Tommaso Stomaci, Francesco Buonamici, Giacomo Gelati, Francesco Meucci and Monica Carfagni
Left atrial appendage occlusion (LAAO) is a structural interventional cardiology procedure that offers several possibilities for the application of additive manufacturing…
Abstract
Purpose
Left atrial appendage occlusion (LAAO) is a structural interventional cardiology procedure that offers several possibilities for the application of additive manufacturing technologies. The literature shows a growing interest in the use of 3D-printed models for LAAO procedure planning and occlusion device choice. This study aims to describe a full workflow to create a 3D-printed LAA model for LAAO procedure planning.
Design/methodology/approach
The workflow starts with the patient’s computed tomography diagnostic image selection. Segmentation in a commercial software provides initial geometrical models in standard tessellation language (STL) format that are then preprocessed for print in dedicated software. Models are printed using a commercial stereolithography machine and postprocessing is performed.
Findings
Models produced with the described workflow have been used at the Careggi Hospital of Florence as LAAO auxiliary planning tool in 10 cases of interest, demonstrating a good correlation with state-of-the-art software for device selection and improving the surgeon’s understanding of patient anatomy and device positioning.
Originality/value
3D-printed models for the LAAO planning are already described in the literature. The novelty of the article lies in the detailed description of a robust workflow for the creation of these models. The robustness of the method is demonstrated by the coherent results obtained for the 10 different cases studied.
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Keywords
Kamola Bayram, Adam Abdullah and Ahamed Kameel Meera
After the collapse of the Bretton Woods fixed exchange rate system in 1971, countries moved towards floating exchange rates, and the expectation was that the requirement for…
Abstract
Purpose
After the collapse of the Bretton Woods fixed exchange rate system in 1971, countries moved towards floating exchange rates, and the expectation was that the requirement for foreign reserves would decrease. However, central banks currently hold more foreign exchange reserves to enhance the credibility of exchange rate policies. The demand for gold, which was the main reserve asset prior the collapse of the Bretton Woods system, has increased as a reserve asset once again following the global financial crisis (GFC) of 2008, given gold’s characteristics as a safe haven asset and a store of value. This study aims to analyse official reserves of four countries, namely, Malaysia, Turkey, KSA and Pakistan. The Black–Litterman model was used to build a new strategic portfolio with optimal allocation to gold. This study shows that all countries under the analyses should increase their gold holdings to preserve the value of the portfolio during times of financial turmoil.
Design/methodology/approach
The Black–Litterman model has been used to build a new strategic portfolio with optimal allocation to gold. The study shows that all countries in our analyses suggested increasing their gold holdings to preserve the value of the portfolio during times of financial turmoil.
Findings
The study found that countries under the analyses, namely, Turkey, Malaysia, KSA and Pakistan, suggested increasing their official gold holding given the outstanding performance of gold during the GFC.
Research limitations/implications
Research can be further extended by including few more countries from Organisation of Islamic Cooperation such as Qatar and Indonesia.
Originality/value
Emerging economies such as China, India and Russia started to sharply increase their official gold holdings in the aftermath of the GFC. According to recent statistics, central banks of China and Russia have been adding to their gold reserves. Of note, only in few European countries and in the USA, is the share of gold in foreign reserves more than 50%. In the rest of the world, this figure is about 3-5%. The paper elaborates the aforementioned subject and suggests the strategic weight of gold reserve for each country under analysis.
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Francesco Buonamici, Tommaso Stomaci and Monica Carfagni
This study aims to examine the efficacy of 3D printing polymers to realistically mimic the fossa ovalis (FO) – a cardiac structure that is positioned in the interatrial septum �…
Abstract
Purpose
This study aims to examine the efficacy of 3D printing polymers to realistically mimic the fossa ovalis (FO) – a cardiac structure that is positioned in the interatrial septum – for simulating transseptal puncture (TP) procedures.
Design/methodology/approach
Specimen of different materials and thicknesses were prepared and tested simulating the puncturing of the FO using a 12F ID/14F OD TP catheter. Force and tenting length results were compared with literature references. Scanning electron microscope images of the specimen were acquired to observe the perforated region as well as the structure of the specimen in the unaffected area.
Findings
Significant changes in the properties of interest were registered for the same material on specimens tested at different moments after fabrication. Suturable vessel wall polyjet material offers the best characteristics to replicate FO anatomy and mimic its behavior to puncturing.
Originality/value
The originality of the work lies in the test of different commercial materials. Similar works are already present in literature but specifically designed materials are used. Demonstrating that off-the-shelf materials could be viable for FO specimens would simplify the design of realistic TP simulators in the future.