Hypertension

Question 1

What is the rationale for treating hypertension with diuretics?

Answer 1

• Hypertension is caused by an increase in blood volume.
• Diuretics decrease the amount of water retained in the body.
• More body water is excreted, thus reducing the blood volume, leading to decreased blood pressure.

Question 2

Which types of diuretics are most effective?

Answer 2

Loop diuretics, such as Frudemide

Question 3

In advanced heart failure, the extracellular fluid volume is expanded and yet the renin-angiotensin-aldosterone system is active. Explain.

Answer 3

• Normally, if the extracellular fluid volume increased, RAAS activity would decrease.
• In heart failure, decreased perfusion of the organs.
• With decreased blood flow, the kidneys sense this and release more renin in an attempt to increase renal blood volume.
• RAAS will remain active.

Question 4

What is blood pressure?

Answer 4

Pressure exerted by the blood on the blood vessels.

Question 5

What is the short-term means of blood pressure regulation?

Answer 5

Baroreceptors

Question 6

What are the long-term means of blood pressure regulation?

Answer 6

Via hormones and Na+ balance, eg. ECFV, degree of vasoconstriction

Question 7

How can high blood pressure arise?

Answer 7

• an increase in ECFV
• an increase in vasoconstrictor agents
• a reduction in vasodilator agents

Question 8

What are the two types of hypertension?

Answer 8

• PRIMARY HYPERTENSION ( >90% of cases): has an unknown cause
• SECONDARY HYPERTENSION (~10% of cases): has an identifiable cause

Question 9

What can hypertension be caused by?

Answer 9

• renal diseases (eg. glomerulonephritis, diabetic nephropathy)
• vascular causes (eg. renal artery stenosis)
• hormonal abnormalities (eg. Conn’s syndrome, Cushing’s syndrome)
• drugs (eg. contraceptive pill)
• pregnancy (eg. pre-eclampsia)
• monogenic genetic diseases (eg. Liddle’s)

Question 10

Describe essential hypertension

Answer 10

• More prevalent in urban areas
• Caused by a combination of genetic and environmental factors

Question 11

Why do we need to treat hypertension?

Answer 11

Reduces the chances of heart attacks by 16%
Reduces vascular mortality by 21%

Question 12

What are the goals of anti-hypertensive treatment?

Answer 12

• adequate blood pressure control
• prevention of organ damage
• controlling other cardiovascular risk factors

Question 13

What are the three main treatment pathways for hypertension?

Answer 13

• non-pharmacological (eg. lifestyle modifications)
• pharmacological treatment
• surgical treatment

Question 14

List some non-pharmacological treatments for hypertension.

Answer 14

• quit smoking (if applicable)
• weight control
• eat less salt
• regular exercise

Question 15

List some pharmacological treatments for hypertension

Answer 15

• ACE inhibitors
• Angiotensin II receptor blockers
• diuretics
• vasodilators

Question 16

What are some side effects of ACE inhibitors (caused by the decreased Angiotensin II effects)?

Answer 16

• cough (common) - due to bradykinin breakdown
• angioedema (rare) - due to bradykinin breakdown (very serious, prevents breathing)

Question 17

What are some side effects of ACE inhibitors and AT1 receptor blockers?

Answer 17

hyperkalemia - due to decreased aldosterone, which leads to decreased Na reabsorption and hence decreased K excretion

Question 18

When are ACE inhibitors and AT1 receptor blockers contraindicated?

Answer 18

contraindicated in pregnancy - foetal problems
contraindicated in renal stenosis

Question 19

Why are ACE inhibitors contraindicated in renal stenosis?

Answer 19

• Decreased efferent renal arteriole constriction
• Decreases the pressure gradient across the Bowman’s capsule
• Decreased GFR

Question 20

What are the consequences of sympathetic nerve stimulation of the CVS?

Answer 20

β1 - increase HR and contractility, which increases CO, which increases BP
α1 - vasoconstriction, which increases TRP, which increases BP

Question 21

How would you decrease sympathetic activity?

Answer 21

CNS: α2 adrenoreceptor agonists (eg. Clonidine, used in hypertensive crisis)
Ganglion blockers: NIC blockers (eg. Trimethapan, used in hypertensive crisis)
Synaptic blockade (eg. Reserpine)

Question 22

List some adrenoceptor blockers.

Answer 22

α1 blockers: cause the relaxation of vascular smooth muscle, eg. prazosin
β1 blockers: cause a reduction in CO and renin release (eg. atenolol)

Question 23

Describe K channel openers as vasodilators.

Answer 23

• Increased K+ efflux from the cells.
• Causes vascular smooth muscle hyperpolarisation.
• Reduction in VGCC activity
• Reduction in intracellular [Ca].
• Reduced MLCK activity
• Increased relaxation - vasodilation.

Question 24

Describe voltage-dependant Ca2+ channel blockers as vasodilators.

Answer 24

• Block VGCC activity in vascular smooth muscle cells.
• Reduction in intracellular [Ca].
• Reduced MLCK activity
• Increased relaxation - vasodilation.

Question 25

Give an example of a voltage-dependant Ca2+ channel blocker.

Answer 25

Dihydropyridines e.g amlodipine

Question 26

What issues do you need to consider in selecting drug therapy?

Answer 26

• essential vs. secondary hypertension
• side effects of the drugs
• drug interactions
• co-existing diseases
• quality of life

Question 27

What are 3 possible mechanisms for essential hypertension?

Answer 27

→ Increased sympathetic nervous system
→ Increased RAAS
→ endothelial dysfunction

Question 28

What are 2 possible defects in essential hypertension?

Answer 28

→ Vascular smooth muscle contraction
→ Na+ handling and excessive salt intake

Question 29

What are 4 risk factors for essential hypertension?

Answer 29

→ Obesity
→ Age
→ Ethnicity

Question 30

What is hypertension a risk factor for?

Answer 30

→ Stroke
→ Ischaemic heart disease
→ Left ventricular hypertrophy and heart failure

Question 31

What is the criteria for hypertension?

Answer 31

140/90 mmHg