15 When the cardiovascular system goes wrong

Question 1

Why can it be difficult for GPs to determine whether you need treatment for hypertension?

Answer 1

You’re nervous when you go to the GP so your blood pressure goes up

Question 2

What happens as you get older CV system

Answer 2

hypertension increases

Question 3

What is considered and unhealthy blood pressure

Answer 3

More than 140/90mmHg

Question 4

What are the two types of hypertension?

Answer 4

• Essentil/idiopathic

- Secondary

Question 5

What is secondary hypertension?

Answer 5

Hypertension arising from a known medical source - an underlying medical condition

Question 6

What is idiopathic hypertension

Answer 6

Essential

Arises from an unknown medical cause e.g. obesity, lack of exercise, alcohol intake, genetic predisposition

Question 7

What causes secondary hypertension?

Answer 7

• kidney disease - increase in angiotensin II or expansions of extracellular fluid
• endocrine disorders
• adrenal medulla disease (phaeochromocytoma - excessive adrenalin secretion)

Question 8

What does angiotensin II do?

Answer 8

narrows vessels by acting on aldosterone production

Question 9

What does the adrenal gland produce?

Answer 9

Cortex - steroid hormones

medulla -adrenalin

Question 10

How do we treat hypertension?

Answer 10

Try to reduce CO by:

• Beta blockers
• ACE inhibitors
• Inhibit membrane depolarisation and therefore the CO
• Reduce total periphery resistance

Question 11

What do beta blockers do and what are they used to treat?

Answer 11

used to treat hypertension:

reduce sympathetic activity, reduce renin, lower renin angiotensin cycle

Question 12

What to ACE inhibitors do and what are they used to treat?

Answer 12

Angiotensin converting enzyme inhibitors: decrease angiotensin II effect on aldosterone production 
inhibit vasoconstriction (by angiotensin II)

Question 13

How is total periphery resistance reduced?

Answer 13

inhibiting the action of noradrenaline

Question 14

What can hypertension increase the risk of?

Answer 14

Stroke
Atherosclerosis
Renal failure
Heart failure 
Aneurysms

Question 15

What happens during arteriosclerosis?

Answer 15

Blood vessel walls harden and thicken
loss of elasticity comes naturally with ageing
clinically significant if caused by atherosclerosis

Question 16

What happens in atheroscleosis?

Answer 16

• damage to endothelium
• Fatty plagues (atheromas) form under epithelial layer
• turbulent blood flow slows flow causing clots formation
• vessel lumen narrows
• arterial remodelling and subsequent expansion of neovessels can lead to aneurysms formation and rupture
• fragments of plaques become lodged and stuck in vessel causing thrombosis

Question 17

Treatments of atherosclerosis:

Answer 17

• Change the levels of lipids in the body
• Statins decrease cholesterol synthesis an reduce LDLs
• Bile acid binding resins reduce LDLs
• Fibrates lower LDLs and increase HDLs

Question 18

Ischaemic heart disease

Answer 18

Also known as coronary artery disease

• blockade of coronary vessels causes insufficient blood supply to the myocardium
• causes cell death
• causes angina pectoris (lactate molecules released in cell death bind to nociceptors (responsible for sensation of pain)
• tissue death can start within 20 minutes
• most common in left ventricle and anterior ventricular artery

Question 19

Treatments for ischaemic heart disease:

Answer 19

Balloon angioplasty and stenting - restructure damaged vessels
Ca channel blockers - increases vasodilation
Organic nitrates - increase vasodilation
Beta-adrenoceptor antagonists -reduce CO

Question 20

What ate the two types of valve defects?

Answer 20

Regurgitation

Stenosis

Question 21

What happens in regurgitation (valve defect)

Answer 21

The valves don’t close properly causing back flow of blood, turbulence and decreased CO

Question 22

What happens in stenosis?

Answer 22

-inadequate opening of the valves obstructs flow
caused by thickening of the valve, papillary muscles or chordae tendinae following disease
-In rheumatic fever white blood cells continue attacking the tissues after infection and cause cumulative damage after 20 yrs.
-severe occlusion can cause left atria hypertrophy (enlargement of cells) which puts more pressure on the right atrium and and pulmonary circulation
this can cause increased CHP and so pulmonary oedema and left ventricular hypertrophy
–> failiure

Question 23

Types of arrhythmia

Answer 23

• tachycardia

- bradychardia

Question 24

What is arrhythmia and what does it arise from?

Answer 24

Deviations from the normal beating of the heart caused by disruptions in the flow of blood due to changes in electrical conditions.
-arise from abnormal electrical conductions (myogenic tissues?)

Question 25

What do arrhythmias cause?

Answer 25

Not many problems associated with arrhythmias but sustained can cause dizziness and palpitations

Question 26

What is bradycardia? and how does it arise?

Answer 26

HR under 60 bpm (untrained individual) - Slowed impulse form the SAN (sinus bradycardia) - Pause in normal SAN activity (sinus arrest) - Tissue damage from injury which blocks electrical impulses from the SAN (from car crashes where sternum hits the steering wheel)

Question 27

What are the treatments for bradycardia?

Answer 27

pacemaker

Question 28

What is tachycardia and what are the different types?

Answer 28

-sinus -non sinus HR above 100 bpm

Question 29

What are the causes of sinus tachycardia?

Answer 29

- overexposure to caffein, amphetamines | - overactive thyroid glands

Question 30

What happens in sinus tachycardia?

Answer 30

SAN beating faster than it should

Question 31

How do you treat sinus tachycardia?

Answer 31

Beta blockers | Ca channel blockers

Question 32

What is non sinus tachycardia?

Answer 32

Abnormal beating of the heart caused by a problem in the conduction pathway or with muscle cells (not SAN)

Question 33

With regard to non sinus tachycardia, what is ventricular fibrillation and what causes it?

Answer 33

chaotic contractions within the ventricles caused by: - congenital heart disease - electrocution accidents or heart injury - heart surgery - ischaemia

Question 34

What causes non sinus tachycardia?

Answer 34

- triggered beats - automaticity - re-entry (circus movement?) - ventricular fibrillation

Question 35

With regard to non sinus tachycardia, what is automaticity and what causes it?

Answer 35

when the heart muscle cells contract on their own, ectopically. -automaticity is increased by a SNS and hypoxia

Question 36

With regard to non sinus tachycardia, what is triggered beats and what causes it?

Answer 36

- Defects in the ion channels of individual cells cause multiple spontaneous depolarisations leading to arrhythmia - leads to substained abnormal rhythm so ventricles can become out of sync with atrial filling - rare but prevalent in youths (Long QT syndrome) - can be lethal

Question 37

With regard to non sinus tachycardia, what is re-entry and what causes it?

Answer 37

Electrical impulses travel in small circular circuits rather than down the heart - caused by conduction block or heart damage - causes atrial flutter and paroxysmal supraventricular tachycardia which is potentially lethal

Question 38

What causes chronic heart failure?

Answer 38

caused by damage to cardiac muscle or hypertension or valve defects

Question 39

What happens in chronic heart failure?

Answer 39

- cardiac output is inadequate despite venous return due to decline in contractility - can cause oedema in lungs and body tissues due to build up of venous return - causes breathlessness and fatigue

Question 40

How do you treat chronic heart failure?

Answer 40

- ACE inhibitors - AGII blockers - Aldosterone blockers