ECGs and arrythmias Flashcards
How do you calculate rate of ECGs?
300/large squares
or number of complexes in rhythm strip x 6
Describe normal sinus rhythm
P followed by QRS
Constant PR interval
What is normal cardiac axis?
I + II both positive
Describe right axis deviation
RAD - reaching
I = negative and II = positive
right ventricular hypertrophy left posterior hemiblock lateral myocardial infarction chronic lung disease → cor pulmonale pulmonary embolism ostium secundum ASD Wolff-Parkinson-White syndrome* - left-sided accessory pathway normal in infant < 1 years old minor RAD in tall people
Describe left axis deviation
Causes?
LAD - leaving
Lead 1 = positive and lead 2 = negative
left anterior hemiblock
left bundle branch block
inferior myocardial infarction
Wolff-Parkinson-White syndrome* - right-sided accessory pathway
hyperkalaemia
congenital: ostium primum ASD, tricuspid atresia
minor LAD in obese people
what do P waves signify?
atrial depolarisation
What sort of P waves are there in right atrial hypertrophy?
Tall
What sort of P waves are there in left atrial hypertrophy?
notched/broad
What is the normal length of the PR interval?
3-5 small squares
120-200ms
What’s the normal width of the QRS complex?
3 small squares
120ms
What does a wider QRS complex signify?
ventricular origin / Bundle Branch Block
What does a tall R in V1 signify?
RVH
What does a tall R in V6 signify?
LVH
What do ST segment changes signify?
MI (region) and pericarditis (all over) - saddle deformity
In what leads is T wave inverted?
Always upright in leads I, II, V3-V6
Always inverted in aVR
Can be inverted in III and v1/2 but be normal
What does a Q wave show?
old infarction
What is the normal length of the QT?
<0.45s
Drugs that prolong QT: amiodarone, sotalol, class 1a antiarrhythmic drugs TCA / SSRI (CITALOPRAM) methadone chloroquine erythromycin haloperidol ondanestron
Where do V1 and V2 go?
4th ICS
Right and left sternal edge
Where does V4 go?
5th ICS MCL
Where does V3 go?
In between V2 and V4
Where does V6 go?
ICS MAL
Where does V5 go?
in between v4 and v6
When are t waves normally inverted?
Avr, III and V1/2
What does t wave inversion signify?
Ischaemia
STEMI
NSTEMI
Happens after 24-48 hours and is permanent
Ventricular hypertrophy
Bundle branch block
Digoxin
PE
What does ST elevation signify?
ACS
Pericarditis (most leads)
What leads could you see a LATERAL MI?
lead 1
V5, V6
What lead would you see an inferior MI?
Leads II, III and Avf
What leads would you see an anterior MI?
WHAT LEADS WOULD YOU SEE POSTERIOR MI?
V1-V4
Tall R waves V1-2
What is a bundle branch block?
depolarisation of wave reaches the septum normally
therefore PR interval is normal
This is due to abnormal conduction through RL bundles of HIS
There is delayed depolarisation and therefore QRS is >120
What are the signs of RBBB?
MaRRoW
Look at V1/V6
What are the causes of RBBB?
normal variant - more common with increasing age
right ventricular hypertrophy
chronically increased right ventricular pressure - e.g. cor pulmonale
pulmonary embolism
myocardial infarction
atrial septal defect (ostium secundum)
cardiomyopathy or myocarditis
What are the signs of LBBB?
WiLLiaM
If present then no further interpretation of ECG possible
What are causes of LBBB?
Always pathological - may be a sign of myocardial infarction
ischaemic heart disease hypertension aortic stenosis cardiomyopathy rare: idiopathic fibrosis, digoxin toxicity, hyperkalaemia
What rate is tachycardia?
> 100bpm
What rate is bradycardia?
<60
What is a normal PR interval?
3-5 small squares
120-200
Over 220ms = heart block
What prolongs the QT interval?
drugs and electrolyte abnormalities
can lead to ventricular tachycardia
What is the sign of first degree heart block?
PR interval >220ms
What is the cause of first degree heart block?
Delay from SAN to ventricles Can indicate: CA disease rheumatic fever electrolyte disturbance digoxin toxicity
What are the three different types of 2nd degree heart block?
Mobitz 1
Mobitz 2
2:1/3:1
What is Mobitz type 1?
WENCKEBACH:
PR interval progressively longer until you get a lost beat
What is Mobitz type 2?
Constant PR interval, sometimes atrial contraction without ventricular contraction
What is the third type of 2nd degree heart block?
2:1 or 3:1
2/3 x p waves as QRS
may need pacing
What is 3rd degree heart block?
Atrial contraction normal button ventricular contraction
P wavers therefore not associated with QRS
Wide QRS
pacing required
How does sinus arrhythmia occur in young people?
heart rate changes with respiration
R-R interval changes on a beat-beat basis
Why might sinus bradycardia occur?
Athletic training
fainting attacks
hypothermia
hypothyroid
Why might sinus tachycardia occur?
exercise fear pain haemorrhage increased thyroid
What are the three places non-sinus rhythms come from?
atrial muscle
ventricular muscle
AVN
What is the location of supraventricular arrythmia?
Sinus - normal P wave
atria - abnormal P wave
junctional - no P wave
What is rhythm controlled by?
the part of heart that beats the fastest
SAN: 70bpm
atrial focus: 50bpm
AVN: 50pbm
ventricular focus 30/min
What is the management of arrhythmia?
A-E
assess for:
adverse features (shock, syncope, heart failure, MI
Asystole risk: recent systole, mobitz I or II or complete block
Bradycardia - atropine 500mcg IV
may need pacing
What is extrasystole?
If any part of the heart depolarises too quickly
atrial: abnormal P wave and normal qrs
ventricular: widened QRS
What is supra ventricular tachycardia?
> 150bpm
P wave merge with previous T wave
Tx: Vagal manœuvrés
Adenosine IV
What is the management of SVT?
A-E resus
adverse features: DC cardio version
if irreg - treat as AF
If regular:
carotid sinus massage, valsalva manoeuvre
IV adenosine - 6mg then 12 the 12
Electrical cardio version
Secondary prevention with B blocker
What is Ventricular tachycardia>
Wide QRS
can transform into VF therefore needs immediate tratment
What is the management of VT?
immediate electrical cardio version if:
BP <90
chest pain
<159bpm
If none of the above, amiodarone (30mg) + cardio version if fails
What is ventricular fibrillation?
independent muscle fibres can’t contract independently
NO QRS complexes
LOC
Mx as cardiac arrest
What is atrial flutter?
Atrial rate >250
NO flat baseline between p waves
saw toohed
Mx as per AF
What is the sign of hyperkalaemia on ECG?
Tall, tented T waves
Wide QRS
Prolonged PR
What is the management of hyperkalaemia?
Stabilise the heart:
Calcium gluconate
To shift K+
combined insulin/dextrose infusion
nebulised salbutamol
Additional:
calcium resonium (orally or enema)
enemas are more effective than oral as potassium is
loop diuretics
dialysis
haemofiltration/haemodialysis should be considered for patients with AKI with persistent hyperkalaemia
What is the sign of hypokalaemia on ECG?
T wave flattened
U wave after T wave
What is the sign of hypocalcaemia on ECG?
QT prolongation
What is the sign of hypercalcaemia on ECG?
QT shortened
What is WPW syndrome?
Some people born with 2nd conducting system in heart
Usually located in LHS
No AVN delay: short pr interval and delta wave
Normal QRS
What are the ECG signs of WPW?
RAD
Sinus
Short PR
Delta wave
What is atrial fibrillation?
abnormal rapid rate - irregularly irregular rhythm: no Ps
What are the underlying causes of AF?
Cardiac: HTN, valve disease, heart failure, IHD
Resp: chest infection, PE, lung cancer
Systemic: increased alcohol, increased thyroid, decreased electrolytes, infection, DM
What are the classifications of AF?
Acute (48 hours)
Paroxysmal - spontaneous termination in 7 days
Recurrent (more than 2 episodes)
Persistent (not self-termination), lasts longer than 7 days or until cardio version
Permanent: over 1 year - rate control and anticoagulant
What are the features of AF?
Asymptomatic SOB Palpitations Syncope Chest pain Stroke/TIA
What are the ECG findings of AF?
Irregular baseline with no P waves
What other investigations are there for AF?
FBC, U+E, TFT, BM, echo, CXR
What is the emergency management of AF?
If harm-dynamic instability and symptoms: electrical cardio version.
<48 hours - immediately
> 48 hours - 3 weeks anticoagulation prior
What is the routine management of AF?
Step 1: Rate control
Step 2: anticoagulation
Anticoagulation based on CHADS-VASC score
1+ = anticoagulation
What is the rate control of AF?
1st line = BISOPROLOL
contraindicated in asthma
Calcium channel blocker: verapamil/diltiazem
What is the anticoagulation part of AF?
Heparin at initial presentation
Assess for long term stroke risk using CHA2DS2-Vasc score
anticoagulant if score is more than 2 for females and more than 1 for males (HEPARIN)
Can also use HASBLED to assess risk of major bleed
What does rhythm control for AF entail?
Electrical cardio version
Medical:
flecainide or amiodarone in those without structural heart disease
amiodarone if structural heart disease
What is the management of bradycardia?
Atropine 500mg IV up to 6 doses
What is the ECG sign of hypokalaemia?
U waves
U have no Pot and no T but a long PR and a Long QT
What is the ECG sign of hypothermia?
J waves
What is the appearance of Torsades de Point?
Arctic Monkeys Cover album
What Is the treatment of Torsades de Point?
IV magnesium sulphate
