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Department
of Podiatry - Vascular Assessment
Hypertension
Hypertension
(hyper + tendere, to stretch) is a common, often asymptomatic
disease characterised by sustained elevated blood pressure. The literature
considers hypertension in the adult to constitute a sustained elevated
systolic pressure in excess of 140mm Hg, and a sustained elevated diastolic
pressure in excess of 90mm Hg (Cotran et al, 1999; Anderson et al, 1999;
Nelson 1992). Based on these figures, 25% of the Western population is
hypertensive (Cotran, 1999). The formula for blood pressure is cardiac
output multiplied by total peripheral resistance, therefore an increase
in either or both of these factors lead to a hypertensive state.
Hypertension can be classified into 2 types:
1) Primary or essential hypertension. This comprises 90 to 95%
of cases, and is of idiopathic aetiology. Whilst not one single factor
can be attributed as the cause, it is believed to develop from environmental
triggers such as obesity, smoking, hyperlipidaemia, stress, and diet (especially
salt intake), in genetically susceptible individuals (Anderson et al.,
1999).
2) Secondary hypertension. This comprises 5 to 10% of cases, most
often caused by renal disease or narrowing of the renal artery by atherosclerotic
plaques. The kidneys regulate blood pressure by detecting cardiac output,
and renal artery stenosis or decreased glomerular flow induces angotensin
II to be released by the kidney which brings about vasoconstriction –
increasing peripheral resistance. The kidney also uses the aldosterone
mechanism to reabsorb sodium and hence water, increasing blood volume
– increasing cardiac output (Cotran, 1999). Secondary hypertension
may also be caused by endocrine, cardiovascular and neurologic factors,
which are too numerous to describe here.
Mild hypertension may be asymptomatic, or can present as headache, tinnitis,
lightheadedness and palpitations. With sustained significant hypertension
over many years, the arterial walls become thickened and inelastic, and
resistant to blood flow, forcing the left ventricle to work harder to
maintain adequate circulation. Subsequently, the left ventricle becomes
distended and hypertrophied, which can lead to congestive heart failure.
A third level of hypertension, malignant hypertension, is rare and involves
rapid rising of blood pressure over a short time to diastolic pressures
of greater than 120 mm Hg. This syndrome presents with severe headache,
blurred vision, confusion, renal failure, and is fatal within 1 to 2 years
(Cotran et al, 1999; Anderson et al, 1999).
The main concern with hypertension for podiatrists is that it is a major
risk factor for thrombus formation, and hence problems such as peripheral
vascular disease, CVA, embolism, aneurysm, congestive
heart failure, and myocardial infarct
(Anderson, 1999). Ensure the patient is being monitored, usually with
pharmacotherapy, and their blood pressure is “under control”.
Exercises, healthy diet, weight loss, avoiding stress and getting rest
are all recommended.
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