ZOLL M Series Defibrillator Rev H - Manual (Page 13)

12-lead
9650-0215-01 12-lead - 11
12SL Wave Measurement
After the P, QRS, and T complexes have been demarcated, the
waves for each complex are identified. This is done separately
for each lead. The program finds the points at which the signal
crosses the baseline within each complex. If the crossing points
define a wave that has an area greater than or equal to 160
µV/ms, the wave is considered to be significant. If the area is
less than this value, the program considers the wave to be
insignificant, and it will not label it as a separate wave. The
measurement matrix contains the amplitudes (with respect to
QRS onset) and durations of all of these individual waves.
Reviewing an ECG
WARNING
All computerized ECG analysis results must be reviewed by a
physician before they are used to determine patient treatment.
ECG data can be viewed in three different ways:
1. ECG Strip: Displays a 12-lead strip of 10 seconds of
ECG snippettes, in four staggered 2.5 second segments.
For more information, see “4x3 Format” in the “12-lead
Summary Reports” section of this insert.
2. Interpretation: Displays the results of interpretation of the
ECG recording by the 12SL program.
3. Measurements: Measurements are displayed based on all
12-leads.
The global measurements include heart rate, PR Interval, QRS
duration, QT & QTc, P axis, QRS axis, and T axis.
Heart Rate: frequency in beats per minute. Normal range is
60-100.
PR Interval: time between beginning of P wave and beginning
of QRS complex. Sometimes referred to as PQ duration.
Smaller values indicate premature excitation of the ventriculars,
larger values indicate conduction defects in the atrioventricular
(AV) node.
QRS Duration: duration of the QRS complex in milliseconds.
Larger values indicate ventricular conduction defects.
QT, QTc Duration: time in milliseconds from beginning of QRS
complex to end of T wave. The QTc value is QT corrected for
heart rate to estimate the value it would have been if the heart
rate were 60 bpm. Abnormal values can be due to electrolyte
imbalances or drugs: short QT due to hyperkalaemia; long QT
due to hypocalcemia or quinidine-like drugs (procainamide,
amiodarone).
P-axis: axis of P wave in degrees.
QRS axis: axis of the QRS complex. Smaller than -30 is called
left axis deviation, larger than 90 is right axis deviation.
Deviations can be due to conduction blocks or hypertrophy.
T-axis: axis of the T-wave.
Following the global measurements is a table of lead-specific
measurements for the standard 12-leads.
Next are amplitudes of individual waves and segments:
PA, PPA: minimum and maximum values of P wave
QA, RA, SA: absolute amplitude of the indicated wave
STJ: ST level at J-point
STM, STE: ST level at the middle and end point of the
S wave.
TA, TPA: minimum and maximum values of T wave.
All amplitudes are in µV (microvolts) or mm (at 10mm/mV)
depending on the setup. Next are durations of individual waves
and segments:
QD, RD, SD: duration of the indicated wave in ms.
RPA, RPD, SPA: These measurements reflect the amplitude
(RPA & SPA) and duration (RPD) of secondary R and S waves
that may appear with RSR patterns such as right or left bundle
branch block.
For interpretation of these results refer to the 12SL
ECG Analysis Program Physicians Guide (ZOLL P/N
3001-0203).