Chapter 2

Question 1

What are the angles that each lead represents on a lateral plane of the heart?

Answer 1

Question 2

What conclusion can you draw from an EKG about the QRS axis if you notice that lead I or lead aVF is not predominantly positive?

Answer 2

The QRS axis does not lie between 0 and 90 degrees and is not normal.

Remember that positive = signals is going in that leads direction; negative means its directed away from it.

Question 3

What does it mean, in the context of the QRS axis, if you notice that the QRS signal for a lead is biphasic?

Answer 3

The signal is directed ~perpendicular to that lead.

You can determine direction of this perpendicular direction via readings of other leads.

Question 4

What’s the difference between these two?

Answer 4

(A) A hypertrophied left ventricle caused by aortic stenosis. The wall is so thick that the chamber size is actually diminished. “concentric hypertropy”. (B) An enlarged left ventricle. The chamber is bigger, but the wall thickness is normal. “encentric hypertropy”

Question 5

Right ventricular hypertrophy is far less common than left ventricular hypertrophy.

What are some common causes in pts that exhibit RVH?

What kind of QRS axis deviation occurs in these patients?

Answer 5

Severe COPD, congenital heart disease that cause volume/pressure overload of the right ventricle.

We will see a right axis deviation in pts with RVH.

Question 6

What is the normal parameter limits for a P-wave (duration and amplitude)?

Answer 6

0. 12 seconds (<3 small X squares)
1. 5 mV (<2.5 small Y squares)

Question 7

What is right atrial enlargement also known as? Why?

Answer 7

P. pulmonale
because it is most commonly caused by severe lung disease

Question 8

What are the angle ranges of the axis deviations?

Answer 8

Question 9

What are some common signs of RAE on an EKG reading?

Answer 9

Amplitude of P-wave > 2.5 mV in leads II, III, and/or aVF.

There will usually be no change in duration of P-wave in RAE since it is being masked by left atrial depolarization. (This doesn’t mean that right atrial signal isn’t elongated slightly)

Question 10

What is left atrial enlargement also known as? Why?

Answer 10

P. mitral
because it is often cuased by mitral valve disease.

Question 11

What are some common signs of LAE on an EKG reading?

Answer 11

Elongated P-wave duration (>.12 sec or 3 x-blocks) in leads II and V1.

Also, there will be two ‘humps’ in the P-wave and the left P-wave >0.04 sec (1 x-block)

Question 12

What is the diagnostic criteria for right ventricular hypertrophy on an EKG reading?

Answer 12

R-axis deviation >100 degrees.

In otherwards, the lead I QRS wave must be more negative than positive.

Question 13

In a normal EKG, what is the pattern we see as our EKG progresses from V1 to V5?

Answer 13

We should see a progressive increase in the R wave as the leads move closer to the left ventricle.

Question 14

How does RVH effect our V1-V6 readings on an EKG?

Answer 14

In V1, R will be increased ( > S wave).

R wave will be smaller in V5 and V6 (< S wave).

Question 15

What are common indications of LVH on an EKG in the precordial leads V1-V6?

Answer 15

Increased R-wave amplitude in leads overlying the left ventricle. (V5 and V6)

Increased S-wave amplitude in leads overlying the right ventricle. (V1 and V2)

Left axis deviation beyond -15 degrees.

Specific criteria* (more met = better predictor):

1. R wave in V5/V6 plus S wave in V1/V2 exceeds 35 mm in height. (RV5/6+SV1/2 > 35)
2. R wave amplitude in V5 > 26 mm
3. R wave amplitude in V6 > 18 mm
4. R wave amplitude in V6 > R wave amplitude in V5

Question 16

What are common indications of LVH on an EKG in the limb leads?

Answer 16

1. R wave amp in aVL > 13 mm
2. R wave amp in aVF > 21mm
3. R wave amp in lead I > 14 mm
4. R wave amp in lead I + S wave amp in lead III > 25 mm

Question 17

What would you expect to see on an EKG reading if both ventricles are hypertrophied?

Answer 17

It may display a combination of features of RVH and LVH, but usually the efects of the LVH obscures those of the RVH.

Question 18

What are secondary repolarization abnormalities of ventricular hypertrophy?

How do they effect EKG readings?

Answer 18

Secondary traits on an EKG reading that may occur with severe hypertrophy of ventricles.

May hearld the onset of ventricular dilatation and cardiac rest (esp T-wave inversion).

Along with standard criteria for ventricular hypertrophies, we may notice a

>Down sloping ST segment depression

>asymmetric T wave inversion

Question 19

How will secondary repolarization abnormalities of ventricular hypertrophy present in LVH?

In RVH?

Answer 19

LVH: most evident ST down-slope and asymmetric T-wave inversions in leads I, aVL, V5, and V6.

RVH: most evident ST down-slope and asymmetric T-wave inversions in V1 and V2.