Relevance of subclinical right ventricular dysfunction measured by feature-tracking cardiac magnetic resonance in non-ischemic dilated cardiomyopathy.

BACKGROUND: Right ventricular (RV) dysfunction in patients with non-ischemic dilated cardiomyopathy (NICM) is associated with cardiovascular events. To analyze the feasibility of assessing RV myocardial deformation by feature tracking (FT)-cardiac magnetic resonance (CMR), and its usefulness as a prognostic marker. METHODS: Retrospective study of NICM patients undergoing CMR. Longitudinal FT-RV free wall (LFT-RVFW) and fractional area change (FAC) were obtained. Correlation with standard RV parameters was studied. An association with combined event (heart failure (HF), ICD implantation or cardiovascular death) was assessed using a logistic regression model. RESULTS: 98 patients (64 ± 13 years) were included. Left ventricular (LV) systolic function (LVEF 29.5 ± 9.6%, 47% with LVEF ≥ 30%) and RV (RVEF 52.2 ± 14.6%, 72% with RVEF ≥ 45%). Follow-up of 38 ± 17 months, 26.5% presented at least one admission for HF. An excellent correlation of LFT-RVFW (r = 0.82) and FAC (r = 0.83) with RVEF was evident. No association of RV-FT parameters with prognosis entire study population was found. However, in patients with LVEF ≥ 30%, admissions for HF were associated with lower LFT-RVFW (-21.6 ± 6.6% vs -31.3 ± 10%; p = 0.006) and FAC (36.6 ± 9.6% vs 50.5 ± 13.4%; p < 0.001) values. Similar differences were observed when only patients with RVEF ≥ 45% were considered. An LFT-RVFW cut-off point of -19.5% and FAC of 36.5% showed good prognostic performance. Decreased LFT-RVFW or FAC represented an independent predictor of combined event in patients with LVEF ≥ 30%. CONCLUSIONS: In NICM patients without severe LV dysfunction, decreased values of LFT-RVFW and/or FAC were associated with HF admissions, independently of RVEF.

Poly(vinylidene) fluoride membranes coated by heparin/collagen layer-by-layer, smart biomimetic approaches for mesenchymal stem cell culture.

The use of piezoelectric materials in tissue engineering has grown considerably since inherent bone piezoelectricity was discovered. Combinations of piezoelectric polymers with magnetostrictive nanoparticles (MNP) can be used to magnetoelectrically stimulate cells by applying an external magnetic field which deforms the magnetostrictive nanoparticles in the polymer matrix, deforming the polymer itself, which varies the surface charge due to the piezoelectric effect. Poly(vinylidene) fluoride (PVDF) is the piezoelectric polymer with the largest piezoelectric coefficients, being a perfect candidate for osteogenic differentiation. As a first approach, in this paper, we propose PVDF membranes containing magnetostrictive nanoparticles and a biomimetic heparin/collagen layer-by-layer (LbL) coating for mesenchymal stem cell culture. PVDF membranes 20% (w/v) with and without cobalt ferrite oxide (PVDF-CFO) 10% (w/w) were produced by non-solvent induced phase separation (NIPS). These membranes were found to be asymmetric, with a smooth surface, crystallinity ranging from 65% to 61%, and an electroactive ß-phase content of 51.8% and 55.6% for PVDF and PVDF-CFO, respectively. Amine groups were grafted onto the membrane surface by an alkali treatment, confirmed by ninhydrin test and X-ray photoelectron spectroscopy (XPS), providing positive charges for the assembly of heparin/collagen layers by the LbL technique. Five layers of each polyelectrolyte were deposited, ending with collagen. Human mesenchymal stem cells (hMSC) were used to test cell response in a short-term culture (1, 3 and 7 days). Nucleus cell counting showed that LbL favored cell proliferation in PVDF-CFO over non-coated membranes.

Vibrational Modes and Phonon and Thermodynamic Properties of the Metaboric Acid Polymorphs α-, ß-, and γ-(BOH)3O3 within a Density Functional Theory Framework.

A combined study of vibrational and thermodynamic properties of metaboric acid (BOH)3O3 crystal polymorphs α, ß, and γ were obtained through density functional theory (DFT) calculations in an attempt to resolve the conflicting assignments that currently exist in the literature for them. A complete correlation between the normal-mode assignment and vibrational signatures to distinguish particular features of each metaboric acid polymorph, in particular, those related to motions of the planar layers in α-(BOH)3O3, with a level of detail surpassing essays based on previous published experimental works has been achieved. Besides, no DFT-based research work was published early on the (BOH)3O3 polymorph vibrational properties, and our DFT-simulated infrared and Raman spectra for all metaboric acid polymorphs agree very well with experiment. Comparison of the previously published experimental IR and Raman spectroscopic results with predictions from higher levels DFT calculations allows identification of the in-plane and out-of-plane B-O bending modes. For example, the strongest measured (DFT-calculated) Raman modes of α-(BOH)3O3 at 591 and 797 cm-1 (599 and 810 cm-1) are identified as vibrational signatures of breathing B3O3/Ag in-plane modes, while the shoulder in the lattice modes region at 135 (143) cm-1 is the vibrational signature of the bending B3O3/B1g out-of-plane mode. Phonon-dispersion bands and their respective phonon densities of states were also evaluated for each system, as well as temperature-dependent curves for entropy, enthalpy, free energy, heat capacity, and Debye temperature. Phonon dispersion curves are singular for each (BOH)3O3 species, and a consistent gap decrease between the lowest and highest frequency vibrational bands was observed. The DFT-based calculations also revealed that the noncovalent interactions prevalent in the α and ß crystals lead to significant differences with respect to the thermodynamic properties in comparison with the γ phase.

Electro-responsive polyelectrolyte-coated surfaces.

The anchoring of polymer chains at solid surfaces is an efficient way to modify interfacial properties like the stability and rheology of colloidal dispersions, lubrication and biocompatibility. Polyelectrolytes are good candidates for the building of smart materials, as the polyion chain conformation can often be tuned by manipulation of different physico-chemical variables. However, achieving efficient and reversible control of this process represents an important technological challenge. In this regard, the application of an external electrical stimulus on polyelectrolytes seems to be a convenient control strategy, for several reasons. First, it is relatively easy to apply an electric field to the material with adequate spatiotemporal control. In addition, in contrast to chemically induced changes, the molecular response to a changing electric field occurs relatively quickly. If the system is properly designed, this response can then be used to control the magnitude of surface properties. In this work we discuss the effect of an external electric field on the adhesion and lubrication properties of several polyelectrolyte-coated surfaces. The influence of the applied field is investigated at different pH and salt conditions, as the polyelectrolyte conformation is sensitive to these variables. We show that it is possible to fine tune friction and adhesion using relatively low applied fields.

Honeycomb Films with Core-Shell Dispersed Phases Prepared by the Combination of Breath Figures and Phase Separation Process of Ternary Blends.

Herein, we propose a strategy to fabricate core-shell microstructures ordered in hexagonal arrays by combining the breath figures approach and phase separation of immiscible ternary blends. This simple strategy to fabricate these structures involves only the solvent casting of a ternary polymer blend under moist atmosphere, which provides a facile and low-cost fabrication method to obtain the porous structures with a core-shell morphology. For this purpose, blends consisting of polystyrene (PS) as a major component and PS40-b-P(PEGMA300)48 amphiphilic copolymer and polydimethylsiloxane (PDMS) as minor components were dissolved in tetrahydrofuran and cast onto glass wafers under humid conditions, 70% of relative humidity. The resulting porous morphologies were characterized by optical and confocal Raman microscopy. In particular, confocal Raman results demonstrated the formation of core-shell morphologies into the ordered pores, in which the PS forms the continuous matrix, whereas the other two phases are located into the cavities (PDMS is the core while the amphiphilic copolymer is the shell). Besides, by controlling the weight ratio of the polymer blends, the structural parameters of the porous structure such as pore diameter and the size of the core can be effectively tuned.

Immobilization of Stimuli-Responsive Nanogels onto Honeycomb Porous Surfaces and Controlled Release of Proteins.

In this article, we describe the formation of functional honeycomb-like porous surfaces fabricated by the breath figures technique using blends of either amino-terminated poly(styrene) or a poly(styrene)-b-poly(acrylic acid) block copolymer with homopoly(styrene). Thus, the porous interfaces exhibited either amino or acid groups selectively located inside of the holes, which were subsequently employed to anchor stimuli-responsive nanogels by electrostatic interactions. These nanogels were prepared from poly(N-isopropylacrylamide) (PNIPAM) cross-linked with dendritic polyglycerol (dPG) and semi-interpenetrated with either 2-(dimethylamino)ethyl methacrylate (DMAEMA) or 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) to produce positively and negatively charged nanogel surfaces, respectively. The immobilization of these semi-interpenetrated networks onto the surfaces allowed us to have unique stimuli-responsive surfaces with both controlled topography and composition. More interestingly, the surfaces exhibited stimuli-responsive behavior by variations on the pH or temperature. Finally, the surfaces were evaluated regarding their capacity to induce a thermally triggered protein release at temperatures above the cloud point temperature (T(cp)) of the nanogels.

Enzymatic Catalysis Combining the Breath Figures and Layer-by-Layer Techniques: Toward the Design of Microreactors.

Herein, we report the fabrication of microstructured porous surfaces with controlled enzymatic activity by combining the breath figures and the layer-by-layer techniques. Two different types of porous surfaces were designed based on fluorinated and carboxylated copolymers in combination with PS, using poly(2,3,4,5,6-pentafluorostyrene)-b-polystyrene (PS5F31-b-PS21) and polystyrene-b-poly(acrylic acid) (PS19-b-PAA10) block copolymers, respectively. For comparative purposes, flat surfaces having similar chemistry were obtained by spin-coating. Poly(sodium 4-styrenesulfonate)/poly(allylamine hydrochloride) (PSS/PAH) multilayers incorporating alkaline phosphatase (ALP) were built on these porous surfaces to localize the enzyme both inside and outside of the pores using PS/PS5F31-b-PS21 surfaces and only inside the pores on PS/PS19-b-PAA10 surfaces. A higher catalytic activity of ALP (about three times) was obtained with porous surfaces compared to the flat ones. The catalysis happens specifically inside the holes of PS/PS19-b-PAA10surfaces, where ALP is located. This opens the route for applications in microreactors.

Dendritic amphiphiles as additives for honeycomb-like patterned surfaces by breath figures: role of the molecular characteristics on the pore morphology.

The current study presents a library of honeycomb-like patterned surfaces developed from a variety of different water-soluble amphiphilic dendrons. When compared to commercial surfactants, the dendrons produce a wide variety of porous surfaces due to their well-defined branched structure. Different functionalities and generations of dendrons have been studied. A singular hierarchical distribution of the dendrons, forming small nanoparticles (micelles) only at the inner edges of the holes (coffee stain effect) is observed. Once the surfaces are fabricated, these dendrons can be easily recovered via simple aqueous washing. After this treatment, the surfaces exhibit a high hydrophobic character (up to 140°) due to the high porosity. This behavior can be described by the Cassie-Baxter model.

Comparative analysis of the outflow water quality of two sustainable linear drainage systems.

Three different drainage systems were built in a roadside car park located on the outskirts of Oviedo (Spain): two sustainable urban drainage systems (SUDS), a swale and a filter drain; and one conventional drainage system, a concrete ditch, which is representative of the most frequently used roadside drainage system in Spain. The concentrations of pollutants were analyzed in the outflow of all three systems in order to compare their capacity to improve water quality. Physicochemical water quality parameters such as dissolved oxygen, total suspended solids, pH, electrical conductivity, turbidity and total petroleum hydrocarbons were monitored and analyzed for 25 months. Results are presented in detail showing significantly smaller amounts of outflow pollutants in SUDS than in conventional drainage systems, especially in the filter drain which provided the best performance.

1-Methyl-2-pyrrolidone: from exfoliating solvent to a paramagnetic ligand.

When 1-methyl-2-pyrrolidone molecule (1m2p) interacts with the T[Ni(CN)4] layer, its carbonyl π bond homolytically disrupts and forms a coordination bond at the axial positions for the metal T, and hybrid inorganic-organic solids of formula unit T(L)2[Ni(CN)4], with T = Mn, Co, Ni, are obtained. The formed solids crystallize with a monoclinic unit cell in the C2/m space group where the metal T is found with octahedral coordination to four N ends of CN groups from a given layer and to two oxygen atoms from the organic ligands, while the inner metal (Ni) preserves its square planar coordination. In the interlayer region, the organic molecules achieve unusual planarity and are stacked through dipole-dipole interactions in a head-to-tail configuration to form a chain of molecular pillars. From such interactions, 3D pillared hybrid solids result. Upon the charge donation to the metal by oxygen atom from 1m2p, the latter becomes an organic radical whose SOMO frontier orbital has a strong π character, associated with an essentially planar structure. The unpaired electron is delocalized between neighboring C and N atoms at the ligand ring plane, and it is featured by an outstanding broad absorption band in the near-IR region. For Ni, the metal of highest polarizing power within the considered series, the existence of π overlapping interaction between organic ligand molecules leads to ferromagnetic ordering at low temperature, with TC = 10.07 K. For Mn and Co, related to the lower metal electron-withdrawing ability, the materials maintain the weak antiferromagnetic character resulting from the interaction between T metals in the layer -T-N≡C-Ni-C≡N-T- chains.

Trastornos del sueño en el paciente con dolor crónico / No disponible

Padecer dolor crónico supone un importante impacto sobre la calidad del sueño del paciente que lo sufre. Una mayor intensidad de dolor se ha asociado a una mayor prevalencia de trastornos del sueño, siendo esta relación recíproca y que perpetúa un círculo vicioso entre ambos. Teniendo en cuenta que algunos de los fármacos que manejamos habitualmente para el control analgésico, fundamentalmente opioides, pueden modificar la arquitectura del sueño, tanto positiva como negativamente, consideramos importante empezar a valorar la calidad del sueño del paciente con dolor crónico como un indicador de calidad en el manejo del tratamiento analgésico(AU)

Having chronic pain is a significant impact on sleep quality of the patient who suffers. Higher pain intensity was associated with a higher prevalence of sleep disorders, this being a mutual and perpetuating a vicious circle between them. Given that some of the drugs commonly used to manage pain control, mainly opioids, may alter the sleep architecture, both positively and negatively, we consider important to begin to assess this quality of sleep of patients with chronic pain as an indicator of quality management of analgesic treatment(AU)

Fabrication and superhydrophobic behavior of fluorinated microspheres.

We describe the preparation of fluorinated microspheres by precipitation polymerization and their use to fabricate superhydrophobic surfaces. For that purpose, two different approaches have been employed. In the first approach, a fluorinated monomer (either 4-fluorostyrene or 2,3,4,5,6-pentafluorostyrene) was added to the initial mixture of monomers constituted by styrene (S) and divinylbenzene (DVB). The second approach is based on the encapsulation of a block copolymer, polystyrene-b-poly(2,3,4,5,6-pentafluorostyrene), during the polymerization of the monomers (S and DVB), thus enabling the formation of particles with perfluorinated chains instead of single functional groups at the interface. Both approaches led to narrow polydisperse particles with fluoro-functional groups at the interface as demonstrated by scanning electron microscopy (SEM), infrared (IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Surface array of particles obtained by simple solvent casting presented superhydrophobic behavior with contact angles of water droplets of ca. 160-165°.

Laboratory analysis of a system for catchment, pre-treatment and treatment (SCPT) of runoff from impervious pavements.

This article reports the development and construction of a 1:1 scale laboratory prototype of a System for Catchment, Pre-treatment and Treatment (SCPT) of runoff polluted by contaminants washed from impervious pavements. The concept of the SCPT is an online system with an up-flow filter. The filter is composed of geotextile layers and limestone. The laboratory tests carried out were focused on determining the SCPT prototype behaviour under different working conditions. The variables studied were: inflow, pollutant loads and filtration system configuration. The results show that the system designed has a high capacity for treatment of solids and oil, with an average efficiency of 85% and 97% respectively. Moreover, the regression equations of the treatment efficiency were determined for each of the pollutants studied, for different inflow conditions and pollution loads.

Design of polypeptide-functionalized polystyrene microspheres.

In this contribution, the principle of spontaneous surface segregation has been applied for the preparation of polypeptide-functionalized polystyrene microspheres. For that purpose, an amphiphilic diblock copolymer was introduced in the mixture styrene/divinylbenzene and polymerized using AIBN as initiator. During the polymerization, cross-linked particles were obtained in which the diblock copolymer was encapsulated. The amphiphilic diblock copolymers used throughout this study contain a hydrophilic polypeptide segment, either poly(L-lysine) or poly(L-glutamic acid) and a hydrophobic polystyrene block. After 4 h of polymerization, rather monodisperse particles with sizes of approximately 3-4 microm were obtained. Upon annealing in hot water, the hydrophilic polypeptides migrate to the interface, hence, either positively charged or neutral particles were obtained when poly(L-lysine) is revealed at the surface and exposed to acidic or basic pH, respectively. On the opposite, negatively charged particles were achieved in basic pH water by using poly(L-glutamic acid) as additive. The surface chemical composition was modified by changing the environment of the particles. Thus, exposure in toluene provoked a surface rearrangement, and due to its affinity, the polystyrene block reorients toward the interface.

The kinetics of the structural relaxation process in PHEMA-silica nanocomposites based on an equation for the configurational entropy.

The enthalpy relaxation of polymer-silica nanocomposites prepared by simultaneous polymerization of poly(2-hydroxyethyl methacrylate) (PHEMA) and tetraethyloxysilane, TEOS, a silica precursor, is investigated. Both the glass transition temperature, Tg, and the temperature interval of the glass transition, DeltaTg , increase as the silica content in the sample does. Structural relaxation experiments show that the temperature interval in which conformational motions take place broadens as the silica content in the hybrid increases. A phenomenological model based on the evolution of the configurational entropy during the structural relaxation process, the SC model, has been used for determining the temperature dependence of the relaxation times during the process. The results show an increase of the fragility of the polymer as the silica content increases, a feature that can be related to the broadening of the distribution of relaxation times characterized by the beta parameter of the stretched exponential distribution. On another hand the silica content increase produces a significant change of the relaxation times in the glassy state.

Boundary lubricant films under shear: effect of roughness and adhesion.

The normal interaction and the behavior under shear of mica surfaces covered by two different triblock copolymers of polylysine-polydimethysiloxane-polylysine were studied by combining the capabilities of the surface forces apparatus and the atomic force microscopy. At low pH values these copolymers spontaneously adsorb on the negatively charged mica surfaces from aqueous solutions as a consequence of the positive charge of the polylysine moieties. The morphology of the adsorbed layer is determined by the molecular structure of the particular copolymer investigated. This morphology plays a fundamental role on the behavior of the adsorbed layers under shear and compression. While nonadhesive smooth layers oppose an extremely small resistance to sliding, the presence of asperities even at the nanometric scale originates a frictional resistance to the motion. The behavior of uniform nonadhesive nanorough surfaces under shear can be quantitatively understood in terms of a simple multistable thermally activated junction model. The electric charge of the adsorbed copolymer molecules and hence the adhesion energy between the coated surfaces can be modified by varying the pH of the surrounding media. In the presence of an adhesive interaction between the surfaces the behavior under shear is strongly modified. Time-dependent mechanisms of energy dissipation have to be evoked in order to explain the changes observed.

Photo-induced charge transfer in Prussian blue analogues as detected by photoacoustic spectroscopy.

The photo-induced charge transfer in four series of Prussian blue (PB) analogues was studied from photoacoustic spectra. In cobalticyanides the observed signals were assigned to a metal-to-ligand charge transfer, which appears as a shoulder below 450 nm, and to d-d transitions for Co(II), Ni(II) and Cu(II) complex salts. No evidence of metal-to-metal charge transfer was observed for this series, which is probably due to the high stability of low spin cobalt(III) in the hexacyanide complex. Photoacoustic spectra for ferricyanides are broad bands, which result particularly intense up to 750 nm. Such features were attributed to the overlapping of contributions from metal-to-ligand (<600 nm) and metal-to-metal charge transfer transitions, with probably also a minor contribution from d-d transitions in the outer metal. The spectra for the ferrocyanides series are dominated by the metal-to-ligand charge transfer band below 550 nm, approximately 100 nm above this transition in cobalticyanides. Within the studied solids, the most intense and broad metal-to-metal charge transfer bands were found for a series of low spin Co(III) high spin Co(II) hexacyanoferrates(II,III) and with similar features also for ferric ferrocyanide (Prussian blue), assigned to Fe(II)-->Co(III) and Fe(II)-->Fe(III) photo-induced transition, respectively. The first of these transitions requires of more energetic photons to be observed, its maximum falls at 580 nm while for Prussian blue it is found at 670 nm. Prussian blue analogues are usually obtained as nanometric size particles and many of them have a microporous structure. The role of surface atoms on the observed charge transfer bands in the studied series of compounds is also discussed.

pH-responsive micelles and vesicles nanocapsules based on polypeptide diblock copolymers.

The self-assembly of well-defined polypeptide-based diblock copolymers into micelles and vesicles is presented. The stimuli-responsive behavior of polypeptides to pH and ionic strength is used to produce stimuli-responsive nanoparticles with controlled size and shape. Results focusing on micelles and vesicles obtained from polypeptide-based diblock copolymers that are particularly promising for biomedical applications are detailed by means of static and dynamic light scattering analysis, UV circular dichroism, NMR and small angle neutron scattering experiments. Also systems able to form vesicles with a narrow size distribution at basic and acid pH going through a single molecule intermediate state are presented. These nanoparticles are particularly interesting for encapsulation and delivery purpose at a controlled pH.

Seguridad de la resonancia mágnetica en pacientes con neuroestimuladores medulares: nuestra experiencia / Safety of magnetic resonance in patients with implanted spinal cord neurostimulators: our experience

Introducción: En la ultima década la resonancia magnética (RM) ha sido introducida como una herramienta rutinaria de diagnóstico clínico por imagen, siendo considerada como una prueba no invasiva y segura. Sin embargo se ha contraindicado su utilización en pacientes que poseen dispositivos electrónicos implantados, entre ellos neurostimuladores medulares y corticales. A diferencia del avance de la tecnología en neuroesti-mulación y su aplicación clínica, hay pocos estudios que avalen la seguridad de la RM en pacientes con neuroestimuladores implantados. Nuestra hipótesis es que la RM es un método diagnóstico seguro en los pacientes con neuroestimuladores implantados. Nuestro trabajo tiene como finalidad aportar más pruebas objetivas acerca de esta cuestión. Material y Métodos: Serie de 8 pacientes con neuroestimuladores implantados (ITRELL III modelo 7425, Medtronic) sometidos a 9 estudios de RM (1,5 T General Electric Sigma Excite) durante el 2005, siguiendo el protocolo de Liem van Dongen en los que se vigiló la aparición de efectos adversos relacionados, durante e inmediatamente después del estudio de imagen. Resultados: Durante los estudios de RM no se produjeron incidencias, ni efectos adversos, en ninguno de los casos, tanto en los que el estudio se realizó en zonas alejadas del implante del neuroestimulador, como en los que se realizó en la misma zona anatómica. Una vez concluido el estudio de RM no se objetivó ninguna referencia de los pacientes a sensaciones relacionadas con el calentamiento o interacción electromagnética de la RM con su neuroestimulador. Tampoco se produjo ningún fallo en la reprogramación de los neuroestimuladores, excepto en un caso en el que fue imposible reprogramar el neuroestimulador una vez concluido el estudio de RM. Conclusiones: Todo parece indicar que en la mayoría de los casos la RM puede ser aplicada de forma segura en pacientes con sistemas de neruroestimulación implantados, siguiendo el protocolo de Liem-van Dongen, pero al parecer existen determinadas circunstancias en las que no queda totalmente claro la fiabilidad de esta recomendación. En el caso de la paciente en la que no fue posible reprogramar su neuroestimulador después de la RM en nuestro estudio, pudiera haber ocurrido un fallo de batería, o bien un daño en el circuito electrónico del generador. El no haber podido examinar el generador con problemas, no nos permite establecer una sospecha fundada sobre el conjunto de hechos que pueden haber concurrido en la producción del fallo. En cualquier caso se impone la realización de más estudios para esclarecer de forma más fiable las condiciones seguras de realización de la RM en pacientes con neuroestimuladores implantados (AU)

Aims: Over the past decade, nuclear magnetic resonance imaging (MRI) has been introduced as a safe, non-invasive routine clinical diagnostic tool. However, its use has been contraindicated in patients with implanted electronic devices, such as motor cortex and spinal cord neurostimulators. Despite the rapid growth in neurostimulation technology and its clinical application, there have been few studies addressing the safety of performing MRI procedures in patients with implanted neurostimulators. Our hypothesis is that MRI is a safe diagnostic technique in patients with implanted neurostimulators. The aim of our study is to offer some objective proof towards this point. Methods: Eight patients with implanted neurostimulators (ITRELL III Model 7425, Medtronic) undergoing 9 MRI procedures (1,5 T General Electric Sigma Excite) in 2005 are presented, following the Liem van Dongen´s protocol, with a focus in the appearance of adverse effects, during and immediately after the imaging study. Results: During the MRI studies there were no overall adverse effects detected in any case, in those in which the scanning was performed on a location away from the site of the implanted neurostimulators, nor in those in which it was performed in the same anatomic region. Once the MRI study concluded, no patient reported any sensation of discomfort attributable to heating or the electromagnetic interaction of the MRI with the neurostimulators. Neither there was any failure in the neurostimulators rescheduling, except in one case in which it was impossible its reprogrammation once the study was completed. Conclusions: In general, all these investigations indicate that in most cases MRI can be performed safely in patients with implanted stimulators, following the Liem van Dongen´s protocol, but it seems that under some circumstances this recommendation is not completely reliable. In the case of our patient in which the neurostimulator was impossible to reschedule after the MRI, this may have been caused by a battery failure, or there could have been a breakup in the generator’s electronic circuit. As the generator could not be examined, a hypothesis about the train of events leading to its failure was not established. In any case more studies are desirable to reliably explain the safety conditions required for the performance of MRI in patients with implanted neurostimulators (AU)