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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 6, November/December 2014
292
AFRICA
Management of severe hypertension
Patients with severe HTN (grade 3; BP
≥
180/110 mmHg) may
fall into one of three categories, which determine the urgency
of their treatment. Patients should be managed or referred to
the appropriate level of care and caregiver in accordance with
local resources. Sustained, severe HTN requires immediate drug
therapy and lifestyle modification, and close follow up.
Asymptomatic severe hypertension
These patients are asymptomatic but have severe HTN without
evidence of progressive TOD or complications. The patient must
be kept in the care setting and BP measurement repeated after
resting for one hour. If still elevated at the same level, commence
oral therapy using two first-line drugs. Follow up within a week
or earlier, with escalation of treatment as needed. Early referral
is advised if BP is not controlled within two to four weeks.
Hypertensive urgencies and emergencies
24
While not common, hypertensive emergencies and urgencies are
likely to be encountered by all clinicians because of the high
prevalence of chronic HTN. It is essential that all professionals
are familiar with treatment. There is a paucity of information
from well-conducted studies on the outcomes of various
antihypertensive drugs and BP-lowering strategies.
Hypertensive urgency
25
This level of HTN is symptomatic, usually with severe headache,
shortness of breath and oedema. There are no immediate life-
threatening neurological, renal, eye or cardiac complications,
such as are seen in hypertensive emergencies. Ideally, all patients
with hypertensive urgency should be treated in hospital.
Commence treatment with two oral agents and aim to lower
the diastolic BP to 100 mmHg slowly over 48 to 72 hours. This
BP lowering can be achieved with the use of: (1) long-acting
CCBs; (2) ACEI, initially used in very low doses, but avoid if
there is severe hyponatraemia (serum Na
<
130 mmol/l indicates
hyper-reninaemia and BP may fall dramatically with ACEI); (3)
β
- blockers; and (4) diuretics.
Hypertensive emergency
A hypertensive emergency is severe, often acute elevation of BP
associated with acute and ongoing organ damage to the kidneys,
brain, heart, eyes (grade 3 or 4 retinopathy) or vascular system.
These patients need rapid (within minutes to a few hours)
lowering of BP to safe levels. Hospitalisation is ideally in an
intensive care unit (ICU) with experienced staff and modern
facilities for monitoring. If an ICU is unavailable, the patient
may be closely monitored and treated in the ward.
Intravenous antihypertensive therapy, tailored to the specific
type of emergency, has become the standard of care. Labetalol,
nitroprusside or nitroglycerin are the preferred intravenous agents.
Overzealous lowering of BP may result in stroke. A 25% reduction
in BP is recommended in the first 24 hours. Oral therapy is
instituted once the BP is more stable. Although most adult patients
with a hypertensive emergency will have BP
>
220/130 mmHg, it
may also be seen at modest BP elevations; for example, in a
previously normotensive woman during pregnancy (eclampsia) or
in the setting of acute glomerulonephritis, especially in children.
Severe HTN associated with ischaemic stroke and
intracerebral haemorrhage should be managed according to
the recommendations of the Neurological Association of South
Africa.
26
Great caution should be exercised in lowering BP after
an ischaemic stroke due to the risk of extending the ischaemic
penumbra.
Resistant hypertension
HTN that remains
>
140/90 mmHg despite the use of three
antihypertensive drugs in a rational combination at full doses and
including a diuretic (hydrochlorothiazide 25 mg or indapamide
2.5 mg) is known as resistant HTN. Common causes of resistant
HTN are listed in Table 8.
The therapeutic plan must include measures to ensure
adherence to therapy and lifestyle changes. Unsuspected causes
of secondary HTN are less common, but need to be considered
based on history, examination and special investigations. It is
essential to exclude pseudo-resistance by performing SBPM or
24-hour ABPM. Referral to a specialist is often indicated for a
patient with resistant HTN.
Table 8. Causes of resistant hypertension in South Africa
Non-adherence
to therapy
• Instructions not understood
• Side effects
• Cost of medication and/or cost of attending at
healthcare centre
• Lack of consistent and continuous primary care
• Inconvenient and chaotic dosing schedules
• Organic brain syndrome (e.g. memory deficit)
Volume over-
load
• Excess salt intake
• Inadequate diuretic therapy
• Progressive renal damage (nephrosclerosis)
Associated
conditions
• Smoking
• Increasing obesity
• Sleep apnoea
• Insulin resistance/hyperinsulinaemia
• Ethanol intake of more than 30 g (three standard
drinks) daily
• Anxiety-induced hyperventilation or panic attacks
• Chronic pain
• Intense vasoconstriction (Raynaud’s
phenomenon), arteritis
Identifiable
causes of hyper-
tension
• Chronic kidney disease
• Renovascular disease
• Primary aldosteronism
• Coarctation
• Cushing’s syndrome
• Phaeochromocytoma
Pseudoresis-
tance
• ‘Whitecoat hypertension’ or office elevations
• Pseudohypertension in older patients
• Use of regular cuff in obese patients
Drug-related
causes
• Doses too low
• Wrong type of diuretic
• Inappropriate combinations
• Rapid inactivation (e.g. hydralazine)
Drug actions
and interactions
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Sympathomimetics: nasal decongestants, appetite
suppressants
• Cocaine, Tik and other recreational drugs
• Oral contraceptives
• Adrenal steroids
• Liquorice (as may be found in chewing tobacco)
• Cyclosporine, tacrolimus, erythropoietin
• Antidepressants (monoamine oxidase inhibitors,
tricyclics)