Chronic Stable Angina - 126

Question 1

Describe the pathophysiology of cell injury (due to lack of O2)

Answer 1

Decreased ATP production, reduction in Na/K pump, Ca, water and Na influx, K efflux.
Causes: ER swelling, cell swelling, loss of microvilli, blebs, decreased ATP so increase in anaeorbic glycolysis, membrane damage and increased intracellular Ca.

Question 2

How is a stable plaque different from an unstable plaque?

Answer 2

Stable: concentric, increased levels of fibrous stroma, increased smooth muscle.
Unstable: eccentric, increased lipid, ++ macrophages, ++inflammation

Question 3

What are the risk factors for atherosclerosis?

Answer 3

Age, gender, FH, smoking, hypertension, hyperlipidaemia, diabetes, obesity, personality (?stress)

Question 4

Define stable angina pectoris

Answer 4

Reversible ischaemia to myocardium brought on by increased work load and relieved by rest. Usually due to coronary artery disease

Question 5

Where can angina radiate to?

Answer 5

Neck, throat, teeth, upper extremity, shoulder

Question 6

What are the 4 acute differential diagnoses for angina that must not be missed?

Answer 6

Aortic dissection
PE
Tension pneumothorax
MI

Question 7

How would you treat angina?

Answer 7

Palliatively - e.g. cessation of activities, positional change
Drugs: nitrates e.g. GTN spray (first line for symptomatic relief)
B-blockers, e.g. bisoprolol (first line for chronic stable angina) contra in asthma

Verapamil (a Ca channel blocker) NOT to be used with a b-blocker

Question 8

What type of flow does Darcy’s law apply to and what does it state?

Answer 8

Laminar flow.

Flow is proportional to pressure difference

Question 9

What does a bruit indicate?

Answer 9

Pathological narrowing of a vessel - it is turbulent flow

Question 10

In vessels where is flow the quickest? Who’s law states this?

Answer 10

In the middle. Poiseuille’s law -> flow rate is proportional to the pressure difference between the ends of the pipe and it’s radius

Question 11

Where is minimum blood viscosity? What does blood viscosity depend on? What effect is this?

Answer 11

In capillaries. It depends on the width of the vessel (viscosity falls as vessels become smaller) Fahraeus-Lindquvst effect

Question 12

What passes more quickly through the microcirculation - red blood cells or plasma?

Answer 12

RBCs. Means the haematocrit is lower in smaller vessels, which reduces the viscosity.

Question 13

What is shear thinning?

Answer 13

As blood flows more quickly the viscosity falls - it minimises the pressure needed to drive cardiac output

Question 14

What does anaemia do to blood viscosity and total peripheral resistance?

Answer 14

Lowers blood viscosity and total peripheral resistance

Question 15

How is local blood flow measured?

Answer 15

Venous occlusion plethysmography

Question 16

What is hyperaemia? What organ does this?

Answer 16

Increasing blood flow to different tissues in the body. Active hyperaemia - increase in blood flow when tissue is active. The heart does this. 
Metabolic vasodilators (e.g. adenosine and CO2 are involved)

Question 17

What is blood flow through an organ dependent on?

Answer 17

Local resistance to flow. For most organs this comes from arterioles, which have the largest drop in pressure

Question 18

When is NO produced by endothelial cells?

Answer 18

It is produced faster by endothelial cells by the shear stress of blood flow over the endothelium. It’s a vasodilator and keeps arterioles dilated and inhibits cGMP breakdown

Question 19

What are the most important hormones in controlling blood flow?

Answer 19

Adrenaline and angiotensin II