Hypertension pathophysiology & treatment Flashcards
Why is treatment of hypertension important?
The world’s number 1 cause of preventable morbidity and mortality
The UK’s number 1 preventable cause of premature mortality and morbidity
> 20% of deaths can be linked with hypertension
It is also the most cost effectively treated condition according to NICE
How big does the increase in BP need to be to pose a threat to your health?
Very small increase in BP has significant effects on health
2 mmHg rise in BP will:
- increase risk of dying from IHD by 7%
- increase risk of dying from a stroke by 10%
Complications of hypertension are described as ‘end-organ’
What organs are at risk?
Brain Heart Eyes Vasculature Kidneys
What complications can arise in the brain, due to hypertension?
Haemorrhage
Stroke
Cognitive decline
What complications can arise in the heart, due to hypertension?
Left ventricular hypertrophy
Coronary heart disease
Congestive heart failure
Myocardial infarction
What complications can arise in the vasculature, due to hypertension?
Peripheral vascular disease
What complications can arise in the Eyes, due to hypertension?
Retinopathy
What complications can arise in the kidneys, due to hypertension?
Renal failure
Dialysis
Transplantation
Proteinurea
Describe the variation in BP across a population
Normal distribution (bell curve)
The Framingham study investigated the correlation between increased BP & risk of stroke and cardiovascular disease
What did the study show?
Increasing blood pressure EXPONENTIALLY increases the risk of stroke & cardiovascular disease
At what blood pressure is a patient hypersensitive?
140/90
What is optimum BP?
120 / 80
or less
What are the classifications of hypertension according to NICE?
Stage 1
Stage 2
Severe
A patient with Clinic blood pressure is 160/100 mmHg or higher is…
Stage 2 hypertensive
A patient with ABPM daytime average 135/85 mmHg or higher is…
Stage 1 hypertensive
A patient with a clinic systolic blood pressure of 180 mmHg or higher or diastolic blood pressure is 110 mmHg or higher is…
Severely hypertensive
A patient with Clinic blood pressure is 140/90 mmHg or higher is…
Stage 1 hypertensive
A patient with ABPM daytime average 150/95 mmHg or higher is…
Stage 2 hypertensive
What is ABPM and why is it useful?
Ambulatory blood pressure monitoring
Takes an average BP over a longer period of time
Avoids problems such as white coat hypertension and gives a more reliable value for BP
What is the cause of most people’s hypertension?
No one knows
90% of hypertension is primary and idiopathic
What are the causes of secondary hypertension?
Chronic renal disease Drug induced Endocrine disease Vascular disease (CoA) Sleep apnoea Pre-eclampsia
What factors increase the risks associated with hypertension?
Smoking
Age
Male
Diabetes mellitus Renal disease Hyperlipidaemia Previous MI or stroke Left ventricular hypertrophy
Why does smoking increase the risk of morbidity with hypertension?
Adds 20/10 mmHg to BP
Why does Diabetes increase the risk associated with hypertension?
5 - 30 times increase in the risk of MI
How much higher is the risk of morbidity with hypertension in men than in women?
Twice as high with men
What effect does left ventricular hypertrophy have on the risk of morbidity from hypertension?
Doubles the risk
Therapy for hypertension targets the 3 main contributors to blood pressure
What are these factors?
Heart rate & Stroke volume (= cardiac output)
Peripheral vascular resistance
One way to manipulate blood pressure is via sympathetic stimulation
What does sympathetic stimulation produce?
Increases blood pressure:
vasoconstriction
reflex tachycardia
increased cardiac output
The Renin-Angiotensin-Aldosterone System is a long term control system for blood pressure
When stimulated, Renin is released and lots of stuff happens (in Big Stephen Davies’s topic) but overall, ANG II is produced
What does ANG II do?
vasoconstrictor
anti-natriuretic peptide
stimulator of aldosterone release from the adrenal glands
potent hypertrophic agent which stimulates myocyte and smooth muscle hypertrophy in the arterioles
ANG II stimulates mycoyte & smooth muscle hypertrophy
Why is this clinically relevant to hypertension?
Myocyte and smooth muscle hypertrophy:
- are both poor prognostic indicators in patients with hypertension
- partially explain why hypertension and the risks of hypertension persist in some patients despite treatment
Primary hypertension is idiopathic, however, what are the likely aetiological causes of primary hypertension?
Increased reactivity in arterioles:
- Overall higher peripheral resistance
- a result of an hereditary defect of the smooth muscle lining arterioles
Sodium Homeostatic effect:
- Kidneys don’t excrete enough Na+ at any given BP
- As a result, sodium & fluid are retained & BP is too high
What is the effect of age on blood pressure?
BP tends to rise with age
Possibly because of decreases arterial compliance
What is the approach to treating hypertension in the elderly?
(nothing specific)
Aggressively treated
treatment is shown by various studies to significantly reduce the risk of MI & stroke
What is the significance of genetics in hypertension?
Hypertension seems to run in families
Closest correlation is between siblings
> 30 genes can be involved hypertension (increase of 0.5 mmHg at most per gene)
What dietary ingredient is linked to hypertension?
Salt (sodium)
Strong correlation between salt intake & stroke, hypertension
What is the significance of alcohol with hypertension?
High alcohol intake is a common cause of hypertension
Large amounts of alcohol increase BP
However, small amounts of alcohol decrease BP
Relaxing beer vs chinning 10 VKs
Reducing a previously high alcohol intake reduces BP by 5/3 mmHg on average
What is the significance of weight with hypertension?
Being obese causes BP to rise
Weight loss for hypertensive obese patients is one of the most important non-pharmacological measures
What is the correlation between birth weight and hypertension in later life?
low birth weight associated with hypertension in later life
Renal disease accounts for 20% of resistant hypertension
What are examples of renal diseases that cause secondary hypertension?
chronic pyelonephritis
fibromuscular dysplasia
renal artery stenosis
polycystic kidneys
Often, secondary hypertension is drug induced
What drugs can cause hypertension?
NSAIDs
Oral contraceptive
Corticosteroids
What is the risk to a pregnant woman with hypertension?
Pre-eclampsia
What endocrine disorders cause hypertension?
Conn’s Syndrome
Cushings disease
Phaeochromocytoma
Hypo and hyperthyroidism
Acromegaly
What vascular problems cause secondary hypertension?
Coarctation of the aorta
What sleeping problem causes hypertension?
Sleep apnoea
Why couldn’t a GP diagnose hypertension in a single clinic?
GP would only have normal BP monitoring cuff which doesn’t give true blood pressure reading
To diagnose TRUE hypertension, must use ABPM or HBPM home blood pressure monitoring
Summarise the different areas of investigations that must be done for a patient with newly diagnosed hypertension
Assess risk
Assess end organ damage
Screen for treatable causes of the hypertension
Describe how end organ damage is investigated for
ECG & echocardiogram:
- to look for left ventricular hypertrophy
Proteinurea:
- ACR urine test
Renal ultrasound & eGFR (function test)
What treatable causes of secondary hypertension are screened for?
Renal artery stenosis / FMD
Cushings disease
Conn’s syndrome
Sleep apnoea
How is the risk posed to a patient with newly diagnosed hypertension assessed?
What does a risk assessment allow?
Assign risk calculator / Q risk - used to determine risk to the patient
Once risk is known - target blood pressure can be set for the patient
Generally, the target risk is < 135/80-85 mmHg
What risk ‘score’ is needed for treatment to be needed?
Risk of CVD at 20% / 10 years
Treating hypertension causes the risk of cerebrovascular disease to drop by _______
40-50%
Treating hypertension causes the risk of MI to decrease by ______
16-30%
What pharmacological approach is taken to treating hypertension?
Low doses of several drugs
This minimises adverse effects and thus increases compliance
If a patient requires new medication for hypertension:
What do you do?
What do you not do?
Add new medication to current therapy until target BP achieved
DO NOT continuously change hypertensive medication
What classes of drugs are used to treat hypertension?
BHS guidelines
A - ACE inhibitor/ARB
C - Calcium channel blocker
D - Diuretic - Thiazide type
(B was for beta blockers)
Young (high renin) patients with hypertension should generally be given what type of drug?
ACE inhibitors / ARB
Elderly (low renin) patients with hypertension should be given what type of drugs?
Calcium channel blockers & Thiazide diuretics
Summarise the treatment route for Stage 1 hypertension
Offer antihypertensive drugs to people under the age of 80 with an ABPM reading above 135/85 if they have ONE OR MORE of the following:
- Organ damage
- Cardiovascular disease
- Renal disease
- Diabetes
- CVD Risk of over 20% / 10 years
If under 40 years old:
- Specialist evaluation for secondary causes
- Detailed assessment of target organ damage
What is the treatment route for people with stage 2 hypertension?
Patients with ABPM > 150/95 (stage 2)
Should be offered antihypertensives regardless of age
How is the treatment route for people 80, or over, different for stage 1 hypertension?
Same drug treatment as people 55-80
Morbidities should be taken into account
Different blood pressure target of < 145/85 instead of 135/80-85 for younger people
How is the response to antihypertensive drug treatment monitored?
BP can be measured at clinic for most people
However, people identified as having ‘white coat hypertension’ can use ABPM or HBPM instead
A 60 year old male patient has been diagnosed with hypertension
What do you prescribe first?
Step 1 treatment = Calcium channel blocker
Amlodipine / Felodipine - vasodilators
Diltiazem / Verapamil - rate limiting
CCBs:
- Aged over 55
- African/caribbean origin of any age
If a calcium channel blocker causes adverse effects on a patient (oedema, intolerance, high risk of heart failure)
(Patient is over 55)
What would you alternatively prescribe?
Thiazide-like diuretic
- Clortalidone
- Indapamide
What is the step 1 treatment for a patient under 55?
ACE Inhibitor /ARB
Not afro-caribbean
Not women of child baring age
Why must you NEVER prescribe ACE inhibitors to women of child baring age?
Teratogenic
If step 1 treatment is proving ineffective, what would you prescribe next?
Step 2
Thiazide type diuretic:
- Clortalidone
- Indapamide
Added on to current prescription (CCB or ACEI/ARB)
If a patient is on CCB’s and Thiazide type diuretic treatment but their BP is still not improving as much as desried
What is the next step?
Step 3
CCB, ACEI & diuretics together
If a patient does not respond to Step 3 treatment, they are said to have _________
Resistant hypertension
What is the treatment for ‘resistant hypertension’?
Add further diuretic treatment to current list (CCB’s, ACEI & diuretic)
If patient has potassium blood level of <4.5 mmol/L:
- Spironolactone 25mg once daily
If patient has potassium blood level > 4.5 mmol/L:
- Higher dosage of thiazide type diuretic
Briefly describe the treatment for young people for hypertension
ACEI ± ARB
If single agent doesn’t work, then use both together
What are ACE inhibitors?
Angiotensin converting enzyme inhibitors
eg Ramipril
ACE enzyme is used in RAA system to convert ANG I into ANG II
ANG II causes increase in BP so ACE inhibitors stop it’s production
What are ARBs?
Angiotensin receptor blockers
Losartan
Valsartan
Candesartan
Irbesartan
(anything with “…sartan”)
Competitive antagonist of ANG II at the AT1 receptor:
- thus blocks effects of ANG II
Advantage over ACE inhibitors = no cough
ACEIs and ARBs reduce production of ANG II which plays a central role in organ damage
What organs are damaged by ANG II?
Brain
Heart
Vasculature
Kidneys
How does ANG II damage the kidneys?
Lowers Glomerular filtration rate
Increase prteinurea
Increases aldosterone release
Glomerular sclerosis
What are the common adverse drug reactions associated with anti-hypertensives?
Cough
First dose hypertension
Taste disturbance
Renal impairment
Angioneurotic oedema
When prescribing anti-hypertensive medications:
For what reason is it necessary to check if the patient takes any over the counter medication?
NSAIDs (aspirin, ibuprofen, naproxen):
- Precipitate acute renal failure
When prescribing anti-hypertensive medications:
Why must you check to see if the patient takes any supplements?
Adverse reaction with potassium supplements
= Hyperkalaemia
When prescribing anti-hypertensives:
What other prescribed medication has adverse drug-drug interactions with antihypertensives?
Potassium sparing diuretics
(spironolactone, amiloride, and triamterene)
= Hyperkalaemia
Aside from ACEIs, ARBs, CCBs & TT diuretics :
What other medication can be used to treat hypertension?
Beta blockers
‘Atenolol’
Describe how Calcium channel blockers work…
Work by blocking “L type calcium channels”
They have selectivity between cardiac and vascular L type channels
Their effect:
- Relax large & small arteries = reduce peripheral resistance
- Reduce cardiac output
When would you prescribe vasodilating CCBs? (amlodipine or Felodipine)
What are it’s advantages?
Its the suitable antihypertensive for:
> 55 years
Women of child baring age
- High compliance
- Especially beneficial in elderly patients with systolic hypertension
- Rarely causes postural hypotension (extreme drop in BP when stood up)
A patient has recently been prescribed diltiazem, and you are giving them an examination
What signs/symptoms would indicate an adverse drug reaction with Diltiazem?
(Diltiazem is a rate limiting CCB)
Inspection:
- Flushing
- Ankle oedema
Palpation:
- Bradycardia (specific to rate limiting CCBs)
Symptoms:
- Headache
- Constipation
- Indigestion & reflux oesophagitis (acid reflux)
If you’ve got a patient who’s a wee wimp and doesn’t like feeling ill
What type of anti-hypertensive is good to prescribe them?
Thiazide type diuretics
Rarely have adverse drug reactions
If they do:
- Gout
- Impotence
What are the less commonly prescribed agents for hypertension?
Alpha-adrenoceptor antagonists:
- Doxazosin
Centrally acting agents:
- Methyldopa
- Moxonidine
Vasodilators:
- Hydralazine
- Minoxidil
How do alpha-adrenocepter antagonists work?
DOXAZOSIN
- Selectively block post synaptic 1-adrenoceptors
- Oppose vascular smooth muscle contraction in arteries
Has a fuck ton of adverse reactions:
- First dose hypotension
- Dizziness
- Dry mouth
- Headache
What is Methyldopa?
Central acting agent
It’s main use is in treating hypertension of pregnancy
It works by doing some spicy stuff:
- Decreases central sympathetic outflow
Adverse reactions:
- Sedation and drowsiness
- Dry mouth and nasal congestion
- Orthostatic hypotension
Summarise the common order of prescribed drugs for someone over 55…
(Assuming BP isnt dropping to target)
1) CCB
2) Thiazide type diuretic
3) ACE inhibitor
4) Spironolactone or increased dose of TTD
5) Beta blocker
6) Spicy medication
Summarise the common order of prescribed drugs for a young male…
1) ACEI
2) Thiazide type diuretic
3) CCB
4) Spironolactone or increased TTD dose
5) Beta blocker
6) Spicy drugs
Why is being hypertensive and getting pregnant risky business?
Approximately 30% of women who have hypertension before pregnancy will develop preeclampsia
2nd most common cause of maternal & foetal death
On top of hypertensive medications
What should be administered to a pregnant woman with pre-eclampsia?
intravenous hydralazine, esmolol, labetalol
