Glycosylated hemoglobin, but not advanced glycation end products, predicts severity of coronary artery disease in patients with or without diabetes.

Background:The association between coronary artery disease (CAD) and diabetes mellitus (DM) is strong but the physiologic mechanisms responsible for this association remain unclear. Patients with DM exhibit high circulating levels of glycated proteins and lipoproteins called advanced glycation end products (AGEs) which have been implicated in the development of oxidative damage to vascular endothelium. We examined the relationships between the presence and extent of CAD and AGEs in patients undergoing elective coronary artery catheterization in an urban teaching hospital. Methods:Patients with possible CAD (n = 364) were recruited prior to elective cardiac catheterization (52% male, 48% diabetic). Regression and correlation analyses were used to examine the relationship between serum AGE concentrations, soluble AGE receptor (sRAGE) concentration, HbA1c, LDL and the presence of obstructive CAD along with the burden of CAD measured by SYNTAX and SYNTAX II scores. Results:AGE and sRAGE levels did not significantly correlate with any of the studied coronary artery disease parameters. HbA1c showed positive correlation with both SYNTAX and SYNTAX II scores in patients with and without diabetes. Conclusion:In this cross-sectional study of patients with possible CAD, serum AGEs and sRAGE concentrations did not correlate with SYNTAX or SYNTAX II scores regardless of diabetic status. HbA1C correlated positively with the SYNTAX and SYNTAX II scores in both diabetic and non-diabetic populations

Lattice Boltzmann simulation on the flow behaviour associated with Helmholtz cavity-backed acoustic liners

Noise from jet engines can be reduced by means of a Helmholtz cavity configuration. The resonance that occurs when a flow passes the neck of the Helmholtz resonator will dissipate acoustic energy. The mechanism for such dissipation is mainly due to the vortex shedding that occurs at the neck of the resonator where the vortex structures absorb acoustic energy and subsequently dissipate it through viscous effects. In this work, numerical simulations utilizing the lattice Boltzmann method are used to aid in visualizing the flow behaviour that is associated with Helmholtz cavity-backed acoustic liners. In both experiments and numerical simulations, the 1-neck cavity is found to result in an amplification of an applied acoustic source. For a 4-neck cavity, the configuration is able to achieve acoustic pressure reductions. Differences in the flow behaviour of the 1-neck and 4-neck cavities are detailed in this work. Results show that the stronger vortex shedding that occurs in the 4-neck cavity configuration could explain its increased effectiveness as a Helmholtz cavity-backed acoustic liner.National Research Foundation (NRF)Submitted/Accepted versionThis research is supported by the National Research Foundation, Singapore, under its NRF-NSFC joint grant (NRF2016NRF-NSFC001-102)

Hybrid Minimally Invasive Approach for Combined Obstructive Coronary Artery Disease and Severe Aortic Stenosis

© The Author(s) 2019. Objective: There is a high prevalence of concomitant coronary artery disease (CAD) and aortic stenosis (AS), and these conditions can be treated with a variety of invasive and/or percutaneous approaches. The aim of this study is to demonstrate the feasibility, efficacy, and safety of a staged transcatheter aortic valve replacement (TAVR) after a hybrid minimally invasive direct coronary artery bypass surgery (MIDCAB) to treat combined complex CAD and AS. Methods: Six patients with concomitant CAD and severe AS underwent staged treatment of their CAD with MIDCAB and TAVR. All patients had significant complex left main or left anterior descending artery (LAD) stenosis deemed to be not amenable to percutaneous coronary intervention (PCI). Results: The average syntax score was 22±8 and the Society of Thoracic Surgeons score for surgical AVR was 8±3%. All patients underwent a single vessel MIDCAB for revascularization of the LAD (three patients required additional PCI for non-LAD disease). Two patients had pre-TAVR balloon aortic valvuloplasty and one patient also required treatment of severe mitral valve regurgitation with percutaneous edge-to-edge repair (the MitraClip). There was no intraprocedural or hospital mortality. No neurological deficits or vascular complications were recorded. Conclusions: A hybrid staged approach for combined complex CAD and severe AS with MIDCAB, PCI, and TAVR is a valid option in high-risk patients. The order and timing of these procedures must be tailored to the patient’s clinical symptoms, stability, and severity of disease