Marco Marques

Institute of Mechanical Engineering and Industrial Mangement

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J. Belinha

Institute of Mechanical Engineering and Industrial Mangement

Renato Natal Jorge

Universidade do Porto

António Oliveira

Universidade Federal do Ceará

María Cristina Manzanares Céspedes

Trinity College Dublin

Marco Parente

Universidade do Porto

Márcio Madeira

Hospital de Santa Cruz

G A Gehring

University of Sheffield

Luís Ferro

Escuela Colombiana de Carreras Industriales

Pedro Quelhas

i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto

Sérgio Boshoff

Hospital de Santa Cruz

Cooperative Institutions

Universidade do Porto

Hospital de Santa Cruz

Institute of Mechanical Engineering and Industrial Mangement

Centro Hospitalar de Lisboa Ocidental

Hospital da Luz

University of Lisbon

National Institute of Statistics and Geography

Hospital Prof. Dr. Fernando Fonseca

Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial

Universidade Católica Portuguesa

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Cross-sectional characteristics of pediatric-onset discoid lupus erythematosus: Results of a multicenter, retrospective cohort study

Journal of the American Academy of Dermatology (2022)

Nnenna Ezeh Kaveh Ardalan Kevin A. Buhr Cordellia Nguyen Omnia Ahmed

Discoid lupus erythematosus

10.1016/j.jaad.2022.04.028

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Citations (4)

Phase transition of a two-dimensional binary spreading model

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics (2002)

Géza Ódor Marco Marques M. Santos

We investigated the phase transition behavior of a binary spreading process in two dimensions for different particle diffusion strengths (D). We found that N>2 cluster mean-field approximations must be considered to get consistent singular behavior. The N=3,4 approximations result in a continuous phase transition belonging to a single universality class along the D subset (0,1) phase transition line. Large scale simulations of the particle density confirmed mean-field scaling behavior with logarithmic corrections. This is interpreted as numerical evidence supporting the bosonic field theoretical prediction that the upper critical dimension in this model is d(c)=2. The pair density scales in a similar way but with an additional logarithmic factor to the order parameter. At the D=0 end point of the transition line we found directed percolation criticality.

Directed percolation

Critical dimension

10.1103/physreve.65.056113

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Citations (28)

Transthyretin amyloid cardiomyopathy: a 2-year single-centre experience

European Heart Journal (2022)

B Rocha R Amador S Maltes Marco Marques Cristina Lamas

Abstract Background Transthyretin Amyloid Cardiomyopathy (ATTR-CM) is an under-diagnosed condition often presenting with Heart Failure (HF). We aimed to assess a cohort of patients with ATTR-CM and HF, focusing on the centre strategies to identify new cases, prognosticate and tailor treatment. Methods We conducted an all-comers single-centre prospective registry of consecutive patients with HF due to ATTR-CM followed in our centre from November 2019 to 2021. As per site protocol, diagnosis is established according to the algorithm by Gilmore et al. and all patients are assessed in our HF outpatient clinic at least twice yearly with systematic electronic chart data collection. We evaluated disease-modifying treatment and compliance with the current European Guidelines and CHAD-STOP management. A summary of this program is presented in the central figure. Results Overall, 60 patients were included (mean age 83±7 years; 80% male). ATTR-CM was confirmed by the non-invasive algorithm in all but 8 patients, in whom endomyocardial biopsy was positive. Of those undergoing genetic testing (n=30), 7 (23%) presented with the hereditary form of ATTR-CM (4 Val50Met and 3 Val142Ile mutations). The initial presentation was most often HF (n=43), atrial fibrillation (n=9), or “incidental” myocardial uptake on 99mTc-HMDP bone scintigraphy (grade 2) performed for cancer staging (n=5). Beta-blockers were reduced or stopped in 40 (67%) patients, all of whom improved in NYHA class and/or NT-proBNP (>30% reduction) at 1–3 months. Tafamidis 61mg was started in 22 patients and 15 more currently await approval. Those initiated on or referred to tafamidis 61mg (n=37) had less severe HF, as per NYHA (class I-II – 94 vs. 50%, p=0.033) and performance status (e.g. Karnofsky score 80–100 – 79 vs. 21%, p=0.010). Of those already on tafamidis (n=22), NYHA class remained stable or improved in all but 1 patient. In the year following vs. preceding treatment there was 2 vs. 3 total HF hospitalizations. No drug-related severe adverse events were reported. Over a 2-year follow-up, 14 (23.3%) patients died, of whom 1 was on tafamidis (compassionate use for 19 months). Conclusions ATTR-CM recognition is improving in our dedicated rare disease program, possibly due to the implementation of several alert pathways. The identification of the disease at an earlier stage allows targeted treatment, compliant with the recommendations. Nonetheless, the rarity of this disease and the required expertise for its optimal management argues in favour of a national strategic plan based on referral centres for ATTR-CM. Funding Acknowledgement Type of funding sources: None.

Cardiac Amyloidosis

Bone scintigraphy

10.1093/eurheartj/ehac544.1775

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P1508A single center analysis of a 10-year period of lead removal

EP Europace (2020)

Rita Marinheiro José Pedro Neves Francisco Morgado Pedro Carmo Diogo Cavaco

Abstract BACKGROUND The number of lead removal of cardiac implantable electronic devices (CIED) has increased in recent years. The recent European registry (ELECTRa) did not include all European centers and not all lead extractions are possible to be performed transvenously. AIMS We aim to analyze all lead extraction procedures (transvenous or open surgery) performed in our center and the short- and long-term follow-up of these patients (pts). METHODS We retrospectively reviewed all lead extractions performed from 2008 to 2017. We analyzed pts´ characteristics (personal history, cardiovascular risk factors, indication for device implantation, laboratory tests); indications for extraction; techniques used and personnel that participate in the procedure, complications peri- and post-procedural and short and long-term follow-up. RESULTS A total of 189 pts (330 leads) were included (mean 69 ± 14 years, 73% male). The follow-up was 54 (IQR 20-87) months. Median time after implant was 47 (IQR 19-98) months. Lead explant was performed in 30 patients (16%) and lead extraction (at least one lead implanted >1 year or a lead requiring assistance of specialized equipment) in 159 (84%). Indications for removal are presented in figure A. In those who were infected, isolation of the microorganism was possible in 35% and Staphylococcus aureus was the most common agent (51%). 101 procedures (53%) occurred in the operating room, while 89 (47%) were performed in the electrophysiology laboratory, but 47% of those with the participation of a surgeon. On the total, cardiac surgeons were responsible for 75% of the procedures. Removal was tried in 330 leads (98 atrium lead, 199 right ventricle lead (79 defibrillator lead) and 33 coronary sinus lead). Of those, 298 were completely removed, 14 were partially removed (<4cm of a lead remained in the patient body) and 18 were not removed (radiologic failure). On an individual patient basis, clinical success was achieved in 185 patients (97%). Techniques used in the 330 leads were distributed in figure B. Surgical approach was necessary in 14 pts due to unsuccessful transvenous removal (n = 3), large vegetation in the lead (n = 4), concomitant valvular endocarditis (n = 2), other indication for open surgery (n = 4) and complicated transvenous removal (n = 1). Complications occurred in 6 patients: 3 persistent infections, 1 stroke, 2 vessel rupture. Related-procedural mortality was 1.5% (n = 3). The long-term survival of pts who performed open heart surgery was not different from those who underwent transvenous lead removal (logrank, p = 0.27) (figure C). CONCLUSION Although being a low volume center (19 procedures/year) and including pts with transvenous and open surgery, lead removal was associated with a high success rate with low all cause complication and mortality rates. Emergent surgery due to acute complications was very rare (0.5%) and open heart surgery was mostly programmed and not associated with a worse outcome. Abstract Figure.

Single Center

Lead (geology)

10.1093/europace/euaa162.041

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Generalized scaling for models with multiple absorbing states

Journal of Physics A Mathematical and General (1994)

J. F. F. Mendes Ronald Dickman Malte Henkel Marco Marques

At a continuous transition into a non-unique absorbing state, particle systems may exhibit non-universal critical behaviour, in apparent violation of hyperscaling. We propose a generalized scaling theory for dynamic critical behaviour at a transition to an absorbing state, which is capable of describing exponents which vary according to the initial configuration. The resulting hyperscaling relation is supported by simulations of two lattice models.

Lattice (music)

Scaling law

10.1088/0305-4470/27/9/017

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Citations (129)

Additive Manufacturing from a Biomedical Perspective

B. Athayde Malafaya Marco Marques Isaac Ferreira Margarida Machado G.A.R. Caldas

This work aims to present a global view of additive manufacturing, focused in biomedical area. With the evolution of technology, there has been an increasing demand for customized products, which has intensified the need for alternative manufacturing techniques. Additive manufacturing (AM) consists in the development of physical models through the deposition of layer-by-layer material from three-dimensional virtual models. About three decades ago, Fusion Deposition Modeling (FDM) technology was developed. FDM is an AM material extrusion technology, in which the material used is extruded by a nozzle. FDM has been growing, as well as the equipment and software involved, to broad applications in the field of biomedical engineering, such as the development of personalized and functional medical devices (including stents). This study presents the state of the art of 3D printing and additive manufacturing, as well as their techniques, obstacles and innovations. In addition, a stent was developed through a CAD software and it was manufactured through a 3D FDM printer using PLA.

10.1109/enbeng.2019.8692538

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Meshless analysis of 2D trabecular patches using a fabric tensor obtained from Micro-CT images

Marco Marques J. Belinha Renato Natal Jorge

A fabric tensor is a symmetric second order tensor that characterizes a multiphase material. A relationship between the fourth order elasticity tensor Cijki and the fabric tensor, A, was developed by Cowin, 1985 [1]. Later, the Mean Intercept Length tensor MIL, was developed by Whitehouse 1974 [2] and was used to estimate the fabric tensors. MIL is usually computed by defining a family of parallel lines to a specified direction v. The number of intersections, C(v), between lines and the interface between both phases is counted. MIL is a function of v, MIL (v), and computed as a reason between the sum of the length of traced lines, h, with the number of intersections, C(v). Researchers found that for many types of materials, particularly bone trabeculae, an ellipse could be fitted to the MIL data [3]. With this, in 2D MIL, tensor, A, can be computed as the 2 × 2 matrix that represents the estimated ellipse. In this work, the MIL technique is applied to obtain directly from the Micro-CT images the constitutive tensor of a trabecular patch.

Ellipse

Strain rate tensor

Elasticity

Structure tensor

10.1109/enbeng.2017.7889439

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Total knee arthroplasty coronal alignment and tibial base stress—a new numerical evaluation

Porto Biomedical Journal (2023)

João Vale Luísa Pinto Bianca Barros Sara Elisa Diniz Filipe Rodrigues

Total knee arthroplasty (TKA) is one of the most frequently performed orthopedic procedures. The correct positioning and alignment of the components significantly affects prosthesis survival. Considering the current controversy regarding the target of postoperative alignment of TKA, this study evaluated the tension at tibial component interface using two numerical methods.The stress of the prosthesis/bone interface of the proximal tibial component was evaluated using two numerical methods: the finite element method (FEM) and the new meshless method: natural neighbor radial point interpolation method (NNRPIM). The construction of the model was based on Zimmers NexGen LPS-Flex Mobile® prosthesis and simulated the forces by using a free-body diagram.Tibiofemoral mechanical axis (TFMA) for which a higher number of nodes are under optimal mechanical tension is between 1° valgus 2° varus. For values outside the interval, there are regions under the tibial plate at risk of bone absorption. At the extremities of the tibial plate of the prosthesis, both medial and lateral, independent of the alignment, are under a low stress. In all nodes evaluated for all TFMA, the values of the effective stresses were higher in the NNRPIM when compared with the FEM.Through this study, we can corroborate that the optimal postoperative alignment is within the values that are currently considered of 0 ± 3° varus. It was verified that the meshless methods obtain smoother and more conservative results, which may make them safer when transposed to the clinical practice.

Tension (geology)

Knee prosthesis

10.1097/j.pbj.0000000000000208

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TOTAL OSSICULAR REPLACEMENT PROSTHESIS OF THE MIDDLE EAR: A BIOMECHANICAL ANALYSIS

Journal of Mechanics in Medicine and Biology (2015)

Fernanda Gentil Marco Marques Marco Parente Pedro Martins Carla Santos

The main goal of the present study is to analyze and characterize the behavior of the middle ear, when a total ossicular replacement prosthesis (TORP) is used in the ossicular chain, in order to troubleshoot conductive hearing loss. Using a finite element model (FEM), a dynamic study of the middle ear was made. The displacement values were obtained at the umbo and stapes footplate, for a sound pressure level of 80 dB sound pressure level (SPL) applied at the tympanic membrane, when a cartilage in membrane-prosthesis interface of different diameters and thicknesses was used. The results were compared with the healthy middle ear model. The usage of this model aims to achieve a set of techniques that promotes the best possible performance of prosthesis in the middle ear. The present study allows to conclude that the rehabilitation of the middle ear with TORP can lead to the best results when used with 4 mm diameter cartilages, with a thin thickness of 0.3 mm.

Footplate

Conductive hearing loss

Incus

10.1142/s0219519415400060

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Citations (10)

Development of an image processing based algorithm to define trabecular bone mechanical properties using the fabric tensor concept

CRC Press eBooks (2019)

Marco Marques J. Belinha Renato Natal Jorge António Oliveira

Bone is as structure that is extensively studied. Many studies attempt to understand the mechanical behaviour of bone tissue. One key factor to fully understand and predict its structural response is the accurate determination of its mechanical properties. As the bone morphology changes (resulting from bone adaptation to external loads), bone tissue mechanical properties change as well. Therefore, its estimation is a never-ending challenging task. In this work, it was developed a methodology that allows, using medical images of micro-CT, to define the mechanical properties of trabecular bone, based on its morphological structure. This methodology uses the fabric tensor concept and a phenomenological material law to estimate the mechanical properties. The developed methodology as overall error of 2% upon the detection of trabecular bone material principal direction.

Structure tensor

10.1201/9780429265297-30

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