RESUMEN
Hypertrophied hearts are known for increased risk of arrhythmias and are linked with reduced ischemic tolerance. However, still little is known about state characterized only by increased left ventricle (LV) mass fraction. Seventeen isolated rabbit hearts with various LV mass were divided into two groups according to LV weight/heart weight ratio (LVW/HW ratio), namely group H and L (with higher and lower LVW/HW ratio, respectively) and underwent three short cycles of global ischemia and reperfusion. The differences in electrogram (heart rate, QRS(max), mean number, onset and dominant form of ventricular premature beats) and in biochemical markers of myocardial injury (creatine kinase, lactate dehydrogenase - LDH) and lipid peroxidation (4-hydroxy-2-nonenal - 4-HNE) were studied. As compared to group L, hearts in group H exhibited lower tolerance to ischemia expressed as higher incidence and severity of arrhythmias in the first ischemic period as well as increase of LDH and 4-HNE after the first reperfusion. In the third cycle of ischemia-reperfusion, the preconditioning effect was observed in both electrophysiological parameters and LDH release in group H. Our results showed consistent trends when comparing changes in electrograms and biochemical markers. Moreover, 4-HNE seems to be good potential parameter of moderate membrane alteration following ischemia-reperfusion injury.
Asunto(s)
Complejos Cardíacos Prematuros/fisiopatología , Hipertrofia Ventricular Izquierda/fisiopatología , Isquemia Miocárdica/fisiopatología , Daño por Reperfusión Miocárdica/fisiopatología , Animales , Complejos Cardíacos Prematuros/patología , Femenino , Corazón , Hipertrofia Ventricular Izquierda/patología , Preparación de Corazón Aislado/métodos , Masculino , Isquemia Miocárdica/patología , Daño por Reperfusión Miocárdica/patología , ConejosRESUMEN
Motion artefact (MA) in voltage-sensitive fluorescent signals causes significant debasement of action potential. During ischemia and reperfusion in isolated rabbit heart, this artefact develops in a manner which may be described by the time of its onset, level, and shape. The MA during ischemia: (a) may become substantial with approximately two minutes delay after establishing global ischemia; (b) may be almost twice as high as the physiological action potential and decreases both with time and repetition of ischemia; (c) the MA shape is unpredictable and depends on individual rabbit.
Asunto(s)
Artefactos , Colorantes Fluorescentes , Daño por Reperfusión Miocárdica/diagnóstico , Compuestos de Piridinio , Imagen de Colorante Sensible al Voltaje/métodos , Potenciales de Acción , Animales , Técnicas In Vitro , Daño por Reperfusión Miocárdica/fisiopatología , Perfusión , Valor Predictivo de las Pruebas , Conejos , Factores de TiempoRESUMEN
It has been shown that, in addition to conventional contact electrode techniques, optical methods using fluorescent dyes can be successfully used for cardiac signal measurement. In this review, the physical and technical fundamentals of the method are described, as well as the properties of the most common systems for measuring action potentials and intracellular calcium concentration. Special attention is paid to summarizing limitations and trends in developing this method.
Asunto(s)
Potenciales de Acción/fisiología , Calcio/metabolismo , Calcio/fisiología , Cardiología/métodos , Corazón/fisiología , Animales , Señalización del Calcio/fisiología , Fenómenos Electrofisiológicos , Colorantes Fluorescentes , HumanosRESUMEN
Three-dimensional electrogram was used for analysis of ischemia manifestation in isolated hearts. Three parameters based on spherical coordination system were used in this study - amplitude of electrical heart vector, its azimuth and elevation. The parameters were presented as a trend. This approach reflected ischemic changes in a manner which can be easily observed and evaluated. Ischemia was analysed in seven isolated hearts of New Zealand white rabbits. It was found that (a) ischemia changes heart electric vector, (b) ischemic preconditioning has a protective effect, and (c) both of these findings can be clearly observed by the proposed method.
Asunto(s)
Técnicas Electrofisiológicas Cardíacas , Interpretación de Imagen Asistida por Computador , Imagenología Tridimensional , Isquemia Miocárdica/diagnóstico , Vectorcardiografía , Potenciales de Acción , Animales , Modelos Animales de Enfermedad , Precondicionamiento Isquémico Miocárdico , Modelos Cardiovasculares , Isquemia Miocárdica/prevención & control , Valor Predictivo de las Pruebas , ConejosRESUMEN
Monophasic action potential (MAP) can be recorded from the heart surface by optical method based on fluorescence measurement. The motion of isolated heart during experiment caused additional noise in recorded signal. The motion artifact can be eliminated by ratiometric fluorescence emission measurements. This study is based on experiments in which optical MAP measurement is done by single-wavelength and dual-wavelength measurement of fluorescence emission. Both recording setups are presented and their advantages and disadvantages are discussed. MAPs recorded by both methods from isolated rabbit hearts perfused according to Langendorff are presented. Simultaneous electrograms (EG) and MAPs recording are analyzed and measurement of velocity of impulse conduction through heart tissue is presented.
