L9 - Hypertension I Flashcards
Why is hypertension normally asymptomatic?
Most people don’t know they have hypertension
- Unless extremely high blood pressure
Hypertension normally declares itself when an event occurs e.g. stroke, chronic renal disease, heart failure
What are the 7 major diseases hypertension is a risk factor for?
Stroke Myocardial infarction Heart failure Chronic renal disease Cognitive renal disease Cognitive decline Atrial fibrillation
What is a stroke?
Ischaemic – cutting off blood supply to part of brain
- Atheroma in coronary arteries
- Super added thrombus
- Embolus – blood clot block blood supply to brain
Haemorrhage – bleed into the brain tissue
What is myocardial infarction?
Ischaemia and infarction into the heart caused by an atheroma
Acute blockage of coronary heart –> heart attack –> myocardial infarction
What is heart failure?
If you have had a heart attack and damage heart –> pump your heart into a high-pressure state –> heart fails more
- Blood pressure = after load
Even if you haven’t had heart failure - changes in heart develop overtime which means the heart becomes inefficient
What is chronic renal disease?
Renal vasculature is susceptible to a sustained rise in blood pressure
Start to lose nephrons in kidney
Hard to know which comes first between hypertension and chronic renal disease
What is cognitive decline?
Hypertension effect small vessels in the
Slowly lose bits of brain tissue overtime – e.g. leads to dementia
What is atrial fibrillation?
Hypertension increases the risk of atrial fibrillation –> increases independent stroke risk
Why is it so important to find hypertension treatments?
Important preventable cause of premature morbidity and mortality
- Morbidity – all the factors that cause symptoms, side effects, inconvenience
Huge opportunity for pharmaceutical companies – commonly used so get a good return
Using population data - each 2 mmHg rise in systolic BP is associated with?
7% increased mortality from ischaemic heart disease
10% increased mortality from stroke
Why is hypertension considered arbitary?
Isn’t a level where we get hypertension
Just a point where blood pressure causes more issues
Set a range which is considered ‘safe’
- Even within this range there is still a continuum in risk level
What is the clinical BP where you are diagnosed with suspected hypertension?
Clinic BP 140/90 mmHg or higher
What are people with suspected hypertension offered to confirm a diagnosis?
Ambulatory BP monitoring (ABPM)
What is ambulatory BP monitoring?
During the day – record every 30min
During the night – record every hour
ABPM results should be slightly lower then clinical results
Don’t need to have both results high to get a diagnosis
Stage 1 hypertension - clinic BP and ABPM values
Clinic - 140/90
ABPM - 135/85
Stage 2 hypertension - clinic BP and ABPM values
Clinic - 160/100
ABPM - 150/95
Severe hypertension - clinic BP and ABPM values
Clinic SBP - 180
Clinical DBP 110
What % of patients have primary hypertension?
85-90% of people have this type
No underlying cause – may be genetic
What is the treatment for primary hypertension?
Lifestyle modification – limit - Obesity/lack of exercise - Salt - Smoking - Alcohol Antihypertensive drug therapy
What is the cause of secondary hypertension?
Symptoms/signs of an underlying cause
- Renal disease
- Endocrine disease - tumours which release steroids or catecholamine
What are the characteristics of secondary hypertension?
More common in young patients
Resistant BP - does not lower when on 1 or more therapies
- Can often be because patients aren’t taking their tablets
When do you offer antihypertensive drug treatment to people aged under 80 with stage 1 hypertension?
When they have one or more of
- Target organ dama
- Established cardiovascular disease - heart attack or stroke
- Renal disease
- Diabetes
- A 10 year cardiovascular risk of 20% or greater - algorithms
What evidence is there that hypertension is damaging organs?
Eye - can see changes in arteries
Heart – left ventricular hypertrophy
Kidney – protein in urine, damaged renal function
When do you offer antihypertensive drug treatment to people of any age with stage 2 hypertension?
Right away
Risk is high enough to warrant it
Why are BP targets different in old people?
Some changes in vasculature/BP are just to do with ageing
Lowering BP too much in old people can be bad
- Can become dizzy – more prone to injuries if they fall
Under 80 years old BP target
< 140/90
Over 80 years old BP target
< 150/90
What two factors is blood pressure dependent on?
Cardiac output and peripheral resistance
In hypertension – raised peripheral resistance is key
What two systems is peripheral resistance dependent on?
Sympathetic nervous system (noradrenaline)
Angiotensin-Aldosterone system
Peripheral resistance is affected by local vascular vasoconstrictors
and vasodilator mediators
Angiotensin II overall role
Bad guy in renin-angiotensin-aldosterone system Vasoconstrictor Enhances noradrenaline release Has vascular effects - Hypertrophy - Aldosterone release - Na reabsorption
Noradrenaline overall role
Bad guy in sympathetic nervous system
Vasoconstrictor and increases cardiac output
Causes renin release – converts angiotensinogen to angiotensin I
Hypertrophy of vasculature
Aldosterone release – Na retention
What do ACE inhibitors do?
Decrease afterload on heart and lower the BP
What are 3 examples of ACE inhibitors?
Ramipril
Enalapril
Perindopril
What are the clinical indications of ACE inhibitors?
Hypertension
Heart failure
Diabetic nephropathy
What are the side effects of ACE inhibitors?
Can get cough – then might swap to angiotensin II receptor blockers
What are the issues with ACE inhibitors?
Substrate for that enzyme builds up and competes with the drug for the enzyme
- Substrate builds up and drugs becomes less effective
- Substrate overcomes the competition - still some angiotensin II still produced
Receptor blockers then block it directly at the receptor
What are 3 examples of Angiotensin II receptor blockers?
Losartan
Valsartan
Candesartan
What are the clinical indications of Angiotensin II receptor blockers?
Hypertension
Diabetic nephropathy
Heart failure (when ACE-I contraindicated)
What are the side effects of Angiotensin II receptor blockers?
Symptomatic hypotension Hyperkalaemia Potential for renal dysfunction Rash Angio-oedema (swelling of tissue) Contraindicated in pregnancy Generally well tolerated
Why do angiotensin II receptor blockers cause symptomatic hypotension?
Especially in volume deplete patients
System tries to maintain BP – many mediated by angiotensin II
If you use ARB you are blocking the thing mediating their circulation
Get lightheaded and faint
Why do angiotensin II receptor blockers cause hyperkalaemia?
Aldosterone encourages K secretion
Blocking this system enhances K retention
Why are angiotensin II receptor blockers contradicted in early pregnancy?
Angiotensin II has key effects in early foetal development
Beta blockers overview
Only used in certain circumstances
Block noradrenaline and renin
Impact cardiac output
Ca channel blockers overview
Impact peripheral resistance
Aldosterone antagonists overview
Block the effect of aldosterone
Other diuretics such as thiazides
Alpha blockers overview
Old drugs – still used in resistance cases
Block pathway from brain through to sympathetic nervous system
Impact peripheral resistance
Renin inhibitors overview
Blocks production of angiotensin I
Why is some angiotensin II still produced with angiotensin II receptor blockers?
ARB blocks at the receptor level
- Angiotensin II competes with the drug for the receptor
- ACE pathway is not the only way angiotensin II can be produced
