4 research outputs found
Why we fail: mechanisms and co-factors of unsuccessful thrombectomy in acute ischemic stroke
Purpose Mechanical thrombectomy (MT) is an effective treatment for patients suffering from acute ischemic stroke. However,
recanalization fails in about 16.5% of interventions. We report our experience with unsuccessful MT and analyze technical
reasons plus patient-related parameters for failure.
Methods Five hundred ninety-six patients with acute ischemic stroke in the anterior circulation and intention to perform MT with
an aspiration catheter and/or stent retriever were analyzed. Failure was defined as 0, 1, or 2a on the mTICI scale. Patients with
failing MT were analyzed for interventional progress and compared to patients with successful intervention, whereby parameters
included demographics, medical history, stroke presentation, and treatment.
Results One hundred of the 596 (16.8%) interventions failed. In 20 cases, thrombus could not be accessed or passed with the
device. Peripheral arterial occlusive disease is common in those patients. In 80 patients, true stent retriever failure occurred. In this
group, coagulation disorders are associated with poor results, whereas atrial fibrillation is associated with success.
The administration of intravenous thrombolysis and intake of nitric oxide donors are associated with recanalization success.
Intervention duration was significantly longer in the failing group.
Conclusion In 20% of failing MT, thrombus cannot be reached/passed. Direct carotid puncture or surgical arterial access could be
considered in these cases.
In 80% of failing interventions, thrombus can be passed with the device, but the occluded vessel cannot be recanalized. Rescue
techniques can be an option. Development of new devices and techniques is necessary to improve recanalization rates.
Assessment of pre-existing illness could sensitize for occurring complications
Preserving Differential Privacy in Convolutional Deep Belief Networks
The remarkable development of deep learning in medicine and healthcare domain
presents obvious privacy issues, when deep neural networks are built on users'
personal and highly sensitive data, e.g., clinical records, user profiles,
biomedical images, etc. However, only a few scientific studies on preserving
privacy in deep learning have been conducted. In this paper, we focus on
developing a private convolutional deep belief network (pCDBN), which
essentially is a convolutional deep belief network (CDBN) under differential
privacy. Our main idea of enforcing epsilon-differential privacy is to leverage
the functional mechanism to perturb the energy-based objective functions of
traditional CDBNs, rather than their results. One key contribution of this work
is that we propose the use of Chebyshev expansion to derive the approximate
polynomial representation of objective functions. Our theoretical analysis
shows that we can further derive the sensitivity and error bounds of the
approximate polynomial representation. As a result, preserving differential
privacy in CDBNs is feasible. We applied our model in a health social network,
i.e., YesiWell data, and in a handwriting digit dataset, i.e., MNIST data, for
human behavior prediction, human behavior classification, and handwriting digit
recognition tasks. Theoretical analysis and rigorous experimental evaluations
show that the pCDBN is highly effective. It significantly outperforms existing
solutions
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Initial Findings From the North American COVID-19 Myocardial Infarction Registry
The coronavirus disease 2019 (COVID-19) pandemic has impacted many aspects of ST-segment elevation myocardial infarction (STEMI) care, including timely access to primary percutaneous coronary intervention (PPCI).
The goal of the NACMI (North American COVID-19 and STEMI) registry is to describe demographic characteristics, management strategies, and outcomes of COVID-19 patients with STEMI.
A prospective, ongoing observational registry was created under the guidance of 3 cardiology societies. STEMI patients with confirmed COVID+ (group 1) or suspected (person under investigation [PUI]) (group 2) COVID-19 infection were included. A group of age- and sex-matched STEMI patients (matched to COVID+ patients in a 2:1 ratio) treated in the pre-COVID era (2015 to 2019) serves as the control group for comparison of treatment strategies and outcomes (group 3). The primary outcome was a composite of in-hospital death, stroke, recurrent myocardial infarction, or repeat unplanned revascularization.
As of December 6, 2020, 1,185 patients were included in the NACMI registry (230 COVID+ patients, 495 PUIs, and 460 control patients). COVID+ patients were more likely to have minority ethnicity (Hispanic 23%, Black 24%) and had a higher prevalence of diabetes mellitus (46%) (all p < 0.001 relative to PUIs). COVID+ patients were more likely to present with cardiogenic shock (18%) but were less likely to receive invasive angiography (78%) (all p < 0.001 relative to control patients). Among COVID+ patients who received angiography, 71% received PPCI and 20% received medical therapy (both p < 0.001 relative to control patients). The primary outcome occurred in 36% of COVID+ patients, 13% of PUIs, and 5% of control patients (p < 0.001 relative to control patients).
COVID+ patients with STEMI represent a high-risk group of patients with unique demographic and clinical characteristics. PPCI is feasible and remains the predominant reperfusion strategy, supporting current recommendations.
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