Angina and Myocardial Infarction

Question 1

What is angina?

Answer 1

When O2 demand of myocardium > O2 supply.

Question 2

What is heart work determined by? (3)

Answer 2

Heart rate
Contractility
Afterload (peripheral resistance)

Question 3

How is angina treated? (with example drugs)

Answer 3

Reduce HR and contractility:

• Beta-blockers
• Ca2+ channel blockers (verapamil and diltiazem)

Dilate resistance vessels:

• Ca2+ channel blockers (dihydropyridines)
• Nitrates

Question 4

How do nitrates work (give two examples) to treat angina?

Answer 4

Glyceryl trinitrate (GTN) and isosorbide nitrate are converted to nitric oxide (NO) by nitrate ester reductase.

NO causes vascular smooth muscle relaxation, reducing peripheral resistance, reducing afterload and thus heart work.

Question 5

Describe the administration of GTN.

Answer 5

GTN has rapid first pass hepatic metabolism, so it can’t be given orally.

Instead it is given by sublingual spray, IV or transcutaneous patch.

Question 6

Describe adminstration of isosorbide nitrate

Answer 6

Isosorbide has lower first pass metabolism than GTN

Can be given in sustained release tabs.