ECG Flashcards
Look at ECG notes
OK
What changes in anterior-septal MI
V1-V4
What coronary artery
LAD
What changes in inferior MI
II, III, aVF
What coronary artery
RCA
What changes in anterior-lateral
V4-6
I
aVL
What coronary artery
LAD or L circumflex
What changes in lateral MI
V5-6
I
aVL
What coronary artery
L circumflex
What changes in posterior MI
Tall R waves V1-V2
ST depression
What artery
L circumflex
Can be RCA
What does LAD supply
Anterior left ventricle
2/3 of inter ventricular septum
What changes in STEMI
ST elevate V1-V4
T wave inversion
What does left circumflex supply
Lateral LV
What changes in STEMI
I, II
aVL
V5-V6
What does RCA supply
R ventricle
Posterior L ventricle
Posterior 1/3 of interventricular septum
AV node so can cause heart block
What do you get cause of supply to AV node if RCA infarction
Can get heart block
What changes in STEMI
ST elevation in II, III, aVF
What changes in posterior infarction
Tall R waves V1-V3
Recipricol changes so ST depression V1,V2,V3
Often pain more in the back
What do you do if ST depression not settling with GTN or troponin
Think posterior MI
What does a defibrillator do
Depolarises all cells into refractory period
Able to achieve AP
How does hypokalaemia present on ECG
U wave Small or absent T wave Prolonged PR ST depression Long QT
How does hyperkalaemia present
Talll T wave PR disappears Broad QRS AV block Sinus Brady or slow AF
Hypothermia on ECG
Bradycardia 1st degree block Long QT, QRS, PR J wave VT / VF / asystole
How does hypercalcaemia present
Short QT
What is a bifasicular block
RBBB with left anterior or posterior semi block
e.g. RBBB with LAD
What is a trifasicular block
Same as above but 1st degree block
How do you report an ECG
RATE RHYTHM - sinus ? Conduction interval Cardiac axis - normal or deviated Morphology - QRS / ST segment / T wave
If dizzy turn what do you do
ECG to look for arrhythmia
Holter monitor
What criteria for a MI
Tall T wave = hyper acute change (lasts only minutes) ST elevation T wave inversion in 1st 24 hours Q wave persist forever New LBBB Posterior - ST Depression Evolving changes
What does ST elevation need to be
> 0.2mv in 2 continuous leads
What do you do if T wave inversion
Look at previous ECG to see if evolving or past
If myocardium stays inflamed or oedematous then T wave inversion may persist
What does persistent ST elevation post MI suggest
Ventricular aneurysm
Pericarditis
What leads look at L lateral side of heart
I, II, aVL
What leads look at inferior
III, aVF
What lead looks at RA
aVR
What causes a +Ve blip
Depolarisation towards +Ve electrode
What do horizontal leads look at
Horizontal plane instead of frontal
What is progression
V1 = -ve blip as away
V6 = +ve as towards
Flips over at V3/V4
R wave grows as you go from V1-V6
What happens if RVH e.g. COPD
Transition moves towards V6
What does V1 and V2 look at
Right ventricle
What does V3 and V4 look at
Septum
What does V5 and V6 look at
Anterior and lateral wall of the left ventricle
Why does progression happen
Electrical from L ventricle outweighs R
Changes in RVH
What does P wave show
Atrial depolarisation
Usually by SA node
R+L at same time so one wave
Can get biphasic wave in pathology
What is the QRS complex
Ventricle depolarisation
How does ventricle depolarise
Down bundle of His which depolarises septum
Purkinke fibres do R+L side of heart in parallel
Q wave
1st deflection of heart below baseline
Serum depolarises from L-R away from +VE so -ve blip
What is QS
If all waves downward and n R wave
What is R
Any upward deflection regardless of whether Q wave before
Big wave of depolarisation
What is S
Any deflection below baseline following R wave
Upper part of septum depolarises away
What is T wave
Ventricular depolarisation
Why is it +Ve
Opposite way to +Ve electrode but depolarisation
What is abnormal with R wave
If opposite way to QRS as usually follows its direction
If QRS +Ve and T wave -ve then pathological
What is a U wave
If follows normal T wave then assume normal
If T wave flattened could be pathological
Why can’t you see atrial repolarisation
At same time as ventricular depolarisation
How do you interpret interval
Choose lead that shows best after checked all leads
What is PR interval
Time for atrial depolarisation to ventricular depolarisation due to transmission through AV node
How long should it be
No more than 1 large box
Should be 3-5
0.1-0.2s
What is QRS
Time for ventricle to depolarise
Shows how well Bundle of His and Purkinje fibres are conducting
How long should it be
No more than 3 little boxes (0.08s)
What is QT
Time spent in ventricular depolarisation
Varies with HR
What is it at 60BPM
0.42s
What can prolong
Drugs
Electrolyte
Can go into VT
What is important with ST
Vertical movement
What does elevation suggest
Infraction
What does depression suggest
Ischaemia
Where do you look from
J point
What do you get from rhythm strip
Speed of ECG - 25mm/s 1 small = 40ms 5 small (1 large) = 0.2s Calibration - 0.5mv Regularity Rate
Where do you get rhythm from
Lead which shows P wave most clearly - usually II
How do you work out if regular or irregular
Mark out R-R then check same distance
If there is an AV block what does this mean
Mark atrial and ventricular rate separately as will be different
How do you get rate if regular
No of bars between 2 QRS and divide into 300
How do you get rate if irregular
Count R waves in 30 large squares (6S)
X10
How do you read an ECG
Name, date, calibration, speed Rate Rhythm Cardiac Axis P wave PR interval / ST / QT QRS T wave U wave Specific changes
What should you look for
Regional changes
What leads to look at cardiac axis
I,II,III
What should cardiac axis be
Lead II = most +Ve if normal
What happens in RAD
III most +Ve
I most -ve
What happens in LAD
1 most +Ve
2+3 -ve
What is important with P wave
Duration - tachy / fibrillation
Amplitude - raised in cor pulmonale
Is it follows by QRS
What causes prolonged PR interval
AV delay IHD Digoxin Hypokalaemia Rheumatic fever Lyme's Sarcoid Myotonic dystrophy
What causes a shortened PR interval
Atrial impulse getting to ventricle by shorter faster circuit
Accessory pathway e.g. in WPW
What else can you get with WPW
Delta wave - slurred upstroke to QRS
What causes broad QRS
Abnormal depolarisation / conduction
Ectopics
Bundle branch blocks
What height should QRS be
<5mm in limb
<10mm in chest
What causes tall QRS
Ventricular hypertrophy
What does presence of delta wave suggest
Sign that ventricles were activated earlier and not from AV node
Spreads across myocardium causing a slurred uptake
How should R wave progress
Small in V1 to large in V6
Poor progression suggests MI
What is a pathological Q wave
> 2mm or 0.04ms
Where is the J wave
Where S joins ST
Can be elevated toking like STEMI but just high take off
How do you differentiate between J wave and MI
Multiple terrotiroy
T will also be raised
Do not change or evolve
What is important to think of with the intervals
Do they change
Is it one off or is there a pattern
What classifies as ST elevation
> 1mm (1 small square) in limb
>2mm in chest
What causes ST elevation
MI Pericarditis Cardiomyopathy ANeurysm SAH = rare but can
What causes ST depression
Ischaemia
Digoxin
Hypokalaemia
What is a tall T wave and what causes
> 5mm in limb or >10 in chest
Hyperkalaemia
STEMI
What causes inverted T wave
Ischaemia PE HCM / arrhythmogenic SAH Brugada Digoxin Illness
When is inverted T normal
V1 and III and aVR
What causes biphasic
Ischaemic
Hypokalaemia
What causes flattened
Ischaemia
Electroylte
What causes U wave
Electrolyte
Anti-arrhythmia
What is the cardiac axis
Heart depolarises from 11-5
Creates +ve deflection as depolarise towards I,II and III with lead ii most +ve
aVR = -ve
What causes R axis deviation
R ventricular hypertrophy Pulmonary conditions Cor-pulmonale PE Lateral MI WPW if L sided accessory pathway
What happens in R axis
Depolarisation distorted to the R Depolarise now 1-7 Lead 1 = -ve Lead 3 = more +Ve aVF and III more +VE
What causes L axis deviation
Usually conduction defect LBBB Inferior MI WPW if R sided pathway Hyperkalaemia
What happens in L axis
Lead 1 = most +Ve
Lead 3 = -ve
Only significant if lead 2 -ve as well
What is 1st degree heart block
PR interval increasing
What is 2nd degree Mobitz Type 1
Prolonged PR until drop in QRS then returns
Can occur in healthy young people with high vagal tone
When do you worry about type 1
If during exercise or cause syncope
What is type 2
PR prolonged but content drop in QRS
Ratio of 2:1 or 3:1
If syncope + type 2
Admit
Pacemaker
High mortality
What is complete heart block
No relationship between atrial and ventricular activity
What is AV dissociation
Atrial and ventricular rate different
Must work out rate separately using P and R wave
If atria faster = heart block
If ventricular faster = VT
Where do you look for BBB
V1 and V6
What does a new onset LBBB suggest
Pathology MI Aortic stenosis IHD Hypertension Cardiomyopathy Digoxin / hyperkalaemia rare
What are signs of LBBB
Broad QRS
William (W in V1 and M in V6)
Slurred / broad R wave
What are signs of RBBB
Broad QRS
Marrow (M in V1 and W in B6)
Wide slurred S wave
What causes RBBB
Normal variant RVH Cor pulmonale PE MI Cardiomyopathy Myocarditis
Why can’t you see P wave in III
Doesn’t pick up depolarisation in lead III
What occurs in AF
P wave absent as no atrial depolarisation from AV node
QRS with wobbly baseline
What does VT look like
Broad mountains
