A collapse of Einthoven’s triangle such that the lead lines meet at a single point gives rise to the triaxial lead system

What is the triaxial lead system?

Positive = The labeled end

Negative = Reference end

Negative = Reference end

What are the positive and negative ends of leads called?

With their origins at the center of the lead system.

I = Left arm

2 = Left leg

3 = Right arm

I = Left arm

2 = Left leg

3 = Right arm

How are cardiac vectors positioned in the Triaxial lead system?

I + III = II

What is Einthoven’s law?

The mean axis of all electrical vectors in the frontal plane; the normal mean vector of the QRS complex in the frontal plane is between -30 degrees and +90 degrees

What is the mean electrical vector in the frontal plane?

Between -30 and + 90 degrees

An example of a normal axis

Outside of the -30 to +90 degree range

An example of axis deviation

The vector will be shifted right.

How is a vector shifted if there is a conduction delay in the right ventricle?

It uses augmented (unipolar) limb leads.

• aVR = RA(+) @ -150, LA and LL(-)

• aVL = LA(+) @ -30, RA and LL(-)

• aVF = LL(+) @ +90, RA and LA(-)

What is the hexaxial lead system?

Describe the electrode placement.

Describe the electrode placement.

The lead with zero NET voltage is identified.

The mean vector is then perpendicular to the lead with zero net voltage.

The mean vector is then perpendicular to the lead with zero net voltage.

What is the null method?

How is the direction of a vector determined with it?

How is the direction of a vector determined with it?

A lead with zero NET voltage.

What is a biphasic lead?

What does a slightly net negative vector from a biphasic Lead I look like?

What does a slightly net positive vector from a biphasic Lead I look like?

Identify:

c) -60 Left axis deviation

d) +75 Normal

c) -60 Left axis deviation

d) +75 Normal