Estimating input parameters from intracellular recordings in the Feller neuronal model

We study the estimation of the input parameters in a Feller neuronal model from a trajectory of the membrane potential sampled at discrete times. These input parameters are identified with the drift and the infinitesimal variance of the underlying stochastic diffusion process with multiplicative noise. The state space of the process is restricted from below by an inaccessible boundary. Further, the model is characterized by the presence of an absorbing threshold, the first hitting of which determines the length of each trajectory and which constrains the state space from above. We compare, both in the presence and in the absence of the absorbing threshold, the efficiency of different known estimators. In addition, we propose an estimator for the drift term, which is proved to be more efficient than the others, at least in the explored range of the parameters. The presence of the threshold makes the estimates of the drift term biased, and two methods to correct it are proposed

Motoneuron membrane potentials follow a time inhomogeneous jump diffusion process

Stochastic leaky integrate-and-fire models are popular due to their simplicity and statistical tractability. They have been widely applied to gain understanding of the underlying mechanisms for spike timing in neurons, and have served as building blocks for more elaborate models. Especially the Ornstein–Uhlenbeck process is popular to describe the stochastic fluctuations in the membrane potential of a neuron, but also other models like the square-root model or models with a non-linear drift are sometimes applied. Data that can be described by such models have to be stationary and thus, the simple models can only be applied over short time windows. However, experimental data show varying time constants, state dependent noise, a graded firing threshold and time-inhomogeneous input. In the present study we build a jump diffusion model that incorporates these features, and introduce a firing mechanism with a state dependent intensity. In addition, we suggest statistical methods to estimate all unknown quantities and apply these to analyze turtle motoneuron membrane potentials. Finally, simulated and real data are compared and discussed. We find that a square-root diffusion describes the data much better than an Ornstein–Uhlenbeck process with constant diffusion coefficient. Further, the membrane time constant decreases with increasing depolarization, as expected from the increase in synaptic conductance. The network activity, which the neuron is exposed to, can be reasonably estimated to be a threshold version of the nerve output from the network. Moreover, the spiking characteristics are well described by a Poisson spike train with an intensity depending exponentially on the membrane potential

Outcomes of bailout percutaneous ventricular assist device versus prophylactic strategy in patients undergoing nonemergent percutaneous coronary intervention

OBJECTIVES: To compare in-hospital outcomes of bailout support to prophylactic support with percutaneous ventricular assist devices (pVAD) for high-risk nonemergent percutaneous coronary intervention (HRPCI). BACKGROUND: Prophylactic support with pVAD for a HRPCI is used in patients felt to be at risk for hemodynamic collapse during PCI. An alternative strategy of bailout pVAD support in the event of hemodynamic collapse is also entertained. METHODS: We compared the outcomes of patients entered in the cVAD database who underwent Impella Protected PCI (ProPCI group) with patients from the cVAD and USpella databases receiving bailout Impella support for hemodynamic collapse during HRPCI (Bailout group). RESULTS: A total of 1,028 patients supported with Impella pVAD were entered into the cVAD database as of July 2019 and were included in this analysis. Of those 971 were in the ProPCI group and 57 in the Bailout group. Patients in the Bailout group were more often female (50.9%vs. 27.2%, p = .0002) with higher median baseline left ventricular ejection fraction (LVEF) (40%vs. 30%, p \u3c .0001) and with lower prevalence of both heart failure (42.1%vs. 56.9%, p = .0385) and left main disease (40.0%vs. 56.1%, p = .0250) compared to the ProPCI group. Unadjusted and adjusted in-hospital mortality was significantly higher in the Bailout group (49.1%vs. 4.3%, and 57.8%vs. 4.4%, p \u3c .0001 for both). CONCLUSIONS: In our study population, the bailout group was associated with significant increased mortality compared to ProPCI group. Female gender was more frequently observed in patients requiring bailout pVAD. Further investigation is warranted in order to generalize the findings of our study

Parents' Perspectives on the School Experiences of Children with Cancer

Interviews with 59 parents of school age children with cancer indicate problems children encountered in returning to school: missing significant amounts of school due to illness and treatments, teasing by classmates and peers, and strained relations with teachers. Most parents report that despite missing much school their child was caught up with schoolwork, suggesting that academic difficulties are not paramount. Most parents also report receiving substantial help from sympathetic and competent educators. However, parents also indicate that some teachers were insensitive to their child's condition, while others were overprotective, suggesting the need for a delicate balance in defining appropriate teacher behavior. A responsive yet normalizing school environment can be facilitated by vigorous and proactive partnerships among the medical staff, family, and school system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68682/2/10.1177_027112148600500405.pd

Wall shear stress estimated by 3D-QCA can predict cardiovascular events in lesions with borderline negative fractional flow reserve

Background and aims: There is some evidence of the implications of wall shear stress (WSS) derived from three-dimensional quantitative coronary angiography (3D-QCA) models in predicting adverse cardiovascular events. This study investigates the efficacy of 3D-QCA-derived WSS in detecting lesions with a borderline negative fractional flow reserve (FFR: 0.81–0.85) that progressed and caused events. Methods: In this retrospective cohort study, we identified 548 patients who had at least one lesion with an FFR 0.81–0.85 and complete follow-up data; 293 lesions (286 patients) with suitable angiographic characteristics were reconstructed using a dedicated 3D-QCA software and included in the analysis. In the reconstructed models blood flow simulation was performed and the value of 3D-QCA variables and WSS distribution in predicting events was examined. The primary endpoint of the study was the composite of cardiac death, target lesion related myocardial infarction or clinically indicated target lesion revascularization. Results: During a median follow-up of 49.4 months, 37 events were reported. Culprit lesions had a greater area stenosis [(AS), 66.1% (59.5–72.3) vs 54.8% (46.5–63.2), p<0.001], smaller minimum lumen area [(MLA), 1.66 mm2 (1.45–2.30) vs 2.10 mm2 (1.69–2.70), p=0.011] and higher maximum WSS [9.0 Pa (5.10–12.46) vs 5.0 Pa (3.37–7.54), p < 0.001] than those that remained quiescent. In multivariable analysis, AS [hazard ratio (HR): 1.06, 95% confidence interval (CI): 1.03–1.10, p=0.001] and maximum WSS (HR: 1.08, 95% CI: 1.02–1.14, p=0.012) were the only independent predictors of the primary endpoint. Lesions with an increased AS (≥58.6%) that were exposed to high WSS (≥7.69Pa) were more likely to progress and cause events (27.8%) than those with a low AS exposed to high WSS (7.4%) or those exposed to low WSS that had increased (12.8%) or low AS (2.7%, p<0.001). Conclusions: This study for the first time highlights the potential value of 3D-QCA-derived WSS in detecting, among lesions with a borderline negative FFR, those that cause cardiovascular events

Cardiac mortality in patients randomised to elective coronary revascularisation plus medical therapy or medical therapy alone: A systematic review and meta-analysis

© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/)Aims:The value of elective coronary revascularisation plus medical therapy over medical therapy alone in managing stable patients with coronary artery disease is debated. We reviewed all trials comparing the two strategies in this population. Methods and results:From inception through November 2020, Medline, Embase, Google Scholar and other databases were searched for randomised trials comparing revascularisation to medical therapy alone in clinically stable coronary artery disease patients. Treatment effects were measured by rate ratios (RR) with 95% confidence intervals using random-effects models. Cardiac mortality was the prespecified primary endpoint. Spontaneous myocardial infarction (MI) and its association with cardiac mortality were secondary endpoints. Further endpoints included all-cause mortality, any MI and stroke. Longest follow-up data were abstracted. The study is registered with PROSPERO (CRD42021225598). Twenty-five trials involving 19,806 patients (10,023 randomised to revascularisation plus medical therapy and 9,783 to medical therapy alone) were included. Compared to medical therapy alone, revascularisation was associated with a lower risk of cardiac death (RR 0.79 [0.67-0.93], p<0.01) and spontaneous MI (RR 0.74 [0.64-0.86], p<0.01). By meta-regression, the cardiac death risk reduction after revascularisation, compared to medical therapy alone, was linearly associated with follow-up duration (RR per 4-year follow-up: 0.81 [0.69-0.96], p=0.008) and spontaneous MI absolute difference (p=0.01). Trial sequential and sensitivity analyses confirmed the reliability of the cardiac mortality findings. All cause mortality (0.94 [0.87-1.01], p=0.11), any MI (p=0.14) and stroke risk (p=0.30) did not differ significantly between strategies. Conclusion:In stable coronary artery disease patients, randomisation to elective coronary revascularisation plus medical therapy led to reduced cardiac mortality compared to medical management alone. The cardiac survival benefit after revascularisation improved with longer follow-uptimes and was associated with fewer spontaneous MIs.Peer reviewedFinal Published versio

Artificial Intelligence, Computational Simulations, and Extended Reality in Cardiovascular Interventions

Artificial intelligence, computational simulations, and extended reality, among other 21st century computational technologies, are changing the health care system. To collectively highlight the most recent advances and benefits of artificial intelligence, computational simulations, and extended reality in cardiovascular therapies, we coined the abbreviation AISER. The review particularly focuses on the following applications of AISER: 1) preprocedural planning and clinical decision making; 2) virtual clinical trials, and cardiovascular device research, development, and regulatory approval; and 3) education and training of interventional health care professionals and medical technology innovators. We also discuss the obstacles and constraints associated with the application of AISER technologies, as well as the proposed solutions. Interventional health care professionals, computer scientists, biomedical engineers, experts in bioinformatics and visualization, the device industry, ethics committees, and regulatory agencies are expected to streamline the use of AISER technologies in cardiovascular interventions and medicine in general

Wall shear stress estimated by 3D-QCA can predict cardiovascular events in lesions with borderline negative fractional flow reserve

Background and aims: There is some evidence of the implications of wall shear stress (WSS) derived from three-dimensional quantitative coronary angiography (3D-QCA) models in predicting adverse cardiovascular events. This study investigates the efficacy of 3D-QCA-derived WSS in detecting lesions with a borderline negative fractional flow reserve (FFR: 0.81-0.85) that progressed and caused events.Methods: In this retrospective cohort study, we identified 548 patients who had at least one lesion with an FFR 0.81-0.85 and complete follow-up data; 293 lesions (286 patients) with suitable angiographic characteristics were reconstructed using a dedicated 3D-QCA software and included in the analysis. In the reconstructed models blood flow simulation was performed and the value of 3D-QCA variables and WSS distribution in predicting events was examined. The primary endpoint of the study was the composite of cardiac death, target lesion related myocardial infarction or clinically indicated target lesion revascularization.Results: During a median follow-up of 49.4 months, 37 events were reported. Culprit lesions had a greater area stenosis [(AS), 66.1% (59.5-72.3) vs 54.8% (46.5-63.2), p= 58.6%) that were exposed to high WSS (>= 7.69Pa) were more likely to progress and cause events (27.8%) than those with a low AS exposed to high WSS (7.4%) or those exposed to low WSS that had increased (12.8%) or low AS (2.7%, p<0.001).Conclusions: This study for the first time highlights the potential value of 3D-QCA-derived WSS in detecting, among lesions with a borderline negative FFR, those that cause cardiovascular events.Cardiovascular Aspects of Radiolog