A new point on ECG: point L as identifier of rapid and slow ejection phases boundary

Aims Description of rapid and slow ejection phases in the cardiac cycle. Materials and methods The theory of cardiac cycle phase analysis and mathematical equations of hemodynamics were used in the paper. The equations were employed to verify the balance of the phase-related diastolic and systolic blood volumes reliant on phase durations, and the identification of boundaries of the cardiac cycle phases on the ECG. Further, synchronous ECG & RHEO recording was used. Aortic blood filling was studied in the stated phases. Results The location of boundaries of rapid and slow ejection phases is traced. The boundaries did not have a precise definition before. Thus, a new symbol, the L point, on the ECG has been introduced to identify the boundaries of phases S - L, L - j. Conclusion Previously the location of point j on the ECG was impossible to identify. It was considered as a hypothermic wave on the ECG that could not always be traced. Point j was defined as the j (Osborn) wave. Thereby the location of boundaries of rapid and slow ejection phases, where volumetric parameters were equal to the stroke volume, was not accurately identified. The research enabled detecting the ECG recording criteria of the rapid and slow ejection phases. The results of the present research are published for the first time.