Ortivus AB 410000409 Manual Do Utilizador
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10 Appendix
ST-Vector magnitude (ST-VM)
By measuring the ST-deviation in X-, Y- and Z-leads the ST-vector can
be calculated.
ST-VM is calculated by Pythagorean thesis:
ST-VM is always a positive value and shows if an ST-alteration is
present; it will not show if there is an ST-depression or an ST-elevation,
only if there is an alteration in one or more leads. ST-VM will show the
occurrence of ischemia/ST-change, but not the location.
QRS-Vector difference (QRS-VD)
With QRS-VD changes of the QRS-complex are measured. If the QRS-
complex is changed, e.g. during infarction or ischemia, this is displayed
as an increase of the QRS-VD on the trend curve. QRS-VD is measured
by comparing the reference complex with present complex. The
difference between them can be described as an area, which is propor-
tional to the change. If the patient has an ongoing infarction the
amplitude of the QRS-complex will gradually be reduced, a Q-wave or
a QS-complex can arise as a result from the infarction. This change is
displayed by QRS-VD as an increasing value.
X
Y
Z
S T x
S T y
S T z
ST VM
–
STX2 STY2 STZ2
+
+
=