CVS 206 MI

Question 1

What 3 clinical features must be present to diagnose an MI?

Answer 1

Pain characteristic of MI
ECG changes
Troponin elevation

Question 2

What are the symptoms characteristic of myocardial pain?

Answer 2

Heavy crushing pain lasting longer than20 minutes

Radiating to arms or neck

Question 3

Besides the pain what are other signs and symptoms of MI?

Answer 3

brady/tachycardia, hyper/hypotension, nausea, belching, sweaty and pale, syncope, breathlessness, peripheral oedema
signs of LV dysfunction: crackles, murmur/3rd heart sound

Question 4

What is the main aetiology behind an MI?

Answer 4

Rupture or erosion of an unstable coronary artery plaque leading to thrombus formation and an emboli

Question 5

What main risk factors can trigger atherogenesis in response to endothelial injury?

Answer 5

Hypertension - higher mechanical shear stresses
Smoking - immunological response to free radics
Increased LDL’s and DM - biochemical abnormalities

Question 6

What is the basic pathophysiology behind coronary athersclerosis?

Answer 6

Accumulation of lipids, macrophages and smooth muscle plaques within the intima of the coronary arteries
Plaque rupture causes platelet aggregation, adhesion, local thrombosis (due to platelet release of 5HT and TxA2) leading to vasoconstriction and distant thrombosis

Question 7

What degree of stenosis is haemodynamically significant in CAs? And what does this mean?

Answer 7

50% or more - this means that small and more distal intra-myocardial arteries and arterioles are maximally dilated = max oxygen supply

Question 8

What does Acute Coronary Syndrome encompass?

Answer 8

STEMI, NSTEMI and unstable angina

Question 9

What are the 6 types of MI?

Answer 9

1 - spontaneous: ischaemia occurs after primary event e.g. plaque erosion
2 - secondary to ischaemia - ca spasm, embolism, anaemia, arrhythmias
???3,4&5 are sudden cardiac death, after PCI and CABG

Question 10

What ST segment changes occur often within minutes after an MI?

Answer 10

T wave peaking and ST elevation

Question 11

What is the J wave (elevation) and what does it suggest?

Answer 11

The point between the QRS complex and the ST segment and if there is no return to baseline this indicates ischaemia and total artery occlusion

Question 12

What would ST depression signify?

Answer 12

Ischaemia and partial artery occlusion

Question 13

What does T wave inversion show?

Answer 13

Acute ischaemia, usually happens within hours

Question 14

What do Q waves indicate?

Answer 14

Myocardial cell death - occur within hours and can be seen long term weeks later to show a previous infarct

Question 15

What leads look at the septal part of the heart?

Answer 15

V1 and V2

Question 16

What leads look at the anterior part of the heart?

Answer 16

V3 and V4

Question 17

What leads look laterally at the heart?

Answer 17

V5, V6, 1, avL

Question 18

What leads look inferiorly at the heart?

Answer 18

II, III, aVF

Question 19

When is trop t released and what is it also associated with?

Answer 19

within 4-6 hours of MI but also associated with PE, septicaemia, renal failure and cardiac cell death of other causes

Question 20

What is MBCK?

Answer 20

A specific cardiac enzyme MB - Creatinine kinase

Question 21

Which lactate dehydrogenase is specific to cardiac muscle? What is LDH also raised in?

Answer 21

LDH1

Tissue breakdown, haemolysis, Ca and meningitis

Question 22

How would you immediately manage a suspected MI?

Answer 22

O2
GTN
IV opiate analgesia/anti emetic
Aspirin

Question 23

What options are there for restoring blood flow in MI?

Answer 23

Reperfusion treatment: PCI and CABG
Nitrates (vasodilation)
Thrombolysis - tPA

Question 24

How do you prevent further coronary thrombosis?

Answer 24

Anti-coagulant e.g. LMWH

Anti plateleys e.g. clopidogrel, aspirin and glycoprotein IIb/IIa inhibitors

Question 25

How do you decrease or reverse ischaemia after an MI?

Answer 25

Beta blockers and nitrates

Question 26

What treatment should be given in the long run to help stabilise CA’s and optimise healing?

Answer 26

Statins and ACE inhibitors