RESUMEN
BACKGROUND: Dandruff caused by Malassezia furfur is a prevailing fungal infection. Although ketoconazole (KTZ) is widely intended for anti-dandruff treatment, poor solubility, and epidermal permeability limits its use and the marketed KTZ shampoo adversely effects scalp and hair. OBJECTIVE: To prepare a novel shampoo loaded with KTZ-coated zinc oxide nanoparticles using green tea extract and evaluate its antifungal activity. METHODS: The KTZ-coated zinc oxide nanoparticles was prepared by green synthesis and was characterized by UV, FTIR, XRD, and the drug entrapment efficiency was investigated. The antifungal activity of the nanoparticles with respect to standard drug, KTZ was tested against Malassezia furfur. Further, a novel antidandruff shampoo was developed by incorporating the prepared nanoparticles into the shampoo base. RESULTS: The formation of KTZ-coated ZnO nanoparticles was confirmed by UV and FTIR analysis. XRD analysis confirmed the amorphous phase of KTZ in nanoparticles. The drug entrapment efficiency was found to be 91.84%. The prepared nanoparticles showed enhanced activity against Malassezia furfur compared to drug of choice, KTZ (1%). The evaluation of shampoo showed an ideal result. CONCLUSION: KTZ-coated ZnO nanoparticles loaded novel shampoo in comparison to marketed anti-dandruff shampoo could be an effective alternate for the treatment of dandruff.
Asunto(s)
Caspa , Preparaciones para el Cabello , Malassezia , Nanopartículas , Óxido de Zinc , Humanos , Cetoconazol , Antifúngicos/uso terapéutico , Caspa/tratamiento farmacológico , Óxido de Zinc/farmacología , Preparaciones para el Cabello/farmacología , Antioxidantes/farmacología , TéRESUMEN
Benzo(a)pyrene, a five-ring polyaromatic hydrocarbon, originating from coal tar, crude oil, tobacco, grilled foods, car exhaust etc, is highly persistent in the environment. It has been classified as a Group I carcinogen, as on its ingestion in human body, diol epoxide metabolites are generated, which bind to DNA causing mutations and eventual cancer. Among various removal methods, bioremediation is most preferred as it is a sustainable approach resulting in complete mineralization of benzo(a)pyrene. Therefore, in this study, biodegradation of benzo(a)pyrene was performed by two strains of Pseudomonas, i. e WDE11 and WD23, isolated from refinery effluent. Maximum benzo(a)pyrene tolerance was 250 mg/L and 225 mg/L against Pseudomonas sp. WD23 and Pseudomonas sp. WDE11 correspondingly. Degradation rate constants varied between 0.0468 and 0.0513/day at 50 mg/L with half-life values between 13.5 and 14.3 days as per first order kinetics, while for 100 mg/L, the respective values varied between 0.006 and 0.007 L/mg. day and 15.28-16.67 days, as per second order kinetics. The maximum specific growth rate of strains WDE11 and WD23 was 0.3512/day and 0.38/day accordingly, while concentrations over 75 mg/L had an inhibitory effect on growth. Major degradation metabolites were identified as dihydroxy-pyrene, naphthalene-1,2-dicarboxylic acid, salicylic acid, and oxalic acid, indicating benzo(a)pyrene was degraded via pyrene intermediates by salicylate pathway through catechol meta-cleavage. The substantial activity of the catechol 2,3 dioxygenase enzyme was noted during the benzo(a)pyrene metabolism by both strains with minimal catechol 1,2 dioxygenase activity. This study demonstrates the exceptional potential of indigenous Pseudomonas strains in complete metabolism of benzo(a)pyrene.
Asunto(s)
Benzo(a)pireno , Petróleo , Humanos , Biodegradación Ambiental , Benzo(a)pireno/metabolismo , Pseudomonas/metabolismo , Petróleo/metabolismo , Pirenos/metabolismo , Redes y Vías MetabólicasRESUMEN
In this study, magnetite nanoparticles (MNPs) were synthesized using the seaweed - Ulva prolifera, an amply found marine source in the Western coastal regions of India. The surface and other properties of MNPs were characterized by many sophisticated methods. Spherical nanoclusters were observed in the FESEM image and iron and oxygen elements were seen in EDS results. XRD peaks were consistent with magnetite standards and MNPs had good crystallinity. FTIR portrayed the specific signals for MNPs and TGA profile ascertained the thermal stability. Magnetic saturation of 41.84 emu/g with negligible hysteresis loop substantiated the superparamagnetism. XPS pointed out the presence of Fe and O with oxidation states specific for MNPs, and the results were consistent with EDS. BET revealed a high specific surface area (144.98 m2/g) of MNPs with mesopores. The synthesized MNPs were used as nanoadsorbent for the removal of As (III) from aqueous solution. The central composite design was used for optimizing As (III) adsorption on MNPs. The optimum conditions were found out as 97.5% at pH: 9, rotation speed: 150 rpm, time: 90 min, and MNPs dosage: 1.15 g/L. The adsorption process fitted in a better way with the Langmuir isotherm and pseudo-second-order model. The highest adsorption capacity was 12.45 mg/g, which is substantially larger than the documenter reports. The spontaneous and endothermic nature of adsorption were ascertained from thermodynamic studies. The results suggested that the synthesized MNPs using the extract of U. prolifera could be alternative nanoadsorbents for eliminating toxic heavy metals from waste streams.
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Nanopartículas de Magnetita , Metales Pesados , Ulva , Contaminantes Químicos del Agua , Adsorción , Óxido Ferrosoférrico , Concentración de Iones de Hidrógeno , Hierro , Cinética , Oxígeno , Extractos VegetalesRESUMEN
Bacillus sp. WD22, previously isolated from refinery effluent, degraded 71% of C8 hydrocarbons present in 1.0% v/v PCO in seawater (control medium), which reduced to 16.3%, on addition of yeast extract. The bacteria produced a biosurfactant in both media, whose surface was observed to be amorphous in nature under FESEM-EDAX analysis. The biosurfactant was characterized as a linear surfactin by LCMS and FT-IR analysis. The critical micelle concentration was observed as 50 mg/L and 60 mg/L at which the surface tension of water was reduced to 30 mN/m. Purified biosurfactant could emulsify petroleum-based oils and vegetable oils effectively and was stable at all tested conditions of pH, salinity and temperature up to 80 °C. The biosurfactant production was found to be mixed growth associated in control medium, while it was strictly growth associated in medium with yeast extract as studied by the Leudeking-Piret model.
Asunto(s)
Bacillus , Petróleo , Petróleo/análisis , Bacillus/metabolismo , Espectroscopía Infrarroja por Transformada de Fourier , Tensoactivos/farmacología , Tensoactivos/química , Tensión Superficial , Biodegradación AmbientalRESUMEN
This study deals with the synthesis of hydroxyapatite nanoparticles (HAPnps) mediated by Acacia falcata leaf extract. Aggregates of needle-shaped crystalline nanostructures were confirmed by FE-SEM and TEM analysis. Well-defined rings in the SAED patterns corroborated the polycrystalline nature of the HAPnps. Individual elements present in the HAPnps were attested by the specific signals for Ca, P, and O in the EDS and XPS analyses. The distinct peaks observed in the XRD spectrum matched well with the HAP hexagonal patterns with a mean crystallite size of 55.04 nm. The FTIR study unveiled the coating of the nanoparticles with the biomolecules from Acacia falcata leaves. The suspension HAPnps exhibited polydispersity (0.446) and remarkable stability (zeta potential: - 31.9 mV) as evident from DLS studies. The pore diameter was 25.7 nm as obtained from BET analysis, suggesting their mesoporous nature. The HAPnps showed the cytotoxic effect on A549 lung and MDA-MB231 breast carcinoma cell lines, with an IC50 value of 55 µg/mL. The distortion of the cell membrane and cell morphology, along with the chromatin condensation and cell necrosis on treatment with HAPnps were detected under fluorescence microscopy post acridine orange/ethidium bromide dye staining. This study reports the anti-cancerous potential of non-drug-loaded plant-mediated HAPnps. Therefore, the HAPnps obtained in this investigation could play a vital role in the biomedical field of cancer therapy.
Asunto(s)
Acacia , Nanopartículas del Metal , Animales , Línea Celular , Durapatita , Mamíferos , Nanopartículas del Metal/química , Extractos Vegetales/farmacología , Plata/químicaRESUMEN
Heavy metals are dumped into the environment as a result of human activities, posing a serious threat to ecology and human health. Surface water, potable drinking water, potable groundwater, and majority of wastewater include their traces, due to which, their detection by nanoparticles has received a lot of attention in recent years. Although microorganisms are utilized for green nanoparticle production, plant materials have recently been explored because they are more environmentally friendly, easier to scale up, and require fewer specific growth conditions. The production and attributes of nanoparticles synthesized by plant mediation could be enhanced through design of experiments approach, extending their feasibility in the detection of heavy metals in polluted environmental samples. A concise review on green synthesis of silver and gold nanoparticles utilizing plant phytochemicals, its mechanism of synthesis along with significance of design of experiments for enhancement, and their use as heavy metal contamination detectors is presented in the current study.
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Nanopartículas del Metal , Metales Pesados , Oro/química , Humanos , Nanopartículas del Metal/química , Extractos Vegetales/química , Plata/químicaRESUMEN
Effect of oil spills on living forms demands for safe, ecofriendly and cost-effective methods to repair the damage. Pseudomonads have exceptional tolerance to xenobiotics and can grow at varied environmental conditions. This study aims at biosurfactant mediated degradation of petroleum crude oil by an indigenous Pseudomonas sp. WD23 in sea water. Pseudomonas sp. WD23 degraded 34% of petroleum crude oil (1.0% v/v) on supplementation of yeast extract (0.05 g/L) with glucose (1.0 g/L) in seawater. The strain produced a biosurfactant which was confirmed as a rhamnolipid (lipid: rhamnose 1:3.35) by FT-IR, LCMS and quantitative analysis. Produced rhamnolipid had low CMC (20.0 mg/L), emulsified petroleum oils (75-80%) and had high tolreance to varied conditions of pH, temperature and ionic strength. OFAT studies were performed to analyse the effect of petroleum crude oil, glucose, inoculum, yeast extract, pH, agitation speed and incubation time on degradation by Pseudomonas sp. WD23. Petroleum crude oil and glucose had significant effect on biodegradation, rhamnolipid production and growth, further optimized by central composite design. At optimum conditions of 3.414% v/v PCO and 6.53 g/L glucose, maximum degradation of 81.8 ± 0.67% was observed at pH 7.5, 100 RPM, 15.0% v/v inoculum in 28 days, with a 3-fold increase in biodegradation. GCMS analysis revealed degradation (86-100%) of all low and high molecular weight hydrocarbons present in petroleum crude oil. Hence, the strain Pseudomonas sp. WD23 can be effectively developed for management of oil spills in seas and oceans due to its excellent degradation abilities.
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Petróleo , Pseudomonas , Biodegradación Ambiental , Glucosa/metabolismo , Glucolípidos , Nitrógeno/análisis , Petróleo/análisis , Pseudomonas/metabolismo , Agua de Mar , Espectroscopía Infrarroja por Transformada de Fourier , Tensoactivos/químicaRESUMEN
The present work reports the study on the green synthesis of hydroxyapatite (HAP) nanoadsorbents using Peltophorum pterocarpum pod extract. HAP nanoadsorbents were characterized by using FESEM, EDS, TEM, XRD, FTIR, XPS, and BET analyses. The results highlighted the high purity, needle-like aggregations, and crystalline nature of the prepared HAP nanoadsorbents. The surface area was determined as 40.04 m2/g possessing mesopores that can be related to the high adsorption efficiency of the HAP for the removal of a toxic dye, - Acid Blue 113 (AB 113) from water. Central Composite Design (CCD) was used for optimizing the adsorption process, which yielded 94.59% removal efficiency at the optimum conditions (dose: 0.5 g/L, AB 113 dye concentration: 25 ppm, agitation speed: 173 rpm, and adsorption time: 120 min). The adsorption kinetics followed the pseudo-second-order model (R2:0.9996) and the equilibrium data fitted well with the Freundlich isotherm (R2:0.9924). The thermodynamic parameters indicated that the adsorption of AB 113 was a spontaneous and exothermic process. The highest adsorption capacity was determined as 153.85 mg/g, which suggested the promising role of green HAP nanoadsorbents in environmental remediation applications.
Asunto(s)
Durapatita , Contaminantes Químicos del Agua , Adsorción , Compuestos Azo , Concentración de Iones de Hidrógeno , Cinética , Extractos Vegetales , Contaminantes Químicos del Agua/análisisRESUMEN
An environmentally sound approach towards the green synthesis of zinc oxide nanostructures has been achieved with an aqueous extract of Calliandra haematocephala leaves. The nanoparticles were characterized using various analytical techniques to substantiate the structural details. An absorption band at 358 nm corresponds to the formation of zinc oxide nanoparticles. Scanning electron microscopy revealed the nanoflower morphology of the nanoparticles. Energy dispersive spectral analysis portrayed the strong presence of zinc and oxygen, while X-ray diffraction showed the nanoparticles to conform to hexagonally-formed wurtzite structure. The crystallite size of the nanoflowers was estimated to be 19.45 nm. Vibrational frequencies, typical of zincoxygen and other functional groups, were revealed using Fourier transform infrared spectroscopy. BET analysis revealed that the pores were of mesoporous nature with an estimated specific surface area of 9.18 m2/g. The photocatalytic nature of the nanoparticles was established by the degradation of methylene blue (MB) dye, under solar radiation. Up to 88% degradation was achieved in a duration of 270 min. Kinetic data from the studies proved that the reaction was compliant with first-order model, with rate constant as 0.01 min-1. The study illustrated the synthesis of zinc oxide nanoparticles using a novel source, viz., the leaves of C. haematocephala.
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Colorantes/química , Fabaceae/química , Luz , Nanopartículas del Metal/química , Óxido de Zinc/química , Catálisis , Fabaceae/metabolismo , Tecnología Química Verde , Azul de Metileno/química , Oxidación-Reducción , Extractos Vegetales/química , Hojas de la Planta/química , Hojas de la Planta/metabolismoRESUMEN
In the current study, the green synthesis of zinc oxide nanoparticles (ZnONPs) using the leaf extract of Cyanometra ramiflora and zinc acetate precursor is presented. The phyto-components of the extract aided the reduction and the formation of nanoparticles. The purified ZnONPs were characterized by UV-Vis spectroscopy, SEM, EDS, XRD, BET, and FTIR techniques. A sharp absorption maximum at 360â¯nm in the UV-Vis data affirmed the formation of ZnONPs. SEM image revealed the nanoflower morphology and EDS showed strong signals for zinc and oxygen elements. XRD spectrum confirmed the hexagonal wurtzite crystalline structure of size 13.33â¯nm. A significant large surface area of 16.27â¯m2/g with mesopores, was affirmed using BET analysis. FTIR substantiated the existence of the characteristic zinc and oxygen bonding vibrations at 557â¯cm-1, 511â¯cm-1 and 433â¯cm-1. The photocatalytic activity of the ZnONPs was examined using the pollutant dye, Rhodamine B. A remarkable degradation efficiency of 98% within 200â¯min was achieved under sunlight irradiation and a degradation constant of 0.017â¯min-1 was obtained. Therefore, ZnONPs synthesized using a cheap and abundant source - the leaf extract of C.ramiflora possibly will play a promising part in the degradation of toxic dyes present in the wastewater.
Asunto(s)
Nanopartículas del Metal/química , Extractos Vegetales/química , Hojas de la Planta/química , Rodaminas/química , Tracheophyta/química , Óxido de Zinc/química , Catálisis , Tecnología Química Verde/métodos , Cinética , Oxidación-Reducción , Oxígeno/química , Procesos Fotoquímicos , Porosidad , Propiedades de Superficie , Rayos Ultravioleta , Contaminación Química del AguaRESUMEN
The present study reports a simple and low cost synthesis of zero-valent silver nanoparticles (ZVSNPs) from silver nitrate using the leaf extract of Spondias dulcis. The ZVSNPs showed a unique peak at 420â nm in UV-vis spectrum. The SEM image portrayed cuboidal shaped particles. The EDX spectrum designated the elemental silver peak at 3â keV. In XRD, a sharp peak at 32.47° denoted the existence of (1 0 1) lattice plane and the average crystallite size was calculated as 48.61â nm. The lattice parameter was determined as 0.39â nm. The FTIR spectra of the leaf extract and ZVSNPs showed shifts in the specific functional group bands which ascertained the involvement of phytoconstituents in the formation and capping of nanoparticles. The average hydrodynamic size was measured as 59.66â nm by DLS method. A low PDI, 0.187 witnessed the monodispersity. A negative zeta potential value of -15.7â mV indicated the negative surface charges of the nanoparticles. The bactericidal action of ZVSNPs was demonstrated against two pathogens S.typhimurium and E.coli during which a dosage dependent zone of inhibition results was observed. Additionally, the catalytic potential of ZVSNPs was examined for the degradation of methylene blue dye in which an accelerated degradation of the dye was observed.
Asunto(s)
Anacardiaceae/química , Antibacterianos/química , Colorantes/química , Nanopartículas del Metal/química , Plata/química , Antibacterianos/síntesis química , Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Colorantes/aislamiento & purificación , Tecnología Química Verde , Pruebas de Sensibilidad Microbiana , Tamaño de la Partícula , Extractos Vegetales/química , Extractos Vegetales/metabolismo , Hojas de la Planta/química , Hojas de la Planta/metabolismo , Plata/farmacología , Espectroscopía Infrarroja por Transformada de Fourier , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificaciónAsunto(s)
Fascículo Atrioventricular Accesorio/fisiopatología , No Compactación Aislada del Miocardio Ventricular/complicaciones , Síndromes de Preexcitación/etiología , Taquicardia Supraventricular/etiología , Potenciales de Acción , Niño , Electrocardiografía , Técnicas Electrofisiológicas Cardíacas , Frecuencia Cardíaca , Humanos , No Compactación Aislada del Miocardio Ventricular/diagnóstico , Masculino , Síndromes de Preexcitación/diagnóstico , Síndromes de Preexcitación/fisiopatología , Taquicardia Supraventricular/diagnóstico , Taquicardia Supraventricular/fisiopatología , Factores de TiempoRESUMEN
AIMS: Sedation is not consistently used during electrophysiology procedures because of concerns regarding effects on tachycardia inducibility. We designed this study to assess the effect of conscious sedation on tachycardia inducibility and patient comfort during supraventricular tachycardia ablation. METHODS AND RESULTS: Patients with narrow QRS tachycardia and no pre-excitation undergoing an electrophysiology study were randomly assigned to sedation or placebo group. Patients in the sedation group received intermittent doses of midazolam and fentanyl, while those in the placebo group received normal saline as placebo. The physician and the patient were blinded to the allocation. Information was collected on tachycardia inducibility, patient discomfort, and complications. A total of 103 patients were included in the study. Proportion of patients with difficult tachycardia induction (27.4% vs. 32.7%) or with non-inducibility (5.8% vs. 3.8%) were not different between the sedation and placebo groups. Patient discomfort as measured by the Wong-Baker scale was significantly less in the sedation group (1.45 ± 1.08 vs. 2.24 ± 1.2, P < 0.0007) compared to the placebo group. There was no difference in incidence of hypotension or hypoxia between the two groups. CONCLUSIONS: Conscious sedation with intermittent midazolam- and fentanyl-reduced patient discomfort during electrophysiology study and ablation of supraventricular tachycardia without affecting tachycardia inducibility. Sedation administered in the absence of an anaesthetist was safe.
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Estimulación Cardíaca Artificial , Ablación por Catéter , Sedación Consciente , Técnicas Electrofisiológicas Cardíacas , Sistema de Conducción Cardíaco/cirugía , Comodidad del Paciente , Taquicardia Supraventricular/cirugía , Potenciales de Acción , Adulto , Ablación por Catéter/efectos adversos , Sedación Consciente/efectos adversos , Método Doble Ciego , Femenino , Sistema de Conducción Cardíaco/fisiopatología , Frecuencia Cardíaca , Humanos , India , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Taquicardia Supraventricular/diagnóstico , Taquicardia Supraventricular/fisiopatología , Resultado del TratamientoRESUMEN
BACKGROUND: The His-ventricular (HV) interval is an important index of atrioventricular conduction, but at present can be reliably measured only during an invasive electrophysiology (EP) study. Magnetocardiography (MCG) is a noninvasive measurement of weak magnetic fields generated by the heart. We compared HV interval noninvasively assessed using MCG with the corresponding values measured directly in an EP study. METHODS: MCG was measured using a 37-channel system inside a magnetically shielded room in patients who had previously undergone an EP study. His-bundle potential was identified in the PR segment after signal averaging. Magnetic field maps representing the spatial distribution of ramp-like signals in the PR segment generated at various instants of time were used to identify His-bundle signals in cases where the deflection representing the His was ambiguous. RESULTS: The study included 23 patients (14 male, nine female) with a wide range of HV intervals measured during EP study (49 ± 17 ms, range 35-120 ms). In 21 (91%) subjects, discernible His-bundle signals are observed in the PR segment of MCG traces. HV intervals measured between the two methods showed a correlation (r2 = 0.87, P < 0.0001) with a mean difference of 5.4 ± 3.2 ms. CONCLUSION: With the use of new criteria to identify the His-bundle deflection in signal-averaged MCG signals, we report a high success rate in noninvasive HV interval measurement and a good agreement with those from EP study. The results encourage the use of MCG as a noninvasive method for measurement of the HV interval.
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Algoritmos , Nodo Atrioventricular/fisiopatología , Fascículo Atrioventricular/fisiología , Diagnóstico por Computador/métodos , Técnicas Electrofisiológicas Cardíacas/métodos , Magnetocardiografía/instrumentación , Conducción Nerviosa , Adulto , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadAsunto(s)
Anomalía de Ebstein/complicaciones , Taquicardia Ventricular/etiología , Válvula Tricúspide/fisiopatología , Potenciales de Acción , Adulto , Estimulación Cardíaca Artificial , Ablación por Catéter , Anomalía de Ebstein/diagnóstico , Electrocardiografía , Técnicas Electrofisiológicas Cardíacas , Femenino , Frecuencia Cardíaca , Humanos , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/fisiopatología , Taquicardia Ventricular/cirugía , Resultado del TratamientoRESUMEN
BACKGROUND: The arrhythmogenic substrate in survivors of unexplained cardiac arrest (UCA) has not been defined. OBJECTIVES: To test the hypothesis that patients with UCA have latent repolarization abnormalities, in particular T-wave alternans (TWA), which may be unmasked with epinephrine (EPI) challenge. METHODS: We prospectively studied 10 UCA survivors (46 ± 9 years) and 11 first-degree relatives (FDRs) of sudden death victims (37 ± 14 years). Patients with UCA underwent standard clinical testing, which was normal. FDRs had normal clinical history and testing. All subjects underwent an EPI infusion (0.05, 0.1, and 0.2 µg/(kg·min), 5 minutes each dose) while recording continuous digital 12-lead electrocardiograms. Corrected QT interval and QT variability index were evaluated at each EPI dose. TWA magnitude (V(alt)) was assessed at each dose by using the spectral method. Positive (+) TWA at each dose was defined as V(alt) > 0 with k ≥ 3 in 1 or more 128-beat segment in ≥2 electrocardiogram leads. A novel metric, TWA burden, reflecting V(alt) integrated over time (s), was also evaluated for each EPI dose. RESULTS: There was no difference between UCA survivors and FDRs with respect to heart rate, QT, corrected QT interval, or QT variability index at baseline or during EPI. At baseline, +TWA was similar between UCA survivors and FDRs (10% vs 0%; P = NS). During EPI, +TWA was more prevalent in UCA survivors than in FDRs (80% vs 18%; P = .009). TWA burden was greater in UCA survivors than in FDRs during EPI 0.1 (P = .039) and EPI 0.2 µg/(kg·min) (P = .009). CONCLUSIONS: UCA survivors are more likely to demonstrate latent TWA compared with FDRs, which becomes manifest with EPI. This novel finding provides evidence for an arrhythmogenic substrate in UCA survivors.
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Paro Cardíaco/fisiopatología , Sistema de Conducción Cardíaco/fisiopatología , Agonistas Adrenérgicos beta/administración & dosificación , Muerte Súbita Cardíaca , Relación Dosis-Respuesta a Droga , Técnicas Electrofisiológicas Cardíacas , Epinefrina/administración & dosificación , HumanosAsunto(s)
Desfibriladores Implantables , Infarto del Miocardio/terapia , Muerte Súbita Cardíaca/prevención & control , Desfibriladores Implantables/normas , Técnicas Electrofisiológicas Cardíacas , Humanos , Guías de Práctica Clínica como Asunto , Medición de Riesgo , Taquicardia Ventricular/terapia , Factores de TiempoRESUMEN
OBJECTIVES: The aim of this study was to define the spatiotemporal distribution of intracardiac alternans and its relationship to body surface alternans in humans. BACKGROUND: Spatial heterogeneity of alternans exists in the animal heart owing to nonuniform calcium cycling and restitution kinetics. Patients with cardiomyopathy manifest similar myocardial substrate, which might influence the distribution of intracardiac alternans and its projection onto the body surface. METHODS: Repolarization alternans was simultaneously measured from unipolar electrograms in the right ventricular endocardium, left ventricular (LV) epicardium, and the surface electrocardiogram in patients with cardiomyopathy (n = 14, LV ejection fraction 29 +/- 2%) during atrial pacing at cycle length (CL) 800, 600, and 500 ms. Alternans was determined from the entire JT interval as well as the early, mid, and late JT interval with spectral analysis. RESULTS: Alternans was not uniformly distributed within the heart, with alternating and nonalternating myocardial segments lying adjacent to one another. A greater number of epicardial sites exhibited alternans than endocardial sites at CL 600 ms. Temporal heterogeneity in alternans was present along the JT interval, and apical segments had proportionately less alternans in the late JT interval than mid or basal segments, resulting in apicobasal alternans heterogeneity in late JT interval. Discordant alternans was seen in 5 patients confined to the epicardium. Patients with surface alternans had a greater proportion of intracardiac sites with alternans when compared with those patients without surface alternans. CONCLUSIONS: Spatiotemporal heterogeneity and discordant alternans are evident in patients with cardiomyopathy. Greater spatial distribution of intracardiac alternans is associated with measurable body surface alternans.