(cardioresp) ecgs & rhythm disturbances

Question 1

name the 6 limb leads

Answer 1

lead I
lead II
lead III
aVR
aVL
aVF

Question 2

what is the angle of lead I?

Answer 2

0 degrees

Question 3

what is the angle of lead II?

Answer 3

+60 degrees

Question 4

what is the angle of lead III?

Answer 4

+120 degrees

Question 5

what is the angle of lead aVF?

Answer 5

+90 degrees

Question 6

what is the angle of lead aVR?

Answer 6

-150 degrees

bit random, excluded from the ECG artery territories

Question 7

what is the angle of lead aVL?

Answer 7

-30 degrees

Question 8

what is the normal cardiac axis?

Answer 8

-30 to 90 degrees

Question 9

what is left axis deviation?

Answer 9

between -30 to -90 degrees

Question 10

what is right axis deviation?

Answer 10

between 90 to 180 degrees

Question 11

which leads are compared to work out cardiac axis?

Answer 11

!! perpendicular !! leads

• lead I + aVF
• lead II + aVL
• lead III + aVR

Question 12

give two reasons why the heart would deviate from normal axis further to the right

Answer 12

1) increased muscle density on the right = right ventricular hypertrophy
2) infarction on the left (more disabled muscle = less healthy muscle on right)

Question 13

why does COPD cause right ventricular hypertrophy?

Answer 13

COPD
= reduced lung ventilation
= reduced pO2
= regional vasoconstriction (hypoxic pulmonary vasoconstriction)
= increased pulmonary blood pressure
= the heart has to eject blood against a higher pressure

(hypoxic pulmonary vasoconstriction (HPV) is a homeostatic mechanism that is intrinsic to the pulmonary vasculature - normally hypoxia would cause vasodilation)

Question 14

why is cardiac axis important?

Answer 14

tells us about the functional myocardium

Question 15

how is an ECG reported?

Answer 15

1) rate & rhythm
2) P wave (presence, duration, P:QRS ratio)
3) P-R interval
4) QRS complex (duration)
5) S-T segment (elevation/depression)
6) T wave (duration, QT)

Question 16

what does ST elevation in leads II, III and aVF indicate?

Answer 16

obstruction of RCA leading to a ST-elevated myocardial infarction (STEMI)

Question 17

what does third-degree heart block look like on an ECG?

Answer 17

1) regular P waves and QRS complex (may not be in normal amounts)
2) no relationship bw P waves and QRS complexes
3) some P waves may be hidden in bigger vectors (!!! - classic, tell-tale sign)

Question 18

what is characteristic of P waves in third-degree heart block on an ECG?

Answer 18

some P waves may be hidden in bigger vectors

when the line should be isoelectric but is not

Question 19

what is a coronary angiogram and when is it done?

Answer 19

using X-ray imaging to study coronary vessels

by injecting a dye into them

Question 20

for an individual with ST elevation in leads II, III, and aVF, what are the expected coronary angiogram results?

Answer 20

obstruction of the RCA

Question 21

for a patient with an obstruction of the RCA, what treatment options are available?

Answer 21

1) coronary angioplasty

2) coronary artery bypass graft

Question 22

what is a coronary angioplasty?

Answer 22

using a stent to widen the arterial lumen of the coronary arteries occluded by an atherosclerotic plaque

Question 23

what is coronary artery bypass surgery?

Answer 23

taking a blood vessel from another part of the body and attaching it to the coronary artery above and below the narrowed area or blockage

= providing another path for blood flow

Question 24

how does second-degree heart block (Mobitz I) look like on an ECG?

Answer 24

1) P-R elongation until a QRS complex is dropped

2) regularly irregular

Question 25

how does second-degree heart block (Mobitz II) look like on an ECG?

Answer 25

1) no P-R elongation

2) random QRS complexes are dropped either in a regular pattern (2:1 etc) or randomly = regularly irregular

Question 26

how can Mobitz II and third degree heart blocks be differentiated on an ECG?

Answer 26

both have regularity and no PR prolongation

BUT

• QRS complexes dropped regularly in Mobitz II but not in third-degree
• third-degree usually has P waves hidden in bigger vectors

Question 27

which two aspects of the ECG are looked at the differentiate between Mobitz II and third degree?

Answer 27

1) P waves and P:QRS ratio

Mobitz II:

• P-wave with every QRS; but not vice versa
• rate will usually be regular
• PR interval regular

3rd Degree Block:

• may not be a P-wave with each QRS
• PR interval not regular with each PQRS