17. Hypertension; Pathophysiology, Presentation and Investigation Flashcards
Is hypertension world’s number 1 cause of preventable morbidity and mortality?
yes
What is hypertension ranked number 1 in the Uk for?
number 1 preventable cause of premature mortality and morbidity
How big does the rise have to be in mmHg to cause significant increase in mortality risk in patients?
2mmHg rise in BP (not that much)
How does 2mmHg rise in BP affect mortality risk from IDH (ischaemic heart disease) and mortality risk from stroke
- 7% increase risk in mortality from IDH
- 10% increase risk in mortality from stroke
40% of strokes are due to BP greater than what?
> 140mmHg
What is the main complication of hypertension?
end-organ damage
Which body regions suffer from end-organ damage due to stroke? (5)
- Brain
- Eye
- Blood vessels
- Kidneys
- Heart
What can brain end-organ damage from hypertension cause? (3)
- haemorrhage
- stroke
- cognitive decline
What can eye end-organ damage from hypertension cause? (1)
-retinopathy
What can blood vessel end-organ damage from hypertension cause? (1)
- peripheral vascular disease
What can kidney end-organ damage from hypertension cause? (4)
- renal failure
- dialysis
- transplantation
- proteinuria
What can heart end-organ damage from hypertension cause? (4)
- left ventricular hypertrophy (LVH)
- chronic heart disease (CHD)
- congestive heart failure (CHF); unable to keep up with its demands
- Myocardial Infarction (MI)
When does BP mainly fluctuate?
during the day
What type of variable is BP?
continous variable
What 2 main factors cause fluctuations in BP during the day?
- physical stress
2. mental stress
Define hypertension.(arbitral definition)
Blood pressure above which the benefits of treatments outweigh the risks in terms of morbidity and mortality (abnormally high BP)
What 2 main factors affect BP normality range?
- age
2. ethnicity (people in s. Pacific seem to have smaller BP than people in Western countries)
Does stroke risk increase with increasing hypertension?
Yes (and cardiovascular)
Is the relationship between BP with stroke or coronary heart disease more linear? What does it mean?
coronary heart disease and BP more linear; it means small changes in pressures can greatly increase stroke risk since heart disease relationship is more linear
What is the “optimum” blood pressure?
120/80 - 140/90
What are clinical values for stage 1 hypertension? (clinical BP and ABPM)
- clinical BP 140/90mmHg or higher
- ABPM daytime average 135/85mmHg or higher
What is ambulatory blood pressure monitoring? (ABPM)
Measure of BP at regular intervals (~30 times in a day to give a more accurate representation of average BP)
What are clinical values for stage 2 hypertension? (clinical BP, and ABPM)
- clinical BP is 160/100mmHg or higher
- ABPM daytime average is 150/95mmHg or higher
What are clinical values for severe hypertension? (clinical systolic and diastolic BP)
- systolic is 180mmHg or higher
OR - diastolic is 110mmHg or higher
What are 2 types of hypertension and what do they mean?
- Primary hypertension; no cause found
2. Secondary hypertension; cause found
What type of hypertension do most people have?
Primary hypertension (95%)
What percentage of people have secondary hypertension? (known cause)
only around 5-10%
What 3 conditions often cause secondary hypertension?
- chronic renal disease
- renal artery stenosis
- endocrine disease
What common endocrine disease cause secondary hypertension? (4)
- Cushing’s syndrome
- Conn’s syndrome
- Phaecochromocytoma
- GRA;Glucocorticoid remediable aldosteronism
What is Cushing’s syndrome?
excess ACTH production and cortisol
What is Conn’s syndrome?
excess aldosterone produced
What is phaecochromocytoma?
rare tumour of adrenal land producing abnormal norepinethrine and epinethrine levels
What is GRA?
Glucocorticoid remediable aldosteronism; aldosterone synthase hyperactivity
To what extent is hypertension responsible for all worldwide deaths?
> 20% responsible for all deaths globally
What is the link between risk factors and chances of stroke or MI due to hypertension?
the more risk factors are added together, the greater the chances of hypertension and CV disease
What are the most common morbidity risk factors for hypertension? (6)
- cigarette smoking
- diabetes mellitus
- renal disease
- male
5.hyperlipidaemia (including high cholesterol) - previous MI or stroke
- left ventricular hypertrophy
(…+low fitness)
What risk factors double the risk of CV disease and hypertension? (2)
- being male
- left ventricular hypertrophy
What risk factor adds 2010 mmHg on average to the BP?
cigarette smoking
What risk factor increases chances of MI 5-30 times? (MASSIVE risk)
diabetes mellitus
What integrated system are prime contributors to blood pressure? (2)
- cardiac output (stroke volume and heart rate)
2. peripheral vascular resistance
What can drug therapy be used on to regulate hypertension? (2)
- cardiac output (stroke volume and heart rate)
2. peripheral vascular resistance
What effect does activation of sympathetic system have on BP?
- increases heart rate (reflex tachycardia)
- vasoconstriction so increase in TPR
- increase cardiac output
THEREFORE BP INCREASES
How can action of activated sympathetic system be described?
short-acting (flight or fight), very rapid and accounts for second to second blood pressure
What will happen if sympathetic system is overactivated?
BP will remain high and will be maintained at high levels
What hormone system is used in long-term control of BP?
renin-angiotensin-aldosterone system (RAAS)
What is RAAS responsible for? (3)
- maintenance of Na balance (conserves salt and water for survival)
- control of blood volume
- control of blood pressure
Why are people who drink more likely to become hypertensive?
- alcohol makes body retain more Na in body as treshold increases for Na retaining
- less Na excreted in urine
- leads to hypertension
What is RAAS stimulated by?
- fall in BP
- fall in circulating volume
- sodium depletion
Where is renin released from?
juxtaglomerular apparatus
What is the function of renin?
converts angiotensinogen to angiotensin I
What converts angiotensin I to angiotensin II?
angiotensin converting enzyme (ACE)
What does RAAS system aim to do?
aims to increase BP (stimulated when BP is low)
What is the function of angiotensin II?
- vasoconstrictor
- anti-natriuretic peptide
- stimulator of aldosterone release from adrenal glands
Where is aldosterone released from?
adrenal glands
What type of peptide is aldosterone? (2)
potent antinatriuretic and antidiuretic peptide
What is the additional role of angiotensin II? What can it lead to?
- potent hypertrophic agent which stimulates myocyte and smooth muscle hypertrophy in arterioles
- arterioles become dilated, stiff and highly susceptible to damage
How can hypertrophy of smooth muscle around heart and blood vessels affect BP?
It can make arterioles unable to relax which increases TPR and MAP
What is a big poor prognostic indicator in patients with hypertension?
myocyte and smooth muscle hypertrophy
What does myocyte and smooth muscle hypertrophy explain in terms of treating hypertensive patients?
explains why hypertension and risks of hypertension persist in some patients despite treatment give
Who 2 systems are crucial to target when treating hypertension?
- sympathetic nervous system
- RAAS; renin-angiotensin- aldosterone system
(Both increase BP naturally)
What is the polygenic aetiology of hypertension? (2)
- major genes
2. poly genes
What is the polyfactorial aetiology of hypertension?
- environment
2. individual and shared
What are common mjor genes which can cause hypertension? (~11)
- GRA
- angiotensinogens
- diabetes
- Kallikrein
- MN blood type
- Na-Li counter transport
- Haptoglobin
- RBC Na
- FDH or FHCL
- increased sympathetics
- nonmodulation
What are common polygens which can cause hypertension? (4)
- obesity
- race
- blood pressure
- major gene traits (background combination)
What are common individual or shared factors which can cause hypertension? (5)
- oral contraceptive
- physical inactivity
- stress
- lower education
- small family size
What are common environment factors which can cause hypertension? (1)
Diet (na,k,cl,ca,mg, alcohol, caffeine, calories, fat, lead)
What are the physiological causes of hypertension? (2)
- Increased reactivity of resistance vessels and resultant increase in peripheral resistance
- An Na homeostatic effect
What causes the increased reactivity of resistance vessels which leads to hypertension?
hereditary defect of the smooth muscle lining arterioles; if reactivity of these is increased they lead to TPR increase and hypertension
What happens to Na and K in hypertensive patients?
- Na and K are retained in the body as they are NOT excreted
- kidneys are unable to excrete the appropriate amount of Na and K (they are retained instead)
What effect does excretion of Na and K have on BP?
dereases it
What effect does retaining of Na and K have on BP?
increases it
What happens to Na and K levels if more of these are constantly consumed?
The level of Na and K are reset in hypertensive patients to higher levels which means the body can accept higher amounts of these since autoregulation is stretched over long time. This leads to eventual hypertension as the body gets used to receiving high levels of Na and K which programme it to have more tolerance towards it which can be damaging over time
What are the main factors for sustained hypertension? (6)
- age
- genetics and family history
- environment
- weight
- alcohol intake
- race
Why are Afro-Carribeans more susceptible to hypertension?
as they’re genetically more susceptible to effects of salts in diet
Why does hypertension risk increase with age?
- due to decreased arterial compliance
How should hypertension in elderly be treated?
- should be treated aggressively as they have more to love
- must be pragmatic treatment ( more practical than theoretical perspective) e.g. treating both systolic and diastolic hypertension
Can history of hypertension run in families?
Yes
Between which two relatives is the closest correlation for hypertension patterns?
between siblings (NOT parent and child) due to similar gene pool and environment
Except from genetics, what other factor is similar between family members that should be considered for hypertension causes?
environmental factors (e.g. lifestyle, fitness, education, background, diet etc)
How many genes have been identified that control to hypertension?
> 30 genes
How much does each gene roughly increase the BP by in mmHg?
~by 0.5mmHg
Which sibling group has a very close correlation when identifying hypertension patterns?
monozygotic twins (very similar genome)
What 2 stresses make up most of the environmental factor that causes hypertension?
- physical stress
2. mental stress
Does removing stress return BP to normal?
Not necessarily; true stress responders have very high BP when they go to doctor’s (but low otherwise)
What is the main disadvantage for treating patients with sustained long term stress induced hypertension?
they are difficult to treat as they are resistant to treatment
What have famous SALT and DASH studies confirmed?
confirmed a strong relationship between hypertension, stroke and salt intake
Does reducing salt intake in hypertensive patients lower their BP?
yes, it lowers BP
In what group of patients does reduction in salt (Na) have little effect?
in normotensives (people with normal BP)
What should daily salt (Na) intake never exceed?
Should be <6gm/day
What should the salt restriction be to effectively lower BP in hypertensive individuals over time?
preferrably 1.5gm/day or even 0.5gm/day to lower BP in the long run
What foods are associated with decrease in hypertension?
- fruit and vegetables
-white meat
-grains
-fat-free dairy products
-nuts and seeds
and many more!
What famous diet is used to treat hypertension?
DASH diet
What is the most common cause of hypertension in young Scots nowadays?
alcohol (affects 1% of population)
What effect on BP does small amount of alcohol and large amount of alcohol have on BP?
- small amount of alcohol decreases BP
- big amount of alcohol increases BP
If alcohol consumption is reduced, how long will it take to reduce BP?
BP will fall over several days to weeks
What is the average fall in mmHg due to lower alcohol consumption?
average fall is relatively small 5/3mHg but still lowers BP
Which pressures increase with large alcohol intake? (2)
- systolic
- diastolic
What percentage of hypertensive patients are obese which causes their hypertension?
up to 30% (a VERY large and preventable number)
If a patient loses weight, what will happen to the BP?
it will fall as well
What is the most important non-pharmacological measure available for patients to lower their BP?
weight reduction
By how much in mmHg can weight reduction decrease BP in untreated and treated individuals?
in untreated; 19/18mmHg
in treated; 30/21mmHg
How can low birth weight affect hypertension in later life?
increases risk of hypertension and heart disease (and many in-utero factors can also affect it)
How do in-utero factors affect genes that are responsible for increased hypertension risk in later life?
they can’t alter the genes but how do genes OPERATE
Which race group has genetically lower and higher BPs?
- Caucasians tend to have lower BPs
- Black Afro-Caribeean populations tend to have higher BPs
What are the possible reasons that explain why black populations are more at risk for CV disease?
- genetic make up
- environment is different (e.g. diet)
- more susceptible to stress
- respond differently to changes in diet
- black populations more genetically selected to be salt retainers so are more sensitive to increase in dietary salt intake
What is the main problem with treating hypertension in many black populations? (3)
- often don’t respond well to treatment
- BPs tend to be more extreme and severe
- often patients present with high BP in 30s and 40s
Does removal of the cause in secondary hypertension guarantee that hypertension or risk will return to normal?
No guarantee
What does sustained hypertension lead to end-organ damage of? (3)
- blood vessels
- kidneys
- heart
What age group of patients who present with hypertension are more likely to have SECONDARY hypertension?
patients under 40
What are the main causes for secondary hypertension? (6)
- renal disease
- drug induced
- pregnancy
- endocrine
- vascular
- sleep apnoea
What percentage of secondary hypertension is caused by renal disease?
20% of resistant hypertension
What common renal diseases lead to secondary hypertension?(4)
- chronic pyelonephritis
- fibromuscular dysplasia
- renal artery stenosis
- polycystic kidneys
What are common drugs which induce secondary hypertension? (3)
- oral contraceptive
- NSAIDs (non-steroidal anti-inflammatory drugs)
- corticosteroids
What common pregnancy problem leads to secondary hypertension?
pre-eclampsia
What common endocrine conditions lead to secondary hypertension? (5)
- Conn’s syndrome
- Cushing’s syndrome
- phacochromocytoma
- hypo and hyperthyrodism
- acromegaly
What common vascular condition leads to secondary hypertension?
coarctation of the aorta (narrowing of aorta)
What are statistics for pre-eclampsia relating to maternal and foetal deaths
2nd most common cause of maternal and foetal deaths (infection is 1st)
What are the main clinical signs for Cushing’s syndrome?
- wasting of thigh muscles
- obesity
- moon shaped face
