9:20 AM
Unknown
Hypertention
Secondary causes:
It is thought that between 5-10% of patients diagnosed with hypertension have primary hyperaldosteronism, including Conn's syndrome. This makes it the single most common cause of secondary hypertension.
Renal disease accounts for a large percentage of the other cases of secondary hypertension.
Conditions which may increase the blood pressure include:
glomerulonephritis
pyelonephritis
adult polycystic kidney disease
renal artery stenosis
Endocrine disorders
(other than primary hyperaldosteronism) may also result in increased blood pressure:
phaeochromocytoma
Cushing's syndrome
Liddle's syndrome
congenital adrenal hyperplasia (11-beta hydroxylase deficiency)
acromegaly
Other causes include:
NSAIDs
pregnancy
coarctation of the aorta
the combined oral contraceptive pill
steroids
MAOI
3- Isolated systolic hypertension
Isolated systolic hypertension (ISH) is common in the elderly,
Affecting around 50% of people older than 70 years old.
The Systolic Hypertension in the Elderly Program (SHEP) back in 1991 established that treating ISH reduced both strokes and ischaemic heart disease.
Drugs such as thiazides were recommended as first line agents.
This approach is contradicated by the 2011 NICE guidelines which recommends treating ISH in the same stepwise fashion as standard hypertension.
Hypertension diagnosis:
NICE published updated guidelines for the management of hypertension in 2011.
Some of the key changes include:
classifying hypertension into stages
recommending the use of ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM)
Why were these guidelines needed?
It has long been recognised by doctors that there is a subgroup of patients whose blood pressure climbs 20 mmHg whenever they enter a clinical setting, so called 'white coat hypertension'. If we just rely on clinic readings then such patients may be diagnosed as having hypertension when the vast majority of time there blood pressure is normal. This has led to the use of both ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM) to confirm the diagnosis of hypertension. These techniques allow a more accurate assessment of a patients' overall blood pressure. Not only does this help prevent overdiagnosis of hypertension - ABPM has been shown to be a more accurate predictor of cardiovascular events than clinic readings.
Blood pressure classification:
This becomes relevant later in some of the management decisions that NICE advocate. Stage Criteria
Stage 1 hypertension
Clinic BP >= 140/90 mmHg and subsequent ABPM daytime average or HBPM average BP >= 135/85 mmHg
Stage 2 hypertension
Clinic BP >= 160/100 mmHg and subsequent ABPM daytime average or HBPM average BP >= 150/95 mmHg
Severe hypertension
Clinic systolic BP >= 180 mmHg, or clinic diastolic BP >= 110 mmHg
4- Diagnosing hypertension:
Secondary causes:
It is thought that between 5-10% of patients diagnosed with hypertension have primary hyperaldosteronism, including Conn's syndrome. This makes it the single most common cause of secondary hypertension.
Renal disease accounts for a large percentage of the other cases of secondary hypertension.
Conditions which may increase the blood pressure include:
glomerulonephritis
pyelonephritis
adult polycystic kidney disease
renal artery stenosis
Endocrine disorders
(other than primary hyperaldosteronism) may also result in increased blood pressure:
phaeochromocytoma
Cushing's syndrome
Liddle's syndrome
congenital adrenal hyperplasia (11-beta hydroxylase deficiency)
acromegaly
Other causes include:
NSAIDs
pregnancy
coarctation of the aorta
the combined oral contraceptive pill
steroids
MAOI
3- Isolated systolic hypertension
Isolated systolic hypertension (ISH) is common in the elderly,
Affecting around 50% of people older than 70 years old.
The Systolic Hypertension in the Elderly Program (SHEP) back in 1991 established that treating ISH reduced both strokes and ischaemic heart disease.
Drugs such as thiazides were recommended as first line agents.
This approach is contradicated by the 2011 NICE guidelines which recommends treating ISH in the same stepwise fashion as standard hypertension.
Hypertension diagnosis:
NICE published updated guidelines for the management of hypertension in 2011.
Some of the key changes include:
classifying hypertension into stages
recommending the use of ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM)
Why were these guidelines needed?
It has long been recognised by doctors that there is a subgroup of patients whose blood pressure climbs 20 mmHg whenever they enter a clinical setting, so called 'white coat hypertension'. If we just rely on clinic readings then such patients may be diagnosed as having hypertension when the vast majority of time there blood pressure is normal. This has led to the use of both ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM) to confirm the diagnosis of hypertension. These techniques allow a more accurate assessment of a patients' overall blood pressure. Not only does this help prevent overdiagnosis of hypertension - ABPM has been shown to be a more accurate predictor of cardiovascular events than clinic readings.
Blood pressure classification:
This becomes relevant later in some of the management decisions that NICE advocate. Stage Criteria
Stage 1 hypertension
Clinic BP >= 140/90 mmHg and subsequent ABPM daytime average or HBPM average BP >= 135/85 mmHg
Stage 2 hypertension
Clinic BP >= 160/100 mmHg and subsequent ABPM daytime average or HBPM average BP >= 150/95 mmHg
Severe hypertension
Clinic systolic BP >= 180 mmHg, or clinic diastolic BP >= 110 mmHg
4- Diagnosing hypertension:
Firstly, NICE recommend measuring blood pressure in both arms when considering a diagnosis of hypertension.
If the difference in readings between arms is more than 20 mmHg then the measurements should be repeated.
If the difference remains > 20 mmHg then subsequent blood pressures should be recorded from the arm with the higher reading.
It should of course be remember that there are pathological causes of unequal blood pressure readings from the arms, such as supravalvular aortic stenosis.
It is therefore prudent to listen to the heart sounds if a difference exists and further investigation if a very large difference is noted.
NICE also recommend taking a second reading during the consultation, if the first reading is > 140/90 mmHg. The lower reading of the two should determine further management.
NICE suggest offering ABPM or HBPM to any patient with a blood pressure >= 140/90 mmHg.
If however the blood pressure is >= 180/110 mmHg:
immediate treatment should be considered
if there are signs of papilloedema or retinal haemorrhages NICE recommend same day assessment by a specialist
NICE also recommend referral if a phaeochromocytoma is suspected (labile or postural hypotension, headache, palpitations, pallor and diaphoresis)
Ambulatory blood pressure monitoring (ABPM):
at least 2 measurements per hour during the person's usual waking hours (for example, between 08:00 and 22:00)
use the average value of at least 14 measurements
If ABPM is not tolerated or declined HBPM should be offered.
Home blood pressure monitoring (HBPM):
for each BP recording, two consecutive measurements need to be taken, at least 1 minute apart and with the person seated
BP should be recorded twice daily, ideally in the morning and evening
BP should be recorded for at least 4 days, ideally for 7 days
discard the measurements taken on the first day and use the average value of all the remaining measurements
Interpreting the results
1) ABPM/HBPM >= 135/85 mmHg (i.e. stage 1 hypertension)
treat if < 80 years of age AND any of the following apply;
target organ damage,
established cardiovascular disease,
renal disease,
diabetes or
a 10-year cardiovascular risk equivalent to 20% or greater
2) ABPM/HBPM >= 150/95 mmHg (i.e. stage 2 hypertension)
offer drug treatment regardless of age
5- Hypertension management:
NICE published updated guidelines for the management of hypertension in 2011.
Some of the key changes include:
classifying hypertension into stages
recommending the use of ambulatory blood pressure monitoring (ABPM) and home blood pressure monitoring (HBPM)
calcium channel blockers are now considered superior to thiazides
bendroflumethiazide is no longer the thiazide of choice
Managing hypertension
1) Lifestyle advice should not be forgotten and is frequently tested in exams:
A low salt diet is recommended, aiming for less than 6g/day, ideally 3g/day.
The average adult in the UK consumes around 8-12g/day of salt.
A recent BMJ paper* showed that lowering salt intake can have a significant effect on blood pressure. For example, reducing salt intake by 6g/day can lower systolic blood pressure by 10mmHg
caffeine intake should be reduced
the other general bits of advice remain: stop smoking, drink less alcohol, eat a balanced diet rich in fruit and vegetables, exercise more, lose weight
2) ABPM/HBPM >= 135/85 mmHg (i.e. stage 1 hypertension)
treat if < 80 years of age AND any of the following apply; target organ damage, established cardiovascular disease, renal disease, diabetes or a 10-year cardiovascular risk equivalent to 20% or greater
3) ABPM/HBPM >= 150/95 mmHg (i.e. stage 2 hypertension)
offer drug treatment regardless of age
For patients < 40 years consider specialist referral to exclude secondary causes.
Step 1 treatment:
patients < 55-years-old: ACE inhibitor (A)
patients > 55-years-old or of Afro-Caribbean origin: calcium channel blocker
Step 2 treatment:
ACE inhibitor + calcium channel blocker (A + C)
Step 3 treatment:
add a thiazide diuretic (D, i.e. A + C + D)
NICE now advocate using either:
chlorthalidone (12.5-25.0 mg once daily) or
indapamide (1.5 mg modified-release once daily or 2.5 mg once daily) in preference to a conventional thiazide diuretic such as bendroflumethiazide
6- NICE define a clinic BP >= 140/90 mmHg after step 3 treatment with optimal or best tolerated doses as resistant hypertension. They suggest step 4 treatment or seeking expert advice
Step 4 treatment:
1) consider further diuretic treatment
if potassium < 4.5 mmol/l add spironolactone 25mg od
if potassium > 4.5 mmol/l add higher-dose thiazide-like diuretic treatment
2) if further diuretic therapy is not tolerated, or is contraindicated or ineffective, consider an alpha- or beta-blocker
Patients who fail to respond to step 4 measures should be referred to a specialist. NICE recommend: If blood pressure remains uncontrolled with the optimal or maximum tolerated doses of four drugs, seek expert advice if it has not yet been obtained.
Blood pressure targets
Age < 80 years, Clinic BP 140/90 mmHg, ABPM / HBPM 135/85 mmHg
Age > 80 years, Clinic BP 150/90 mmHg , ABPM / HBPM 145/85 mmHg
New drugs: Direct renin inhibitors:
e.g. Aliskiren (branded as Rasilez)
by inhibiting renin blocks the conversion of angiotensinogen to angiotensin I
No trials have looked at mortality data yet. Trials have only investigated fall in blood pressure.
Initial trials suggest aliskiren reduces blood pressure to a similar extent as angiotensin converting enzyme (ACE) inhibitors or angiotensin-II receptor antagonists
adverse effects were uncommon in trials although diarrhoea was occasionally seen
only current role would seem to be in patients who are intolerant of more established antihypertensive drugs
7- Malignant hypertension
Basics:
severe hypertension (e.g. >200/130 mmHg)
occurs in both essential and secondary types
fibrinoid necrosis of blood vessels, leading to:
retinal haemorrhages, exudates, and
proteinuria, haematuria due to renal damage (benign nephrosclerosis).
can lead to cerebral oedema → encephalopathy
Features:
classically: severe headaches, nausea/vomiting, visual disturbance
however chest pain and dyspnoea common presenting symptoms
papilloedema
severe: encephalopathy (e.g. seizures)
Management:
reduce diastolic no lower than 100mmHg within 12-24 hrs
bed rest
most patients: oral therapy e.g. atenolol
if severe/encephalopathic: IV sodium nitroprusside/labetolol
