Resumen La fibrilación auricular es la arritmia más prevalente en la práctica clínica, y se asocia con una morbimortalidad significativa, la cual, en parte, se explica por el riesgo de fenómenos embólicos. En la actualidad, el uso de anticoagulantes es el estándar de manejo en aquellos pacientes con riesgo embólico significativo (dado por un puntaje ≥ 2 en la escala CHA2DS2Vasc). Sin embargo, algunos pacientes tienen contraindicaciones que impiden recibir este tipo de tratamiento a largo plazo, en cuyo caso se considera el cierre percutáneo de la orejuela como medida para la disminución del riesgo de embolia. Al requerir una punción transeptal, la presencia de dispositivos de cierre de defectos del septo interauricular dificulta el procedimiento de manera significativa. Se presenta el caso de una paciente con contraindicación absoluta para recibir anticoagulantes debido a sangrado gastrointestinal y antecedente de cierre percutáneo de comunicación interauricular sometida a cierre percutáneo de orejuela como alternativa terapéutica a la anticoagulación.

Abstract Atrial fibrillation is the most prevalent arrythmia in clinical practice, associated with a significant morbimortality explained, in part, by the high risk of embolic phenomena. The use of anticoagulation is the standard of care in those patients with increased embolic risk (given by a score ≥ 2 in the CHA2DS2Vasc scale). However, some patients have contraindications to receiving this treatment long-term, in which case percutaneous left atrial appendage occlusion can be considered as a means of decreasing their embolic risk. Because the procedure requires transeptal puncture, the presence of devices for atrial septal defect closure can difficult the technique. We present the case of a patient with absolute contraindication to anticoagulation therapy given gastrointestinal bleeding, with history of percutaneous closure of interauricular communication, who was treated with percutaneous left atrial appendage occlusion as an alternative to oral anticoagulants.

In this work, the capability to use pine rosin as a biodegradable coupling agent/compatibilizer is studied. To formulate composites, post-consumer polypropylene and discarded agave fibers (as reinforcing agent) are coupled with pine rosin (in pure or maleated form). Besides, poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate) (PBAT) are compatibilized with maleated pine rosins to prepare biodegradable blends. For the coupling agent role, the pure or maleated rosin (Amberyl M-15A) are compared with a commercial polyolefin coupling agent (Epolene E-43), while for the blends, two maleated rosins (Amberyls M-15A and MP-30) are used as compatibilizers. Dynamic and static mechanical tests show considerable increments in moduli and strength for both types of polymeric materials surpassing the role of the Epolene E-43 for the composite materials (v.g. 45.2 vs 16.5 increment in storage modulus, or 61.5 vs 40.3 for Young’s modulus in specific tests). Scanning electron microscopy photographs clearly show the interfacial interaction effect within composites and polymer blends. Fourier transform infrared spectroscopy allowed the observation of the aforementioned interactions at bond level. Blends biodegradation performed by composting for 3 months exceeded 76% of weight loss. The multirole of modified natural maleated gums as coupling agents/compatibilizers is demonstrated.

Castor oil was modified by transesterification with pentaerithritol. In a parallel step, starch was divided into monosaccharide units by glycosylation in order to obtain products with high hydroxyl content. The values of hydroxyl index were measured according to the content of pentaerithritol and starch used in the synthesis. Novel simultaneous interpenetrating polymer networks (SINs) of polyurethane (PU) and poly(methyl methacrylate) (PMMA) in different weight ratios of 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50 were prepared based on polyol-glucosides. The polyurethane network was created by reacting the poliol-glucosides with isophorone diisocyanate maintaining a molar ratio NCO/OH = 1. The PMMA network was synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate as the crosslinker. The SINs were characterized in their mechanical properties, such as Shore A hardness, tensile strength and elongation at break. Thermal stability of SINs was measured using thermogravimetric analysis (TGA). Surface morphology measured using scanning electron microscope (SEM) showed two-phase morphology for all the SINs. SINs based on polyurethane from castor oil modified and poly(methyl methacrylate) show limited compatibility at low concentrations of PMMA, but are totally incompatible at higher concentrations of PMMA.

El aceite de ricino se modificó por transesterificación con pentaeritritol. Paralelamente, se utilizó la reacción de glucosilación con glicerol para dividir el almidón en unidades monosacáridos. El glucósido obtenido reaccionó por transesterificación con el aceite modificado por transesterificación con pentaeritritol. Se determinó el índice de hidroxilo de los poliol-glucósidos en función del contenido de pentaeritritol y almidón utilizados en la síntesis. Se sintetizaron redes interpenetradas de polímero de manera simultánea (SINs) con diferentes relaciones en peso poliuretano/PMMA de 100/0, 90/10, 80/20, 70/30, 60/40 y 50/50. Para la síntesis de la red de poliuretano (PU) se utilizaron los poliol-glucósidos y diisocianato de isoforona (IPDI) o con una relación NCO/OH = 1 y para la síntesis de la red de polimetilmetacrilato (PMMA) se utilizó peróxido de benzoílo como agente iniciador y dimetacrilato de etilenglicol como agente entrecruzante. Los SINs se caracterizaron por sus propiedades fisicomecánicas como resistencia al ataque químico, dureza, resistencia a la tensión y elongación de ruptura. La estabilidad térmica de los SINs se determinó usando análisis termogravimétrico (TGA). La morfología de superficie se determinó usando microscopia electrónica de barrido (SEM) y mostró una morfología de dos fases para todos los SINs.

Chemical modification of cassava starch was conducted through an acylation reaction by using pyridine and propionic anhydride to replace the functional groups of starch. Polyurethane elastomers were prepared using suspensions of the mixture obtained from castor oil and yucca starch that was modified by a propionic anhydride reaction. The suspensions were characterized by means of tests based on The Fourier Transform Infrared Spectroscopy and the Hydroxyl Index. The castor oil-AMP suspensions were used for the PU synthesis. The PUs were characterized by their physical-mechanical properties like tension- deformation and Shore A. hardness, thermal gravimetric analysis and swelling test. The density cross-linking of from swelling tests was determined by applying the Flory-Rehner equation.

Two series of polyols were obtained from castor oil modified by transesterification with various amounts of pentaerythritol and glycerol. The resultant polyol properties were characterized as a function of the hydroxyl functionality. Polyurethane elastomers (PU) were synthesized from the two series of polyols obtained. The crosslink density of those polyurethanes was determined by swelling tests data adjusted to the Flory-Rehner's equation and according to the elasticity theory. The variation of the crosslink density of polyurethanes was studied by following the hydroxyl value of the modified polyol utilized in the synthesis and based on the average structure of each polyurethane repeating unit, as determined by the method of matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI TOF MS). The results show that the PU obtained through castor oil modified with pentaerythritol had a higher crosslink density than PU obtained from unmodified castor oil and from PU prepared by transesterification reaction of castor oil with glycerol. PU based on polyols with the higher hydroxyl functionality presented the higher crosslink density.

Se obtuvo una gama de polioles a partir del aceite de ricino modificado por transesterificación con pentaeritriol y glicerina. Los productos resultantes fueron caracterizados físico-químicamente. Se sintetizaron elastómeros de poliuretano a partir de los polioles derivados del aceite de ricino modificado. La densidad de entrecruzamiento se determinó por ensayos de hinchamiento a partir de la ecuación de Flory-Rehner apoyada en la espectroscopia MALDI TOF MS para determinar la estructura química de la unidad repetitiva promedio del poliuretano. Se estudió la variación de la densidad de entrecruzamiento de los poliuretanos con base en el índice de hidroxilo del poliol utilizado en la síntesis. Los resultados muestran que los PU obtenidos a través de la modificación del aceite con pentaeritriol tienen una mayor densidad de entrecruzamiento que los PU obtenidos a partir del aceite original y de los polioles derivados de la reacción de transesterificación del aceite con glicerina, debido a que estos polioles poseen una mayor funcionalidad hidroxílica.

Castor oil was reacted by transesterification with various percentages in mass of pentaerythritol to obtain different esters of pentaerythritol. Alternatively, glycerol was also used instead of pentaerythritol for the same reaction in order to establish comparative reference products. The products of the reactions were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy in order to detect and quantify (in terms of the molecular mass and structural information) the components of the products obtained. Analysis for hydroxyl value, acid value, viscosity and specific gravity were used to complete the characterization of the polyols obtained and also of the original castor oil. The polymer characterization was accomplished by tensile stress-strain tests, Shore A hardness, thermogravimetric analysis and chemical resistance to solvents.