RESUMEN
AIMS: To present a comparison of electrocardiogram-based non-invasive measures of atrial fibrillation (AF) substrate complexity computed on invasive animal recordings to discriminate between short-term and long-term AF. The final objective is the selection of an optimal sub-set of measures for AF complexity assessment. METHODS AND RESULTS: High-density epicardial direct contact mapping recordings (234 leads) were acquired from the right and the left atria of 17 goats in which AF was induced for 3 weeks (short-term AF group, N = 10) and 6 months (long-term AF group, N = 7). Several non-invasive measures of AF organization proposed in the literature in the last decade were investigated to assess their power in discriminating between the short-term and long-term group. The best performing measures were identified, which when combined attained a correct classification rate of 100%. Their ability to predict standard invasive AF complexity measures was also tested, showing an average R(2) of 0.73 ± 0.04. CONCLUSION: An optimal set of measures of the AF substrate complexity was identified out of the set of non-invasive measures analysed in this study. These measures may contribute to improve patient-tailored diagnosis and therapy of sustained AF.
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Fibrilación Atrial/diagnóstico , Electrocardiografía/métodos , Mapeo Epicárdico/métodos , Animales , Fibrilación Atrial/clasificación , Modelos Animales de Enfermedad , Técnicas Electrofisiológicas Cardíacas/métodos , CabrasRESUMEN
BACKGROUND/OBJECTIVES: Older adults in sub-Saharan Africa (SSA) are at greatest risk of an impending noncommunicable diseases epidemic, of which cardiac disease is the most prevalent contributor. Thus, it is essential to establish electrocardiographic reference values for a population that is likely to differ genetically and environmentally from others where reference values are established. METHODS: Two thousand two hundred thirty-two apparently healthy community-based participants without known cardiac disease aged 70+ in rural Tanzania underwent 12-lead electrocardiography. Electrocardiograms were digitally analyzed and gender-specific reference values for P duration (PD), P amplitude (PAMP), P area (PAREA), P terminal negative force (V1) (PTNF), PR interval, QRS duration (QRSD), QT/QTc, R amplitude (II, V5) (RAMP) LVH index (LVHI), R axis and R/S ratio (V1) reported, following univariate analysis of covariance using a multiple linear regression model, adjusting for age, systolic blood pressure (SBP), body mass index (BMI), and RR interval. RESULTS: Data from 1824 subjects were suitable for analysis. Adjusted mean values for men/women were: PD 115/110 ms, PAMP (avg) 123/114 µV, PAMP (II) 203/190 µV, PAREA (avg) 5.3/4.6 mV*s, PAREA (II) 9.3/8.1 mV*s, PTNF 1.7/1.4 mV*s, PR 158/152 ms, QRSD 89/84 ms, QT 370/375 ms, QTc 421/427 ms, RAMP (II) 805/854 µV, (V5) 2022/1742 µV, LVHI 3.0/2.8 mV (Sokolow-Lyon), 1.293/1.146 mV (Cornell), R axis 51/49°, R/S 0.2/0.2. Excluding PTNF , R axis and R/S ratio, all gender differences were significant (P < 0.001 apart from LVHI [Sokolow-Lyon; P < 0.005)] and RAMP (II) [P < 0.05]) following adjustment for age, SBP, BMI, and RR interval. CONCLUSIONS: Our description of comprehensive electrocardiographic parameters establishes reference values in this genetically and environmentally diverse SSA population thereby allowing identification of "outliers" with potential cardiac disease.
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Electrocardiografía/métodos , Electrocardiografía/estadística & datos numéricos , Evaluación Geriátrica/métodos , Evaluación Geriátrica/estadística & datos numéricos , África del Sur del Sahara , Anciano , Análisis de Varianza , Índice de Masa Corporal , Femenino , Humanos , Masculino , Valores de Referencia , Población Rural/estadística & datos numéricos , Factores Sexuales , TanzaníaRESUMEN
Considerable research effort has been devoted to the estimation of the degree of organisation of atrial fibrillation (AF), to potentially support clinical decision making. The aims of this study were to: (1) analyse the temporal variability of spatial organisation (complexity) and spectral distribution of AF in body surface potential maps (BSPM), proposing an automated implementation of the analysis and (2) assess the applicability to reduced lead-sets. Twenty-one persistent AF recordings of 3 min each (64 BSPM: 32 anterior, 32 posterior) were analysed. The relationship between spatial organisation (C) and its variability (CV) was quantified on automatically delineated TQ segments. The relationship between spectral concentration (SC) and spectral variability (SV) was quantified on the atrial activity (AA) extracted using principal component analysis. Three different lead-sets: 64, 32 anterior and 10 anterior channels were considered. Significant (p < 0.001) correlation (ρ) was found: ρ(CV, C) ≥ 0.80, ρ(SC, SV) ≤-0.83 for all lead-sets. The results suggest that a higher degree of spatial organisation is associated with reduced variability of spatial organisation over time, and lower spectral variability associated with more prominent spectral peak in the AF frequency band (4-10 Hz).
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Fibrilación Atrial/fisiopatología , Mapeo del Potencial de Superficie Corporal/métodos , Anciano , Atrios Cardíacos/fisiopatología , Humanos , Persona de Mediana Edad , Análisis de Componente Principal , Procesamiento de Señales Asistido por ComputadorRESUMEN
BACKGROUND: Since the first well-known electrocardiogram (ECG) delineator based on Wavelet Transform (WT) presented by Li et al. in 1995, a significant research effort has been devoted to the exploitation of this promising method. Its ability to reliably delineate the major waveform components (mono- or bi-phasic P wave, QRS, and mono- or bi-phasic T wave) would make it a suitable candidate for efficient online processing of ambulatory ECG signals. Unfortunately, previous implementations of this method adopt non-linear operators such as root mean square (RMS) or floating point algebra, which are computationally demanding. METHODS: This paper presents a 32-bit integer, linear algebra advanced approach to online QRS detection and P-QRS-T waves delineation of a single lead ECG signal, based on WT. RESULTS: The QRS detector performance was validated on the MIT-BIH Arrhythmia Database (sensitivity Se = 99.77%, positive predictive value P+ = 99.86%, on 109010 annotated beats) and on the European ST-T Database (Se = 99.81%, P+ = 99.56%, on 788050 annotated beats). The ECG delineator was validated on the QT Database, showing a mean error between manual and automatic annotation below 1.5 samples for all fiducial points: P-onset, P-peak, P-offset, QRS-onset, QRS-offset, T-peak, T-offset, and a mean standard deviation comparable to other established methods. CONCLUSIONS: The proposed algorithm exhibits reliable QRS detection as well as accurate ECG delineation, in spite of a simple structure built on integer linear algebra.