ECG

Question 1

Describe what each wave does in one ECG heart beat.

Answer 1

i) p wave = atrial depolarization.
ii) QRS complex = ventricular depolarization.
iii) T wave = ventricular repolarization.

Question 2

Name two way to determine HR on ECG.

Answer 2

i) Six Second Rule (30 blocks): # of beats in 6s X 10.

ii) Block Rule: 300/150/100/75/60/50 at each subsequent block apart. May use RR or PP.

Question 3

What would the ECG of a PAC look like?

Answer 3

i) absent or irregular p wave
ii) followed by normal QRS
iii) followed by delay until next beat

Question 4

Name 3 causes of PAC?

Answer 4

i) caffiene
ii) stress
iii) heart disease

Question 5

What a PJC (originates in AV node) look like on ECG? Name 2 causes.

Answer 5

i) absent, abnormal or retrograde p wave
ii) normal QRS
iii) followed by a pause
Causes: MI, drug toxicity

Question 6

What would the ECG of a PVC look like?

Answer 6

i) absent p wave
ii) wide and bizarre QRS
iii) t wave MAY be inverted
Note: often occur in bigeminy and trigeminy

Question 7

How is HR affected by respiration on ECG?

Answer 7

Elongated RR interval during expiration.

Question 8

How would atrial flutter present on ECG?

Answer 8

i) p waves in saw tooth pattern (220-350)

ii) AV node has its own refractory period so RR intervals would be 100-150 bpm.

Question 9

How would atrial fib present on ECG?

Answer 9

i) continuous multifocal firing (350-650)

Note: atria do not contract, but quiver.

Question 10

How would ventricular tachycardia present on ECG?

Answer 10

i) > or = 3 PVCs in a row (trigeminy)

ii) >100bpm

Question 11

How would v-fib present on ECG?

Answer 11

i) rapid, multifocal firing (120-500)

ii) irregular, rapid, no normal shapes.

Question 12

What is a 1st degree heart block and how would it present on ECG?

Answer 12

Prolonged AV node conduction.

i) Prolonged PR interval (>0.2s)
ii) normal or slightly bradycardic

Question 13

What is a 2nd degree heart block and how would it present on ECG?

Answer 13

MORBITZ I:
Block occurs transiently at AV node
i) PR lengthens until totally blocked and missed beat.
MORBITZ II:
Block occurs in Bundle of His below AV node.
i) 2-3 p waves per QRS
ii) occasional dropped beats and mildly bradcardic

Question 14

What is a 3rd degree heart block and how would it present on ECG?

Answer 14

Complete block/dissociation at AV node, Bundle of His OR bundle branches.
i) absolute ventricular bradycardia
ii) independent atrial and ventricular rhythms.
Note in bundle branch blocks QRS is longer.

Question 15

List the dangerous rhythyms found on ECG.

Answer 15

i) V-fib
ii) V-tachy
iii) 3rd degree heart block
iv) >2 PVCs in a row of >/= 5 per minute.
v) sinus arrest

Question 16

What would an MI look like on ECG?

Answer 16

i) elevated or depressed ST segment indicated ischemia and injury.
ii) inverted t wave
iii) eventual sinus arrest.