ECG Interpretation

Question 1

How do you know if someone has hypertrophy? Where would you likely see this?

Answer 1

Left Ventricule!

Sum of S wave in V1 and R wave in V5 = >35 mm

Called Left Ventricular Hypertrophy

Question 2

What is ischemia?
How does ischemia occur?
How would you be able to read it on an ECG?

Answer 2

Ischemia: reduced blood supply to myocardium
Occurs due to occulsion of coronary arteries
ECG: ST Depression and T wave that is flat or inverted

Question 3

How do you determine if someone has just had injury done to their heart?

Answer 3

• Signified by ST Segment Elevation
• Only see in acute case of infarction
• Return to baseline within 24-48 hours

Question 4

What is infarction and what does it look like on an ECG?

Answer 4

• Infarction: cell death due to occlusion of coronary arteries
• ECG: Significant Q waves (> 1 small box; 0.33 height of QRS); Long Q wave due to the electrical impulse having to go around the damaged portion of the heart.

Question 5

What leads of the heart can you see injury and infarction?

Answer 5

Inferior Leads: II, III, aVF
Lateral Leads: I, aVL, V5
Anterior Leads: V1, V2, V3, V4

Question 6

Why do we normallt read Lead II?

Answer 6

Mean QRS vector points leftward and inferiorly (follows electrical pulse direction)

Question 7

Normal QRS axis lies between

Answer 7

+90 and 0 degrees

QRS comples is + in leads I and AVF

Question 8

What would indicate left axis deviation? What causes it?

Answer 8

+ QRS Lead I and - QRS aVF lead

Axis lies between 0 to -90 degrees

Causes:
- Hyperkalemia
- Wolf Parkinson White Syndrome - Right Sided Accessory Pathway (WPW)

Question 9

What would indicate right sided deviation?
What would cause it?

Answer 9

• • QRS lead I and + QRS AVF lead
• Axis lies between +90 to +180
• Causes:
  Right Ventricular Hypertrophy
  MI
  PE
  Wolff-Parkinson-White Syndrome - Left Sided Accessory Pathway
  Atrial or Ventricular Septal Defect
  Normal finding in children

Question 10

What would indicate extreme right axis deviation?
What causes it?

Answer 10

• • QRS lead I and - QRS aVF lead
• Axis lies between +180 to -90 degrees
• Causes
  Emphysema
  Ventricular Tachycardia
  Hyperkalemia

Question 11

If a right bundle branch is blocked, what happens?

Answer 11

• Right Ventricule depolarization is prolonged (delayed)
• QRS >.12 sec
• RSR V1 (R prime)
• Wide S in V6

Question 12

If a left bundle branch is blocked, what happens?

Answer 12

• Left ventricle depolarization is delayed
• QRS is wide >0.12 sec
• Broad OR notched R wave V1 and V6

Question 13

What does Wolff-Parkinson-White Syndrome look like?

Answer 13

• Between the P wave and QRS; Slow up which is called a Delta T wave
• Accessory Pathway meaning alternate; surgeons have to fo in and kill some of the tissue to get scarring over so it doesn’t fire.