Hypertension in Adults: Part 2. Assessment
and management
Author(s): Dr Muhammad Ilyas
Specialist Registrar Acute Medicine, St Mary’s Hospital Isle of Wight, UK
Assessment
Include the following:
- Confirmation of hypertension
- Risk factors for
cardiovascular disease
- Underlying cause(s)
- End organ damage
- Indications and
contraindications for anti-hypertensive drugs
History
A thorough history is essential - note particularly:
- Age, gender, family
history
- Drugs: non-steroidal
anti-inflammatory drugs, oral contraceptives, steroids, liquorice,
sympathomimetics e.g. cocaine or epinephrine contained in cold remedies
and cough medicines.
- Renal disease:
- present, past and
family history
- history of haematuria and
/or proteinuria
- Paroxysmal (intermittent)
symptoms (?phaeochromocytoma)
- Muscle weakness, polyuria
(?Conn’s syndrome)
- Rounded face and abdominal
obesity (?Cushing’s syndrome)
- Cardiovascular risk factors
and co-morbidities:
- Overweight
- Excess alcohol intake
(>3 units/day for men, >2 units/day for women)
- Cigarette smoking
- Excess salt intake (>10g/day)
- Diabetes mellitus
- Dyslipidaemia (arcus
cornealis, xantholasmata).
- Complications or end organ
damage:
- “Stroke”,
transient ischaemic attack (TIA)
- Coronary artery
disease, heart failure
- Peripheral vascular
disease
- Visual problems
- Renal disease.
Physical examination
- Confirm the hypertension with
repeated measurements over about four weeks. This may not
be feasible where travelling to clinics is difficult - and may not be
needed if there is end organ damage and malignant hypertension.
- Look for secondary causes
(see Part 1).
- Record cardiovascular
abnormalities:
- Peripheral pulses
- Radio-femoral delay,
diminished femoral pulses with low femoral blood pressure (BP) (aortic
coarctation)
- Carotid and abdominal
arterial bruits
- Aortic aneurysm.
- Identify end organ damage:
- Brain: motor or
sensory defects
- Retinal fundoscopic
abnormalities
- Heart: displacement of
apical impulse, dysrhythmias, sounds and murmurs, ventricular gallop,
pulmonary rales, peripheral oedema
- Peripheral arterial pulses:
absence, reduction or asymmetry, ischaemic skin lesions.
- Identify other conditions
(co-morbidities):
- High Body Mass Index
(BMI). [BMI = weight in kg/height in meters²] BMI >25 =
overweight; BMI >30 = obesity
- High abdominal girth
measured through the umbilicus. A value of >88centimetres for females
and >102centimetres for males is considered an independent risk factor
for cardiovascular disease
- Bronchial asthma and
chronic obstructive pulmonary disease (COPD): These are considered
contraindications to beta blocker use. COPD is rare in black populations.
Investigations
Routine Tests
These should be available in most health centres:
- Haemoglobin, haematocrit,
ESR.
- Urine “stix” test for
proteinuria, haematuria, and glycosuria.
The following are desirable but are less likely to be available:
- Blood glucose (preferable
fasting)
- Serum urea and creatinine
- Electrolytes, calcium and
phosphate
- Estimated creatinine
clearance
- Serum uric acid
- Lipid profile
- Electrocardiogram for cardiac
rhythm and evidence of left ventricular hypertrophy
- Echocardiogram if cardiac
structural abnormalities suspected.
Consider referral to a specialist for extended evaluation if there are
these conditions:
- Age <40 years
- Severe hypertension with end
organ damage
- Poorly controlled hypertension
- Suspected secondary
hypertension.
Indications for drug therapy
- Sustained systolic blood
pressure (BP) >160mmHg or sustained diastolic BP >100mmHg
despite non-pharmacological measures.
- Sustained systolic BP
140–159mmHg or diastolic blood pressure 90–99mmHg if there
is:
- End organ damage or
- Diabetes mellitus.
A target systolic BP
<140mmHg and diastolic blood pressure
<85mmHg
is ideal. For patients with diabetes mellitus a target of 130/80mmHg is ideal.
Non - pharmacological measures
Attempt non-pharmacological methods of lowering BP in patients with mild
hypertension but no cardiovascular complications or end organ damage. Start
non-pharmacological measures in parallel with drug therapy in patients with
severe hypertension (see British Hypertension Society guidelines – see website
below).
Benefits of non-pharmacological measures
- Lowers BP as much as drug
monotherapy
- Reduces the need for drug
therapy
- Enhances the
antihypertensive effect of drugs
- Reduces the need for
multiples drug regimens
- Reduces overall
cardiovascular risk.
Non-pharmacological measures recommended by the British Hypertension
Society
That lower BP:
- Weight reduction – aim for
Body Mass Index 20-25 Kg/m²
- Reduced salt intake to
<100 mmol/day (<6g NaCl or <2.4 g Na+/day. One flat teaspoonful =
~6g salt)
- Reduced alcohol consumption
to ≤ 3 units/day for men and ≤ 2 units/day for women (500 ml beer = ~2
units)
- Regular aerobic exercise
(brisk walking rather than weightlifting for ≥30 minutes per day), on at
least three days each week
- At least five portions of
fruit and vegetable each day (e.g. banana, mango, tomato, green leaves)
- Reduced total fat and
saturated fat intake. Saturated fats come mainly from animal foods such as
milk and meat.
That reduce cardiovascular risk:
- Stopping smoking
- Reducing total fat intake
and replacing saturated fats with unsaturated fats. Unsaturated fats and
oils come from plant foods and fish.
Pharmacological therapy
Classes
of antihypertensive drugs
The main purpose of treating hypertension is to reduce the incidence of
cardiovascular (especially left ventricular failure), cerebrovascular disease
(“stroke”) and renal failure. The five major classes of antihypertensive drugs
are:
- Diuretics (e.g. thiazide
diuretics)
- Calcium channel blockers
(e.g. nifedipine)
- Angiotensin converting
enzyme inhibitors (ACEI) (e.g. lisinopril)
- Angiotensin receptor
antagonists (e.g. losartan)
- Beta blockers (e.g.
atenolol)
Other antihypertensive drugs are:
- Alpha receptor antagonists
(e.g. prazosin)
- Vasodilators (e.g.
hydralazine)
- Mineralocorticoid receptor
antagonists (e.g. spironolactone)
- Sympatholytics (e.g.
clonidine, alpha methyldopa).
The choice of antihypertensive drug (s)
Factors influencing the choice of antihypertensive drug(s) are:
- Age
- Ethnicity
- Co-morbidities e.g.
diabetes mellitus, renal disease, peripheral arterial disease, “stroke”,
prostate disease, obesity, pregnancy
- Contraindications
e.g. beta blockers in bronchial asthma
- Cardiovascular risk profile
e.g. ischaemic heart disease
- Severity of hypertension
and presence of end organ damage
- Etiology of hypertension –
e.g. Cushing’s disease, renal artery stenosis
- Side effects to previous
treatment e.g. angio-oedema with an ACEI
- Drug compliance of patient
- Socio-economic status
- Economic factors and
sustainable supply of drug(s) chosen.
- Patient’s choice.
The ideal drug is one that is given once each day, lowers the BP
satisfactorily without significant side effects, has a sustainable supply and
is not expensive.
“ABCD” treatment Algorithm
Most patients require more than one drug to control BP. The British
Hypertension Society recommends an algorithm based on the AB/CD rule to assist
with the selection of drug schedules. The idea of the AB/CD algorithm is based
upon the broad classification of hypertension into:
- High renin hypertension
- Low renin hypertension
Therefore BP is best initially treated by one of 2 categories of drugs:
- Drugs which inhibit the
renin-angiotensin system (e.g. ACE inhibitors, Angiotensin
receptors blockers or Beta blockers) or
- Drugs which do not inhibit
the renin-angiotensin system (e.g. Calcium antagonists or
Diuretics).
Because African (black) patients of all ages tend to have low renin levels,
initial therapy should be a calcium-channel blocker or a thiazide diuretic. If
a second drug is required, add an ACE inhibitor (or an angiotensin-II receptor
antagonist if an ACE inhibitor is not tolerated).
If treatment with
three drugs is required, use a
combination of ACE inhibitor (or angiotensin-II receptor antagonist),
calcium-channel blocker and thiazide diuretic.
If blood pressure remains uncontrolled on adequate doses of three drugs,
consider adding a fourth and/or seeking expert advice.
If a
fourth drug is required, consider one of the
following:
- Beta-blocker
- Selective alpha-blocker.
Beta-blockers are not a preferred initial therapy as they are less effective
in reducing major cardiovascular and cerebrovascular events. However,
beta-blockers may be considered in younger people, particularly:
- Those with an intolerance
or contraindication to ACE inhibitors and Angiotensin-II receptor
antagonists or
- Women of child-bearing
potential or
- People with evidence of
increased sympathetic drive.
If therapy is initiated with a beta-blocker and a second drug is required,
add a calcium-channel blocker. However if a beta-blocker is withdrawn, the dose
should be stepped down gradually.
Offer patients with isolated systolic hypertension (systolic
BP 160 mmHg or more) the same treatment as patients with both raised
systolic and diastolic blood pressure.
Offer patients over 80 years old the same treatment as other patients
over 55 years, taking account of any co-morbidity and their existing burden of
drug use.
Other medications for hypertensive
patients
Prevention of arteriole-vascular disease
Primary
- Aspirin:
use 75 mg daily if patient is aged ≥50 years with BP controlled to
<150/90 mm Hg and end organ damage, diabetes mellitus, or 10 year risk
of cardiovascular disease of ≥20%. (Measured by using the new Joint
British Societies cardiovascular disease risk chart – see http://www.bhsoc.org/resources/prediction_chart.htm).
- Statin: use
sufficient doses to reach cholesterol targets if patient is aged up to 80
years, with a 10 year risk of cardiovascular disease of ≥20% and with
total cholesterol concentration ≥3.5mmol/l.
Secondary (including patients with type 2 diabetes)
- Aspirin:
use for all patients unless contraindicated.
- Statin:
use sufficient doses to reach cholesterol targets if patient is aged up to
80 years with a total cholesterol concentration ≥3.5 mmol/l.
Hypertension in black patients is different
Hypertension occurs more frequently in black
populations and is
associated with:
- a higher incidence of cardiovascular and renal complications (end-stage renal
failure is up to 20 times more common)
- a two-fold higher incidence
of left ventricular hypertrophy with an increased risk of left ventricular
failure.
Salt (sodium) handling is different and associated with an expanded
plasma
volume and a higher prevalence of low plasma renin activity.
Management of hypertension in black patients
Non-pharmacological management
Lifestyle and non-pharmacological interventions
may significantly
reduce blood pressure hence minimising the need for anti hypertensive drugs.
So advise patients to:
- Eat less salt: Sodium
restriction to an intake of <100 mmol day (i.e. total of one
teaspoon/day) may have the same effect as a low-dose thiazide diuretic.
- Lose weight: Black
hypertensives are often obese and a fall in weight usually leads to a
reduced blood pressure.
- Drink less alcohol: Even
moderate alcohol ingestion (three to five drinks daily) is
associated with a raised blood pressure in black patients.
- Take more exercise.
Pharmacological management
Diuretics: A thiazide diuretic (e.g. bendroflumethiazide
2.5mg daily) is the first-line treatment
in most black
hypertensives.
However the clinician should be aware of
potential adverse metabolic
effects: hypokalaemia, hyperlipidaemia
and glycaemic control in diabetics.
Beta-blockers: Beta-blockers (e.g. atenolol) are less
effective in black hypertensives
although younger patients may be
more
responsive than elderly ones.
Angiotensin-converting enzyme (ACE) inhibitors: ACE
inhibitors (e.g. captopril) appear less effective when used alone in black
patients although this
is eliminated by the addition of a diuretic.
ACE inhibitors remain the first-line anti-hypertensive
agents
in patients with diabetic nephropathy, particularly in the
presence
of proteinuria.
The complication of
ACE-inhibitor-induced
angio-oedema is more common in black patients.
Calcium channel blockers: Calcium channel blockers (e.g.
nifedipine) are highly effective.
Verapamil is also a calcium
channel blocker. It must never be used with a beta blocker because the two
together may have a serious negative effect on cardiac function.
Alpha-blockers: Alpha-receptor-blocking agents (e.g.
doxazocin) reduce blood pressure by reducing peripheral vascular resistance.
However, the addition of a diuretic
is often required.
Angiotensin receptor antagonists: There is limited
information concerning
the efficacy and tolerability of the
angiotensin receptor antagonists (e.g. losartan)
in black patients.
In view of the high prevalence of hypertension and associated complications
in the black
population consider starting effective screening
programmes.
