Impact of VA-ECMO on Dynamic LV Outflow Obstruction After Transcatheter Aortic Valve Replacement.

Dynamic left ventricular outflow obstruction is a rare but severe complication of transcatheter aortic valve replacement. It presents as a paradoxical hemodynamic collapse after relieving the left ventricular afterload. Considering its unique pathophysiology, this entity dictates counterintuitive treatments. We describe a case of left ventricular outflow obstruction treated with venoarterial extracorporeal membrane oxygenation and discuss its management principles.

Acute Hemodynamic Compromise After Transcatheter Aortic Valve Replacement Due to Dynamic Left Ventricle Obstruction: A Systematic Review.

Acute hemodynamic compromise after transcatheter aortic valve replacement (TAVR) because of dynamic left ventricle (LV) obstruction (LVO), also known as suicide LV, is an infrequent but severe complication of TAVR that is poorly defined in previous studies. Understanding this complication is essential for its prompt diagnosis and optimal treatment. We conducted a systematic literature review using PubMed, Embase, Web of Science, and Medline databases for studies describing acute hemodynamic compromise after TAVR because of dynamic LVO or suicide LV. Each study was reviewed by 2 authors individually for eligibility, and a third author resolved disagreements. From a total of 506 studies, 25 publications were considered for the final analysis. The majority of patients with this condition were women demonstrating a hypertrophic septum, a small ventricle, and hyperdynamic contractility on pre-TAVR echocardiographic assessment. An intraventricular gradient before TAVR was found in half of the cases. Acute hemodynamic compromise after TAVR because of dynamic LVO manifested mainly as significant hypotension and occurred most often immediately after valve deployment. The LV outflow tract was the most common site of obstruction. Advanced therapies were required in nearly 65% of the cases. In conclusion, acute hemodynamic compromise after TAVR because of dynamic LVO occurred almost invariably in women. Echocardiography before TAVR may offer essential information to anticipate this complication. LV outflow tract obstruction appears to carry the highest risk of developing this phenomenon. Advanced therapies should be promptly considered as a bailout strategy in patients with hemodynamic collapse refractory to medical therapy.

Epidemiologic and Clinical Characteristics of Marantic Endocarditis: A Systematic Review and Meta-analysis of 416 Reports.

Nonbacterial thrombotic endocarditis (NBTE) is a distinctive condition marked by the presence of aseptic fibrin depositions on cardiac valves due to hypercoagulability and endocardial damage. There is a scarcity of large cohort studies clarifying factors associated with morbidity and mortality of this condition. A systematic literature review was performed utilizing the PubMed, Embase, Cochrane, and Web-of-Science databases to retrieve case reports and series documenting cases of NBTE from inception until September-2022. A descriptive analysis of basic characteristics was carried out, followed by multivariate regression analysis to identify risk factors associated with morbidity and mortality. A total of 416 case reports and series were identified, of which 450 patients were extracted. The female-to-male ratio was around 2:1 with an overall sample median age of 48 (interquartile range [IQR]:34-61). Stroke-like symptoms were the most common presentation and embolic phenomena occurred in 70% of cases, the majority of which were due to stroke. Cancer was associated with higher embolic complications (aOR:6.38, 95% CI = 3.75-10.83, p < 0.01) in comparison to other NBTE etiologies, while age, sex, and vegetation size were not (p > 0.05). All-cause in-hospital mortality was 36%, with cancer etiology being associated with higher mortality: 56% (aOR:3.64, 95% CI = 1.57-8.43, p < 0.01) in comparison to other NBTE etiologies:19%. A significant decrease in NBTE mortality was seen in recent years in comparison to admissions that occurred during the 20th century (aOR:0.07, 95% CI = 0.04-0.15, p < 0.01). While there has been an observed improvement in overall in-hospital mortality rates for patients admitted with NBTE in recent years, it is important to note that cases associated with a cancer etiology are still linked to high morbidity and mortality during hospitalization.

Synthesis and Application of ZSM-5 Catalyst Supported with Zinc and/or Nickel in the Conversion of Pyrolytic Gases from Recycled Polypropylene and Polystyrene Mixtures under Hydrogen Atmosphere.

Currently, catalytic pyrolysis has become a versatile and highly useful technology in the treatment of different plastic wastes. Thus, the development of selective catalysts to carry out cracking reactions and obtain a greater fraction of the desired products is essential. This study focuses on the synthesis of monometallic (Ni) and bimetallic (Ni-Zn) catalysts supported on ZSM-5 zeolite using an impregnation and co-impregnation method, respectively. The obtained catalysts were characterized by FTIR spectroscopy, N2 adsorption/desorption measurements, scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS), temperature programmed NH3 desorption (TPD-NH3) and thermogravimetric analysis (TGA). In this way, a mixture of polystyrene and polypropylene recycled with a catalyst/plastic waste ratio of 1:500 was used for pyrolysis tests. The best results were obtained using the Ni-Zn/ZSM-5 catalyst, which included better impregnation, increased surface acidity, decreased dispersion and a shorter reaction time in the catalytic pyrolysis process. Under the optimized conditions, catalytic pyrolysis showed an excellent performance to generate hydrocarbons of greater industrial interest.

Assessment of the Utilization of Validated Diagnostic Predictive Tools and D-Dimer in the Evaluation of Pulmonary Embolism: A Single-Center Retrospective Cohort Study from a Public Hospital in New York City.

INTRODUCTION: A significant increase in the use of computed tomography with pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism (PE) has been observed in the past twenty years. We aimed to investigate whether the validated diagnostic predictive tools and D-dimers were adequately utilized in a large public hospital in New York City. METHODS: We conducted a retrospective review of patients who underwent CTPA for the specific indication of ruling out PE over a period of one year. Two independent reviewers, blinded to each other and to the CTPA and D-dimer results, estimated the clinical probability (CP) of PE using Well's score, the YEARS algorithm, and the revised Geneva score. Patients were classified based on the presence or absence of PE in the CTPA. RESULTS: A total of 917 patients were included in the analysis (median age: 57 years, female: 59%). The clinical probability of PE was considered low by both independent reviewers in 563 (61.4%), 487 (55%), and 184 (20.1%) patients based on Well's score, the YEARS algorithm, and the revised Geneva score, respectively. D-dimer testing was conducted in less than half of the patients who were deemed to have low CP for PE by both independent reviewers. Using a D-dimer cut-off of <500 ng/mL or the age-adjusted cut-off in patients with a low CP of PE would have missed only a small number of mainly subsegmental PE. All three tools, when combined with D-dimer < 500 ng/mL or 95%. CONCLUSION: All three validated diagnostic predictive tools were found to have significant diagnostic value in ruling out PE when combined with a D-dimer cut-off of <500 ng/mL or the age-adjusted cut-off. Excessive use of CTPA was likely secondary to suboptimal use of diagnostic predictive tools.

Meta-Analysis and Clinical Features of Perioperative Takotsubo Cardiomyopathy in Noncardiac Surgery.

Perioperative takotsubo cardiomyopathy (pTCM) is an increasing condition defined as cardiomyopathy in the setting of emotional and physiologic stressors imposed by surgery. We aimed to classify and understand the presentation, management, and prognosis of noncardiac surgery pTCM in published cases. As such, a review of previous studies using the PubMed, Embase, Cochrane, and Web of Science databases was conducted to obtain case reports and series reporting noncardiac pTCM from inception to September 2022, and a crude analysis was conducted to classify the clinical features. Of the 1,002 studies, 96 met our inclusion criteria, of which 101 cases were extracted and included in the final systematic review. A total of 29.7% of cases occurred during general surgery and 20.8% during transplant procedures. The median age at presentation was 55 years, with a 42 to 65 interquartile range. The prevalence of hypertension and mood disorders were 22.8% and 9.9%, respectively. Before the procedures, physiologic stressors occurred more commonly than emotional stressors (20.8% and 11%, respectively). Objective findings, including ST-T-wave changes, new arrhythmias, and hypotension, were the most common initial presenting symptoms. Most cases occurred during emergence from surgery or on the first postoperative day. Mechanical circulatory support was required in 15.8% of the cases, and the all-cause in-hospital mortality was 6.9%. The ejection fraction and symptoms improved within a median of 2 weeks after diagnosis (interquartile range 1 to 6). In conclusion, the risk factors, triggers, and outcomes of pTCM appear to differ from those of classic nonperioperative TCM presentations. Future studies will help shed light on this more frequently diagnosed condition complicating some noncardiac surgical cases.

Kinetic Analysis of Thermal Degradation of Recycled Polypropylene and Polystyrene Mixtures Using Regenerated Catalyst from Fluidized Catalytic Cracking Process (FCC).

The pyrolysis process is a thermochemical recycling process that in recent years has gained importance due to its application in plastic waste, which is one of the biggest environmental problems today. Thus, it is essential to carry out kinetic and thermodynamic analyses to understand the thermocatalytic degradation processes involved in plastic waste mixtures. In this sense, the main objective of this study is to analyze the degradation kinetics of the specific mixture of polypropylene (25%) and polystyrene (75%) with 10% mass of regenerated FCC catalyst which was recovered from conventional refining processes using 3 heating rates at 5, 10 and 15 K min-1 by thermogravimetric analysis (TGA). The obtained TGA data were compared with the isoconversional models used in this work that include Friedman (FR), Kissinger Akahira Sunose (KAS), Flynn-Wall-Ozawa (FWO), Starink (ST) and Miura-Maki (MM) in order to determine the one that best fits the experimental data and to analyze the activation energy and the pre-exponential factor; the model is optimized by means of the difference of minimum squares. Activation energy values between 148 and 308 kJ/mol were obtained where the catalytic action has been notorious, decreasing the activation energy values with respect to thermal processes.

Multifunctional Portable System Based on Digital Images for In-Situ Detecting of Environmental and Food Samples.

The development of a portable device created by 3D printing for colorimetric and fluorometric measurements is an efficient tool for analytical applications in situ or in the laboratory presenting a wide field of applications in the environmental and food field. This device uses a light-emitting diode (LED) as radiation source and a webcam as a detector. Digital images obtained by the interaction between the radiation source and the sample were analyzed using a programming language developed in Matlab (Mathworks Inc., Natick, MA, USA), which builds the calibration curves in real-time using the RGB colour model. In addition, the entire system is connected to a notebook which serves as an LED and detector power supply without the need for any additional power source. The proposed device was used for the determination in situ of norfloxacin, allura red, and quinine in water and beverages samples, respectively. For the validation of the developed system, the results obtained were compared with a conventional spectrophotometer and spectrofluorometer respectively with a t-test at a 95% confidence level, which provides satisfactory precision and accuracy values.

Production and Analysis of the Physicochemical Properties of the Pyrolytic Oil Obtained from Pyrolysis of Different Thermoplastics and Plastic Mixtures.

The constant search for the proper management of non-degradable waste in conjunction with the circular economy makes the thermal pyrolysis of plastics an important technique for obtaining products with industrial interest. The present study aims to produce pyrolytic oil from thermoplastics and their different mixtures in order to determine the best performance between these and different mixtures, as well as to characterize the liquid fraction obtained to analyze its use based on said properties. This was carried out in a batch type reactor at a temperature of 400 °C for both individual plastics and their mixtures, from which the yields of the different fractions are obtained. The liquid fraction of interest is characterized by gas chromatography and its properties are characterized by ASTM standards. The product of the pyrolysis of mixtures of 75% polystyrene and 25% polypropylene presents a yield of 82%, being the highest, with a viscosity of 1.12 cSt and a calorific power of 42.5 MJ/kg, which has a composition of compounds of carbon chains ranging between C6 and C20, for which it is proposed as a good additive agent to conventional fuels for industrial use.

Determination of the Thermodynamic Parameters of the Pyrolysis Process of Post-Consumption Thermoplastics by Non-Isothermal Thermogravimetric Analysis.

Currently, the pyrolysis process is an important technology for the final treatment of plastic waste worldwide. For this reason, knowing in detail the chemical process and the thermodynamics that accompany cracking reactions is of utmost importance. The present study aims to determine the thermodynamic parameters of the degradation process of conventional thermoplastics (polystyrene (PS), polyethylene terephthalate (PET), high-density polyethylene (HDPE), polypropylene (PP) and polyvinyl chloride (PVC)) from the study of their chemical kinetics by thermogravimetric analysis (TG). Non-isothermal thermogravimetry was performed at three heating rates from room temperature to 550 °C with an inert nitrogen atmosphere with a flow of 20 mL min-1. Once the TG data is obtained, an analysis is carried out with the isoconversional models of Friedman (FR), Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO) in order to determine the one that best fits the experimental data, and with this, the calculation of the activation energy and the pre-exponential factor is performed. The validation of the model was carried out using the correlation factor, determining that the KAS model is the one that best adjusts for the post-consumer thermoplastic degradation process at the three heating rates. With the use of the kinetic parameters, the variation of the Gibbs free energy is determined in each of the cases, where it is necessary that for structures containing aromatic groups a lower energy is presented, which implies a relative ease of degradation compared to the linear structures.

Design of an automatic spectrophotometric system.

A Multi-Syringe Flow Injection Analysis (MSFIA) fluorometric system based on a 3D printing device hosting a CCD detector has been designed for the determination of quinine in soft drinks. A LED controlled by an electronic circuit was used as a radiation source. The entire system is connected to two USB outputs of a computer. The AutoAnalysis program has been used for data acquisition and treatment. The results are more accurate and precise than those obtained with a manual method using a conventional spectrofluorometer. This developed system is a viable alternative to reduce the consumption of reagents, the impact on the environment and reduce measurement costs.