ECG Interpretation

Question 1

What does an ECG do?

Answer 1

Records electrical activity of the heart from the skin.

• first line investigation for chest pain, palpitations or blackouts

Question 2

Systematic approach to ECG (1)

1. Before you get to traces:
   - always ask for c_____ c_____
   - check date/time/patient
   - assess technical quality (_______ [outside interference], speed, gain)

Answer 2

Systematic approach to ECG (1)

1. Before you get to traces:
   - always ask for clinical context
   - check date/time/patient
   - assess technical quality (artefact [outside interference], speed, gain)

Question 3

Systematic approach to ECG (2)

2. Look at _____ ___ (bottom one usually):
   - check QRS rate
   - Identify _, ___, _ and determine rhythm

Answer 3

Systematic approach to ECG (2)

2. Look at rhythm strip (bottom one usually):
   - check QRS rate
   - Identify P, QRS, T and determine rhythm

Question 4

Systematic approach to ECG (3)

3. Look at the ____ ____:
   - determine the ___ ____ (i.e. the direction the ___ current flows)

Answer 4

Systematic approach to ECG (3)

3. Look at the limb leads:
   - determine the QRS axis (i.e. the direction the QRS current flows)

Question 5

Systematic approach to ECG (4)

4. Look across all leads:
   - _, ___, _ morphology/shape

Answer 5

Systematic approach to ECG (4)

4. Look across all leads:
   - P, QRS, T morphology/shape

Question 6

Do not rely on:
_ or _

It is [[not helpful / very helpful]] to look at old ECGs

Answer 6

Do not rely on:
Scribbles or automatic interpretation

It is very helpful to look at old ECGs

Question 7

Determining heart rate:

___ divided by number of large squares between each QRS
(e.g. 1 square = ___/min, 2 = ___/min, 3 = ___/min, 4 = __/min, 5 = __/min, 6 = __/min)

OR

number of QRS complexes across the ECG (which is __sec) multiplied by _.

Answer 7

Determining heart rate:

300 divided by number of large squares between each QRS
(e.g. 1 square = 300/min, 2 = 150/min, 3 = 100/min, 4 = 75/min, 5 = 60/min, 6 = 50/min)

OR

number of QRS complexes across the ECG (which is 10sec) multiplied by 6.

Question 8

Normal time ranges

Match the following interval to the appropriate time.

• PR interval
• QRS
• QT interval
  (good pic showing these in lecture (slide11) )
• <11 small squares (<440ms)
• <3 small squares (<120ms)
• <1 large square/5 small (<200ms)

Answer 8

Normal time ranges

• PR interval
• <1 large square/5 small (<200ms)
• QRS
• <3 small squares (<120ms)
• QT interval
• <11 small squares (<440ms)

Question 9

The only way to narrow a QRS complex is for the atrial-ventricular conduction to use a normal ___-_______ system

Answer 9

His-Purkinje

pic in lecture (slide 13)

Question 10

5 important questions to ask to determine rhythm

1. What is the QRS ___?
2. Are the QRS complexes ______?
3. Is the QRS _____ or ______?
4. Are there _ waves?
5. What is the _:___ relation?

Answer 10

5 important questions to ask to determine rhythm

1. What is the QRS rate?
2. Are the QRS complexes regular?
3. Is the QRS broad or narrow?
4. Are there P waves?
5. What is the P:QRS relation?

Question 11

Normal P/QRS/T morphology:

• Normal P wave is [[postive / negative]] in _______ leads
• Normal ST segment is ___
• Normal T wave has the same ______ (on same side) as the ___

Answer 11

Normal P/QRS/T morphology:

• Normal P wave is positive in inferior leads
• Normal ST segment is flat
• Normal T wave has the same polarity (on same side) as the QRS