STEMI’s & NSTEMI

Question 1

What is a STEMI

Answer 1

STEMI is a diagnosis made based on ECG criteria and clinical symptoms:

ST segment Elevation , MYOCARDIAL INFARCTION

Question 2

Transmural and Non-transmural

Answer 2

Transmural = refers to a heart muscle infarction that involves the full thickness of the heart wall.

Non-Transmural = indicates an infarction that doesn’t extend through the entire wall.

Question 3

What is the ST segment?

Answer 3

The ST segment represents the period between electrical depolarisation and re polarisation.

In most cases , measuring the ST segment is an estimation, as the J point is often not sharp, or the beginning of the T wave isn’t clearly visible.

Question 4

How to measure the ST segment?

Answer 4

Measured from the J point, to the beginning of the T wave.

Question 5

How to measure ST segment elevation?

Answer 5

Measured from ISOELECTRIC LINE to the J point

Question 6

How much ST segment elevation indicates a STEMI?

Answer 6

CHEST LEADS =2mm or above

LIMB LEADS = 1mm or above

This must be observed in two or more anatomically contiguous leads , with or without depression

Question 7

What ST depression indicates posterior STEMI?

Answer 7

ST depression more than 0.5mm in leads V1 - V3, if also presenting with ST elevation above 0.5mm in V7-V9

Question 8

Right Ventricular Infarction

Answer 8

In patients with inferior STEMI, right ventricular Infarction is suggested by:

• ST elevation v3-v6
• ST is isoelectric/elevated in V1 and ST depression in V2 (highly specific for RV Infarction)
• Isoelectric ST segment in V1 with marked depression in V2.
• elevation in lead 2 and 3. ST elevation higher in lead 3, compared to lead 2

Question 9

Left Coronary Mainstem?

Answer 9

• more than 1mm of ST segment DEPRESSION in 6 leads and ST elevation in aVR +/- V1

Question 10

Which pathway is NSTEMI?

Answer 10

• no ST segment elevation but has other ST segment or T wave changes and:or history and symptoms consistent of AMI.

Question 11

NSTEMI is what type of blockage

Answer 11

Subendocardial Infarct

Normal, inverted T waves or ST depression

Question 12

How can NSTEMI present on an ECG?

Answer 12

Non-Q wave infarctions (lower mortality rate):

• ST segment depression
• T wave inversion

Q-wave infarctions (higher mortality rate):

• Pathological Q wave

Question 13

What does ST segment depression represent?

Answer 13

Represents Subendocardial Ischaemia, with no infarction

Question 14

T WAVES, Normal VS abnormal?

Answer 14

• Asymmetry is the NORMAL morphology of the T wave.
• Symmetrical T wave, is therefore thought to be ABNORMAL.

Question 15

What is Wellens Syndrome?

Answer 15

Clinical Syndrome , characterised by biphasic or deeply inverted T waves in V2-V3 , plus a history of recent chest pain.

Highly specific for CRITICAL STENOSIS of LEFT ANTERIOR DESCENDING ARTERY.

Question 16

Biphasic T waves ?

Answer 16

Can be a sign of Ischaemia or Hypokalaemia, and can go UP —> DOWN

Or

DOWN —> UP

Question 17

UNSTABLE ANGINA vs NSTEMI ?

Answer 17

In patients with Unstable Angina (UA) = may observe T wave changes, or ST segment depression.

A Pathological Q wave is developed due to infarction . You will only see these in NSTEMI

Question 18

What makes a Q wave pathological ?

Answer 18

• longer than 40ms (1mm wide/ 1 small box)
• over 2mm deep
• more than 25% the depth of the QRS
• observed in leads V1-V3

Question 19

How to spot Inferior STEMI?

Answer 19

• ST ELEVATION of more than 1mm in:

•lead 2
•lead 3
•aVF

• pathological Q waves in:
  •lead 3
  •aVF
• reciprocal ST segment DEPRESSION in:
  •lead 1
  •aVL

(lateral leads)

Question 20

How to spot Anterolateral STEMI?

Answer 20

• ST ELEVATION of more than or equal too 2mm in:
  • LEAD V1-V6
• ST ELEVATION of >/-1mm in:
  • Lead 1
  • aVL
• reciprocal ST DEPRESSION in:
  •lead 3
  •aVF

(INFERIOR LEADS)

• Pathological Q waves in lead V1 and V2

Question 21

How to spot Lateral STEMI?

Answer 21

• ST ELEVATION of more than 1mm in:
  •lead 1
  •aVL
  (lateral leads)
• reciprocal ST segment DEPRESSION in:
  •lead 3
  •aVF

Question 22

How to spot infarction (in general not in a specific location)?

Answer 22

• ST-segment elevation (especially in contiguous leads) - leads adjacent to each other.

-hyper acute T waves (tall, broad-based, and symmetrical T waves)

• and/or pathological Q waves ( wider than normal > 1 small box and/or deeper than normal (more than 25% the depth of the R wave)

Question 23

How to spot Ischaemia on an ECG (generalised , not in a specific location) ?

Answer 23

ST-segment depression:

This is a key indicator of ischemia. Flat or downsloping ST-segment depression of 1.0 mm or greater is a significant finding.

Symmetric T-wave inversion (TWI):

This is another hallmark of ischemia, often seen in combination with ST-segment depression.

Tall T-waves:

In the anterior chest leads, tall T-waves (hyperacute T-waves) can be an early sign of myocardial infarction.

New or deeper T-wave inversion:

New or deeper T-wave inversions, especially when accompanied by ST-segment depression, suggest ongoing or evolving ischemia.