2. 2
Vectorial Analysis
A Vector is an arrow such that:
• it points in the direction of the electrical
potential generated by current flow
• the arrowhead is in the positive direction,
• the length of the arrow is proportional to the
voltage of the potential
3. 3
Instantaneous Mean Vector
The summated
vector of the
generated potential
at any given instance
is the Instantaneous
Mean Vector
(IMV)
9. 9
Correlation Of Recorded Voltage
And Axis Of The IMV
• When the Instantaneous Mean Vector is
almost perpendicular to the axis of the lead,
the voltage recorded in that lead is very low.
• When the Instantaneous Mean Vector is
almost parallel to the axis of the lead, the
voltage recorded in that lead will be almost
the same as the vector.
25. 25
Increased Voltage
• When the sum of the
voltages of the QRS
complexes in standard
limb leads exceeds 4.0
mV., the patient is said
to have high voltage
EKG.
• Usually seen in
muscular hypertrophy.
LVH
RVH
27. 27
Current of Injury
• A damaged part of the heart tends to remain
partially or totally depolarized (outside is
negative) all the time.
• The current will therefore flow from the
pathologically depolarized part to the
normally polarized part even between
heartbeats.
This is called the Current of Injury
When a heart becomes damaged a heart loses its capacity to repolarize, so once it becomes depolarized it remains depolarized. It displays a steady negative charge in the area. (NO CURRENT FLOW)
As in a normal heart there is no current flow as the area is uniformly negative.
In current of injury we will see a current flowing at the “TP” segment
If current is flowing towards the positive electrode we have a positive deflection
If current is flowing away from the positive electrode we have a negative deflection
“J” point is the location on the ECG when the QRS complex is completed
If the QRS complex is broadened the t-wave is inverted
