Atherosclerosis, MI, Heart Failure

Question 1

What is atherosclerosis?

Answer 1

Chronic inflammation in the intima of large arteries characterised by intimal thickening and lipid accumulation

Question 2

Describe the 7 steps of atherosclerosis

Answer 2

1. Endothelial injury
2. LDL enters intima and is trapped in sub-intimal space
3. LDL converted into modified & oxidised LDL, causing inflammation
4. Macrophages take up modified &oxidised LDL, becoming foam cells
5. Apoptosis of foam cells causes inflammation & cholesterol core of plaque
6. Inc adhesion molecules on endothelium recruit more macrophages & T cells into plaque
7. Vascular smooth muscle cells form fibrous cap

Question 3

State the 3 principal components of atherosclerotic plaques

Answer 3

Cells (smooth muscle cells, macrophages, other leucocytes), extracellular membrane (including collagen), intracellular and extracellular lipid

Question 4

What are foam cells?

Answer 4

Macrophages containing modified and oxidised LDL

Question 5

Is atherosclerosis more prominent in the thoracic or abdominal aorta?

Answer 5

Abdominal

Question 6

Which cells form the fibrous cap?

Answer 6

Vascular smooth muscle cells

Question 7

Where is atherosclerosis most prominent?

Answer 7

Sites of slow/ turbulent flow, e.g. ostia of major branches

Question 8

State at least 3 modifiable risk factors for atherosclerosis

Answer 8

Type 2 diabetes mellitus, hypertension, hypercholesterolaemia, smoking

Question 9

State 3 non-modifiable risk factors for atherosclerosis

Answer 9

Male gender, increasing age, family history

Question 10

Describe the pathogenesis of myocardial infarction

Answer 10

A dynamic interaction between coronary atherosclerosis, plaque rupture, superimposed platelet activation, thrombosis, and vasospasm leads to coronary artery occlusion. Occlusion causes ischaemia which progresses to myocardial necrosis

Question 11

How long does myocardial ischaemia have to be before myocytes die and injury becomes irreversible?

Answer 11

20-40 minutes

Question 12

State at least three mechanical complications of myocardial infarction

Answer 12

Contractile dysfunction, congestive cardiac failure, left ventricular infarct and mitral regurgitation, ventricular rupture and haemopericardium, septal rupture, ventricular aneurysm

Question 13

What does septal rupture lead to?

Answer 13

Left to right cardiac shunt

Question 14

What does a ventricular aneurysm lead to?

Answer 14

Persistent ST elevation

Question 15

What % of patients develop an arrhythmia after a myocardial infarction?

Answer 15

90%

Question 16

When is ventricular fibrillation likely to develop post-MI?

Answer 16

Within 24h

Question 17

When is a ventricular aneurysm likely to develop post-MI?

Answer 17

After at least 4 weeks

Question 18

What is Dressler’s syndrome?

Answer 18

Pericarditis with chest pain, fevers, and effusion weeks to months after a myocardial infarction

Question 19

What causes fibrinous pericarditis?

Answer 19

Myocardial infarction extending to the epicardium

Question 20

What is the main risk of left ventricular dysfunction or ventricular aneurysm?

Answer 20

Mural thrombus, which can cause stroke

Question 21

What are the histological findings 0-6 hours after a myocardial infarction?

Answer 21

Normal histology

Question 22

What are the histological findings 6-24 hours after a myocardial infarction?

Answer 22

Loss of nuclei, homogenous cytoplasm, necrotic cell death

Question 23

What are the histological findings 1-4 days after a myocardial infarction?

Answer 23

Infiltration of polymorphs then macrophages

Question 24

What are the histological findings 5-10 days after a myocardial infarction?

Answer 24

Evidence of removal of debris by macrophages

Question 25

What are the histological findings 1-2 weeks after a myocardial infarction?

Answer 25

Granulation tissue, new blood vessels, myofibroblasts, collagen synthesis

Question 26

What are the histological findings weeks to months after a myocardial infarction?

Answer 26

Decellularising scar tissue

Question 27

State at least four common causes of heart failure

Answer 27

Ischaemic heart disease, valve disease, myocarditis, hypertension, dilated cardiomyopathy, arrhythmias

Question 28

State the four main complications of heart failure

Answer 28

Systemic emboli, arrhythmias, DVT and PE, sudden death

Question 29

How does heart failure cause fluid overload?

Answer 29

Cardiac damage leads to decreased cardiac output. This activates the renin-angiotensin system, leading to salt and water retention to maintain perfusion. This causes fluid overload

Question 30

Describe the pathophysiology of heart failure

Answer 30

Cardiac damage leads to decreased stroke volume. This is detected by baroreceptors which activate the sympathetic nervous system, increasing heart rate and total peripheral resistance to maintain perfusion. This increases afterload, which leads to left ventricular hypertrophy and increased end diastolic volume. The heart becomes dilated with poor contractility

Question 31

What are the symptoms of left ventricular failure?

Answer 31

Dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea, wheeze, fatigue

Question 32

What are the two main causes of right ventricular failure?

Answer 32

Left ventricular failure, chronic severe pulmonary hypertension

Question 33

What are the symptoms of right ventricular failure?

Answer 33

Peripheral oedema, ascites, facial engorgement

Question 34

What investigations are required to diagnose heart failure?

Answer 34

Brain natriuretic peptide (BNP), chest x-ray, ECG, echocardiogram