12 ECGs 2- Recognising common abnormalities

Question 1

What are the different types of heart block?

Answer 1

• First degree
• Second degree
  
  • Mobitz Type 1
  • Mobitz Type 2
• Third degree (complete heartblock)

Question 2

What is heart block?

Answer 2

Delay/failure in conduction of impulses from atrium to ventricles via AV node and bundle of his

Question 3

What are the 2 main causes of heart block?

Answer 3

1. Acute MI
2. Degenerative changes

Question 4

Differentiate between the different types of heart block (how do they appear on the ECG?

Answer 4

1. First degree
   
   1. PR interval= prolonged (>5 small boxes)
2. Second degree
   
   1. Mobitz type 1 (aka Wenkebach)
      
      1. Successively longer PR intervals until 1 QRS dropped- then cycle starts again
   2. Mobitz type 2
      
      1. PR intervals do not lengthen but suddenly drop QRS- high risk of progression to complete heart block
3. Third Degree
   
   1. ​Wide QRS
   2. PR interval=Abnormal but normal sinus rate
      
      1. Ventricular pacemaker takes over

Question 5

What can be seen on an ECG if there is bundle branch block?

Answer 5

• P wave normal
• PR interval normal
• Wide QRS complex

Question 6

How will the ECG appear in atrial fibrillation?

Answer 6

No p waves, just wavy baseline

Narrow QRS complex

Irregular R-R intervals

Question 7

How will the ECG appear if there are ventricular ectopic beats?

Answer 7

Wide QRS complex

Unusual in shape

Question 8

What does ventricular tachycardia look like and why is it dangerous?

Answer 8

High risk- ventricular fibrillation

Question 9

How does ventricular fibrillation appear on an ECG?

Answer 9

Question 10

In which leads would we be able see ischaemia/damage in the following arteries:

• Right coronary
• Left anterior descending
• Circumflex

Answer 10

Question 11

How could a blood test differentiate between myocardial infarction and ischaemia?

Answer 11

Ischaemia- no muscle necrosis- NO TROPONIN

Myocardial infarction- muscle necrosis- TROPONIN

Question 12

What causes a STEMI?

Answer 12

Complete occlusion of coronary artery by thrombus

Question 13

How would we identify a pathological Q wave?

Answer 13

Question 14

How would a NSTEMI present on an ECG?

Answer 14

Question 15

How can you differentiate between severe ischaemia and N-STEMI?

Answer 15

Blood test for myocyte necrosis

TROPONIN

Question 16

What ECG signs do you see with hyperkalaemia?

Answer 16

Question 17

What ECG changes would you see for stable angina?

Answer 17

ST depression during exercise

(taken whilst patient= running on treadmill)

Question 18

Useful info on causes of abnormalities on ECG:

Answer 18