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Resumen Introducción: El ángulo QRS-T espacial es la diferencia entre el vector del QRS y la T. Se conoce el valor diagnóstico y pronóstico de este marcador en enfermedades cardíacas. Es prioritario determinar si estas mediciones son reproducibles con confiabilidad en nuestro medio. Métodos: En 30 adultos se obtuvieron electrocardiogramas, independientemente del diagnóstico. Las mediciones las realizaron dos estudiantes de Medicina de quinto año, un médico interno y un cardiólogo, posterior a un reentrenamiento sobre la medición del ángulo por el método de transformación visual. Con identificación cegada, ingresaron en un aplicativo web las mediciones del QRS y la T. El ángulo fue estimado a partir de la plantilla de Cortez y colaboradores. Sobre el 20% de las lecturas se estimó un acuerdo intraobservador y en el 100% de las lecturas un acuerdo interobservador. Los puntos de corte para estimar el acuerdo Kappa fueron < 105s (normal), 105° a 135° (limítrofe) y > 135° (anormal). Resultados: Se excluyó un ECG por calidad deficiente. El rango del ángulo estuvo entre 72.9° y 176.2°. El acuerdo interobservador entre los 4 evaluadores fue kappa = 0.786 (IC95% 0.728-0.823, p < 0.0001) y el intraobservador kappa = 1.0 (p 0.007). Conclusión: Es el primer estudio sobre el ángulo QRS-T espacial realizado en Colombia. Se logró un acuerdo inter- e intraobservador adecuado en la medición del ángulo por el método de transformación visual, en observadores con diferente experticia, con un kappa mayor de 0,75. Este resultado apoya la reproducibilidad de esta medición en estudios posteriores en Colombia.
Abstract Introduction: The spatial QRS-T angle is the difference between the QRS vector and T vector. The diagnostic and prognostic value of this marker in heart disease is well-known. It is essential to determine whether these measurements are reproducible and reliable in Colombia. Methods: Electrocardiograms (ECG) were obtained from 30 adults, regardless of the diagnosis. The measurements were made by two fifth-year medical students, a houseman/ intern, and a cardiologist. They were all re-trained on the measurement of the angle using the visual transformation method. With blinded identification, they entered the QRS and T measurements into a web application. The angle was estimated from the template of Cortez et al. About 20% of the readers showed an intra-observer agreement and an inter-observer agreement in 100%. The cut-off points to estimate the agreement Kappa were < 105° (normal), 105° a 135° (borderline), and >135° (abnormal). Results: One ECG was excluded due to poor quality. The range of the angle was between 72.9° and 176.2°. The inter-observer agreement between the 4 evaluators gave a kappa = 0.786 (95% CI; 0.728-0.823, P < .0001), and the intra-observer agreement a kappa = 1.0 (P = .007). Conclusion: This the first study on the spatial QRS-T angle performed in Colombia. A good inter- and intra-observer agreement was achieved in the measurement of the angle by the visual transformation method by observers with different levels of expertise, with a Kappa greater than 0.75. These results support the reproducibility of this measurement in subsequent studies in Colombia.
Subject(s)
Humans , Adult , Reproducibility of Results , Vectorcardiography , ElectrocardiographyABSTRACT
Objective@#To investigate the clinical significance of verticalization of frontal P axis on electrocardiagraphy (ECG) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) and asthma.@*Methods@#Thirty five COPD patients and 20 asthma patients with acute exacerbation admitted in Jing′an District Central Hospital were enrolled and 20 health subjects served as a control group. The 12 lead ECG examination, pulmonary function test and high resolution CT (HRCT) scan of lung were performed. The P axis in ECG, pulmonary function and CT emphysema score were compared among three groups. The correlation of P axis verticalization with pulmonary function and CT emphysema score was analyzed.@*Results@#There were significant differences in P axis(F=24.36), FEV1/FVC(F=39.36), FEV1(F=28.82), FEV1%(F=30.64), FVC%(F=3.45), PEF%(F=13.22), RV/TLC(F=10.46) and total emphysema score (F=50.60) among the three groups (all P<0.01). P axis was positively correlated with age(r=0.229), total emphysema score(r=0.567), upper lung emphysema score(r=0.542), middle lung emphysema score(r=0.507), lower lung emphysema score(r=0.572)(all P<0.01), and negative correlation with body mass index(r=-0.491), cardiothoracic ratio (r=-0.396), FEV1/FVC(r=-0.609), FEV1(r=-0.389), FEV1%(r=-0.460), and PEF% (r=-0.419)(all P<0.01). Taking P axis>60 ° as cut-off value for screening COPD, the sensitivity was 0.933, specificity was 0.667, positive predictive value was 0.833 and negative predictive value was 0.857.@*Conclusion@#The verticalization of frontal P axis on ECG is significantly associated with obstructive ventilation disorder and CT emphysema score, which can be used as a preliminary screening index for COPD.
ABSTRACT
Se resume la historia de los estudios acerca de la llamada irritabilidad de los tejidos animales, señalada en el siglo XVII por el médico inglés Francis Glisson. Estudios sustentables sobre las propiedades bioeléctricas de dichos tejidos se iniciaron en el siglo XVIII por el científico suizo Albrecht von Haller y se continuaron por el naturalista italiano Felice Fontana. Durante ese siglo arreció la polémica entre los partidarios de la llamada electricidad animal y los de la electricidad de contacto. La demostración por el danés Oersted en 1820 de la íntima relación existente entre magnetismo y electricidad llevó a la preparación de los electrómetros. Con estos fue posible detectar y medir el flujo eléctrico. Se llegó así, a mediados del siglo XIX, a la identificación de la verdadera electricidad animal en forma de corriente de lesión. Más tarde fue posible registrar la corriente eléctrica, originada en el miocardio, también al exterior de la caja torácica primero con el electrómetro capilar de Lippmann y después con el galvanómetro de cuerda construido por el holandés Willem Einthoven a principios del siglo XX. Despegó así la moderna electrocardiografía por obra del investigador inglés Thomas Lewis, del norteamericano Frank N. Wilson y del mexicano Demetrio Sodi Pallares. Este último trató de racionalizar la exploración electrovectocardiográfica mediante una base experimental.
The history of the investigations about of the so-called irritability of animal tissues showed by English physician Francis Glisson in the 17th century, is summarized. During the 18th century, reliable studies on the bioelectric properties of these tissues began, due to the Swiss scientist Albrecht von Haller and continuated by the Italian naturalist Felice Fontana. In the second half of this century, multiple controversies of the partisans of the animal electricity against the partisans of the contact electricity took place. The Danish scientist Oersted in 1820 proved the close relation of magnetism to electricity, which led to construction of electrometers. These instruments allowed to register and measure record of the electric current. On this way, at middle 21st century, the true animal electricity was identified as the injury current. Later it was possible to record the electric current, risen in the myocardium, out the thorax first by means of the Lippmann' capillary electrometer and later thanks to the Einthoven's string galvanometer at the beginning of the 20th century. So the modern electro-vectorcardiography took off, due to English Thomas Lewis, the North-American Frank N. Wilson and the Mexican Demetrio Sodi Pallares. The last one allowed to rationalize the electro-vectorcardiographic exploration on experimental bases.
Subject(s)
Animals , Dogs , History, 17th Century , History, 18th Century , History, 19th Century , History, 20th Century , Humans , Vectorcardiography/history , Electrocardiography/history , MexicoABSTRACT
PURPOSE--To describe groups of patients who have obstructive and non-obstructive coronary artery disease, through computadorized exercise stress test. METHODS--The test was done in 121 patients, all male, divided into 3 groups: GN group, 50 patients with normal electrocardiographic response to exercise; GLO group, 40 patients with obstructive coronary artery disease and GNO group, 31 patients with normal coronary arteries, showing one or more of the following entities: intramural coronary traject, coronary tortuosity, slow flow, mitral valve prolapse or left ventricular hypertrophy. GLO and GNO groups presented with abnormal response of the ST segment during exercise. The quantitative variables registered by computer were particularly analyzed as follows: STL (point Y depression), slope, index and ST segment integral. The magnitude of ST vector was visually measured and quantified. The statistic study was made through ANOVA and multiples comparison by the Scheffe's method, Fisher's test, quisquare and sensibility, specificity and accuracy calculation. RESULTS--There was a significant statistic difference among the 3 groups relative to slope and index (p < 0.05). The integral variable of ST segment did not allow us to differentiate the GLO and GNO groups. In the association study between the ST vector magnitude and abnormal T loop, there was an increase in sensibility of 15//in the exercise stress test. CONCLUSION--The ST segment slope below zero values, define patients having obstructive disease, and the opposite, non-obstructive disease. Values of ST segment index lower than -2 are linked to obstructive disease and higher than -2 linked to non-obstructive. Values of ST segment lower than -7 microV. s separate individuals with normal exercise stress test from those with ischemic type response. The magnitude of ST vector equal to or lower than 0.20mV define normal vectorcardiographic response to the exercise