L10 Hypertension 1

Question 1

Define hypertension.

Answer 1

Sustained increases in systemic blood pressure > 140/90mm Hg

Question 2

define the 2 cases of hypertension:

Answer 2

Essential/primary hypertension: cause in unknown, due to genetic and environmental factors. 90-95% of patients.
Secondary hypertension: secondary to another disease or the use of medications. 5-10% of patients.

Question 3

List factors associated with primary hypertension.

Answer 3

age
salt intake
weight
race
potassium concentration
alcohol
exercise

Question 4

What are some causes of secondary hypertension?

Answer 4

kidney disease
analgesic neuropathy
adrenocorticol hypertension (cushiness disease and primary aldosteronism)
cerebral tumour
pre-eclampsia
renal artery stenosis

Question 5

What are some drugs that can cause hypertension?

Answer 5

Alcohol
effervescent antacids
NSAIDs
corticosteroids
OCs and oestrogen
sympathomimetics
MAOIs
venlafaxine
eryhtropoetin
cyclosporin
licorice

Question 6

What is myocardial infarction?

Answer 6

the death of an area of heart muscle as a result of being deprived of its blood supply.
Characterised by severe chest pain.
AKA Heart attack.

Question 7

What is proteinuria?

Answer 7

Protein is allowed to leak into the urine as a result of a defect in the glomerular capillary.

Question 8

What is the target BP for patients with hypertension? What is the target BP for patients with CHD, diabetes, renal disease or stroke?

Answer 8

140/90

130/80

Question 9

What are some non-pharmacological therapy of hypertension?

Answer 9

Diet: low KCl and saturated fats
Weight reduction
Cessation of smoking
reduce excessive alcohol consumption
30 minutes of moderate intensity on 5 or more days per week

Question 10

When should treatment for hypertension be commenced?

Answer 10

Depends on level of BP and patients risk level and response to lifestyle changes.
Low risk: try lifestyle changes and reassess after 2 years. treat if BP> 160/100
med risk: try lifestyle changes for 3-6 months and treat if no improvement, high BP or family history of CVD, indigenous. reassess after 6-12 months.
High risk: treat promptly with lifestyle changes AND drugs. reassess frequently.

Question 11

How is blood pressure regulated?

Answer 11

Baroreceptors in the carotid arteries and aortic arch detect drop in BP. Impulses sent to brain and increased sympathetic outflow to the heart, blood vessels and adrenal gland. Increased release of NA activates beta-1 receptors in the heart, and alpha-1 receptors in the blood vessels to cause vasoconstriction.

Question 12

what are the two mechanisms by which blood pressure is increased?

Answer 12

Increased cardiac output

increased total peripheral resistance

Question 13

how is systolic blood pressure controlled?

Answer 13

bardiac output: depends on venous return

Question 14

how is diastolic blood pressure controlled?

Answer 14

Total peripheral resistance

Question 15

describe the renin-angiotensin-aldosterone system

Answer 15

Important role in maintaining BP, blood volume and electrolyte balance.
Renin is secreted by the kidney in response to decreased renal blood flow, decreased salt intake and stimulation from the sympathetic nervous system.

Question 16

What is the role of renin in the RAAS?

Answer 16

Catalyses conversion of angiotensin to angiotensin 1.

Question 17

Outline the steps in RAAS control of BP.

Answer 17

Renin catalyses conversion of angiotensin to angiontensin 1.
angiotensin 1 is converted to angiotensin 2 by angiotensin-converting enzyme (ACE)
angiotensin 2 stimulates AT(II)1 and AT(II)2 receptors to cause vasoconstriction and aldosterone secretion.
Aldosterone secretion increases sodium excretion, increasing blood volume –> increased CO and BP.

Question 18

What are the 3 mechanisms of action of angiotensin II?

Answer 18

1. vasoconstriction, particularly in efferent arterioles of kidney. Due to increased release of noradrenaline from sympathetic nerves increasing vasoconstriction (indirect effect)
2. salt retention: angiotensin II stimulates proximal tubular reabsorption of sodium ions. initiates secretion of aldosterone from adrenal cortex, thus stimulating reabsorption of sodium ions.
3. cardiovascular growth: cell growth in the left ventricle and arteriolar wall.

Question 19

What are the target tissues for antihypertensives?

Answer 19

Heart: cardiac output
Arterioles: determine peripheral resistance
Kidney: blood volume
CNS: baroreceptors and set point
Sympathetic nerves: relase NA
Endothelial cells: regulate levels of angiotensin II, ET-1 (vasoconstrictor) and NO (vasodilator).

Question 20

List the 5 major drug classes of antihypertensives, and their general mechanism of action.

Answer 20

1. ACE inhibitors and angiotensin receptor antagonists (sartans)
2. beta blockers
3. thiazide and related diuretics
4. calcium channel blockers
5. selective alpha-blockers

Question 21

What are some other antihypertensives?

Answer 21

1. centrally-acting alpha-2 agonists
2. arteriolar vasodilator
3. nonselective arteriolar and venous vasodilator

Question 22

What are the first choice drugs for hypertension?

Answer 22

an ACE inhibitor or saran, or,
a dihydropyradine calcium channel blocker, or,
low dose thiazide diuretic if over 65 years

Question 23

Why are thiazides not recommended as a first line mono therapy in younger patients?

Answer 23

Assosciation with new onset diabetes.

Question 24

What are the rationale for staged introduction of drugs?

Answer 24

High doses of antihypertensives are often not effective during chronic use, and often result in side effects.
Blood pressure can be controlled without side effects by combining low doses of different drugs with complimentary mechanisms of action.
the dose of a single agonist is often limited by homeostatic mechanisms.

Question 25

What are the preferred drug combinations for hypertension?

Answer 25

ACE inhibitor with a thiazide diuretic or calcium channel blocker.
Calcium channel blocker with a thiazide diuretic.