Hypertension-Pathophysiology, Presentation and Investigation Flashcards
What does a 2mmHg rise in BP increase?
- Risk of mortality from IHD by 7%
- Risk of mortality from stroke by 10%
What organs can be effected by hypertension?
- Brain
- Eye
- Vasculature
- Kidneys
- Heart
What are the possible complications of hypertension involving the brain?
- Haemorrhage
- Stroke
- Cognitive decline
What are the possible complications of hypertension involving the eye?
Retinopathy
What are the possible complications of hypertension involving the vasculature?
Peripheral vascular disease
What are the possible complications of hypertension involving the kidneys?
- Renal failure
- Dialysis
- Transplantation
- Proteinuria
What are the possible complications of hypertension involving the heart?
- Left ventricular hypertrophy
- Coronary heart disease
- Congestive heart failure
- Myocardial infarction
What can cause BP to fluctuate during the day?
- Physical stress
- Mental stress
Hypertension
Blood pressure above which the benefits of treatment outweigh the risks in term of morbidity and mortality
What kind of distribution does BP exhibit amongst a population?
Normal distribution with a bell curve
What were the findings of the Framingham Study?
- Increasing blood pressure is associated with a progressive increase in the risk of stroke and CV disease
- Risk however rises exponentially and not linearly with pressure
- Age clearly plays a significant role also
What is considered to optimum BP?
< 120/80
What do most guidelines consider the point of hypertension?
140/90
Stage 1 hypertension
- Clinic blood pressure is 140/90 mmHg or higher
- ABPM daytime average 135/85 mmHg or higher
Stage 2 hypertension
- Clinic blood pressure is 160/100mmHg or higher
- ABPM daytime average is 150/95 mmHg or higher
Severe hypertension
Clinic systolic blood pressure is 180 mmHg or higher or diastolic blood pressure is 100 mmHg or higher
What are most cases of hypertension caused by?
Primary hypertension when no cause can be found
What are the causes of some cases of hypertension?
- Secondary hypertension
- Chronic renal disease
- Renal artery stenosis
- Endocrine disease: Cushings, Conn’s syndrome, phaechromocytoma, GRA
What other factors can increase the risk of morbidity of hypertension exponentially?
- Cigarette smoking
- Diabete mellitus
- Renal disease
- Male
- Hyperlipidemia
- Previous MI or stroke
- Left ventricular hypertrophy
How is BP controlled by the body?
By an integrated system
What are the prime contributors to blood pressure?
- Cardiac output
- Stroke volume
- Heart rate
What system can account for second to second blood pressure control?
Sympathetic system
How does the sympathetic system increase BP?
- Produces vasoconstriction
- Reflex tachycardia
- Increased cardiac output
Which system is pivotal in long term BP control?
Renin-angiotensin- aldosterone system
What is the RAAS responsible for?
- Maintenance of sodium balance
- Control of blood volume
- Control of blood pressure
What is RAAS stimulated by?
- Fall in BP
- Fall in circulating volume
- Sodium depletion
Where is renin released from?
Juxtaglomerular apparatus
What stimulates renin release?
- Fall in BP
- Fall in circulating volume
- Sodium depletion
What does renin do?
Converts angiotensinogen to angiotensin I
What coverts angiotensin I to angiotensin II?
Angiotensin converting enzyme
Angiotensin is a potent…
- Vasoconstrictor
- Anti-natriuretic peptide
- Stimulator of aldosterone release from the adrenal gland
Aldosterone is a potent…
- Anti-natriuretic peptide
- Antidiuretic peptide
Angiotensin II is a potent…
Hypertrophic agent which stimulates myocyte and smooth muscle hypertrophy in the arterioles
What kind of prognostic indicator s are myocyte and smooth muscle hypertrophy??
Poor prognostic indicators in patients with hypertension
What may explain why hypertension and its associated risks persist in some patients despite treatment?
Myocyte and smooth muscle hypertrophy
What are key targets in the treatment of hypertension?
- Sympathetic system
- RAAS
What is the aetiology of hypertension?
-Polygenic
: major genes, poly genes
-Polyfactorial: environment, individual/shared
What are the likely causes of hypertension?
- Increased reactivity of resistance vessels and resultant increase in peripheral resistance
- A sodium homeostatic effect
What may increase reactivity of resistance vessels?
Hereditary defect of the smooth muscle lining arterioles
Why does BP increase due to a sodium homeostatic effect?
In essential hypertension the kindeys aree unable to excrete appropriate amounts of sodium for any given BP. As a result sodium and fluid are retained and BP increases
What other factors may influence hypertension?
- Age
- Genetics and family history
- Environment
- Weight
- Alcohol intake
- Race
How does age effect BP?
-BP tends to rise with age, possibly as a result of decreased arterial compliance
How should hypertension be addressed in the elderly?
- Should be treated aggressively
- Treating both systolic and diastolic hypertension in the elderly significantly reduces stroke and MI
How do genetics effect BP?
A history of hypertension tends to run in families
Where does the closest genetic correlation exist?
Between siblings
How do genes influence hypertension?
To date >30 genes recognised as important but individually they account for at most 0.5mmHg each
Why does removing stress not necessarily return BP to normal values?
True stress responders who have very high BP when they attend their doctor but low normal pressures otherwise tend to be highly resistant to treatment
What effect does reducing salt intake have on BP?
- In hypertensive individuals lowers BP
- In normotensives appears to have little effect
What is one the most common cause of hypertension in young adults?
Alcohol
What effect does alcohol have on BP?
- Small amounts tend to decrease BP
- Large amounts tend to increase BP
What happens if alcohol consumption is reduced?
BP will fall over several days to weeks
How does weight effect BP?
Obese patients have a higher BP
What will happen if patients lose weight?
Their BP will fall
What is the most important non-pharmacological measure available for hypertension in obese patients?
Weight reduction
What effect does birth weight have on BP?
-The lower the birth weight the higher the likelihood of developing hypertension and heart disease
How does race effect BP?
- Caucasians have a lower BP than black populations living in the same environment
- Black populations living in rural Africa have a lower BP than those living in towns
What is the genetic reasoning behind black populations having higher BP?
Black populations are genetically selected to be salt retainers and so are more sensitive to an increase in dietary salt intake
What can sustained hypertension result in?
End-organ damage to blood vessels, heart and kidney
What renal diseases can cause secondary hypertension?
- Chronic pyelonephritis
- Fibromuscular dysplasia
- Renal artery stenosis
- Polycystic kidneys
What drugs can induce secondary hypertension?
- NSAIDs
- Oral contraceptive
- Corticosteroids
How can pregnancy lead to secondary hypertension?
Pre-eclampsia
What endocrine disorders can lead to secondary hypertension?
- Conn’s Syndrome
- Cushings
- Phaeochromocytoma
- Hyperthyroidism
- Hypothyroidism
- Acromegaly
What vascular condition can lead to secondary hypertension?
Coarctation of the aorta
What respiratory condition can lead to secondary hypertension?
Sleep apnoea
