Acute myocardial infarction 1B

Question 1

What is acute coronary syndrome?

Answer 1

a spectrum of Ischaemic conditions ranging from stable angina, unstable angina and MI

Question 2

What is the pathophysiology of acute coronary syndrome?

Answer 2

it involves a rupture of atheromatous plaque in the coronary artery leading to thrombus formation which results in vessel occlusion locally or elsewhere in the heart

Question 3

What are the 3 types of ACS?

Answer 3

ST elevation myocardial infarction (STEMI), Non-STEMI and Unstable angina

Question 4

What is characteristic of STEMI?

Answer 4

ST elevation on ECG and ↑troponin

Question 5

What is characteristic of NSTEMI?

Answer 5

↑troponin and Ischaemia symptoms and ecg changes

Question 6

What is characteristic of unstable angina?

Answer 6

it is prolonged severe angina usually at rest, possible ECG changes and normal troponin after 12hrs

Question 7

What are the 5 types of MI?

Answer 7

• Type 1 (Due to atherosclerotic plaque rupture);
• Type 2 (Due to imbalance in myocardial oxygen supply and demand e.g. anaemia, ↑HR, ↓BP, arterial spasm, embolism or arrhythmia. May also happen due to surgery or illness. ;
• Type 3 (Due to sudden cardiac death.) ;
• Type 4( due to PCI)
• Type 5 (Due to CABG)

Question 8

What is typical of the chest pain in MI?

Answer 8

usually a sudden, central, a tight crushing but not sharp pain

Question 9

Where does the pain in MI radiate to and why?

Answer 9

to the left arm, neck and jaw.

This is because of presence of heart on the left of chest, so pain radiates along left sided cervical nerve roots.

Question 10

What is angor animi?

Answer 10

it is a symptom some patients feel when having an MI which is an impending sense of doom

Question 11

What ECG changes are seen in the acute stages of a STEMI?

Answer 11

peaked T waves (<5mins), then ST elevation (<20 mins)

Question 12

Where does ST elevation occur on the ECG and what is the criterion for diagnosis of STEMI from an ECG?

Answer 12

Occurs at the J point (end of the QRS) and it must be ≥ 2 consecutive leads

Question 13

what is the minimum height of ST elevation in V2 and V3 occurring in a 40 year old man and woman respectively?

Answer 13

≥2mm and ≥1.5mm

Question 14

What happens within days in STEMI?

Answer 14

Q waves then T wave inversion. Q wave indicating the net direction of early ventricular depolarization (QRS) electrical forces projects towards the negative pole of the lead axis in question.

Question 15

Which coronary artery is implicated in an inferior MI and which leads can these be seen on?

Answer 15

Right coronary artery (RCA), with STE in lead II,III and AVF

Question 16

What are other causes of inferior MI due to?

Answer 16

Due to LCX infarction in 10% of inferior MI known as inferolateral MI

Question 17

What coronary artery is is implicated in anterior MI?

Answer 17

Left anterior descending, STE is seen in leads V1-4

Question 18

Which leads are referred to as the septal leads in an anterior MI?

Answer 18

V1 and V2

Question 19

What is seen in leads III and aVF in an anterior MI?

Answer 19

reciprocal ST depression

Question 20

What coronary artery is implicated in a lateral MI and what leads show ST elevation?

Answer 20

the left circumflex artery and in leads I, aVL, V5 and V6

Question 21

What is seen in a posterior MI?

Answer 21

peaked R and horizontal ST depression in V1-3, upright T waves