Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37
Filtrar
3.
Sci Rep ; 10(1): 2898, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-32076033

RESUMO

Arrhythmia constitutes a problem with the rate or rhythm of the heartbeat, and an early diagnosis is essential for the timely inception of successful treatment. We have jointly optimized the entire multi-stage arrhythmia classification scheme based on 12-lead surface ECGs that attains the accuracy performance level of professional cardiologists. The new approach is comprised of a three-step noise reduction stage, a novel feature extraction method and an optimal classification model with finely tuned hyperparameters. We carried out an exhaustive study comparing thousands of competing classification algorithms that were trained on our proprietary, large and expertly labeled dataset consisting of 12-lead ECGs from 40,258 patients with four arrhythmia classes: atrial fibrillation, general supraventricular tachycardia, sinus bradycardia and sinus rhythm including sinus irregularity rhythm. Our results show that the optimal approach consisted of Low Band Pass filter, Robust LOESS, Non Local Means smoothing, a proprietary feature extraction method based on percentiles of the empirical distribution of ratios of interval lengths and magnitudes of peaks and valleys, and Extreme Gradient Boosting Tree classifier, achieved an F1-Score of 0.988 on patients without additional cardiac conditions. The same noise reduction and feature extraction methods combined with Gradient Boosting Tree classifier achieved an F1-Score of 0.97 on patients with additional cardiac conditions. Our method achieved the highest classification accuracy (average 10-fold cross-validation F1-Score of 0.992) using an external validation data, MIT-BIH arrhythmia database. The proposed optimal multi-stage arrhythmia classification approach can dramatically benefit automatic ECG data analysis by providing cardiologist level accuracy and robust compatibility with various ECG data sources.


Assuntos
Algoritmos , Arritmias Cardíacas/classificação , Idoso , Idoso de 80 Anos ou mais , Arritmia Sinusal/diagnóstico por imagem , Arritmias Cardíacas/diagnóstico por imagem , Fibrilação Atrial/diagnóstico por imagem , Bases de Dados como Assunto , Eletrocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Cardiovasculares
7.
Sensors (Basel) ; 18(12)2018 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-30544689

RESUMO

This paper presents non-contact vital sign monitoring in neonates, based on image processing, where a standard color camera captures the plethysmographic signal and the heart and breathing rates are processed and estimated online. It is important that the measurements are taken in a non-invasive manner, which is imperceptible to the patient. Currently, many methods have been proposed for non-contact measurement. However, to the best of the authors' knowledge, it has not been possible to identify methods with low computational costs and a high tolerance to artifacts. With the aim of improving contactless measurement results, the proposed method based on the computer vision technique is enhanced to overcome the mentioned drawbacks. The camera is attached to an incubator in the Neonatal Intensive Care Unit and a single area in the neonate's diaphragm is monitored. Several factors are considered in the stages of image acquisition, as well as in the plethysmographic signal formation, pre-filtering and filtering. The pre-filter step uses numerical analysis techniques to reduce the signal offset. The proposed method decouples the breath rate from the frequency of sinus arrhythmia. This separation makes it possible to analyze independently any cardiac and respiratory dysrhythmias. Nine newborns were monitored with our proposed method. A Bland-Altman analysis of the data shows a close correlation of the heart rates measured with the two approaches (correlation coefficient of 0.94 for heart rate (HR) and 0.86 for breath rate (BR)) with an uncertainty of 4.2 bpm for HR and 4.9 for BR (k = 1). The comparison of our method and another non-contact method considered as a standard independent component analysis (ICA) showed lower central processing unit (CPU) usage for our method (75% less CPU usage).


Assuntos
Arritmia Sinusal/diagnóstico , Monitorização Fisiológica/métodos , Fotopletismografia/métodos , Arritmia Sinusal/diagnóstico por imagem , Arritmia Sinusal/fisiopatologia , Frequência Cardíaca/fisiologia , Humanos , Recém-Nascido , Taxa Respiratória/fisiologia , Processamento de Sinais Assistido por Computador/instrumentação
11.
BMC Cardiovasc Disord ; 15: 7, 2015 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-25618133

RESUMO

BACKGROUND: Noncompaction cardiomyopathy (NCC) is a rare genetic cardiomyopathy characterized by a thin, compacted epicardial layer and an extensive noncompacted endocardial layer. The clinical manifestations of this disease include ventricular arrhythmia, heart failure, and systemic thromboembolism. CASE PRESENTATION: A 43-year-old male was anticoagulated by pulmonary thromboembolism for 1 year when he developed progressive dyspnea. Cardiovascular magnetic resonance imaging showed severe biventricular trabeculation with an ejection fraction of 15%, ratio of maximum noncompacted/compacted diastolic myocardial thickness of 3.2 and the presence of exuberant biventricular apical thrombus. CONCLUSION: Still under discussion is the issue of which patients and when they should be anticoagulated. It is generally recommended to those presenting ventricular systolic dysfunction, antecedent of systemic embolism, presence of cardiac thrombus and atrial fibrillation. In clinical practice the patients with NCC and ventricular dysfunction have been given oral anticoagulation, although there are no clinical trials showing the real safety and benefit of this treatment.


Assuntos
Arritmia Sinusal/etiologia , Cardiomiopatias/complicações , Cardiomiopatias/diagnóstico , Trombose Coronária/etiologia , Embolia Pulmonar/etiologia , Disfunção Ventricular/etiologia , Adulto , Arritmia Sinusal/diagnóstico por imagem , Angiografia Coronária , Ecocardiografia , Coração/diagnóstico por imagem , Humanos , Angiografia por Ressonância Magnética , Masculino , Miocárdio/patologia , Tomografia Computadorizada por Raios X
12.
Eur J Nucl Med Mol Imaging ; 41(6): 1224-31, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24577949

RESUMO

PURPOSE: The use of SPECT phase analysis to optimize left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT) was performed at baseline, but CRT works as simultaneous right ventricular (RV) and LV pacing. The aim of this study was to assess the impact of RV apical (RVA) pacing on optimal LV lead positions measured by SPECT phase analysis. METHODS: This study prospectively enrolled 46 patients. Two SPECT myocardial perfusion scans were acquired under sinus rhythm with complete left bundle branch block and RVA pacing, respectively, following a single injection of (99m)Tc-sestamibi. LV dyssynchrony parameters and optimal LV lead positions were measured by the phase analysis technique and then compared between the two scans. RESULTS: The LV dyssynchrony parameters were significantly larger with RVA pacing than with sinus rhythm (p ~0.01). In 39 of the 46 patients, the optimal LV lead positions were the same between RVA pacing and sinus rhythm (kappa = 0.861). In 6 of the remaining 7 patients, the optimal LV lead positions were along the same radial direction, but RVA pacing shifted the optimal LV lead positions toward the base. CONCLUSION: The optimal LV lead positions measured by SPECT phase analysis were consistent, no matter whether the SPECT images were acquired under sinus rhythm or RVA pacing. In some patients, RVA pacing shifted the optimal LV lead positions toward the base. This study supports the use of baseline SPECT myocardial perfusion imaging to optimize LV lead positions to increase CRT efficacy.


Assuntos
Arritmia Sinusal/terapia , Terapia de Ressincronização Cardíaca/métodos , Tomografia Computadorizada por Emissão de Fóton Único de Sincronização Cardíaca , Imagem de Perfusão do Miocárdio , Idoso , Arritmia Sinusal/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Compostos Radiofarmacêuticos/uso terapêutico , Tecnécio Tc 99m Sestamibi/uso terapêutico , Função Ventricular Esquerda , Função Ventricular Direita
13.
J Stroke Cerebrovasc Dis ; 22(8): 1370-6, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23608370

RESUMO

BACKGROUND: This study aimed to investigate whether left atrial appendage (LAA) dysfunction evaluated by transesophageal echocardiography (TEE) during sinus rhythm is predictable of paroxysmal atrial fibrillation (PAF) as an embolic source in the acute stage of stroke. METHODS AND RESULTS: We measured and analyzed LAA flow velocity (LAA-FV) and LAA ejection fraction (LAA-EF) in 300 acute ischemic stroke patients by TEE. We divided the acute ischemic stroke patients into 3 groups. The atrial fibrillation (AF) group (n=58) comprised patients whose TEE was performed during AF rhythm. The PAF group (n=42) comprised patients with a history of AF but with normal sinus rhythm when TEE was performed. The normal sinus (sinus) group (n=200) did not have any history of AF. We found that mean LAA-FV and LAA-EF values in the PAF group were significantly lower than those in the sinus group (P<.001). The diagnostic accuracy of LAA-FV for the diagnosis of PAF calculated as the area under receiver operating characteristic curves was low (.582, 95% confidence interval [CI]=.498-.665) but that of LAA-EF was modest (.721, 95% CI=.653-.789), with an optimal cutoff point of 49.1%. CONCLUSIONS: LAA dysfunction as determined by TEE (LAA-EF<49.1%) in the acute stage of stroke is predictive of PAF with moderate accuracy. Long-term electrocardiographic monitoring is recommended for cryptogenic stroke patients with LAA dysfunction.


Assuntos
Arritmia Sinusal/fisiopatologia , Apêndice Atrial/fisiopatologia , Fibrilação Atrial/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Arritmia Sinusal/diagnóstico por imagem , Apêndice Atrial/diagnóstico por imagem , Fibrilação Atrial/diagnóstico por imagem , Fibrilação Atrial/etiologia , Ecocardiografia Transesofagiana , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Fatores de Risco , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/diagnóstico por imagem
14.
Spinal Cord ; 51(6): 511-3, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23588569

RESUMO

STUDY DESIGN: Case report. OBJECTIVE: to report and discuss the development of sudden symptomatic sinus bradycardia in a 35-year-old woman with acute myelitis. CASE REPORT: A 35-year-old woman presented rapidly progressive weakness and hypoesthesia in the left hemibody. Five days after symptom onset, she developed symptomatic sinus bradycardia up to 30 b.p.m. Bradycardia was completely resolved ∼36 h after its onset. RESULTS: Cervical spine magnetic resonance imaging showed a focal T2-hyperintense intramedullary lesion at C2 level, with moderate cord swelling. The lesion involved bilaterally dorsal funiculi, and left lateral and ventral funiculi. Cardiac I-123 metaiodobenzylguanidine (MIBG) scintigraphy showed a decreased cardiac MIBG uptake suggesting sympathetic denervation. CONCLUSION: The most likely explanation for bradycardia in our patient is the myelitis-related disruption of descending vasomotor pathways, resulting in sympathetic hypoactivity. Our case extends the spectrum of the clinical presentations of cervical myelitis and emphasizes the importance of careful cardiac monitoring in acute phase of cervical myelitis.


Assuntos
Bradicardia/etiologia , Mielite Transversa/complicações , Mielite Transversa/fisiopatologia , Adulto , Arritmia Sinusal/diagnóstico por imagem , Arritmia Sinusal/etiologia , Bradicardia/diagnóstico por imagem , Feminino , Imagem do Acúmulo Cardíaco de Comporta , Humanos , Mielite Transversa/diagnóstico por imagem
15.
Am J Cardiol ; 109(12): 1792-6, 2012 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-22444731

RESUMO

Atrial arrhythmia (AA) is common in adult patients with congenital heart disease (CHD). To enable the prevention of AA or its complications, timely identification of adult patients with CHD at risk of AA is crucial. Long total atrial activation times have been related to AA. Tissue Doppler imaging (TDI) permits noninvasive evaluation of the total atrial conduction time (PA-TDI duration). The present study evaluated the association between the PA-TDI duration and the development of AA in adult patients with CHD. A total of 223 adult patients with CHD were followed up for the occurrence of AA after PA-TDI duration assessment. The PA-TDI duration was defined as the interval from the onset of the P wave on the electrocardiogram to the peak of the A' wave at the lateral atrial wall on TDI tracings. Among the various clinical and echocardiographic parameters, the association between the PA-TDI duration and AA occurrence was investigated. The median follow-up was 39 months (interquartile range 21 to 57). A PA-TDI duration of ≥126 ms was associated with AA during follow-up (log-rank, p <0.001). On multivariate analysis, a PA-TDI duration >126 ms (hazard ratio 2.25, 95% confidence interval 1.21 to 4.19) and history of AA (hazard ratio 4.89, 95% confidence interval 2.75 to 8.71) were independently associated with the occurrence of AA. In conclusion, PA-TDI duration and a history of AA were independently associated with the occurrence of AA in adult patients with CHD. The PA-TDI duration is a useful tool to identify patients with CHD at risk of AA during follow-up.


Assuntos
Arritmia Sinusal/fisiopatologia , Ecocardiografia Doppler/métodos , Sistema de Condução Cardíaco/fisiopatologia , Cardiopatias Congênitas/fisiopatologia , Adulto , Arritmia Sinusal/diagnóstico por imagem , Feminino , Seguimentos , Sistema de Condução Cardíaco/diagnóstico por imagem , Cardiopatias Congênitas/diagnóstico por imagem , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Curva ROC , Sensibilidade e Especificidade , Fatores de Tempo
16.
J Cardiovasc Transl Res ; 3(5): 559-69, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20559779

RESUMO

American black bears survive winter months without food and water while in a mildly hypothermic, hypometabolic, and inactive state, yet they appear to be able to return to near-normal systemic function within minutes of arousal. This study's goal was to characterize the cardiovascular performance of overwintering black bears and elicit the underlying mechanisms enabling survival. Mid-winter cardiac electrophysiology was assessed in four wild black bears using implanted data recorders. Paired data from early and late winter were collected from 37 wild bears, which were anesthetized and temporarily removed from their dens to record cardiac electrophysiological parameters (12-lead electrocardiograms) and cardiac dimensional changes (echocardiography). Left ventricular thickness, primary cardiac electrophysiological parameters, and cardiovascular response to threats ("fight or flight" response) were preserved throughout winter. Dramatic respiratory sinus arrhythmias were recorded (cardiac cycle length variations up to 865%) with long sinus pauses between breaths (up to 13 s). The accelerated heart rate during breathing efficiently transports oxygen, with the heart "resting" between breaths to minimize energy usage. This adaptive cardiac physiology may have broad implications for human medicine.


Assuntos
Arritmia Sinusal/fisiopatologia , Frequência Cardíaca , Hibernação , Estações do Ano , Ursidae/fisiologia , Animais , Nível de Alerta , Arritmia Sinusal/diagnóstico por imagem , Regulação da Temperatura Corporal , Ecocardiografia , Eletrocardiografia Ambulatorial , Feminino , Humanos , Masculino , Reflexo , Telemetria
20.
Circ J ; 72(7): 1071-8, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18577814

RESUMO

BACKGROUND: ECG-gating is necessary for cardiac computed tomography, but is not suitable for arrhythmias, so the aim of this study was to evaluate the usefulness of the ECG-edit function for this purpose. METHODS AND RESULTS: Of 1,221 patients undergoing 64-row multidetector-row computed tomography coronary angiography (coronary MDCT), 123 patients (28 atrial fibrillation (Af), 39 premature atrial contractions (PAC), 42 premature ventricular contractions (PVC), 3 PAC + PVC, 10 sinus arrhythmias (SA), and a second-degree atrioventricular block (2 degrees AVB)) had arrhythmias necessitating the ECG-edit function. Short R-R interval was deleted and mid-diastolic phases were selected from the long R-R intervals using the "R+absolute time" method. In the present study, the reconstructed images were evaluated using a triple-grade scale A-C, representing excellent, acceptable, and unacceptable image quality. Image quality, categorized as A, B and C, respectively, was 50%, 36% and 14% for the 28 patients with Af; 56%, 36% and 8% for the 39 PAC patients, and 65%, 33% and 2% in the 42 PVC patients. None of the scans of the PAC + PVC, SA, and 2 degrees AVB patients was ranked as C. CONCLUSIONS: The ECG-edit function is useful for reconstructing coronary MDCT images in many arrhythmias, and provides clinically acceptable images in most cases.


Assuntos
Arritmias Cardíacas/diagnóstico por imagem , Eletrocardiografia/métodos , Tomografia Computadorizada por Raios X/métodos , Idoso , Arritmia Sinusal/diagnóstico por imagem , Complexos Atriais Prematuros/diagnóstico por imagem , Bloqueio Atrioventricular/diagnóstico por imagem , Angiografia Coronária , Vasos Coronários , Feminino , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Complexos Ventriculares Prematuros/diagnóstico por imagem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...