Endovascular repair of the aortic arch

Objectives

The gold standard for the treatment of pathologies of the aortic arch remains the open surgical reconstruction of the affected segments. However, endovas-cular treatment options have emerged that eliminate the need for invasive open surgery. Several endograft devices - with fenestrations or branches for the supraaortic vessels - are currently available to address different pathologies and anatomical variations. Parallel-graft techniques and in situ fenestrations expand the treatment options for emergent cases. In this selective review of the literature of 2020 and 2021, we summarize the current chances and challenges of endovascular aortic repair.

Content

Reported mortality rates range from 0 to 13.2 %. Although technical success rates for fenestrated and branched devices are promising (98 %), stroke rates remain a relevant issue (10 and 3 % for BTEVAR and FTEVAR respectively). The reported technical success rate for in situ fenestrations is also encouraging (94 %) and the stroke rates acceptable (5 %). Parallel-graft techniques are associated with high early and late endoleak rates (early 76 %; late 31 %), but still hold a valuable place in the treatment of emergent cases or in bail-out situations.

Summary and Outlook

The endovascular repair of the aortic arch expands the range of patients with pathologies of the arch eligible for treatment to those unfit for open surgery offering a minimally invasive, yet technically challenging procedure. More data and meta-analyses are needed to define the benefits and drawbacks of this promising treatment option in an aging population with increasing co-morbidities.

Exchange rate volatility and manufacturing commodity exports in ASEAN-5: A symmetric and asymmetric approach

This study aims to investigate the influence of the volatility of exchange rates on manufacturing commodity exports in the ASEAN-5 (Indonesia, Singapore, Thailand, Malaysia, and the Philippines). The study used the ARCH/GARCH, ARDL, and Nonlinear ARDL to determine the symmetrical and asymmetrical influence of the volatility of the exchange rate on manufacturing exports in both the short run and long run. Five leading commodity exports for each of the ASEAN-5 countries were used and analyzed over the period January 2007-March 2019. Our strategy using the ARDL approach revealed that volatility has a significant influence on 13 commodity exports in the short term. While the Nonlinear ARDL approach revealed that volatility influenced 19 commodity exports. Additionally, in the long run, finding from ARDL and Nonlinear ARDL also indicates risk-averse behaviour by exporters. However, in the long run, the nonlinear model demonstrates that volatility asserts an asymmetric influence on nearly all commodity exports. With this, therefore, there is the need for policymakers to uphold steadiness in the exchange rate via the use of adequate foreign reserves and amplified the level of investment.

The variability and volatility of sleep: An ARCHetypal behavior

Using 1975-2005 Dutch time-diary data covering over 10,000 respondents for 7 consecutive days each, we show that sleep time exhibits non-constant variability, or volatility, characterized by stationary autoregressive conditional heteroscedasticity: The absolute values of deviations from a person's average sleep on one day are positively correlated with those on adjacent days. Sleep is more variable on weekends and among younger people, those without young children, or with less education. Volatility is greater among parents with young children, slightly greater among men, but independent of other demographics. Economic incentives to minimize the dispersion of sleep imply higher-wage workers will exhibit less dispersion, which we observe. Sleep volatility spills over onto volatility in other personal activities, with no reverse causation onto sleep. The results illustrate a novel dimension of inequality among people and could be applied to a wide variety of human behavior and biological processes.

Stochastic modeling of mortality rates and Mortality-at-Risk forecast by taking conditional heteroscedasticity effect into account

Mortality and mortality rate have become the major issues in insurance industries, for instance, life insurance and pension fund. Such industries will, in particular, be concerned with the quantification of risk attached, say longevity risk, to insurance products that may receive severe impacts from the fall of mortality rate. In this paper, we model the mortality rate by using an Autoregressive (AR) model with a conditional heteroscedasticity effect. This effect is accommodated by a stochastic model of Autoregressive Conditional Heteroscedastic (ARCH) as well as a Stochastic Volatility Autoregressive (SVAR) model. Furthermore, we do forecasting of what so-called Mortality-at-Risk (MaR) by adopting the Value-at-Risk framework and its improvement. The calculation of the MaR forecast for those two models is conducted with significantly different approaches.

Murine models of clonal hematopoiesis to assess mechanisms of cardiovascular disease

Clonal hematopoiesis (CH) is a phenomenon whereby somatic mutations confer a fitness advantage to hematopoietic stem and progenitor cells (HSPC) and thus facilitate their aberrant clonal expansion. These mutations are carried into progeny leukocytes leading to a situation whereby a substantial fraction of an individual's blood cells originate from the HSPC mutant clone. Although this condition rarely progresses to a hematological malignancy, circulating blood cells bearing the mutation have the potential to affect other organ systems as they infiltrate into tissues under both homeostatic and disease conditions. Epidemiological and clinical studies have revealed that CH is highly prevalent in the elderly and is associated with an increased risk of cardiovascular disease and mortality. Recent experimental studies in murine models have assessed the most commonly mutated "driver" genes associated with CH, and have provided evidence for mechanistic connections between CH and cardiovascular disease. A deeper understanding of the mechanisms by which specific CH mutations promote disease pathogenesis is of importance, as it could pave the way for individualized therapeutic strategies targeting the pathogenic CH gene mutations in the future. Here, we review the epidemiology of CH and the mechanistic work from studies using murine disease models, with a particular focus on the strengths and limitations of these experimental systems. We intend for this review to help investigators select the most appropriate models to study CH in the setting of cardiovascular disease.

Prognostic factors and follow-up parameters in patients with paroxysmal nocturnal hemoglobinuria (PNH): experience of the Austrian PNH network

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disease characterized by a deregulated complement system, chronic Coombs-negative, intravascular hemolysis, and a variable clinical course with substantial risk to develop thromboembolic events. We analyzed diagnostic and prognostic parameters as well as clinical endpoints in 59 adult patients suffering from PNH in 5 hematology centers in Austria (observation period: 1978-2015). Median follow-up time was 5.6 years. The median clone size at diagnosis amounted to 55% and was higher in patients with classical PNH (81%) compared to patients with PNH associated with aplastic anemia (AA) or myelodysplastic syndromes (MDS) (50%). The clone size also correlated with lactate dehydrogenase (LDH) levels. In one patient, anemia improved spontaneously and disappeared with complete normalization of LDH after 16 years. Seventeen patients received therapy with eculizumab. The rate of thromboembolic events was higher in the pre-eculizumab era compared with eculizumab-treated patients but did not correlate with the presence of age-related clonal hematopoiesis or any other clinical or laboratory parameters. Peripheral blood colony-forming progenitor cell counts were lower in PNH patients compared with healthy controls. Only two patients with classical PNH developed MDS. Overall, 7/59 patients died after 0.5-32 years. Causes of death were acute pulmonary hypertension, Budd-Chiari syndrome, and septicemia. Overall survival (OS) was mainly influenced by age and was similar to OS measured in an age-matched healthy Austrian control cohort. Together, compared with previous times, the clinical course and OS in PNH are favorable, which may be due to better diagnosis, early recognition, and eculizumab therapy.

Cardiovascular Disease, Aging, and Clonal Hematopoiesis

Traditional risk factors are incompletely predictive of cardiovascular disease development, a leading cause of death in the elderly. Recent epidemiological studies have shown that human aging is associated with an increased frequency of somatic mutations in the hematopoietic system, which provide a competitive advantage to a mutant cell, thus allowing for its clonal expansion, a phenomenon known as clonal hematopoiesis. Unexpectedly, these mutations have been associated with a higher incidence of cardiovascular disease, suggesting a previously unrecognized connection between somatic mutations in hematopoietic cells and cardiovascular disease. Here, we provide an up-to-date review of clonal hematopoiesis and its association with aging and cardiovascular disease. We also give a detailed report of the experimental studies that have been instrumental in understanding the relationship between clonal hematopoiesis and cardiovascular disease and have shed light on the mechanisms by which hematopoietic somatic mutations contribute to disease pathology.

Estimating the volatility of cryptocurrencies during bearish markets by employing GARCH models

This study examines the volatility of certain cryptocurrencies and how they are influenced by the three highest capitalization digital currencies, namely the Bitcoin, the Ethereum and the Ripple. We use daily data for the period 1 January 2018-16 September 2018, which represents the bearish market of cryptocurrencies. The impact of the decline of these three cryptocurrencies on the returns of the other virtual currencies is examined with models of the ARCH and GARCH family, as well as the DCC-GARCH. The main conclusion of the study is that the majority of cryptocurrencies are complementary with Bitcoin, Ethereum and Ripple and that no hedging abilities exist among principal digital currencies in distressed times.

Clonal Hematopoiesis and risk of Acute Myeloid Leukemia

Acute Myeloid Leukemia, the most common form of acute leukemia in adults, is an aggressive hematopoietic stem cell malignancy that is associated with significant morbidity and mortality. Though AML generally presents de novo, risk factors include exposure to chemotherapy and/or radiation, as well as both familial and acquired bone marrow failure syndromes. Clonal Hematopoiesis (CH) refers to an expansion of blood or marrow cells resulting from somatic mutations in leukemia-associated genes detected in individuals without cytopenias or hematological malignancies. While CH is considered part of normal ageing, CH is also significantly associated with cardiovascular disease, solid tumors, and hematological malignancies. In this review, we will discuss evidence linking CH with the development of AML, as well as describe challenges in and strategies for monitoring patients with high risk CH mutations.

Estimating long-run equilibrium real exchange rates: short-lived shocks with long-lived impacts on Pakistan

The purpose of this study is to investigate the factors that affect real exchange rate volatility for Pakistan through the co-integration and error correction model over a 30-year time period, i.e. between 1980 and 2010. The study employed the autoregressive conditional heteroskedasticity (ARCH), generalized autoregressive conditional heteroskedasticity (GARCH) and Vector Error Correction model (VECM) to estimate the changes in the volatility of real exchange rate series, while an error correction model was used to determine the short-run dynamics of the system. The study is limited to a few variables i.e., productivity differential (i.e., real GDP per capita relative to main trading partner); terms of trade; trade openness and government expenditures in order to manage robust data. The result indicates that real effective exchange rate (REER) has been volatile around its equilibrium level; while, the speed of adjustment is relatively slow. VECM results confirm long run convergence of real exchange rate towards its equilibrium level. Results from ARCH and GARCH estimation shows that real shocks volatility persists, so that shocks die out rather slowly, and lasting misalignment seems to have occurred.