Impact of improved stroke green channel process on the delay of intravenous thrombolysis in patients with acute cerebral infarction during the COVID-19 pandemic: An observational study.

Objective: This study analyzed the impact of the improved stroke green channel process on the delay of intravenous thrombolysis in patients with acute cerebral infarction under coronavirus disease 2019 (COVID-19) prevention and control measures. Methods: We included 57 patients from the stroke center of the Seventh People's Hospital of Shanghai University of Traditional Chinese Medicine before the improvement of the stroke green channel process (March-July 2019), as well as 94 patients during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak (March-July 2020) and 68 patients during the Omicron variant outbreak (March-July 2022) after the improvement of stroke green channel process. The door-to-needle time (DNT), door-to-imaging time (DIT), and door-to-test completion time were compared among the three groups. We analyzed the impact of this process improvement in the emergency green channel during the pandemic on the delay of intravenous thrombolysis. Results: This study included a total of 229 patients with acute cerebral infarction who went through the green channel for intravenous thrombolysis (57 in the pre-pandemic group, 94 in the SARS-CoV-2 outbreak group, and 68 in the Omicron outbreak group). The percentages of patients undergoing intravenous thrombolysis in the pre-pandemic, SARS-CoV-2 outbreak, and Omicron outbreak groups differed significantly (19.32%, 22.27%, and 28.94%, respectively, P = 0.029). Compared to the pre-pandemic group, the National Institutes of Health Stroke Scale (NIHSS) score at admission was significantly higher in the Omicron outbreak group (7.71 ± 7.36 in the Omicron outbreak group vs. 5.00 ± 4.52 in the pre-pandemic group) (P = 0.026) but not in the SARS-CoV-2 outbreak group (4.79 ± 5.94 in the SARS-CoV-2 outbreak group vs. 5.00 ± 4.52 in the pre-pandemic group, P = 0.970). Significantly higher proportions of patients undergoing emergency intravenous thrombolysis came to the hospital by ambulance in the SARS-CoV-2 and Omicron outbreak groups compared to the pre-pandemic group (38.6% in the pre-pandemic group, 51.1% in the SARS-CoV-2 outbreak group, and 82.4% in the Omicron outbreak group, P < 0.001). Compared to the pre-pandemic group, the DIT was significantly higher in the SARS-CoV-2 outbreak group (22.42 ± 7.62 min in the SARS-CoV-2 outbreak group vs. 18.91 ± 8.23 min in the pre-pandemic group, P =0.031) but not the Omicron outbreak group (20.35 ± 10.38 min in the Omicron outbreak group vs. 18.91 ± 8.23 min in the pre-pandemic group, P = 0.543). The door-to-test completion time was significantly longer in the SARS-CoV-2 and Omicron outbreak groups compared to that in the pre-pandemic group (78.37 ± 25.17 min in the SARS-CoV-2 outbreak group, 92.60 ± 25.82 min in the Omicron outbreak group vs. 65.11 ± 22.35 min in the pre-pandemic group, P < 0.001); however, the DNT in the SARS-CoV-2 and Omicron outbreak groups did not differ significantly from those in the pre-pandemic group (both P > 0.05). Conclusion: During the two periods of the COVID-19 outbreak (SARS-CoV-2 and Omicron), after the improvement of the green channel for intravenous thrombolysis, there might be some delay in in-hospital DIT during the SARS-CoV-2 outbreak, however, the in-hospital delay indicator DNT for intravenous thrombolysis were not affected.

Microglia-derived PDGFB promotes neuronal potassium currents to suppress basal sympathetic tonicity and limit hypertension.

Although many studies have addressed the regulatory circuits affecting neuronal activities, local non-synaptic mechanisms that determine neuronal excitability remain unclear. Here, we found that microglia prevented overactivation of pre-sympathetic neurons in the hypothalamic paraventricular nucleus (PVN) at steady state. Microglia constitutively released platelet-derived growth factor (PDGF) B, which signaled via PDGFRα on neuronal cells and promoted their expression of Kv4.3, a key subunit that conducts potassium currents. Ablation of microglia, conditional deletion of microglial PDGFB, or suppression of neuronal PDGFRα expression in the PVN elevated the excitability of pre-sympathetic neurons and sympathetic outflow, resulting in a profound autonomic dysfunction. Disruption of the PDGFBMG-Kv4.3Neuron pathway predisposed mice to develop hypertension, whereas central supplementation of exogenous PDGFB suppressed pressor response when mice were under hypertensive insult. Our results point to a non-immune action of resident microglia in maintaining the balance of sympathetic outflow, which is important in preventing cardiovascular diseases.