Hypertension is a blood pressure >140/90mmHg.
Background
- Around 30% of adults have a BP of >140/90mmHg
- Prevalence increases with age (30% aged 45-54; about 70% in peopler ages 75+ years)
- More common in African-Caribbean than in Caucasian people
- Hypertension is one of the most common conditions seen in patients and one of the most common reason for prescribing medications
- Accounts for >£1 billion worth of drugs per year
Aetiology/Pathophysiology
- In the majority of individuals, a specific cause of hypertension is not found (essential hypertension)
- There are many factors that are thought to contribute to primary hypertension:
- renal dysfunction (via RAAS as well as salt/water excretion)
- peripheral resistance and vessel tone
- endothelial dysfunction
- autonomic tone
- insulin resistance
- neurohumoral/immunological factors
- genetic factors
- Secondary hypertension can be caused by
- Alcohol
- Obesity
- Pregnancy
- Renal disease
- Endocrine disease
- Drugs
- e.g. OCP, anabolic/cortico-steroids, NSAIDs, sympathomimetic agents
NB It is important to take a full history from a patient with hypertension to rule out any underlying causes for secondary hypertension and to evaluate whether the patient has any target organ damage. E.g. Full drug hx; do they have any symptoms e.g. headache, sweats/palpitations (could this be a phaeochromocytoma?). Is there a family history of renal disease? Does the patient appear cushingoid?
Diagnosis/Classification
- Note that “white coat” hypertension can be confounding. This is blood pressure that is unusually high simply due to the anxiety and/or concerns about seeing the doctor.
- Measuring blood pressure
- It is important to try and keep the environment constant whilst measuring blood pressure e.g. relaxed, quiet, seated with arm outstretched and supported at heart level (ideally the arm should be bare)
- If there is a difference of >20mmHg between arms, record measurements from the arm with higher BP
- If the first reading is >140/90mmHg, take a second after a minute interval. If this is substantially different, record a third measurement too. Use the lower of the last two measurements.
- If all measurements are consistently >140/90mmHg, recheck BP on 2-3 occasions over the next few weeks
- If clinic BPs are persistently above 140/90mmHg, offer ambulatory blood pressure monitoring or home blood pressure monitoring
- Classification
- Mild (Stage I)
- clinic BP >140/90mmHg and ABPM average is >=135/85mmHg
- Moderate (Stage II)
- clinic BP >160/100mmHg and ABPM average is =>150/95mmHg or there is isolated SBP of >=160mmHg
- Severe (Stage III)
- clinic BP >180/110mmHg
- NB if a patient has this high a BP, check the retina for hypertensive retinopathy (papilloedema and/or retinal haemorrhage). Also take bloods (FBC, U&Es and LFTs), urinalysis and do an ECG for signs of other system failure e.g. acute kidney injury
- Malignant hypertension is defined as grade III hypertension with signs of secondary organ damage
- Mild (Stage I)
Other investigations
- As well as BP, ECG, Bloods and urinalysis
- Test glucose (diabetes)
- Test cholesterol for cardiac risk
Management
- Lifestyle advice
- Alcohol consumption; caffeine consumption; salt consumption
- Smoking
- Stress
- Don’t take electrolyte supplements
- Exercise/physical activity
- Weight loss
- Diet
- Assess cardiac risk
- Antihypertensive medication
- Offer if
- <80yo; mild hypertension and one or more of
- Target organ damage, established CVD, renal disease, diabetes and/or a 10 year CV risk of 20% or more (using ASSIGN or QRISK2)
- Moderate Hypertension (all)
- <80yo; mild hypertension and one or more of
- If <55yo (and not African-Caribbean)
- start an ACE inhibitor or (if intolerant/contraindicated) an Angiotensin-II-receptor blocker
-
In Moderate to severe renal disease, reduce the dose of ACEIs (cleared by the kidney)
-
Relatively contraindicated in bilateral renal artery stenosis
-
Drug interactions (important ones): DO NOT CO-PRESCRIBE ACEI, NSAID +/- ARB
-
- Alternatively, a beta-blocker can be used in young patients
- who can’t tolerate ACEIs/ARBs
- women who might become pregnant or are planning a pregnancy
- NOTE that whilst beta-blockers are recommended by NICE for the treatment of hypertension, SIGN does not recommend their use first line (only after 3-combination therapy has been tried)
- this is because ‘beta blockers were the least clinically and cost effective drug at preventing major CV events’
-
Use can be limited by side effects: cool peripheries, fatigue and impotence are common. Headache/postural hypotension is also possible.
- start an ACE inhibitor or (if intolerant/contraindicated) an Angiotensin-II-receptor blocker
- If >55yo or Afro-Caribbean
- Offer a calcium-channel blocker (dihydropyridine type e.g. amlodipine) unless there is evidence of oedema, heart failure (or risk of heart failure), or drug intolerance
- In this case, offer a thiazide diuretic or a thiazide-like diuretic
- Offer a calcium-channel blocker (dihydropyridine type e.g. amlodipine) unless there is evidence of oedema, heart failure (or risk of heart failure), or drug intolerance
- Note that if BP remains uncontrolled on one drug
- Offer combination of CCB/TD/TLD and ACEI/ARB*/BB
- Preferred in African/Caribbean patients
- If the patient’s BP remains high with 2 drugs at optimal doses
- consider ACEI/ARB + CCB + TD/TLD
- If still resistant to treatment (resistant hypertension)
- sensible to refer to a specialist
- It is possible to combine all 3 drug types. Alternatively, low dose spironolactone can be added (or higher dose thiazide diuretic)
- the former if K < 4.5 and the latter if >4.5
- patients require close monitoring of their U&Es (particularly K+)
- Offer combination of CCB/TD/TLD and ACEI/ARB*/BB
- Offer if
- Admit a patient if they have
- Malignant hypertension
- Hypertensive encephalopathy
- Suspected phaeochromocytoma and severe hypertension
- Severe hypertension and high risk of vascular complications
