ECG Interpretation

Question 1

Normal Interpretation

Answer 1

Rate - count no. of squares between R, divide 300 by that number = heart rate
Rhythm - is there equal spaces between the QRS complexes?
P wave - consistent shape? do they precede a QRS complex? <0.12 secs
PR Interval - 0.12-0.2 secs
QRS complex - normal shape, 1:1 with p wave, <0.12 secs
ST segment - consistent with isoelectric line?
Interpretation?

Question 2

ST Depression

Answer 2

Indicative of myocardial ischaemia
Appearance - 
ST line horizontal
downwards sloping 
upwards sloping from downwards position 

Causes -

• myocardial ischaemia
• ventricular hypertrophy
• right and left bundle branch block
• digoxin toxicity

Course of Action

• monitor pulse and BP, stay with teh patient
• stop treatment
• report to medical stagg
• consider emergency response

Question 3

ST Elevation

Answer 3

Indicative of myocardial infarction 
Early Acute MI 
- no Q waves
- ST elevation sloping upwards
- tall, widened T waves 

Established MI

• prominent Q waves
• elevated ST segments
• inverted T wave

ST line may be horizontal, convex or coved

Causes - 
- MI 
myocardial ischaemia 
myocardial injury 
myocardial infection 
coronary vasospasm 
pericarditis 

Course of Action

• stop treatment
• seek medical assistance
• prep emergency equipment
• monitor the patient
• prep for CPR

Question 4

Sinus Tachycardia

Answer 4

• increased rate in atrial contraction originating from the
  SA node
• 100bpm +
• normal shapes and ratios just increased rate
• not pathological if during increased activity
• source for concern if at rest

Question 5

Atrial Fibrillation (tachycardia)

Answer 5

a disorganised electrical signal from abnormal ectopic foci in the atria

Appearance -

• bag of worms
• no distinct p waves
• irregular RR interval

Causes - any disease process that changes the structure of atrial tissue

Course of Action - 
Chronic 
- look at current symptoms, changes in BP, pulse or pallor
- is the rate controlled?
- would they be able to tolerate functional rehab?
Acute
- if new onset - cease intervention 
- refer on medical assessment

Question 6

Atrial Flutter (tachycardia)

Answer 6

flutter occurs when automaticity foci fire when they shouldn’t
rate is normally 250bpm
due to AV node refractory period, AV depolarisation doesn’t occur with each flutter

Appearance

• multiple, saw tooth p waves
• occasional QR complex
• regular RR interval

Course of Action - 
Chronic 
- look at current symptoms, changes in BP, pulse or pallor
- is the rate controlled?
- would they be able to tolerate functional rehab?
Acute
- if new onset - cease intervention 
- refer on medical assessment

Question 7

Premature Atrial Contraction

Answer 7

premature beat arising from the atria 
Appearance - 
- abnormal p wave 
- followed by a normal QRS complex 
- occurs in pairs, groups or threes 

Course of Action - 
Chronic 
- look at current symptoms, changes in BP, pulse or pallor
- is the rate controlled?
- would they be able to tolerate functional rehab?
Acute
- if new onset - cease intervention 
- refer on medical assessment

Question 8

Premature Ventricular Contraction

Answer 8

premature discharge of an ectopic focus in the ventricles

Appearance

• can occur as a single beat, every second beat or in pairs
• abnormal QRS complex
• no preceding p wave

Causes -

• anxiety
• excessive caffeine/alcohol
• drugs
• congestive heart failure
• myocardial infarction
• valvular heart disease

Not life threatening
Issue if have other heart condition or if occurs very frequently

Question 9

Ventricular Fibrillation

Answer 9

chaotic electrical discharge from multiple foci in the ventricles
- lose cardiac output - ventricles aren’t working properly

Appearance -

• extremely disorganised
• no rate
• no wave or QRS complex
• series of random peaks, no regular shape or rate

Causes -

• may be spontaneous
• electrolyte disturbance
• reperfusion of the myocardium after thrombolysis
• mechanical stimulation
• myocardial infarction

Course of Action

• medical emergency
• stop treatment
• seek medical assistance
• need to commence CPR

Question 10

Ventricular Tachycardia

Answer 10

originates from a ventricular ectopic focus
- between 140-250bpm

Appearance

• regular QRS complexes, wide, abnormal shape, just look like wide peaks
• no p wave

Causes -

• digoxin toxicity
• electrolyte disturbances
• myocardial infarction
• cardiomyopathy
• congestive heart failure
• medications

Course of Action

• medical emergency
• stop treatment
• seek medical assistance
• need to commence CPR

Question 11

Pulseless Electrical Activity

Answer 11

form of cardiac arrest
no pulse but still have electrical impulse
severe cardiac/circulatory dysfunction means that despite electrical impulse there is no contraction of the heart
can’t use defib

Question 12

Asystole

Answer 12

absence of all electrical activity
- flat line

Causes - 
ischaemia 
degeneration of the conducting system 
electrocution 
can't use defib