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In this study, we investigate the crystallization behavior of the precursor HfO2–ZrO2 (HZO) thin film to increase the fraction of the ferroelectric phase with orthorhombic symmetry in the resulting crystallized films. The precursor film of Hf0.5Zr0.5O2 prepared by the chemical solution deposition (CSD) process was crystallized to the tetragonal phase (at 600 °C) or a mixture of the orthorhombic and monoclinic phases (at 700 °C and above), depending on the crystallization temperature. A saturated P–E hysteresis loop with a remanent polarization (Pr) of 8 µC/cm2 was observed for the HZO films crystallized at 700 °C, whereas a distorted P–E curve with a lower Pr value was confirmed for the film crystallized at 600 °C. [ABSTRACT FROM AUTHOR]

In this study, the effect of Fe doping on the crystal structure and electrical properties in 20-nm-thick HfO2 epitaxial thin films were systematically investigated. X-ray diffraction measurements revealed that undoped HfO2 films were composed of a paraelectric monoclinic phase. On the other hand, the formation of non-centrosymmetric orthorhombic phase was observed in Fe doped HfO2 films and was most promoted at an optimum doping concentration. In addition, high-temperature X-ray diffraction measurements showed that an orthorhombic phase to a highly symmetric phase transition occurs between 500 and 600 °C. Microstructural analysis using scanning transmission electron microscopy revealed multidomain structure consisting of orthorhombic and monoclinic phases. Ferroelectricity depended on Fe doping concentration, and the maximum remanent polarization value was 8.8 µC/cm2. These results indicate that Fe doped HfO2 thin films can be applied as nanoscale ferroelectrics. [ABSTRACT FROM AUTHOR]

Lead (Pb)-free perovskite thin films of the ternary BaTiO3–Ba(Mg1/2Ti1/2)O3–BiFeO3 (BT–BMT–BF) solid solution system with preferential crystal orientation were fabricated and the dependence of their polarization behavior on crystal anisotropy was evaluated. The chemical solution deposition (CSD) technique was utilized for the film deposition while controlling the chemical composition. The films fabricated on single-crystal perovskite substrates of (100)SrRuO3//(100)SrTiO3 and (111)SrRuO3//(111)SrTiO3 exhibited preferential (100)pc and (111)pc orientations, respectively, depending on the crystallographic feature on the substrate surface. Excess Bi addition into the precursor solution to compensate for the volatile Bi component enhanced the polarization behavior of the resulting films heat-treated at 750 °C to induce crystallization. The (111)pc-oriented BT–BMT–BF film had a larger remanent polarization (Pr) of approximately 35 µC/cm2 than the (100)pc-oriented film (Pr = approximately 20 µC/cm2). [ABSTRACT FROM AUTHOR]

The dependence of applied rectangular pulses with various widths on the crystal structure change was investigated by time-resolved synchrotron-based X-ray diffraction measurement. A (001)-oriented epitaxial Pb(Zr0.5Ti0.5)O3 film of 2.1 µm thickness grown on a (100)cSrRuO3//(100)LaNiO3//(100)CaF2 substrate by metal organic chemical vapor deposition was investigated. The crystal lattice increased almost linearly with increasing applied electric field up to 230 kV/cm in the case of a 0.3-µs-width pulse. This elongation with the application of an electric field was ascertained to be almost independent of the pulse width from 0.3 to 2000 µs at 190 kV/cm. These values were almost consistent with the macroscopic measurements obtained at 5 and 1000 Hz by piezoelectric force macroscopy. The present results show that the time-resolved XRD measurement is very useful for analyzing the frequency dependence of the piezoelectric response in view of the crystal structure change because the crystal structure change under an applied electric field can be systematically investigated by changing the applied pulse width. [ABSTRACT FROM AUTHOR]

(111)-oriented epitaxial (K0.5Na0.5)NbO3 films of 2 µm thickness were deposited at 240 °C on (111)cSrRuO3//(111)SrTiO3 substrates by a hydrothermal method. Scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy (STEM-EDS) mapping revealed that a K-rich interfacial region existed in the obtained films. Although the as-deposited films were annealed between 240 and 600 °C in O2 atmosphere, the crystal structure did not markedly change. On the other hand, the leakage current density drastically decreased from 10−2–100 to 10−6 A/cm2 at ±80 kV/cm after annealing above 240 °C. In addition, the relative dielectric constant (εr), remanent polarization (Pr), and piezoelectric constant (d33,PFM) increased with increasing annealing temperature from 300 to 600 °C, and their values were respectively 840, 5.7 µC/cm2, and 64 pm/V for the films annealed at 600 °C. [ABSTRACT FROM AUTHOR]

A strongly {110}-oriented perovskite-type thin film of tetragonal Pb(Zr0.4Ti0.6)O3 (PZT) was successfully obtained on a (100)Si substrate using a {101}PdO//{111}Pd thin film as a buffer layer. The {101}PdO//{111}Pd thin film buffer layer was obtained by oxidizing {111}Pd after depositing {111}Pd on a {111}Pt/TiOx/SiO2/{100}Si substrate. Using this buffer layer, a {110}c-oriented SrRuO3 (SRO) thin film was deposited by sputtering as a bottom electrode of PZT thin films. Subsequently, the {110}-oriented PZT thin film can be deposited on a (110)cSRO thin film by metal–organic chemical deposition (MOCVD) and its properties can be compared with those of PZT thin films with other orientations of {100} and {111}. Among the {100}, {110}, {111}-oriented PZT films, the {100}-oriented one showed the largest remnant polarization, which is in good agreement with those of the PZTs epitaxially grown in the 〈100〉, 〈110〉, and 〈111〉 directions. The other properties, i.e., piezoelectricity and dielectric constants, also showed similar anisotropic tendencies, which is in good agreement with the data reported in the epitaxially grown PZTs. [ABSTRACT FROM AUTHOR]

For the application of electronic devices using ferroelectric/piezoelectric components, one-axis-oriented tetragonal Pb(Zr0.40Ti0.60)O3 (PZT) films with thicknesses of up to 1 µm were fabricated with the aid of a Ca2Nb3O10 nanosheet (ns-CN) template for preferential crystal growth for evaluating their polarization switching behavior. The ns-CN template was supported on ubiquitous silicon (Si) wafer by a simple dip coating technique, followed by the repetitive chemical solution deposition (CSD) of PZT films. The PZT films were grown successfully with preferential crystal orientation of PZT(100) up to the thickness of 1020 nm. The (100)-oriented PZT film with ∼1 µm thickness exhibited unique polarization behavior of ferroelectric polarization, i.e., a marked increase in remanent polarization (Pr) up to approximately 40 µC/cm2 induced by domain switching under high electric field, whereas the film with a lower thickness showed only a lower Pr of approximately 11 µC/cm2 even under a high electric field. The ferroelectric property of the (100)-oriented PZT film after domain switching on ns-CN/Pt/Si can be comparable to those of (001)/(100)-oriented epitaxial PZT films. [ABSTRACT FROM AUTHOR]

Mg2Si thin films were deposited at 320 °C on (001)Al2O3 and (100)CaF2 substrates by radio-frequency magnetron sputtering. Both films showed a preferential (111) out-of-plane orientation with an in-plane random orientation irrespective of post-heat treatment. Mg2Si films on (001)Al2O3 substrates were under in-plane tensile strain, while those on (100)CaF2 substrates were under in-plane compressive strain both before and after heat treatment. Heat-treated films showed p-type conduction up to 500 °C. Their electrical conductivity and Seebeck coefficient were almost independent of the kind of substrate within the limit of the present study, from 0.22% compressive strain to 0.34% tensile strain at room temperature. [ABSTRACT FROM AUTHOR]

(Bi,K)TiO3 films were grown on (001)cSrRuO3 // (100)SrTiO3 substrates by pulsed laser deposition (PLD) at various temperatures. The K/Ti and Bi/Ti ratios of the films were almost the same at 350 and 500 °C, but decreased markedly at 650 °C. The ferroelectric property was ascertained for epitaxial tetragonal (Bi,K)TiO3 films grown at 500 °C from polarization–electric field relationships, and their saturation polarization (Psat) and coercive field (Ec) at a maximum electric field of 800 kV/cm were 18 µC/cm2 and 300 kV/cm, respectively. To improve the ferroelectric property, the films were heat-treated at 650 °C while keeping the films in the PLD chamber after film deposition. These films also maintained a (001)-oriented epitaxy and had a tetragonal symmetry. The Psat and Ec obtained at an electric field of 800 kV/cm were changed to 22 µC/cm2 and 95 kV/cm, respectively. Moreover, these Psat and Ec values increased to 31 µC/cm2 and 165 kV/cm, respectively, at a maximum electric field of 1500 kV/cm. These heat-treated (Bi,K)TiO3 films showed piezoelectricity with an apparent piezoelectric coefficient (d33(AFM)) of 22 pm/V. [ABSTRACT FROM AUTHOR]

In the present work, we aim to achieve the preferred crystal orientation of chemical solution deposition (CSD)-derived BaTiO3 films on ubiquitous Si wafers with the assistance of Ca2Nb3O10 nanosheet (ns-CN) template layers. The ns-CN on platinized Si (Pt/Si) substrates aligned the BaTiO3(100) plane to the substrate surface, because of the favorable lattice matching of the ns-CN (001) plane. The CSD process in air required a high crystallization temperature of 900 °C for the preferred crystal orientation of BaTiO3(100) because of the BaCO3 byproduct generated during the combustion reaction of the precursor gel. The processing in vacuum to remove CO2 species enhanced the crystal orientation even at the crystallization temperature of 800 °C, although it can generate oxygen vacancies () that cause distorted polarization behavior under an applied field higher than approximately 150 kV/cm. The relative dielectric constant (εr) of the (100)-oriented BaTiO3 film on the ns-CN-supported Pt/Si substrate (ns-CN/Pt/Si) was generally larger than that of the randomly oriented film on Pt/Si, depending on the degree of crystal orientation. [ABSTRACT FROM AUTHOR]

Herein, we investigate the angular dependence of the Raman spectra of (001)/(100)-oriented tetragonal and (111)/-oriented rhombohedral epitaxial lead zirconate titanate (PZT) films. The A1 and E modes have the same angular dependence for the (111)/-oriented rhombohedral epitaxial PZT film, but not for the (001)/(100)-oriented tetragonal epitaxial PZT film. These results agree well with theoretical predictions. On the basis of the fact that the angular dependence of the phonon mode in PZT films is linked to the crystal orientation and structure, the angular dependence of the Raman modes can be used to investigate the orientation and structure of PZT films. [ABSTRACT FROM AUTHOR]

When carbon suspended in water was irradiated repetitively by pulsed laser at 532 nm, the carbon particles were gradually consumed, being accompanied with morphology change. Transmission electron microscopy (TEM) showed formation of seemingly entangled long fibrils and/or thin shells from the particles. In the copresence of silver ions, characteristic plasmon absorption peak appeared and formation of nanosized silver particles was evidenced by TEM. Under the typical fluence of 125 mJ.cm-2.pulse-1, the quantum yield of silver reduction was 10-3. [ABSTRACT FROM AUTHOR]

Energy-harvesting properties were investigated for the flexible piezoelectric devices, Pt/hydrothermally synthesized (K0.88Na0.12)NbO3/SrRuO3/metal foil, fabricated at low process temperatures below 300 °C. Fabricated devices had high flexibility, and cracking and peeling were not observed under the bending condition with the maximum curvature of 5.2 mm. The estimated Young’s modulus of the fabricated flexible devices was 37 GPa. The pulse poling treatment with AC voltage above 150 V enhanced the energy-harvesting properties. Although the dielectric constant was almost unchanged (εr = 120 at 200 Hz), the maximum output voltage measured at an acceleration of 10 m/s2 was observed at a resonance frequency of 126 Hz, and this voltage increased from 7.2 to 11 V after pulse poling treatment at 200 V. The maximum output power was 7.7 µW at a load resistance of 560 kΩ. The calculated Q and K2 values were 30 and 0.0014, respectively. The power density was 1.8 µW/(G2·mm3), which is higher than the previous reports for films and sintered bodies of (KxNa1−x) fabricated above 500 °C. [ABSTRACT FROM AUTHOR]

A new orientation control method for depositing (110)-oriented perovskite thin films was demonstrated using a (101)PdO//(111)Pd buffer layer on (100)Si substrates, which is widely used in integrated ferroelectric and dielectric applications. The (101)-oriented PdO was obtained by oxidizing (111)Pd films deposited on a (111)Pt/TiOx/SiO2/(100)Si substrate and (110)-oriented perovskites including SrRuO3 and (Ba0.5,Sr0.5)TiO3 (BST) were obtained on (101)PdO by the RF magnetron sputtering method. Although the BST films deposited at 500 °C were not crystallized, the BST films deposited above 600 °C are fully crystallized and the (110)-orientation is dominant. The (110)-oriented BST thin film showed good dielectric property with high dielectric constant (>600) at 0 kV/cm and high tunability (>50% at ±200 kV/cm). Comparing this dielectric property with those of other oriented BST films, both the dielectric constant and the tunability tend to decrease in the order of (111)-, (100)-, and (110)-preferred orientations. [ABSTRACT FROM AUTHOR]

Highly ordered ‘Chrysanthemum petal’ arrangements of silver nano wires were fabricated in a biodegradable polymer of polyvinyl alcohol using a simple one-step blending method without any template. The degree of the arrangement increased with the decreasing content of polyvinyl alcohol. The mechanism for the formation of these ‘Chrysanthemum petal’ arrangements was discussed specifically. These ‘Chrysanthemum petal’ arrangements will be helpful to increase the electrical conductivity of silver nano wires films. [ABSTRACT FROM AUTHOR]

Lead- and alkali-metal-free BaTiO3–Bi(Mg0.5Ti0.5)O3–BiFeO3 solid-solution thin films were prepared on (111)cSrRuO3/(111)Pt/TiO2/SiO2/(100)Si substrates by chemical solution deposition (CSD) and their crystal structure and dielectric properties were investigated. The lattice spacing as a function of z/(x + z) in xBaTiO3–0.1Bi(Mg0.5Ti0.5)O3–zBiFeO3 indicated the existence of phase boundaries (pseudocubic/rhombohedral) in the range of z/(x + z) = 0.33–0.56, where the relatively high relative dielectric constant, εr, of above 800 was obtained. On the other hand, dielectric loss, tan δ, of below 0.2 was confirmed in the range z/(x + z) = 0–0.87, which rapidly increased toward z/(x + z) = 1.0. The relatively high εr values of these films deposited on Si substrates by a solution-based process suggest that they can be used as alternative to Pb(Zr,Ti)O3, KNbO3, and (Bi1/2Na1/2)TiO3-based films. [ABSTRACT FROM AUTHOR]

Thin films of the BaTiO3–Bi(Mg1/2Ti1/2)O3 (BT–BMT) solid-solution system were fabricated with the aim of achieving a stable temperature coefficient of capacitance (TCC) favorable for high-temperature electronics. A single perovskite phase with pseudocubic symmetry was obtained for the films fabricated by chemical solution deposition on (111)Pt/TiO2/(100)Si substrates in the composition range of x = 0–0.80 for (1 − x)BT–xBMT. BMT added to the BaTiO3-based films enhanced the crystallinity of the perovskite phase and resulted in saturated P–E hysteresis behavior with remanent polarization of up to 13 µC/cm2. BMT addition led to gradual dielectric relaxation, which also resulted in stable TCC behavior with a relative dielectric constant of approximately 400 in the temperature range of RT − 400 °C, especially for the BT–BMT films with x = 0.20–0.40. [ABSTRACT FROM AUTHOR]

KNbO3 films were synthesized at 120–240 °C by a hydrothermal method. The deposition amount of KNbO3 films decreased with decreasing deposition temperature because the deposition rate decreased together with the increase in the starting time of precipitation. The KNbO3 phase was ascertained at temperature as low as 120 °C in films deposited on (100)cSrRuO3//(100)SrTiO3 substrates. On the other hand, powders prepared at 150 °C included the Nb2O5 phase as well as the KNbO3 phase. In addition, powders prepared at 120 °C consist of the K3Nb7O19 phase instead of the KNbO3 phase. KNbO3 films were deposited at 150 °C on LaNiO3/Pt/Ti/polysulfone substrates. Films consisting of the polycrystalline KNbO3 phase were obtained, and their ferroelectricity and piezoelectricity were observed. The remanent polarization and piezoelectric coefficient were 4.2 µC/cm2 and 20–32 pm/V, respectively. [ABSTRACT FROM AUTHOR]

The real-time translocation of iron (Fe) in barley (Hordeum vulgare L. cv. Ehimehadaka no. 1) was visualized using the positron-emitting tracer 52Fe and a positron-emitting tracer imaging system (PETIS). PETIS allowed us to monitor Fe translocation in barley non-destructively under various conditions. In all cases, 52Fe first accumulated at the basal part of the shoot, suggesting that this region may play an important role in Fe distribution in graminaceous plants. Fe-deficient barley showed greater translocation of 52Fe from roots to shoots than did Fe-sufficient barley, demonstrating that Fe deficiency causes enhanced 52Fe uptake and translocation to shoots. In the dark, translocation of 52Fe to the youngest leaf was equivalent to or higher than that under the light condition, while the translocation of 52Fe to the older leaves was decreased, in both Fe-deficient and Fe-sufficient barley. This suggests the possibility that the mechanism and/or pathway of Fe translocation to the youngest leaf may be different from that to the older leaves. When phloem transport in the leaf was blocked by steam treatment, 52Fe translocation from the roots to older leaves was not affected, while 52Fe translocation to the youngest leaf was reduced, indicating that Fe is translocated to the youngest leaf via phloem in addition to xylem. We propose a novel model in which root-absorbed Fe is translocated from the basal part of the shoots and/or roots to the youngest leaf via phloem in graminaceous plants. [ABSTRACT FROM AUTHOR]

BACKGROUND The complex molecular pathways governing implantation are unclear and ethical limitations limit studies in humans. Reversible histone acetylation regulates gene transcription and histone deacetylase inhibitors (HDACI) induce specific genes. Suberoylanilide hydroxamic acid (SAHA), a HDACI recently approved as an anti-cancer drug, induces the morphological and functional differentiation of human endometrial gland cells through up-regulation of glycodelin, a secretory phase dominant protein. METHODS We investigated whether SAHA improves implantation in an in vitro implantation assay using the human endometrial adenocarcinoma cell line, Ishikawa and the choriocarcinoma cell line, JAR. RESULTS In an in vitro implantation assay, JAR spheroids attached and adhered to Ishikawa cells in a time dependent manner. Glycodelin induction, following treatment with ovarian steroid hormones or SAHA, enhanced implantation. The improvement in implantation was also obtained when glycodelin was overexpressed without stimulation and was almost completely abrogated by glycodelin gene silencing. CONCLUSIONS This study demonstrates that glycodelin is a key regulatory protein of implantation and suggests that SAHA may have a capacity to supplant steroid derivatives in the treatment of infertility. [ABSTRACT FROM AUTHOR]

We monitored the Northern Goshawk Accipiter gentilis at six sites in Japan to determine trends in the number of breeding pairs. In addition, to identify changes in the reproductive performance of goshawks at a wide geographic scale, breeding data was collected from via web form from observers nationwide and were analyzed regionally. From 2001 to 2021, the number of breeding pairs of goshawks at the six monitoring sites decreased significantly by 2.8%/year. From 2016 to 2021, the proportion of previouslyknown nests that failed to breed had increased in the Kanto and Chubu regions. Also, a significant decreasing trend in the number of fledglings was observed at 47 nests under continuous survey. On September 21, 2017, the Northern Goshawk was removed from the list of "Nationally Endangered Species of Wild Fauna and Flora" under the Law for the Conservation Endangered Species of Wild Fauna and Flora. The present results do not point to a direct effect attributable to removal from the list. Our data, however, indicates reduced breeding performance and a decline in the number of active pairs, and we recommend continued monitoring of those parameters. [ABSTRACT FROM AUTHOR]

Orientation control of {100}-oriented epitaxial orthorhombic 0.07YO1.5-0.93HfO2 films grown by pulsed laser deposition was investigated. To achieve in-plane lattice matching, indium tin oxide (ITO) and yttria-stabilized zirconia (YSZ) were selected as underlying layers. We obtained (100)- and (001)/(010)-oriented films on ITO and YSZ, respectively. Ferroelastic domain formation was confirmed for both films by X-ray diffraction using the superlattice diffraction that appeared only for the orthorhombic symmetry. The formation of ferroelastic domains is believed to be induced by the tetragonal-orthorhombic phase transition upon cooling the films after deposition. The present results demonstrate that the orientation of HfO2-based ferroelectric films can be controlled in the same manner as that of ferroelectric films composed of conventional perovskite-type material such as Pb(Zr, Ti)O3 and BiFeO3. [ABSTRACT FROM AUTHOR]

Atomic-scale Mn distributions in ferromagnetic ZnSnAs2:Mn thin films grown on InP substrates have been studied by applying three-dimensional atom probe (3DAP) microscopy. It is found that Mn atoms in cross-sectional 3DAP maps show the presence of inhomogeneities in Mn distribution, which is characteristic patterns of a spinoidal decomposition phase with slightly high and low concentration regions. The high Mn concentration regions are expected to be coherently clustered MnAs in the zinc-blende structure, resulting in the formation of Mn-As random connecting patterns. The origin of room-temperature ferromagnetism in ZnSnAs2:Mn on InP can be well explained by the formation of atomic-scale magnetic clustering by spinoidal decomposition without breaking the continuity of the zinc-blende structure, which has been suggested by previous theoretical works. The lattice-matching between magnetic epi-layers and substrates should be one of the most important factors to avoid the formation of secondary hexagonal MnAs phase precipitates in preparing ferromagnetic semiconductor thin films. [ABSTRACT FROM AUTHOR]

There are several papers in literature that prove in a conclusive and incontestable way, that the left branch of the His bundle, in most instances (85% of the cases) splits into three fascicles of variable morphological pattern, and not into two: left anterior fascicle (LAF), left posterior fascicle (LPF), and left septal fascicle (LSF). The abovementioned papers have anatomical, histological, anatomo-pathological, electrocardiographic, and vectocardiographic, body surface potential mapping or ECG potential mapping and electrophysiological foundation. Additionally, the mentioned papers have been performed both in animal models (dogs) and in the human heart. Several clinical papers have shown that the left septal fascicular block (LSFB) may occur intermittently or transitorily as a consequence of a temporary dromotropic alteration, constituting an aberrant ventricular conduction, rate-dependent or by the application of atrial extra-stimuli, or naturally during the acute phase of infarction when this involves the anterior descending artery, before the septal perforating artery that supplies the central portion of the septum, where the mentioned LSF runs. The ECG/VCG manifestation of LSFB consists in anterior shift of electromotive forces, known as Prominent Anterior Forces (PAF), which can hardly be diagnosed in the clinical absence of other causes capable of causing PAF, such as the normal variant by counterclockwise rotation of the heart on its longitudinal axis, in right ventricular enlargement, in the dorsal or lateral infarction of the new nomenclature, in type-A WPW, in CRBBB, and others. In this historical manuscript, we review in a sequential fashion, the main findings that confirmed the unequivocal existence of this unjustifiably "forgotten" dromotropic disorder. In the developed countries, its most important cause is coronary insufficiency, particularly the proximal involvement of the left anterior descending coronary artery, and in Latin America, Chagas disease.

A eletrocardiografia ambulatorial é um método nao-invasivo utilizado na prática clínica para detectar, documentar e caracterizar ocorrências de comportamento anormal da atividade elétrica cardíaca durante as atividades diárias rotineiras. Como tais anormalidades ocorrem raramente, o eletrocardiograma deve ser registrado por longos períodos de tempo. Desde a introduçao, em 1961 por Norman Holter, os sistemas de eletrocardiografia ambulatorial tem sido desenvolvidos com uma ampla variedade de fidelidade de registro, peso e tamanho dos equipamentos, capacidades de análise e formatos de relatórios. Existem três tipos básicos de gravadores: gravadores contínuos, intermitentes (gravador de eventos) e gravadores de análise em tempo real. Gravadores contínuos possuem um gravador analógico para capturar o eletrocardiograma continuadamente e tipicamente registram na fita dois ou três canais do eletrocardiograma por 24 horas. Gravadores intermitentes registram somente um limitado número de curtos segmentos de dados; sua proposta é a de capturar o comportamento elétrico anormal quando o paciente apresenta o sintoma para o qual o estudo foi indicado. Os registros intermitentes podem ser transmitidos por telefone no momento da ocorrência do evento, ou os dados podem ser armazenados e transmitidos posteriormente. Os gravadores com análise em tempo real avaliam o eletrocardiograma continuamente. Os sinais eletrocardiográficos recebidos, ao invés de serem armazenados em uma fita analógica, sao digitalizados e armazenados em memória sólida. Utilizando-se do sistema Holter, podemos também investigar: arritmias, efeito terapêutico de drogas ou procedimentos, marcapassos e desfibriladores, doença cardíaca isquêmica e variabilidade da freqüência cardíaca. As indicaçoes gerais para a eletrocardiografia ambulatorial seguem as recomendaçoes da Força Tarefa ACP/ACC/AHA e sao discutidas neste artigo.

A eletrocardiografia ambulatorial é um método nao-invasivo, utilizado na prática clínica para detectar, documentar e caracterizar ocorrências de comportamento anormal da atividade elétrica cardíaca durante as atividades diárias rotineiras. Como tais anormalidades ocorrem raramente, o eletrocardiograma deve ser registrado por longos períodos de tempo. Desde a introduçao, em 1961, por Norman Holter, os sistemas de eletrocardiografia ambulatorial têm sido desenvolvidos com uma ampla variedade de fidelidade de registro, peso e tamanho dos equipamentos, de capacidade de análise e de formato de relatórios. Existem três tipos básicos de gravadores: contínuos, intermitentes (gravador de eventos) e gravadores de análise em tempo real. Os contínuos possuem um gravador analógico para capturar o eletrocardiograma continuadamente e tipicamente registram na fita dois ou três canais do eletrocardiograma por 24 horas. Os intermitentes registram somente um número limitado de curtos segmentos de dados; sua proposta é capturar o comportamento elétrico anormal quando o paciente apresenta o sintoma para o qual o estudo foi indicado. Os registros intermitentes podem ser transmitidos por telefone no momento da ocorrência do evento, ou os dados podem ser armazenados e transmitidos posteriormente. Os gravadores com análise em tempo real avaliam o eletrocardiograma continuamente. Os sinais eletrocardiográficos recebidos, ao invés de serem armazenados em uma fita analógica, sao digitalizados e armazenados em memória sólida. Utilizando o sistema Holter, podemos também investigar as arritmias, o efeito terapêutico de drogas ou procedimentos, marcapassos e desfibriladores, a doença cardíaca isquêmica e a variabilidade da freqüência cardíaca. As indicaçoes gerais para a eletrocardiografia ambulatorial seguem as recomendaçoes da Força Tarefa ACP/ACC/AHA e sao discutidas neste artigo.