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Flashcards in 4. Hypertension Deck (32):
1

What is BP determined by?

By the cardiac output and the resistance of the blood vessels to blood flow

2

How do you work out BP?

BP = CO x SVR

3

"Systolic BP"

The maximum BP during ventricular contraction

4

"Diastolic BP"

The minimum level of BP measured between the contractions of the heart

5

"Hypotension"

Blood pressure less than 90/60

6

"Postural hypotension"

AKA. Orthostatic hypertension

Reduction in systolic BP of 20mmHg or more after standing for at least one minute

May also see in increase in diastolic BP by 10mmHg or more

Associated with dizziness and fainting

7

When does postural hypotension tend to occur/how can it be caused?

More frequent in older patients - especially those with diabetes

Can be caused by drugs such as antihypertensives (diuretics, vasodilators), alcohol

8

CNS symptoms occurring with hypotension

Dizziness

Impaired cognition (espeically in the elderly)

Lethargy and Fatigue

Visual disturbances due to hypo-perfusion of the brain e.g. blurred vision, tunnel vision etc

9

Symptoms of hypotension associated with the muscles

Paracervical (upper back) ache

General fatigue

10

Symptoms of hypotension associated with the heart

Angina - due to hypo-perfusion of the heart, especially during exercise

11

"Prehypertension"

Aka. High normal BP

Systolic - 130-139
Diastolic - 85-89

12

What should be implemented for patients with prehypertension?

Should encourage lifestyle changes - this group has an increased risk of becoming hypertensive

NB. These are not candidates for drug therapy

13

"Isolated systolic hypertension"

Systolic BP greater than 140mmHg and a diastolic less than 90mmHg (SO high systolic but normal diastolic)

Less serious than full hypertension

14

What should be implemented for patients with isolated systolic hypertension?

Lifestyle changes - diet low in sodium, rich in whole grains, fruits and vegetables due to the presence of nitrate which can be converted to nitric oxide

Should encourage weight loss, increased physical activity and reduced alcohol consumption

If these do not reduce the systolic hypertension to safe levels then drugs should be used

15

"Hypertension"

When the systolic and diastolic are persistently greater than 140/90

Persistently meaning that the diagnosis must be based on repeated measurements on separate occasion days or weeks

16

Why is the recognition of hypertension so important?

Cardiovascular mortality risk is proportional to increased BP

Elevated BP is a major cause of stroke, coronary heart disease, renal impairment and peripheral vascular disease

17

What is the impact of hypertension on the heart?

Leads of a thickening of the left ventricle - concentric hypertrophy

This causes the lumen diameter of the ventricle to decrease

18

"Concentric hypertrophy"

The walls of the ventricle hypertrophy and increase, causing the size of the ventricle chamber to decrease

SO to maintain the CO in this instance, the HR must increase

19

"Eccentric hypertrophy"

The whole ventricle enlarges

The wall may or may not increase in thickness

The enlarged heart is weaker and this can lead to heart failure

20

What clinical impact might hypertension have on the eyes?

Damage to the retina - arteriolar narrowing and abnormalities

Can cause damage to the eyes that appears as 'silver wiring' and 'cotton wool spots'

IMAGES ARE IN MILLAR PP _ RECOGNISE THESE

21

"Primary hypertension"

90-95% of the causes of hypertension

Aka. 'essential' or 'idiopathic'

There is no obvious underlying cause

Strong polygenic familial trent

22

"Secondary hypertension"

About 5% of the cases

There is a clear underlying cause e.g. renal or renovascular disease, endocrine disease, coarctation of the aorta, iatragoenic (hormonal/oral contraceptive/NSAIDS), Thyroid or parathyroid disease

23

How is BP normally controlled? (year 1)

1. Baroreceptors in the carotid artery via the neuronal system

2. Renin-angiotensin-aldosterone system via the hormonal system

24

Describe the control of BP via the baroreceptor system

Immediate control - works in seconds - a rapid response system

This is important during changes in posture or during exercise

25

Describe the control of BP via the RAAS system and give the mechanism

Responsible for the maintenance of steady, longterm BP

Pathology in this system can lead to chronic hypertension

Mechanism:
-Angiotensinogen to angiotensin 1 via renin
-Angiotensin 1 to angiotensin 2 via ACE
-Angiotensin 2 causes the release of aldosterone
-Aldosterone increases Na+ reabsorption from the collecting duct of the kidney (upregulates ENaC channels) and hence also increases the reabsorption of Cl- (follows Na+) - this results in an increased BP
-Angiotensin 2 also has a sympathetic effect on the body which causes an increased BP
-Also results in an increased secretion of ADH

26

What are some clinical signs of hypertension (would be present in the blood)?

Elevated levels of renin angiotensin 2

27

What is the impact of elevated levels of renin and angiotensin 2?

What does this mean for treatment?

Leads to excess sodium retention

Leads to retention of water via raised ADH

SO dietary salt restriction should always be part of treatment and diuretics should be used

28

"Hyponatremia"

If the extracellular fluid sodium is below 135mmol/L

Serious as it can lead to brain swelling

29

Symptoms of hyponatremia

Mild:
Loss of energy and fatigue
Confusion
Muscle weakness

Severe: (these are all due to teh swelling of the brain)
Nausea and vomiting
Headache
Spasms
Restlessness and irritability
Seizures
Coma

30

What is the suggested link between diabetes and hypertension?

Suggested that diabetes damages the kidneys and can hence result in an increased release of renin

31

What is the link between obesity and hypertension?

Obesity causes increased release of renal renin

This causes increased formation of angiotensin and sodium retention

This then results in hypertension (increased sodium and water retention)

32

How is hypertension treated? (Ladder of treatments)

Lifestyle changes - exercise, diet (increased fruit and veg, reduced salt intake), reduced weight

Thiazide diuretic e.g. Bendroflumethazide

Thazide + beta blocker or ACE inhibitor

Angiotensin receptor blocker

Calcium channel blocker

Alpha blocker