Electrocardiograms PCM and Newman

Question 1

What are the Lateral Leads?

• what artery does this correspond to?

Answer 1

I, aVL, V5, V6

• Circumflex Artery

Question 2

What are the Inferior Leads?

• what artery does this correspond to?

Answer 2

II, III, aVF

• Right Coronary

Question 3

What are the Left Anterior Descending Leads?

Answer 3

V1, V2 Septal/Anterior Leads

• Left Anterior Descending Coronary

Question 4

What are the 2 major causes of QRS widening?

Answer 4

• Bundle Branch Block

* Ventricular Origin of Beat

Question 5

How would you differentiate between the 2 major causes of QRS widening?

Answer 5

Bundle Branch Block will have RABBIT EARS in V2 and V3, you will also still have a P wave in BBB

• Ventricular Origin of Beat = no rabbit ears

Question 6

What are 2 possibilities for pathology if you see a P wave before a widened QRS?

Answer 6

• BBB (bundle branch block) or 3rd degree heart block

Question 7

What causes the Rabbit Ear Appearance on EKG?

Answer 7

Right and Left Ventricle are depolarizing at different times so you have 2 QRS complexes Overlapping

Question 8

How do you determine between a Right or Left Bundle Branch Block?

Answer 8

Right Bundle Branch
• Rabbit ears in V1 or V2 (septal electrodes)

Left Bundle Branch
• Rabbit ears in V5 or V6

Question 9

What if you take an EKG on a patient that comes in with chest pain and its normal, then 30 minutes later you re-do the EKG and see Rabbit ears in V5 or V6?

Answer 9

• the Patient has had a STEMI

Question 10

What if QRS is widened but you don’t see any other abnormalities?

Answer 10

• Intraventricular Conduction Delay (IVCD)

Question 11

What is commonly seen on the EKG in ischemia?

Answer 11

• ST segment Depression (2 little boxes down)

* T wave inversion

Question 12

What is commonly seen on the EKG with Injury rather than ISCHEMIA?

Answer 12

• ST ELEVATION (not depression like with ischemia)
• T wave HYPERTROPHY (not inversion with ischemia)

If you see T go all the way until it becomes flat then comes back down this is called Tombstone T waves

Question 13

How can you tell ST elevation in a healthy individual from one in someone that was having an MI?

Answer 13

In II you will see a wave with a DOWNWARD convexity (frowning)

Question 14

What do you see in actual INFARCTION?

Answer 14

• HUGE Q WAVES that are 1/3 size of the overall QRS complex

Question 15

What is the most important factor to take into account anytime your looking at an ECG?

Answer 15

Clinical Context

Question 16

How do you find rate off of an ECG?

Answer 16

300 / (Number of LARGE boxes between QRS)

Question 17

How do you determine sinus rhythm?

Answer 17

1. Look in lead II and Make sure P-wave is upright
2. Find Rate (less than 60 = brady, greater than 150 = tachy)

**Sinus arrythmia between 60 and 100 is normal

Question 18

What are some reasons that you might have a NARROW QRS complex in a SUPRAVENTICULAR rhythm?

Answer 18

• Atrial Fibrillation (irregularly irregular)
• Atrial Flutter (irregularly irregular)
• PSVT (paroxysmal supraventricular tachycardia)

Question 19

How differentiate atrial and ventricular rhythms?

Answer 19

Atrial Rhythm = Narrow QRS complex

Ventricular Rhythm = Wide QRS complex (greater than or equal to 120 msec)

Question 20

What characterizes Ventricular Tachycardia?

• Fibrillation

Answer 20

• A wide QRS with a rate greater than 120

* Fibrillation has no organization to it

Question 21

What is the PR interval most useful for?

Answer 21

*Key to determining 1st, 2nd, or 3rd degree (Mobitz) atrioventricular block

Question 22

What happens in Mobitz type I?

Answer 22

PR interval gradually increases until the QRS is dropped

Question 23

What happens in Mobitz type II?

Answer 23

PR interval is CONSTANT but the QRS complex is still dropped

Question 24

What happens in Mobitz type III?

Answer 24

Atrial and Venticular Rhythms are completely independent of each other

Question 25

What is the QRS interval useful for that the PR interval isn’t?

Answer 25

PR - good to determine heart Block

QRS - good to determine BUNDLE block

Question 26

What are some possible problems that could cause the QRS interval to exceed 120?

Answer 26

• Bundle Branch Block
• Abnormal Ventricular Beat (like PVC)
• Ventricular Rhythm

Question 27

What does a prolonged QT interval tell you?

• how long should the QT interval be?

Answer 27

That there is a Delay in Repolarization

• QT interval should be less than half of the RR interval (at normal rates btwn 60 and 100)

Question 28

How does ischemia typically show up on an ECG?

Answer 28

ST depression and/or T-wave inversion

Question 29

How does Injury typically show up on an ECG?

Answer 29

ST-elevation or Tombstone T waves

Question 30

How does infarct show up on an ECG?

Answer 30

Q waves are a minimum of one small box wide and are 1/4 to 1/3 height of R waves (BIG Q waves)

Question 31

Where would you expect an infarct of LAD to show up?

Answer 31

V1-V4 - this makes sense because LAD supplies the Left Ventricle which makes up most of the front wall of the heart

Question 32

Where would you expect an RCA infarct to show up?

Answer 32

II, III, and aVF - these are the inferior nodes and the bottom/back part of the heart is mostly Right Atria supplied by the RCA

Question 33

Where would you expect an Circumflex infarct to show up?

Answer 33

I and aVL