ECG

Question 1

Problem in QRS segments means there is a problem in which part of the heart?

Answer 1

ventricle

Question 2

what does PR interval measure?
how is it measured + normal range

Answer 2

• Measures AV conduction time transmitting impulse from SA node via AC node to bundle of His immediately before onset of ventricular depolarisation
• 0.12-0.2 sec (3-5 small squares)

Question 3

P wave represents:
Produced by:
normal width & height

Answer 3

• Atrial depolarisation
• produced by SA node and spread of depolarisation through Right Atrium then Left Atrium
  0.06-0.12 second in width; 2-2.5mm in height

Question 4

what does QRS complex represent?
normal range

Answer 4

Represents ventricular depolarisation
normal range 0.06-0.1 sec

Question 5

What does ST segment represent?
how to measure + reference potential

Answer 5

• Represents the end of ventricular depolarisation and beginning of ventricular repolarisation
• extends from end of S wave to beginning of T wave
• zero reference potential

Question 6

What is first degree heart block?

Answer 6

A delay between SA node & ventricles, prolonged PR interval
may be a sign of coronary heart disease

Question 7

What is second degree heart block?
what are the 3 types?

Answer 7

Excitation completely fails to pass through the AV node/ bundle of His, this happens intermittently
1. Mobitz type 2
2. Wenckebach phenomenon
3. 2:1 type

Question 8

what is Mobitz type 2?

Answer 8

A type of second degree heart block
occasional atrial contraction without a subsequent ventricular contraction
(P wave not followed by QRS complex)

Question 9

what is Wenckebach phenomenon?

Answer 9

Progressive lengthening of PR interval then failure of conduction of atrial beat,
followed by a conducted beat with a shorter PR interval, then repeat cycle

Question 10

what is 2:1 type?

Answer 10

1 conducted atrial beat then one non conducted beat
–> 2 P waves : 1 QRS complex

Question 11

What is 3rd degree heart block and what to do when discovered?

Answer 11

normal atrial contraction but no beats are conducted to ventricles
(SA node no problem - P regular; P & R waves have no relationship)

Patient requires pacemaker immediately

Question 12

Describe right bundle branch block

Answer 12

no conduction down the right bundle branch of bundle of His
septum depolarized as usual (from left to right), but takes longer to spread excitation to right ventricle

Question 13

Describe left bundle branch block

Answer 13

septum depolarized from right to left

Question 14

Definition of arrythmia

Answer 14

any change from normal sequence of electrical impulses
rhythm is not generated from SA node