physiological conditions and during known triggers of SCs (high Ca2+, ß-adrenergic stimulation). To determine whether EAT could trigger SCs, trabeculae were exposed to superfusate of fresh human EAT, and medium of 24 h-cultured human EAT treated with ß1/2 (isoproterenol) or ß3 (BRL37344) adrenergic agonists. Without exposure to EAT, high Ca2+ and ß1/2-adrenergic stimulation acutely triggered SCs in, respectively, 47% and 55% of the trabeculae that previously were not spontaneously active. Acute ß3-adrenergic stimulation did not trigger SCs. Exposure of trabeculae to either superfusate of fresh human EAT or untreated medium of 24 h-cultured human EAT did not induce SCs; however, specific ß3-adrenergic stimulation of EAT did trigger SCs in the trabeculae, either when applied to fresh (31%) or cultured (50%) EAT. Additionally, fresh EAT increased trabecular contraction and relaxation, whereas media of cultured EAT only increased function when treated with the ß3-adrenergic agonist. An acute functional interaction between human EAT and human atrial myocardium exists that increases the propensity for atrial arrhythmias, which depends on ß3-adrenergic rather than ß1/2-adrenergic stimulation of EAT.


Assuntos
Tecido Adiposo/fisiopatologia , Arritmias Cardíacas/fisiopatologia , Átrios do Coração/fisiopatologia , Coração/fisiopatologia , Pericárdio/fisiopatologia , Agonistas de Receptores Adrenérgicos beta 3/farmacologia , Agonistas Adrenérgicos beta/farmacologia , Idoso , Etanolaminas/farmacologia , Feminino , Humanos , Isoproterenol/farmacologia , Masculino , Contração Miocárdica , Miocárdio/metabolismo
9.
Adipocyte ; 8(1): 412-420, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31829077

RESUMO

Macroscopic deposition of epicardial adipose tissue (EAT) has been strongly associated with numerous indices of obesity and cardiovascular disease risk. In contrast, the morphology of EAT adipocytes has rarely been investigated. We aimed to determine whether obesity-driven adipocyte hypertrophy, which is characteristic of other visceral fat depots, is found within EAT adipocytes. EAT samples were collected from cardiac surgery patients (n = 49), stained with haematoxylin & eosin, and analysed for mean adipocyte size and non-adipocyte area. EAT thickness was measured using echocardiography. A significant positive relationship was found between EAT thickness and body mass index (BMI). When stratified into standardized BMI categories, EAT thickness was 58.7% greater (p = 0.003) in patients from the obese (7.3 ± 1.8 mm) compared to normal (4.6 ± 0.9 mm) category. BMI as a continuous variable significantly correlated with EAT thickness (r = 0.56, p < 0.0001). Conversely, no correlation was observed between adipocyte size and either BMI or EAT thickness. No difference in the non-adipocyte area was found between BMI groups. Our results suggest that the increased macroscopic EAT deposition associated with obesity is not caused by adipocyte hypertrophy. Rather, alternative remodelling via adipocyte proliferation might be responsible for the observed EAT expansion.

10.
N Z Med J ; 132(1503): 75-82, 2019 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-31581184

RESUMO

BACKGROUND: Last year, there were 2,000 out-of-hospital cardiac arrests (OHCA) in New Zealand, 74% received CPR but only 5.1% accessed an automated external defibrillator (AED). The average survival rate of OHCA is 13%. The aim of this study was to visit all 50 AED locations shown on www.hamiltoncentral.co.nz to assess their true availability and visibility to the public in the event of an OHCA. METHOD: All premises were visited and the first staff member encountered was asked if they were aware an AED was onsite, its location, hours of availability, if restricted access applied and whether it had been used. RESULTS: Of the 50 locations, three sites no longer exist and two AEDs were listed twice. Therefore, only 45 AEDs exist. Two sites had grossly inaccurate locations. Three AEDs (7%) were continuously available. Nine AEDs were accessible after 6pm at least one day of the week. Thirteen AEDs were available on weekends; however, five required swipe card access. None of the AEDs were located outdoors. CONCLUSION: Far fewer than 50 listed AEDs are freely available to the public, especially after 6pm and on weekends. Lack of signposting and restrictions to access would lead to delayed defibrillation. This important health issue needs addressing.


Assuntos
Desfibriladores/provisão & distribução , Cardioversão Elétrica , Serviços Médicos de Emergência , Acesso aos Serviços de Saúde/estatística & dados numéricos , Parada Cardíaca Extra-Hospitalar , Reanimação Cardiopulmonar/instrumentação , Reanimação Cardiopulmonar/métodos , Reanimação Cardiopulmonar/estatística & dados numéricos , Intervenção Médica Precoce/organização & administração , Intervenção Médica Precoce/normas , Cardioversão Elétrica/instrumentação , Cardioversão Elétrica/métodos , Cardioversão Elétrica/estatística & dados numéricos , Serviços Médicos de Emergência/métodos , Serviços Médicos de Emergência/organização & administração , Humanos , Nova Zelândia/epidemiologia , Parada Cardíaca Extra-Hospitalar/epidemiologia , Parada Cardíaca Extra-Hospitalar/terapia , Melhoria de Qualidade
11.
N Z Med J ; 132(1500): 40-49, 2019 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-31415498

RESUMO

AIMS: The ANZACS-QI Cardiac Implanted Device Registry (ANZACS-QI DEVICE) collects data on cardiac implantable electronic devices inserted in New Zealand. We evaluated completeness of data capture and quality of ANZACS-QI DEVICE in 2016. METHODS: Complete datasets within ANZACS-QI DEVICE, comprising DEVICE-PPM (permanent pacemakers) and DEVICE-ICD (implantable cardioverter defibrillators), from 1 January 2016 to 31 December 2016 were linked with the National Hospitalisation dataset (all New Zealand public hospital admissions). The total number of implants included procedures captured in either dataset. Variables assessed included age, gender, ethnicity, procedure type, implanting centre, admission and procedure date. RESULTS: DEVICE-PPM captured 85.9% of all PPM procedures (n=2,512). This was similar regardless of age, sex and ethnicity. In the 84.4% of procedures captured in both datasets, agreement was >97% for all variables except admission date (90.1%). DEVICE-ICD captured 81.3% of all ICD procedures (n=690). Capture was similar across age, sex and ethnicity groups. In the 76.8% of procedures captured in both datasets, agreement was >96% for all variables except admission date (90.6%). CONCLUSION: The ANZACS-QI DEVICE registry had a good capture rate and excellent agreement with the national dataset. This high concordance supports the use of both datasets for future research.


Assuntos
Bases de Dados Factuais/normas , Desfibriladores Implantáveis/estatística & dados numéricos , Marca-Passo Artificial/estatística & dados numéricos , Sistema de Registros/normas , Adulto , Idoso , Idoso de 80 Anos ou mais , Pesquisa Biomédica , Coleta de Dados , Feminino , Hospitalização , Humanos , Masculino , Pessoa de Meia-Idade , Nova Zelândia
12.
J Arrhythm ; 35(3): 485-493, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31293697

RESUMO

The 2015 HRS/EHRA/APHRS/SOLAECE Expert Consensus Statement on Optimal Implantable Cardioverter-Defibrillator Programming and Testing provided guidance on bradycardia programming, tachycardia detection, tachycardia therapy, and defibrillation testing for implantable cardioverter-defibrillator (ICD) patient treatment. The 32 recommendations represented the consensus opinion of the writing group, graded by Class of Recommendation and Level of Evidence. In addition, Appendix B provided manufacturer-specific translations of these recommendations into clinical practice consistent with the recommendations within the parent document. In some instances, programming guided by quality evidence gained from studies performed in devices from some manufacturers was translated such that this programming was approximated in another manufacturer's ICD programming settings. The authors found that the data, although not formally tested, were strong, consistent, and generalizable beyond the specific manufacturer and model of ICD. As expected, because these recommendations represented strategic choices to balance risks, there have been reports in which adverse outcomes were documented with ICDs programmed to Appendix B recommendations. The recommendations have been reviewed and updated to minimize such adverse events. Notably, patients who do not receive unnecessary ICD therapy are not aware of being spared potential harm, whereas patients in whom their ICD failed to treat life-threatening arrhythmias have their event recorded in detail. The revised recommendations employ the principle that the randomized trials and large registry data should guide programming more than anecdotal evidence. These recommendations should not replace the opinion of the treating physician who has considered the patient's clinical status and desired outcome via a shared clinical decision-making process.

13.
Artigo em Inglês | MEDLINE | ID: mdl-31240569

RESUMO

PURPOSE: Diagnostic electrophysiology catheters are single-use and their expense can act as a barrier to their use. A decapolar catheter with a re-sterilisable handle and inner core was developed, along with a disposable outer sheath. This initial experience evaluated the performance of the Khelix partially recyclable steerable decapolar electrophysiology catheter. METHODS: Sequential patients requiring a decapolar steerable catheter were included in the study. Parameters such as time to positioning from right femoral vein, fluoroscopy time and dose, pacing and sensing thresholds, and the requirement for reposition and/or support sheath were recorded. A retrospective analysis from cases using a standard disposable decapolar catheter was used to compare CS cannulation success, support sheath requirement and cost. RESULTS: 11 re-sterilisable catheter handles were used in 64 patients, each time with a disposable sheath, at two New Zealand centres from December 2017 to June 2018. Pre-defined safety measures were met in all patients, with no catheter-related adverse events. The catheter was successfully positioned in the coronary sinus for 59 cases (92%). Based on initial manufacturer recommendations, the inner recyclable portion of the catheter was able to be re-used successfully up to 12 times with re-sterilisation between cases. CONCLUSIONS: This initial study of an innovative, partially reusable, steerable decapolar electrophysiology catheter demonstrates that it may be used safely and successfully. Use of such a catheter may decrease the cost required for electrophysiology studies.

14.
Europace ; 21(9): 1442-1443, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31090914

RESUMO

The 2015 HRS/EHRA/APHRS/SOLAECE Expert Consensus Statement on Optimal Implantable Cardioverter-Defibrillator Programming and Testing provided guidance on bradycardia programming, tachycardia detection, tachycardia therapy, and defibrillation testing for implantable cardioverter-defibrillator (ICD) patient treatment. The 32 recommendations represented the consensus opinion of the writing group, graded by Class of Recommendation and Level of Evidence. In addition, Appendix B provided manufacturer-specific translations of these recommendations into clinical practice consistent with the recommendations within the parent document. In some instances, programming guided by quality evidence gained from studies performed in devices from some manufacturers was translated such that this programming was approximated in another manufacturer's ICD programming settings. The authors found that the data, although not formally tested, were strong, consistent, and generalizable beyond the specific manufacturer and model of ICD. As expected, because these recommendations represented strategic choices to balance risks, there have been reports in which adverse outcomes were documented with ICDs programmed to Appendix B recommendations. The recommendations have been reviewed and updated to minimize such adverse events. Notably, patients who do not receive unnecessary ICD therapy are not aware of being spared potential harm, whereas patients in whom their ICD failed to treat life-threatening arrhythmias have their event recorded in detail. The revised recommendations employ the principle that the randomized trials and large registry data should guide programming more than anecdotal evidence. These recommendations should not replace the opinion of the treating physician who has considered the patient's clinical status and desired outcome via a shared clinical decision-making process.

16.
Front Physiol ; 9: 1158, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30279660

RESUMO

While isolation of the pulmonary veins is firmly established as effective treatment for the majority of paroxysmal atrial fibrillation (AF) patients, there is recognition that patients with persistent AF have substrate for perpetuation of arrhythmia existing outside of the pulmonary veins. Various computational approaches have been used to identify targets for effective ablation of persistent AF. This paper aims to discuss the clinical aspects of computational approaches that aim to identify critical sites for treatment. Various analyses of electrogram characteristics have been performed with this aim. Leading techniques for electrogram analysis are Complex Fractionated Atrial Electrograms (CFAE) and Dominant Frequency (DF). These techniques have been the subject of clinical trials of which the results are discussed. Evaluation of the activation patterns of atria in AF has been another avenue of research. Focal Impulse and Rotor Modulation (FIRM) mapping and forms of Body Surface Mapping aim to characterize multiple atrial wavelets, macro-reentry and focal sources which have been proposed as basic mechanisms perpetuating AF. Both invasive and non-invasive activation mapping techniques are reviewed. The presence of atrial fibrosis causes non-uniform anisotropic impulse propagation. Therefore, identification of fibrosis by imaging techniques is an avenue of potential research. The leading contender for imaging-based techniques is Cardiac Magnetic Resonance (CMR). As this technology advances, improvements in resolution and scar identification have positioned CMR as the mode of choice for analysis of atrial structure. AF has been demonstrated to be associated with obesity, inactivity and diseases of modern life. An opportunity exists for detailed computational analysis of the impact of risk factor modification on atrial substrate. This ranges from microstructural investigation through to examination at a population level via registries and public health interventions. Computational analysis of atrial substrate has moved from basic science toward clinical application. Future directions and potential limitations of such analyses are examined in this review.

17.
Sci Rep ; 8(1): 15642, 2018 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-30353147

RESUMO

Transcription factors TBX5 and PITX2 involve in the regulation of gene expression of ion channels and are closely associated with atrial fibrillation (AF), the most common cardiac arrhythmia in developed countries. The exact cellular and molecular mechanisms underlying the increased susceptibility to AF in patients with TBX5/PITX2 insufficiency remain unclear. In this study, we have developed and validated a novel human left atrial cellular model (TPA) based on the ten Tusscher-Panfilov ventricular cell model to systematically investigate how electrical remodeling induced by TBX5/PITX2 insufficiency leads to AF. Using our TPA model, we have demonstrated that spontaneous diastolic depolarization observed in atrial myocytes with TBX5-deletion can be explained by altered intracellular calcium handling and suppression of inward-rectifier potassium current (IK1). Additionally, our computer simulation results shed new light on the novel cellular mechanism underlying AF by indicating that the imbalance between suppressed outward current IK1 and increased inward sodium-calcium exchanger current (INCX) resulted from SR calcium leak leads to spontaneous depolarizations. Furthermore, our simulation results suggest that these arrhythmogenic triggers can be potentially suppressed by inhibiting sarcoplasmic reticulum (SR) calcium leak and reversing remodeled IK1. More importantly, this study has clinically significant implications on the drugs used for maintaining SR calcium homeostasis, whereby drugs such as dantrolene may confer significant improvement for the treatment of AF patients with TBX5/PITX2 insufficiency.


Assuntos
Fibrilação Atrial/metabolismo , Átrios do Coração/metabolismo , Proteínas de Homeodomínio/metabolismo , Modelos Cardiovasculares , Proteínas com Domínio T/metabolismo , Fatores de Transcrição/metabolismo , Potenciais de Ação , Animais , Cálcio/metabolismo , Humanos , Canais Iônicos/metabolismo , Íons , Camundongos , Miócitos Cardíacos/metabolismo , Fenótipo
18.
Physiol Meas ; 39(9): 094006, 2018 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-30102248

RESUMO

OBJECTIVE: The electrocardiogram (ECG) provides an effective, non-invasive approach for clinical diagnosis in patients with cardiac diseases such as atrial fibrillation (AF). AF is the most common cardiac rhythm disturbance and affects ~2% of the general population in industrialized countries. Automatic AF detection in clinics remains a challenging task due to the high inter-patient variability of ECGs, and unsatisfactory existing approaches for AF diagnosis (e.g. atrial or ventricular activity-based analyses). APPROACH: We have developed RhythmNet, a 21-layer 1D convolutional recurrent neural network, trained using 8528 single-lead ECG recordings from the 2017 PhysioNet/Computing in Cardiology (CinC) Challenge, to classify ECGs of different rhythms including AF automatically. Our RhythmNet architecture contained 16 convolutions to extract features directly from raw ECG waveforms, followed by three recurrent layers to process ECGs of varying lengths and to detect arrhythmia events in long recordings. Large 15 × 1 convolutional filters were used to effectively learn the detailed variations of the signal within small time-frames such as the P-waves and QRS complexes. We employed residual connections throughout RhythmNet, along with batch-normalization and rectified linear activation units to improve convergence during training. MAIN RESULTS: We evaluated our algorithm on 3658 testing data and obtained an F 1 accuracy of 82% for classifying sinus rhythm, AF, and other arrhythmias. RhythmNet was also ranked 5th in the 2017 CinC Challenge. SIGNIFICANCE: Potentially, our approach could aid AF diagnosis in clinics and be used for patient self-monitoring to improve the early detection and effective treatment of AF.


Assuntos
Arritmias Cardíacas/diagnóstico , Diagnóstico por Computador/métodos , Eletrocardiografia/métodos , Redes Neurais de Computação , Humanos , Reconhecimento Automatizado de Padrão/métodos , Sensibilidade e Especificidade
19.
Front Physiol ; 9: 835, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30018571

RESUMO

Background: Meta-analysis is a widely used tool in which weighted information from multiple similar studies is aggregated to increase statistical power. However, the exponential growth of publications in key areas of medical science has rendered manual identification of relevant studies increasingly time-consuming. The aim of this work was to develop a machine learning technique capable of robust automatic study selection for meta-analysis. We have validated this approach with an up-to-date meta-analysis to investigate the association between diabetes mellitus (DM) and new-onset atrial fibrillation (AF). Methods: The PubMed online database was searched from 1960 to September 2017 where 4,177 publications that mentioned both DM and AF were identified. Relevant studies were selected as follows. First, publications were clustered based on common text features using an unsupervised K-means algorithm. Clusters that best matched the selected set of potentially relevant studies (a "training" set of 139 articles) were then identified by using maximum entropy classification. The 139 articles selected automatically on this basis were screened manually to identify potentially relevant studies. To determine the validity of the automated process, a parallel set of studies was also assembled by manually screening all initially searched publications. Finally, detailed manual selection was performed on the full texts of the studies in both sets using standard criteria. Quality assessment, meta-regression random-effects models, sensitivity analysis and publication bias assessment were then conducted. Results: Machine learning-assisted screening identified the same 29 studies for meta-analysis as those identified by using manual screening alone. Machine learning enabled more robust and efficient study selection, reducing the number of studies needed for manual screening from 4,177 to 556 articles. A pooled analysis using the most conservative estimates indicated that patients with DM had ~49% greater risk of developing AF compared with individuals without DM. After adjusting for three additional risk factors i.e., hypertension, obesity and heart disease, the relative risk was 23%. Using multivariate adjusted models, the risk for developing AF in patients with DM was similar for all DM subtypes. Women with DM were 24% more likely to develop AF than men with DM. The risk for new-onset AF in patients with DM has also increased over the years. Conclusions: We have developed a novel machine learning method to identify publications suitable for inclusion in meta-analysis.This approach has the capacity to provide for a more efficient and more objective study selection process for future such studies. We have used it to demonstrate that DM is a strong, independent risk factor for AF, particularly for women.

20.
Comput Biol Med ; 98: 147-158, 2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29793096

RESUMO

Segmentation of histological images is one of the most crucial tasks for many biomedical analyses involving quantification of certain tissue types, such as fibrosis via Masson's trichrome staining. However, challenges are posed by the high variability and complexity of structural features in such images, in addition to imaging artifacts. Further, the conventional approach of manual thresholding is labor-intensive, and highly sensitive to inter- and intra-image intensity variations. An accurate and robust automated segmentation method is of high interest. We propose and evaluate an elegant convolutional neural network (CNN) designed for segmentation of histological images, particularly those with Masson's trichrome stain. The network comprises 11 successive convolutional - rectified linear unit - batch normalization layers. It outperformed state-of-the-art CNNs on a dataset of cardiac histological images (labeling fibrosis, myocytes, and background) with a Dice similarity coefficient of 0.947. With 100 times fewer (only 300,000) trainable parameters than the state-of-the-art, our CNN is less susceptible to overfitting, and is efficient. Additionally, it retains image resolution from input to output, captures fine-grained details, and can be trained end-to-end smoothly. To the best of our knowledge, this is the first deep CNN tailored to the problem of concern, and may potentially be extended to solve similar segmentation tasks to facilitate investigations into pathology and clinical treatment.


Assuntos
Fibrose/diagnóstico por imagem , Cardiopatias/diagnóstico por imagem , Histocitoquímica/métodos , Interpretação de Imagem Assistida por Computador/métodos , Redes Neurais de Computação , Aprendizado Profundo , Fibrose/patologia , Cardiopatias/patologia , Humanos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA