Machine learning-accelerated computational fluid dynamics.

Numerical simulation of fluids plays an essential role in modeling many physical phenomena, such as weather, climate, aerodynamics, and plasma physics. Fluids are well described by the Navier-Stokes equations, but solving these equations at scale remains daunting, limited by the computational cost of resolving the smallest spatiotemporal features. This leads to unfavorable trade-offs between accuracy and tractability. Here we use end-to-end deep learning to improve approximations inside computational fluid dynamics for modeling two-dimensional turbulent flows. For both direct numerical simulation of turbulence and large-eddy simulation, our results are as accurate as baseline solvers with 8 to 10× finer resolution in each spatial dimension, resulting in 40- to 80-fold computational speedups. Our method remains stable during long simulations and generalizes to forcing functions and Reynolds numbers outside of the flows where it is trained, in contrast to black-box machine-learning approaches. Our approach exemplifies how scientific computing can leverage machine learning and hardware accelerators to improve simulations without sacrificing accuracy or generalization.

Local provision of percutaneous coronary intervention increases stenting rates and reduces length of hospital stay in remote regional centre.

INTRODUCTION: An early invasive strategy with follow-on percutaneous coronary intervention (PCI) is recommended in the management of high risk acute coronary syndromes (ACS). This article aimed to assess the impact of a new PCI service in a remote population. METHOD: The study compared patient treatment pre- and post-introduction of the PCI service in a remote regional centre. Patients were identified using ICD discharge code during two 12 week periods ('pre' and 'post' introduction of the new PCI service). Further data was obtained from a catheter laboratory database, electronic patient management systems and clinical notes. Non-parametric statistical tests were used. RESULTS: There were 182 patients in the pre-PCI group and 204 in the post-PCI group. There were no demographic differences between the groups. Patients admitted post service introduction who required active treatment were more likely to have PCI rather than an angiogram only (p = 0.046). Furthermore, patients admitted after the introduction of the PCI service had a shorter period of time from admission to PCI (p = 0.002), were less likely to be transferred to another hospital (p < 0.001), and on average had a shorter hospital stay (p = 0.017). CONCLUSION: A local PCI service in a remote regional centre increased efficiency in the management of patients with ACS with increased rates of PCI, shorter waiting times, reduced requirement for hospital transfer, and shorter length of stay. Nevertheless, many patients still required transfer to other centres. Therefore, maintaining links with other regional centres with clear patient pathways are necessary to provide optimal ACS care to all patients in a rural area.

Life-Threatening Coronary Vasospasm Treated by Implantable Cardioverter Defibrillator: The Warning Signs.

Coronary artery vasospasm is the sudden narrowing of an artery caused by rapid prolonged contraction. It reduces blood supply to the heart and can present with typical cardiac chest pain symptoms. Vasospasm can lead to fatal arrhythmic complications such as ventricular fibrillation. Our case report describes an example of this occurring in a 53-year-old female, and the management plan that ensued. We look at the importance of accurate and prompt diagnosis of vasospasm and how this can have implications for treatment options. One of the available treatments for vasospasm is placement of an implantable cardioverter defibrillator (ICD). This delivers a shock in the event of future life-threatening arrhythmia, with the aim of preventing cardiac arrest. ICD placement, however, is not always a suitable option. This case report discusses the various challenges that arose while making the decision for ICD placement and gives insight into the best available treatment options for coronary artery vasospasm. We also highlight early warning signs that predict life-threatening vasospastic events and how this can be diagnosed and treated appropriately.

Arterial trauma during ultrasound-guided axillary vein puncture for endocardial lead placement.

The axillary vein is an accepted route for gaining central venous access, particularly for pacing and implantable cardioverter defibrillator leads, with ultrasound guidance a useful way of facilitating venous puncture. We report a series of cases demonstrating the important complication of inadvertent arterial injury with this technique.

Hybrid Instantaneous Wave-Free Ratio-Fractional Flow Reserve versus Fractional Flow Reserve in the Real World.

BACKGROUND: The instantaneous wave-free ratio (iFR) is a novel method to assess the ischemic potential of coronary artery stenoses. Clinical trial data have shown that iFR has acceptable diagnostic agreement with fractional flow reserve (FFR), the reference standard for the functional assessment of coronary stenoses. This study compares iFR measurements with FFR measurements in a real world, single-center setting. METHODS AND RESULTS: Instantaneous wave-free ratio and FFR were measured in 50 coronary artery lesions in 42 patients, with FFR ≤ 0.8 classified as functionally significant. An iFR-only technique, using a treatment cut-off value, iFR ≤ 0.89, provided a classification agreement of 84% with FFR ≤ 0.80. Use of a hybrid iFR-FFR technique, incorporating FFR measurement for lesions within the iFR gray zone of 0.86-0.93, would improve classification agreement with FFR to 94%, with diagnosis achieved without the need for hyperemia in 57% patients. CONCLUSION: This study in a real-world setting demonstrated good classification agreement between iFR and FFR. Use of a hybrid iFR-FFR technique would achieve high diagnostic accuracy while minimizing adenosine use, compared with routine FFR.

Matrix metalloproteinase-1 promoter polymorphisms and changes in left ventricular volume following acute myocardial infarction.

The relation between matrix metalloproteinase-1 promoter genotype and remodeling was studied in 42 patients after their first acute myocardial infarctions. Patients possessing 2 GG alleles were at increased risk for remodeling compared with homozygotes for the G allele and heterozygotes possessing 1 G and 1 GG allele.