THE CONTEXT
Investigation confirms hypertension, evaluates cardiovascular risk and identifies causes, complications and comorbidities before treatment that generally entails a lifelong commitment.
Objectives of investigation
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Confirm the diagnosis using accurate, representative blood-pressure measurements.
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Identify contributory factors and underlying causes, assess other risk factors and quantify cardiovascular risk.
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Detect existing complications and identify comorbidities that may influence the choice of antihypertensive treatment.
Blood-pressure measurement
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Measure to the nearest 2 mmHg with the patient sitting and the arm supported. If the first recording is high, repeat it after 5 minutes of rest.
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In obese subjects, the cuff bladder should encompass at least two-thirds of the arm circumference to avoid spuriously high readings.
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Exercise, anxiety, discomfort and unfamiliar surroundings can transiently raise blood pressure.
White coat hypertension
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Sphygmomanometry, particularly when performed by a doctor, can produce a transient blood-pressure elevation termed white coat hypertension.
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Up to 20% of patients with raised outpatient clinic blood pressure are estimated to have normal readings with automated home devices.
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Their cardiovascular disease risk is lower than that of patients with sustained hypertension but higher than that of normotensive subjects.
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Ambulatory or home-based measurements help confirm the diagnosis when clinic readings are borderline or white coat hypertension is suspected.
Grades of hypertensive retinopathy
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Grade 1 consists of arteriolar thickening, tortuosity and increased reflectiveness, termed silver wiring.
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Grade 2 adds constriction of veins at arterial crossings, termed arteriovenous nipping.
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Grade 3 adds retinal ischaemic changes, including flame-shaped or blot haemorrhages and cotton wool exudates.
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Grade 4 adds papilloedema to grade 3 changes. The illustrated example shows a swollen optic disc, retinal haemorrhages and multiple cotton wool spots representing infarcts.
Retinal vein thrombosis
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The illustrated central retinal vein thrombosis shows a swollen optic disc and widespread fundal haemorrhage and is described as commonly associated with systemic hypertension.