Coronary Artery Disease: Acute coronary syndrome

Question 1

This is a term that covers a wide range of concepts:

Answer 1

• Blood stopped to the heart:
  1) unstable angina with partial blockage of a vessel
  2) acute myocardial infraction with full blockage of vessel
• Rupture of an arthomatus plaque leading to possible thrombosis or embolism

Question 2

How will a thrombus cap rupture?

Answer 2

IF there is a sturcutral defect in the fibrous cap, it exposes the thrombogenic core to the blood.
Where the cap is thinnest, there is infiltration of foam cells and loss of smooth muscle in the cap
The plaque will then rupture

Question 3

WHen is thromus rupture likely to happen?

Answer 3

It is often spontaneous, but increase stress may increase the chance of a rupture e.g. winter between 6.30 and 9.00 monday morning

Question 4

What happens to a ruptured cap?

Answer 4

This is called a STENOSIS which is a healed ruptured cap that will narrow the lumen.

Question 5

What are the symptoms of Acture Coronary Symptoms?

Answer 5

Chest pain, tightness, pressure, pain, discomfort, shortness of breath, dizy, light headed, nausea, sweating

Question 6

What differentiates these symptoms from Stable Angina?

Answer 6

It is NOT relieved by Nitrates.

Question 7

What are the two types of Myocardial Infraction in Acute coronary syndrome?

Answer 7

ST-elevated myocardial infarction

Non-ST elevated myocardial infarction

Question 8

What is a STEMI?

Answer 8

ST-elevated myocardial infarction: Persistent ST elevation on the ECG, and rise in Troponin levels.

Question 9

What is NSTEMI?

Answer 9

Non-ST elevated myocardial infarction: ST is not elevated, but there are abnormalities in the ECG, either ST depression, or a T inversion. Also has a rise in Troponin levels

Question 10

WHat if there are ST/T abnormalities, but the Troponin levels are normal?

Answer 10

This is UNSTABLE ANGINA

Question 11

What if the ECG is normal or undetermined, but the Troponin levels are high?

Answer 11

NSTEMI

Question 12

What is Troponin?

Answer 12

It is attached to tropomysin and is an actin filaments. Action potentials cause Calcium to attach to troponin, exposing the myosin binding site, cross bridge and contraction takes place.

Question 13

What are Biomarkers and how are they used?

Answer 13

These are Troponins, Creatinine Kinase Isoforms, or Beta type natriuretic peptide. They are used in addition to ECG for diagnosis. They will appear in the plasma over a period of hours after first onset of symptoms if there is damage to muscle.

Question 14

Advantage and Disadvantage of Creatinine Kinase Isoforms?

Answer 14

Less-selective but build up quicker

Question 15

What is the molecular pathology of a Myocardial Infarction?

Answer 15

It is when a major vessel is completely occluded by a thrombus causing an area of the myocardium to be completely deprived from oxygen.
This causes hypoxia of the tissues.
Cessation of mitochondria producing ATP causing anaerobic glycolysis to try to compensate for this but only 7% of requirement is produced
Acid and Lactate build up and there is production of reactive oxygen species
There is impaired contration and contracture which is deformaties of the tissue (stunned myocyte)
This develops to cell death by oncosis, apoptosis and autophagy.
Necrosis at tissue level

Question 16

What is the major determinant in the extent of irreversible injury from Myocardial Infarction?

Answer 16

TIME

Question 17

Where does the Infarction progress from?

Answer 17

The endothelium to the epicardium

Question 18

Is there collateral circulation?

Answer 18

Little or no collateral vcirculation

Question 19

What is infarction?

Answer 19

Obstruciton of the blood flow by a thrombus or embolus causing local death to tissue

Question 20

What are the goals for treating for Acute coronary Syndromes (heart attacks)

Answer 20

This can be fatal. The goals are:

1) reduce and relieve acute symptoms and distress
2) prevent or limit extent of myocardial necrosis
3) REduce risk of early death due to arrhythmia or acute heart failure
4) Reduce risk of reoccurance (secondary prevention)
5) Limit development of chronic iscahemic cardiomyopathy and heart failure

Question 21

What is the Primary Treatment?

Answer 21

This is ttrreatment while waiting for diagnosis.
GTN to reduce the cardiac preload and oxygen demand
Loading dose of aspirin 300mg to reduce further thrombus formation
Morphine to relieve the pain
ANti-emetic to relieve nausea

Question 22

What is the treatment after diagnosis of STEMI?

Answer 22

STEMI: Reperfusion therapy (emergancy)
DO this either with drugs that prevent fibrin build up or
Emergancy operation (PCI) within 12 hours of onset of symptoms and 2 hours of fibrinolytic therapy

Question 23

What is the treatment after diagnosis of NSTEMI?

Answer 23

Clopidogrel loading dose of 300mg and asprin (unless contraindicated)
High risk patients may get the PCI operation or CABG ssurgery

Question 24

What are the 2 class of drugs used for these primary treatment?

Answer 24

Anticoagulant

Antiarrhythmic

Question 25

What is the long-term management post STEMI (prophylaxis)

Answer 25

Anti-platelet therapy: low dose aspirin for life and clopidogrel for 6-12 months
Anit-coagulation can be added or used as an alternative (warfarin or Rivaroxaban)
Statins regardless of HDL levels
ACE inhibitors or ARB if not already used
B-blocker
Aldosterone antagonist (spironoloctane) if Left ventricular dysfunction