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Introduction: The accuracy of surface ECG algorithms for predicting the origin of outflow tract ventricular arrhythmias (OT‐VAs) might be questioned. Intracardiac electrograms recorded at anatomic landmarks could provide new predictive insights. We aim to evaluate the efficacy of a novel criterion utilizing the activation pattern of the coronary sinus (CS) in localizing OT‐VAs, including VAs originating from the right ventricular outflow tract (RVOT), endocardial left ventricular outflow tract (Endo‐LVOT), and epicardial left ventricular outflow tract (Epi‐LVOT). Methods: We measured the ventricular activation time of the mitral annulus (MA) from the onset of the earliest QRS complex of VAs to the initial deflection over the isoelectric line at local signals, namely the QRS‐MA interval. The activation at 3 and 12 o'clock of the MA was recorded as the QRS‐MA3 and QRS‐MA12 intervals, respectively. Their predictive values were compared to previous ECG algorithms. Results: A total of 68 patients with OT‐VAs were enrolled (51 for development and 17 for validation). From early to late, the ventricular activation sequences at MA12 were as follows: Epi‐LVOT, Endo‐LVOT, and RVOT. In LBBB morphology OT‐VAs, the QRS‐MA12 interval was significantly earlier for LVOT origins than RVOT origins. In the combined cohort of development and validation cohort, a cut‐off value of ≤10 ms predicted the LVOT origin with a sensitivity of 100% and specificity of 78%. The QRS‐MA12 interval ≤ −24 ms additionally predicted epicardial LVOT sites of origin. Conclusions: The QRS‐MA interval could accurately differentiate the OT‐VAs localization. [ABSTRACT FROM AUTHOR]

In view of the limitations of several existing stress measurement methods under extremely high stress conditions (stress − strength ratio σ / R c > 0.5), this paper proposes a slot relief method based on partial deformation recovery to measure rock mass surface stress under extremely high stress conditions and justifies its viability with the help of an infinite element model. This method is then used to measure and study a research tunnel in West China's Jinping II Hydropower Station, where the maximum stress measured reached 80 MPa. In the process of measurement, this method needs neither complete borehole core nor ultrahigh pressure equipment. On the contrary, the test equipment is easy to carry and operate on, suitable for rock mass surface stress measurement under extremely high stress conditions, and able to provide in situ stress measurements for cavern rockburst prevention and slope management. [ABSTRACT FROM AUTHOR]