Hypertension

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Systemic hypertension

Elevated arterial blood pressure is a major cause of premature vascular disease leading to: • cerebrovascular events
• ischaemic heart disease
• peripheral vascular disease.

Hypertension can be said to be present in 20-30% of the adult population.

The WHO International Society of Hypertension classifies non-hypertensive subjects with a systolic pressure of 130-139 mmHg or a diastolic pressure of 85-89 mmHg as having a 'high' normal blood pressure.

Causes of essential hypertension

Genetic factors.

Blood pressure tends to run in families and children of hypertensive parents tend to have higher blood pressure than age-matched children of people with normal blood pressure.

Obesity.

Fat people have higher blood pressures than thin people. There is a risk.

Alcohol intake.

There is a close relationship between the consumption of alcohol and blood pressure level.

Sodium intake.

Populations with higher sodium intake have higher average blood pressures than those with lower sodium intake. The restriction of salt intake have shown a beneficial effect on blood pressure in hypertensives.

Stress.

Acute pain or stress can raise blood pressure.
It remains uncertain whether chronic stress can be implicated in the pathophysiology of essential hypertension.

Humoral mechanisms

The autonomic nervous system (as well as the renin- angiotensin, natriuretic peptide and kallikrein-kinin system) has been implicated in the pathogenesis of essential hypertension.

Insulin resistance
'Metabolic syndrome' or 'syndrome X':
• hyperinsulinaemia
• glucose intolerance
• reduced levels of HDL cholesterol
• hypertriglyceridaemia
• central obesity (all of which are related to insulin resistance) in association with hypertension. It is a major risk factor for cardiovascular disease.

Secondary hypertension

1. Renal diseases >80%.
• diabetic nephropathy
• chronic glomerulonephritis
• adult polycystic disease
• chronic tubulointerstitial nephritis
• and reno-vascular disease.
Hypertension can itself cause or worsen renal disease (due to sodium and water retention, elevation of plasma renin levels).

2. Endocrine causes
These include:
• Conn's syndrome
adrenal hyperplasia
phaeochromocytoma
Cushing's syndrome
acromegaly.

3. Cardiovascular causes
The major cause is coarctation of the aorta.
4. Drugs
• oral contraceptive pill
• steroids
• carbenoxolone
• vasopressin
Patients taking monoamine oxidase inhibitors, who consume tyramine-containing foods, may develop paroxysms of severe hypertension.

5. Pregnancy
Blood pressure in pregnant women is usually lower .
Hypertension detected in the first half of pregnancy or persisting after delivery is usually due to pre-existing essential hypertension. Hypertension presenting in the second half of pregnancy - or 'pregnancy-induced hypertension' - usually resolves after delivery. Pre-eclampsia is a syndrome consisting of pregnancy-induced hypertension with proteinuria.

Evaluation of hypertensive patients

Causes of hypertension

5. Drugs (non-steroidal anti-inflammatory drugs, oral contraceptives, steroids, liquorice, sympathomimetics, some cold cures) 6. Renal disease (present, past, or family history, proteinuria or haematuria: palpable kidney(s)—polycystic, hydronephrosis, or neoplasm) Renovascular disease (abdominal or loin bruit)

Phaeochromocytoma (paroxysmal symptoms)
Conn's syndrome (tetany, muscle weakness, polyuria, hypokalaemia) Coarctation (radio-femoral delay or weak femoral pulses).
Cushing's (general appearance)

Contributory factors

12. Overweight
13. Excess alcohol (> 30 ml/day for men; > 20 ml/day for women) 14. Excess salt intake
15. Lack of exercise
16. Environmental stress
Complications of hypertension or target organ damage
17. Stroke, transient...
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