Hypertension
DEFINITION
Defined as systolic BP >140 mmHg and/or diastolic BP >85 mmHg measured on three separate occasions. Malignant hypertension is defined as BP 200/ 130 mmHg.
AETIOLOGY
Primary:
. Essential or idiopathic hypertension (Commonest, >90% of cases).
Secondary:
- . Renal: Renal artery stenosis, chronic glomerulonephritis, chronic pyelonephritis, polycystic kidney disease, chronic renal failure.
- . Endocrine: Diabetes mellitus, hyperthyroidism, Cushings syndrome, Conns syndrome, hyperparathyroidism, phaeochromocytoma, congenital adrenal hyperplasia, acromegaly.
- . Cardiovascular: Aortic coarctation, " intravascular volume.
- . Drugs: Sympathomimetics, corticosteroids, oral contraceptive pill.
- . Pregnancy: Pre-eclampsia.
EPIDEMIOLOGY
Very common. 10–20% of adults in the Western world.
HISTORY
Often asymptomatic.
Symptoms of complications (see Complications).
Symptoms of the cause.
Accelerated or malignant hypertension: Scotomas (visual field loss), blurred vision, headache, seizures, nausea, vomiting, acute heart failure.
EXAMINATION
Measure on two to three different occasions before diagnosing hypertension and record lowest reading.
There may be loud second heart sound, fourth heart sound.
Examine for causes, e.g. radiofemoral delay (aortic coarctation), renal artery bruit (renal artery stenosis). Examine for end-organ damage, e.g. fundoscopy for retinopathy.
Keith–Wagner classification of retinopathy:
(I) ‘silver wiring’;
(II) as above, plus arteriovenous nipping;
(III) as above, plus flame haemorrhages and cotton wool exudates;
(IV) as above, plus papilloedema.
PATHOLOGY/PATHOGENESIS
Fibrotic intimal thickening of the arteries, reduplication
of elastic lamina and smooth muscle hypertrophy. Arteriolar wall layers replaced by pink hyaline material with luminal narrowing (hyaline arteriosclerosis).
INVESTIGATIONS
Blood:
U&E, glucose, lipids.
Urine dipstick:
Blood and protein.
ECG:
May show signs of left ventricular hypertrophy (deep S wave in V1–2, tall R wave in V5–6, inverted T waves in I, aVL, V5–6, left-axis deviation) or ischaemia.
Ambulatory BP monitoring (BP measured throughout the day):
Excludes ‘white coat’ hypertension, allows monitoring of treatment response, assesses preservation of nocturnal dip.
Others:
Especially in patients <35 years or other suspected secondary cases (see relevant topics).
MANAGEMENT
Assessment and modification of other cardiovascular risk factors.
Conservative:
Stop smoking, ↓alcohol ,lose weight, reduce dietary Na + .
Investigate for secondary causes:
Worthwhile in young patients, malignant hypertension or poor response to treatment.
Medical :
Treatment recommended for systolic BP 160 mmHg and/or diastolic BP 100 mmHg, or if evidence of end-organ damage. Other hypertension patients may still require treatment depending on other cardiac risk factors. Multiple drug therapies often necessary.
. Thiazide diuretics (e.g. bendrofluamethiazide): Recommended first line, especially in >55- year-olds or black patients.
. ACE inhibitors (e.g. ramipril) or angiotensin-II antagonist (e.g. losartan): First line in <55- year-olds, diabetic patients, heart failure or left ventricular dysfunction.
. Ca2 þ channel antagonists (e.g. amlodipine): Recommended first line, especially in >60- year-olds or black patients.
. b-Blockers (e.g. atenolol): Not preferred initial therapy, but may be considered in younger patients. Avoid combining with thiazide diuretic to reduce patient risk of developing diabetes. May increase risk of heart failure.
. a-Blockers (e.g. doxazosin): Fourth-line agent. May be useful for patients with prostatism.
Target BP:
- . 140/85 mmHg (non-diabetic);
- . 130/80 mmHg (diabetes without proteinuria);
- . 125/75 mmHg (diabetes with proteinuria).
Severe hypertension (diastolic BP > 140 mmHg):
Atenolol or nifedipine.
Acute malignant hypertension:
IV b-blocker, labetolol or hydralazine sodium nitroprusside. Avoid very rapid lowering which can cause cerebral infarction.
COMPLICATIONS
Heart failure, coronary artery disease and MI, CVA, peripheral vascular disease, emboli, retinopathy, renal failure, hypertensive encephalopathy, posterior reversible encephalopathy syndrome (PRES), malignant hypertension.
PROGNOSIS
Good, if BP controlled. Uncontrolled hypertension linked with increased mortality (6 stroke risk and 3 cardiac death risk). Treatment reduces incidence of renal damage, stroke and heart failure.
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