Measurements; Heart Rate (Hr); Intervals - Welch Allyn AT-1 Manual

Measurements

Note: This section gives the measurements that are calculated by the AT-1 software.

Heart Rate (HR)

Average heart rate (HR) calculated on the basis of the entire 10 second recording and shown as number of beats per
minute.

Intervals

Parameter
RR
P
PQ
QRS
QT
QTC
Description
Average time interval between two consecutive QRS complexes.
Duration of the P wave (of averaged ECG complexes)
P-Q interval: the period of time between the beginning of the P wave and the beginning of the QRS
complex (of averaged ECG complexes)
The duration of the QRS complex from the beginning of the Q wave to the end of the S wave ( of
averaged ECG complexes)
Interval between the beginning of the QRS (beginning of ventricular depolarisation) and the end of the
T wave (end of repolarisation phase) ( of averaged ECG complexes)
Normalised QT interval. As the QT interval is dependent on the heart rate, it is often converted to the
normalised QTC interval i.e. the QT the patient would show at a heart rate of 60 / min. Usually, the
QTC amounts to 390 + 40 ms.
The conversion is according to Bazetts` formula :
1000
QTC = QT x
RR
AT-1 User Guide Art. No. 2. 510 270
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