ECG interpretation for ECG interpretation for beginnersbeginners

Part 4 – Acute coronary Part 4 – Acute coronary syndromessyndromes

Paul WilliamsCardiology Specialist Registrar

Normal ECG!Normal ECG!

MI diagnosisMI diagnosisUse your systemDon’t forget rate, rhythm etc.

Need to have basic understanding of:◦Pathology of heart attacks

◦Coronary arteries and regions of heart

Coronary arteriesCoronary arteries2 coronary arteries come off aortaTotal of 3 main coronary arteries

LCA◦LMS branches into:◦Left anterior descending (LAD)◦Circumflex (Cx)

RCA

Left ventricle supplyLeft ventricle supply

LAD – Supplies anterior wall, septum +- lateral walls(60%)

Cx – Supplies lateral wall (15%)RCA – Supplies inferior and

posterior walls (25%). Also supplies RV & conducting tisse

Inferior

Lateral

Lateral

Septal

Anterior

Other territoriesOther territoriesInferior MI – can have RV

involvement◦RV leads - V4R

Posterior MI – Usually ST depression V1-V3

The hallmark of acute ischaemia is ST segment shift

ST elevation = complete blockage = STEMI

ST depression = partial blockage = NSTEMI/USA

Generally only occurs when patient has symptoms: ACS are dynamic

If real, usually have changes in contiguous leads

STEMISTEMIOccluded coronary arteryEmergency = myocardium is

dying!

STEMISTEMIChanges evolve:

◦Often “hyperacute” T waves initially◦T wave inversion◦Q waves

Dynamic - repeat ECGs if not sure

What territory is it?◦Two contiguous leads◦Can get reciprocal ST depression◦Remember posterior & RV involvement

DifferentialDifferentialPericarditis

◦Widespread concave upsloping ST depression

◦Would involve multiple coronary arteries if MI

◦PR depression (II)◦Look at the patient – common sense

Management of STEMIManagement of STEMIABCCardiac monitor (can go into VF)AnalgesiaAspirinClopidogrelReperfusion therapy

◦ Thrombolysis◦ Primary PCI

Medical Rx

Inferior

Lateral

Lateral

Septal

Anterior

Old MIsOld MIsOld STEMIs can leave permanent

Q wavesTerritories are the same

(anterior, inferior lateral etc.)Poor R wave progression can also

indicate an old anterior STEMI

ST depressionST depression

ST depressionST depressionOften get T wave inversion as wellRemember your territoriesGenerally ST depression only

occurs during acute ischaemia

Differential◦Digoxin (downsloping lateral: V4-V6, I,

aVL)◦LVH (downsloping lateral)

Management of Management of NSTEMI/USANSTEMI/USAABCCardiac monitorAnalgesiaInitial medical Rx

◦Aspirin◦Clopidogrel◦Beta-blocker◦Statin◦LMWH

IP angiography

Question 1Question 1

What are the ECG abnormalities?What is the differential?

Question 2Question 2

What are the ECG abnormalities?What sort of ACS?What territory is affected?

Question 3Question 3

What are the ECG abnormalitiesWhat sort of ACS?What territory?

Question 4Question 4

What are the ECG abnormalities?Give 3 possible differentials

Question 5Question 5

• What are the ECG abnormalities?• What sort of ACS?What territory?