The Exact Definition of the Boundary between the Rapid and Slow Ejection Phases on ECGs and Accurate Location of the j Point

The aim of the study was to describe the boundary between the phases of rapid and slow ejection in the cardiac cycle and to define the exact location of the j point on ECGs. MATERIALS AND METHODS. The work is based on the theory of heart cycle phase analysis using mathematical equations of hemodynamics. The balance of phase diastolic and systolic blood volumes depending on the duration of the cardiac cycle phases has been verified by these equations. The interrelation of phase duration and phase blood volumes was employed to exactly define the cardiac cycle boundaries on ECGs. Synchronous recording of the ECG and rheogram was used to determine the precise location of the j point. RESULTS. The exact boundary between the phases of rapid and slow ejection has been defined. A new point L determining the boundary between SL–Lj phases was introduced for its designation. CONCLUSION. The j point was previously considered to be part of an ECG depending on the body temperature and which does not always appear. It had an ambiguous definition: Osborn wave or j wave. At the same time, the precise boundary between the rapid and slow ejection phases, the blood volumes of which in the total amount are equal to the blood stroke volume, has not been identified exactly. The work performed allows for accurate definition of criteria for recording rapid and slow ejection phases and j point location on the ECG.