ECG

Question 1

Describe a brief approach to ECGs

Answer 1

1. check calibration
2. check rhythm
   - normal sinus
   - sinus tachy
   - regularly irregular
   - irregularly irregular
3. check rate
   - 300-150-100-75-60-50
4. intervals
   - PR 3-5 small boxes
   - QRS less than 2.5 small boxes
   - QT less than 1/2 the R-R interval if HR normal
5. axis
   - look at I, II and AVF
6. p wave abnormalities
   - look at II and V1 for LA or RA enlargement
7. QRS abnormalities
   - LVH, RVH, bundle branch blocks or pathologic Q waves
8. ST segment or T wave abnormalities
   - ST elevation, ST depression, T wave inversion
9. compare with previous ECGs

Question 2

define normal sinus rhythm

Answer 2

every p wave is followed by a QRS

every QRS is preceded by a p wave

p waves are upright in leads I, II and III

PR interval of 3-5 small boxes

rate between 60-100 bpm

Question 3

how long does each small box represent

Answer 3

0.04 s (4ms)

Question 4

name the atrial arrhythmias

Answer 4

(tachy)

atrial premature beats

atrial flutter

atrial fibrillation

paroxysmal SVTs

focal atrial tachy

multifocal atrial tachy

Question 5

name the AV node arrhythmias

Answer 5

brady:
conduction blocks
junctional escape rhythms

tachy:
AVRT
AVNRT

Question 6

name the ventricular arrhythmias

Answer 6

brady:
ventricular escape rhythm

tachy:
ventricular premature beats
ventricular tachycardia
torsades
ventricular fibrillation

Question 7

how do you identify an escape rhythm

Answer 7

no p waves before QRS

narrow QRS–> junctional
wide QRS–> ventricular

Question 8

define 1st degree AV block

Answer 8

1 to 1 p to QRS ratio

long PR interval (more than 5 small boxes)

Question 9

define second degree heart block

Answer 9

intermittent failure of AV conduction and so some p waves dont have a QRS after

two types–

Type I–> gradual lengthening of the PR interval until a QRS is missed and then the cycle starts over

Type II–> sudden loss of AV conduction so random QRS are missed

Question 10

define 3rd degree/complete heart block

Answer 10

disconnects the atria from the ventricles so atria are controlled by the SA node and the ventricles by a distal escape rhythm

Question 11

what is atrial flutter

Answer 11

rapid REGULAR atrial activity

Question 12

how do you identify atrial flutter

Answer 12

sawtooth waves

rate is 180-350

Question 13

what is atrial fibrillation

Answer 13

chaotic

distinct p waves are NOT discernible

random bumpy shit between QRS complexes

Question 14

what is multifocal atrial tachy

Answer 14

IRREGULAR rhythm with multiple (more than 3) p wave morphologies

Question 15

what often triggers torsades

Answer 15

long QTc–> can degenerate to VF

Question 16

what is ventricular fibrillation

Answer 16

immediately life threatening

major cause of mortality in acute MI

Question 17

where do you look for RVH and what do you look for

Answer 17

leads V1 and V2

R wave bigger than S wave and right axis deviation

Question 18

how do you determine a normal axis

Answer 18

if QRS is upright in leads I and lead aVF–> normal

also if more positive than negative in I and II

Question 19

what pattern suggest left axis deviation

Answer 19

upright QRS in lead I and downward in lead II

or upright QRS in lead I, downward in aVF and downward in lead II

(if upright in lead I, downward in aVF and upward in lead II–> normal)

Question 20

list some conditions that cause left axis deviation

Answer 20

normal varient

left anterior fascicular block

LVH

LBBB

mechanical shift of heart in the chest

inferior MI

wolff parkinson white syndrome

ventricular rhythms

ostium primum ASD

Question 21

what pattern suggests right axis deviation

Answer 21

downward QRS in lead I and positive in aVF

or downward in lead I and upward in lead II

Question 22

what causes right axis deviation

Answer 22

normal variant

RBBB

RVH

left posterior fascicular block

dextrocardia

ventricular rhythms

lateral wall MI

WPW

acute right heart strain/pressure overload

Question 23

what does the p wave indicate

Answer 23

atrial depolarization

occurs when the SA node creates an action potential that depolarizes the atria

Question 24

where do you look to make sure the p wave is originating from the SA node

Answer 24

p wave should be upright in lead II

Question 25

what can widen or increase the amplitude of the p wave

Answer 25

atrial enlargements

RA enlargement indicated by big bump then little bump in lead II

LA enlargement indicated by little bump then big bump in lead II, inverted in V1