Peak systolic pressure is defined as the peak
pressure during ventricular ejection. In a normal situation this
pressure is equal to the systolic peak pressure in the artery
beyond the semilunar valve. 
The events that occur in the ventricles are simpler in
comparison.
Peak systolic pressure is defined as the peak
pressure during ventricular ejection. In a normal situation this
pressure is equal to the systolic peak pressure in the artery
beyond the semilunar valve.
End
diastolic pressure (EDP) is defined as the pressure in
the ventricle immediately prior to the onset of ventricular
contraction. This is considered to occur at the midpoint in the
QRS complex on the electrocardiogram and does not necessarily
represent the lowest pressure achieved in the ventricle. The
lowest pressure occurs just prior to EDP.