There has been an epidemic of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) delta variant in Jingmen, China, and the clinical and epidemiological characteristics of all patients infected with SARS-CoV-2 delta variant in an epidemic are rarely reported. All the coronavirus disease 2019 (COVID-19) patients diagnosed in Jingmen in August 2021 were enrolled in this study. Epidemiological data and clinical characteristics were analyzed. Of 58 patients (38 male and 20 female), 11 were children. The mean age was 35 years, and the median age was 39 years (range, 1-60 years; interquartile range, 28-51). The infectivity of the SARS-CoV-2 Delta variant may have increased, but pathogenicity could have decreased significantly. The vast majority of patients had either no symptoms or mild symptoms. Even though the variant virus is highly contagious, control measures have proven effective. Symptoms included fever (53%), cough (48%), headache (6%), runny nose (13%), loss of smell and taste (6%), elevated C-reactive protein (26%), increased neutrophil count (13%), decreased eosinophil count (21%), and elevated mononuclear granulocytes (26%). Thirty-eight of the 47 adults showed lymphocyte decline, but none of the children showed a significant decline, and more than half of them showed an increase. Thirty patients had no pneumonia, 27 patients had mild pneumonia, and only one patient with multiple chronic diseases had severe pneumonia. None of the 11 children had been vaccinated, 10 did not have pneumonia, and 1 had a small lung lesion. The number of new patients disappeared in 15 days after the lockdown of the city.Abbreviations: COVID-19 = the coronavirus disease 2019, SARS-CoV-2 = severe acute respiratory syndrome coronavirus-2, RT-PCR = real-time reverse transcription polymerase chain reaction.

At present, the mechanism of reciprocal ST-segment depression (RSTD) is unclear. ST-segment changes may be caused by the potential difference between the positive and negative electrodes, although this requires further investigation. The characteristics of RSTD and their relationship with ST-segment elevation in acute ST segment elevation myocardial infarction (STEMI) patients were analyzed. We replaced the negative electrode of the precordial leads of an inferior wall myocardial infarction patient and observed the changes in the ST-segment of the precordial leads. A total of 85 patients were included, of which 75 were patients with RSTD. All 45 patients with inferior myocardial infarction had limb lead RSTD, and 37 had anterior lead ST-segment depression. All ST-segment changes in STEMI can be explained by the proposed mechanism, and the value of ST segment depression in limb leads can be calculated by the value of ST segment elevation. In summary, the mechanism of RSTD in acute myocardial infarction may be that the action potential (AP) of the negative electrode of the lead weakens or disappears and the AP of the positive electrode may not be completely offset, resulting in ST-segment depression. Animal experimental studies are needed for further confirmation. When the negative electrode of the precordial lead is changed in acute inferior wall myocardial infarction patient, the ST-segment of the precordial lead changes accordingly. All the changes are consistent with our analysis.

Background: At present, the mechanism of reciprocal ST-segment depression(RSTD) is still not clear.Methods: The electrocardiogram and angiography of 85 STEMI patients were retrospectively analyzed to summarize the characteristics of ST segment changes and explore the mechanism of RSTD.Results: A total of 85 patients were included, of which 75 were patients with RSTD (10 patients with anterior myocardial infarction had no RSTD), all 45 patients with inferior myocardial infarction had limb leads RSTD, and 37 of them had anterior lead ST segment depression.Thirty patients with anterior myocardial infarction were accompanied by mild ST segment changes in the limb leads. According to the characteristics of RSTD, it is speculated that the mechanism of RSTD is that the action potential of infarct area decreased , which could not offset the action potential in non-infarct area.Conclusion: the mechanism of RSTD in acute myocardial infarction maybe that the negative electrode action potential of the lead was weakened or disappeared, and the positive electrode action potential could not be completely offset, resulting in ST segment depression.

Background:At present, the mechanism of reciprocal ST-segment depression(RSTD) is still not clear. Purpose : We proposed the mechanism of RSTD: the action potential of negative electrode of the lead was weakened or disappeared, and the AP of positive electrode could not be completely offset. The electrocardiograms of patients with acute STEMI were analyzed to explore the mechanism of RSTD. Methods: The electrocardiogram and angiography of 85 STEMI patients were retrospectively analyzed to summarize the characteristics of ST segment changes. Results: A total of 85 patients were included, of which 75 were patients with RSTD (10 patients with anterior myocardial infarction had no RSTD), all 45 patients with inferior myocardial infarction had limb leads RSTD, and 37 of them had anterior lead ST segment depression.Thirty patients with anterior myocardial infarction were accompanied by mild ST segment changes in the limb leads. According to the characteristics of RSTD, it is speculated that the mechanism of RSTD is that the action potential of infarct area decreased , which could not offset the action potential in non-infarct area. By using this mechanism, all ST segment changes in STEMI can be explained by the proposed mechanism, and the value of the ST segment changes can be calculated in limb leads. Conclusion: the mechanism of RSTD in acute myocardial infarction is that the negative electrode action potential of the lead was weakened or disappeared, and the positive electrode action potential could not be completely offset, resulting in ST segment depression.