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UT (Upstroke Time)
This is the time from the start of the pulse wave to its peak. However, for measurement in the
carotid artery, this is the time from the start of the pulse wave to the peak of the ejected wave or the
start point of the reflected wave.
Ejected wave
Reflected wave
In a pulse wave in a carotid artery,
the ejected wave and the reflected wave each form humps near the peak of the wave.
When the ejected wave is higher than the reflected wave,
the time until the peak of the ejected wave is the UT.
When the reflected wave is higher than the ejected wave,
the time until the start of the reflected wave is the UT.
ET (Ejection Time)
This index evaluates cardiac function based on the time from the opening to the closing of the
aortic valve. The normal range is 285 ±25 msec, however, this is affected by the heart rate.
PEP (Pre-Ejection Period)
The time between electrical agitation in the heart chamber and the opening of the aortic valve. The
normal range is 96 ±10 msec. The value becomes greater as cardiac function deteriorates.
ET/PEP (Ejection Index)
This index is calculated from the ET (Ejection Time) and PEP (Pre-Ejection Period). Correlations
with left ventricular end-diastolic volume and pressure (LVEDV, LVEDP), ejection efficiency (EF),
stroke volume (SV), and cardiac muscle contraction speed (VCF) can also be indicated.
This index can be expressed in the form ET/PEP or in the form PEP/ET.
Q-II (Overall control period)
The time from the start of the Q wave to the closing of the aortic valve (II sound) in an
electrocardiogram.
STI (Systolic Time Interval)
ET and PEP are generally called STI and are used for quantitative evaluation of cardiac functions.
5-10. Explanation of Technical Terms
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