Predictors of QT Interval Prolongation in Critically-ill Patients with SARS-CoV-2 Infection Treated with Hydroxychloroquine

BackgroundHydroxychloroquine (HCQ) has been described as a potential treatment for SARS-CoV-2 infection. However, there are safety concerns regarding its QT interval and pro-arrhythmic effects.ObjectiveThis trial aimed to determine the predictors of QT interval prolongation and pro-arrhythmic effects in patients hospitalized for SARS-CoV-2 infection and receiving HCQ.MethodsWe performed a retrospective observational study of 45 critically-ill patients hospitalized because of SARS-CoV-2 infection and treated with 800 mg of HCQ at day 1 and 400 mg on days 2–5. Clinical aspects and outcomes, basal and final corrected QT (QTc) interval, and the incidence of arrhythmias and arrhythmogenic death were observed. Independent predictors of QTc prolongation were identified using multivariable logistic regression analysis. QT interval prolongation was considered substantial at final QTc ≥ 480 ms.ResultsThe mean age was 60.9 ± 16.67 years and 28 (62.2%) patients were men. Basal QTc was 442 ± 28 ms, and the final QTc interval was 458 ± 34 ms, for a mean QTc interval variation of 15 ± 11 ms. There was no arrhythmogenic death. The need for hemodialysis remained a statistically significant predictor of QT interval enlargement (odds ratio, 10.34; 95% confidence interval, 1.04 – 102.18; p = 0.045).ConclusionsHCQ promotes mild to moderate QT interval prolongation. The risk of QT interval prolongation is higher among patients with acute renal failure requiring hemodialysis.

Fault Tree Interval Analysis of Complex Systems Based on Universal Grey Operation

The objective of this study is to propose a new operation method based on the universal grey number to overcome the shortcomings of typical interval operation in solving system fault trees. First, the failure probability ranges of the bottom events are described according to the conversion rules between the interval number and universal grey number. A more accurate system reliability calculation is then obtained based on the logical relationship between the AND gates and OR gates of a fault tree and universal grey number arithmetic. Then, considering an aircraft landing gear retraction system as an example, the failure probability range of the top event is obtained through universal grey operation. Next, the reliability of the aircraft landing gear retraction system is evaluated despite insufficient statistical information describing failures. The example demonstrates that the proposed method provides many advantages in resolving the system reliability problem despite poor information, yielding benefits for the function of the interval operation, and overcoming the drawback of solution interval enlargement under different orders of interval operation.

Endovascular reconstruction of enlarging traumatic internal carotid artery pseudoaneurysm

Traumatic dissecting pseudoaneurysms of the cervical and petrous internal carotid artery are often a result of blunt or penetrating trauma. These patients are at high risk for thromboembolic complications and are managed with antiplatelet agents. Patients who develop neurologic symptoms while on antiplatelet agents, or have interval enlargement of their pseudoaneurysms, may require repair of the vessel. We describe a case in which we performed an endovascular repair of an enlarging distal cervical internal carotid artery pseudoaneurysm, with placement of a covered stent.The video can be found here: http://youtu.be/uCypcsBvOZ4.