Ortivus AB 410000409 User Manual

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.

S T x

S T y

S T z

ST VM

–

STX2 STY2 STZ2