Characteristics and mechanism of reciprocal ST-segment depression in acute ST segment elevation myocardial infarction: Reciprocal ST-segment depression and ST segment elevation myocardial infarction.

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.

A new method to determine the QRS axis-QRS axis determination.

BACKGROUND: The development of a perfect method for determining the mean QRS axis (ÂQRS) is still lacking. HYPOTHESIS: We proposed a new simple method, whether this method is accurate is unknown. METHODS: The axis perpendicular to the mean QRS axis (P-ÂQRS) divides six limb leads into two groups. All the leads that are in the range of 180° along the ÂQRS are positive, while all the leads in another 180° are negative, one lead is isodiphasic if it is on the P-ÂQRS. If no lead is isodiphasic, then the P-ÂQRS is located in the middle of two adjacent leads, which can help us determine the P-ÂQRS. The six limb leads that fall in the range of -30° to 120° are as follows: aVL (-30°), I (0°), -aVR (30°), II (60°), aVF (90°), and III (120°). We can check an external lead (aVL or III) first. For example, if lead III is isodiphasic and lead aVF is positive, the P-ÂQRS is 120°; if lead III is negative and lead aVF is positive, then the P-ÂQRS is 105°. If more than one lead is negative, all such leads can be checked individually until a positive or isodiphasic lead is found. The ÂQRS can be easily decided once we know the P-ÂQRS. In total, 200 recorded ECGs were investigated. We obtained the ÂQRS from our new method, computer interpretations, and a standard bipolar method. The Pearson correlation coefficient and Bland-Altman analysis were performed. RESULTS: The mean and SDs were remarkably similar, the correlation coefficient between the P-ÂQRS method and the bipolar method was 0.976 (P < .001). Mean bias (Bland-Altman limits of agreement) between the two methods was 0.885 (-12.37 to 14.14). CONCLUSION: The new method is simple and is able to assess the mean QRS axis accurately.

The epidemiological characteristics of 2019 novel coronavirus diseases (COVID-19) in Jingmen, Hubei, China.

There is currently a global outbreak of coronavirus disease 2019 (COVID-19), and its epidemic characteristics in the areas where the outbreak has been successfully controlled are rarely reported.Describe the epidemic characteristics of COVID-19 in Jingmen, Hubei, introduce the local prevention and control experience, and observe the impact of various prevention and control measures on the number of new cases.All the COVID-19 patients diagnosed in the municipal districts of Jingmen from January 12 to February 29, 2020 were enrolled in this study. We described epidemiological data and observed the impact of control measures on the epidemic.Of the 219 cases (110 men and 109 women), 88 (40%) had exposure to Wuhan. The median age was 48 years (range, 2-88 years; IQR, 35-60). Thirty-three severe patients with a median age of 66 years (range, 33-82 years, IQR, 57-76) were treated in intensive care units; out of these patients, 66.7% (22) were men and 19 (57.5%) had chronic diseases, including hypertension, diabetes, heart failure, stroke, and renal insufficiency. Under the control measures, the number of new patients gradually decreased and nearly disappeared after 18 days. Wearing masks in all kinds of situations prevents most infections and is one of the most effective prevention and control measures.In conclusion, all people are susceptible to COVID-19, and older males and those with comorbid conditions are more likely to become severe cases. Even though COVID-19 is highly contagious, control measures have proven to be very effective, particularly wearing masks, which could prevent most infections.