Acute myocardial infarction

Question 1

What is acute myocardial infarction (AMI)?

Answer 1

The period where myocardial tissue is ischaemic. Infarction is the death of myocytes (ischaemic for >60m)

Question 2

How can AMI cause heart failure?

Answer 2

Less blood flow = impaired ability of cardiac muscle to contract = cells die = chronic heart failure

Question 3

How can AMI cause cardiac arrhythmias?

Answer 3

Ischaemia causes many changes that affect electrophysiology = ventricular cells develop acute changes in AP duration = causes regional slow conduction = arrhythmias

Question 4

What is the early treatment of AMI of paramedics or upon hospitalisation?

Answer 4

Morphine (relieves angina cause by AMI, reduces stress-related catecholamine hormone drive)

Question 5

How to limit the death of cardiac cells in the hospital? What is the early therapeutic intervention?

Answer 5

• PCI (stent) to perfuse ischaemic tissue (within 3h), give clopidogrel to reduce adverse cardiac events and formation of clot
• Thrombolytics IV (plasminogen activators)
• Injectable anticoagulants (heparin, bivalrudin)

Question 6

What is the prophylaxis with AMI?

Answer 6

1. Aspirin (COX inhibitor) - synthesises prostacyclin (PGI2) & less thromboxane (TXA2) = less platelet aggregation and more vasodilation
2. Beta-blockers - inhibit remodelling of CVS

Question 7

How do you treat arrhythmias occurring in the hospital (after AMI)?

Answer 7

Electrical defibrillation to eliminate ventricular fib

Question 8

How do you treat cardiogenic shock occurring in the hospital (after AMI)?

Answer 8

IV of beta-adrenoreceptor agonists

Question 9

How do you treat cardiogenic shock occurring in the hospital (after AMI)?

Answer 9

IV of beta-adrenoreceptor agonists