ECG Flashcards
What ECG leads will show changes if RCA is occluded?
II, III, aVF
Inferior
What ECG leads will show changes if distal LAD is occluded?
V3 and V4
Anteroapical
What ECG leads will show changes if circumflex artery is occluded?
I, aVL, V5 and V6
Anterolateral
What ECG leads will show changes if proximal LCA is occluded?
I, aVL, V2-V6
Extensive anterior
What ECG leads will show changes if RCA (true posterior) is occluded?
Tall R in V1
How to measure heart rate from an ECG?
REMEMBER one BIG box = 300bpm
What is an atrial flutter look like? What is it?
It is the ectopic focus in atria
P waves right next to each other - one BIG box
How to diagnosis atrial fibrillation? what is it?
No p waves but you see small waves of atrial depolarisation
It is multiple ectopic foci - atrial rate 350-450 bpm and ventricular rate is greater than 120bpm AND high Irregular
How to see a bundle branch block on ECG? AND what is it?
It is when a signal is blocked down one or both bundle branches
See wide QRS
What to see in a 3rd degree heart block?
P waves that are not followed up straight by QRS and ventricular rate is low (around 40bpm)
What is the ECG axis of the chest leads normally? (look at QRS)
V1 and V2 - negative
V3 and V4 - Isoelectric
V5 and V6 - positive
What happens if there was a right ventricular hypertrophy on an ECG? what causes it?
Dominant R wave in V1
V5 and V6 has dominant S wave.
width of QRS is normal (unlike RBBB which is wide)
Causes: Pulmonary hypertension
What happens if there was a left ventricular hypertrophy on an ECG? (between -90 and -30)
V1 has deep S wave and st elevation
V5 and V6 has tall R wave, and st depression
[v1 (s) and v5(r) = above 35mm]
Causes: System hypertension
What is a normal PR interval? What does changes mean?
3-5 small boxes
Atrial ectopic focus (father = longer and closer = shorter)
OR long = first degree heart block
What causes changes in QRS complex?
widens if there is a ventricular ectopic focus.
intermediate
prolonged - more than 3 small boxes
Changes in QT interval?
changes depending on the rate - as rate increases QT interval decreases.
What can cause prolonged QT interval?
medications: Amiodarone
Inherited - mutation of LQT1/T2/T3
Torsades de pointes
Other than cardiac hypertrophy what else can cause QRS transition? (the positive)
Myocardial infarction
what can be seen in an ECG for right atrial enlargement? what causes this?
- large p wave at V1, v2, II, III and aVF
- caused by stenotic tricuspid valve
What happens if there was a left ventricular hypertrophy on an ECG?
- see two peaks in lead II. (gap of 40ms)
- biphasic p wave in lead V1 (hill with valley next to it)
causes by stenosis of mitral valve
When does subendocardial ischemia occur?
incomplete blockage in coronary artery - angina
When is seen on an ECG for subendocardial ischemia?
- ST depression (J point goes down)
affects I, II, V4 to V6
When does sub-endocardial infarction happen?
complete blockage of coronary artery for more than 20 minutes resulting in necrosis.
NSTEMI
see ST depression and T inversion (deep and seen in chest leads and in two contiguous leads (right next to each other), Dominant R wave)
increased cardiac enzyme
NOTE: T wave inversion can be normal in III, aVR and V1.
BUT abnormal in V2 to V6
What causes transmural ischemia?
occurs second to vasospastic angina - triggered by alcohol, cocaine or tobacco
What ECG changes is seen with transmural infarction?
T wave inversion
hyper-acute - T wave (in two continguous leads)
ST elevation (STEMI) - above 1 mm or at V2/V3 above 2mm
big negtaive pathologic Q waves (1 small wide and 2 small boxes deep)
How to see a hyperkalaemia on ecg?
Tall tended T waves
