SYSTEMIC HYPERTENSION Hypertension is one of the leading causes of the global burden of - PowerPoint Presentation

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SYSTEMIC HYPERTENSION

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Hypertension is one of the leading causes of the global burden of disease.

Hypertension

doubles the risk of cardiovascular diseases, including coronary heart disease (CHD), congestive heart failure (CHF), ischemic and hemorrhagic stroke, renal failure, and peripheral arterial disease

.

Although

antihypertensive therapy clearly reduces the risks of cardiovascular and renal disease, large segments of the hypertensive population are either untreated or inadequately treated.

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Definition

Hypertension currently is defined as a usual BP of 140/90 mm Hg or higher, for which the benefits of drug treatment have been definitively established

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Staging of Office Blood Pressure

BP STAGE

SYSTOLIC BP (mm Hg)

DIASTOLIC BP (mm Hg)

Normal

<120

<80

Prehypertension

120-139

80-89

Stage 1 hypertension

140-159

90-99

Stage 2 hypertension

≥160

≥100

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Aetiology

Primary (Essential) hypertension

The majority

(90–95%)

of patients with

hypertension have primary

elevation of blood pressure, i.e. essential

hypertension of

unknown cause

.

Secondary hypertension (5-10%).

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Many factors may contribute

to development of essential HT

Neural

Mechanisms

Baroreflex

control of sinus node function is

abnormal

Obesity-Related

Hypertension

Obstructive Sleep Apnea

Renal

Mechanisms

acquired or inherited defect in the kidneys' ability to excrete the excessive sodium

load

Low Birth

Weight

Genetic Contributions

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Vascular

Mechanisms

Endothelial Cell

Dysfunction

Vascular

Remodeling: An

increase in the medial thickness relative to lumen diameter (increased media-to-lumen ratio) is the hallmark of hypertensive remodeling in small and large arteries

.

Hormonal

Mechanisms

Activation of the renin-angiotensin-aldosterone system (RAAS) is one of the most important mechanisms contributing to endothelial cell dysfunction, vascular remodeling, and hypertension

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Secondary hypertension

Renal diseases

These account for over 80% of the cases of

secondary hypertension

.

The

common causes are:

■ diabetic nephropathy

■ chronic glomerulonephritis

■ adult polycystic disease

■ chronic

tubulointerstitial

nephritis

■

renovascular

disease.

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Endocrine causes

These include:

Conn’s syndrome

Congenital adrenal

hyperplasia

phaeochromocytoma

Cushing’s syndrome

acromegaly

.

Hyperparathyroidism

Primary

hypothyroidism

Thyrotoxicosis

Congenital cardiovascular causes

The major cause is

coarctation

of the aorta

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Drugs:

NSAIDs, oral contraceptives,

steroids,

carbenoxolone

,

liquorice

,

sympathomimetics

and vasopressin

.

Pregnancy (pre-

eclampsia

)

Alcohol

Obesity

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All adults should have blood pressure measured

routinely at

least every 5 years until the age of 80 years

.

Seated

blood pressure

when measured after 5 minutes’ resting with

appropriate cuff

size and arm supported is usually sufficient,

but

standing

blood pressure

should be measured in diabetic

and elderly

subjects to exclude orthostatic hypotension

.

The

cuff should

be deflated at 2 mm/s and the blood pressure

measured to

the nearest 2 mmHg

.

Two consistent blood

pressure measurements

are needed to estimate blood pressure,

and more

are recommended if there is variation in the pressure.

When assessing the cardiovascular risk, the average

blood pressure

at separate visits is more accurate than

measurements taken

at a single visit.

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Assessment

History

Family history, lifestyle (exercise, salt intake, smoking habit) and other risk factors should be recorded.

The patient with mild hypertension is usually asymptomatic.

Higher levels of

blood pressure may be associated with headaches,

epistaxis or

nocturia

.

Attacks of sweating, headaches and palpitations point towards the diagnosis of

phaeochromocytoma

.

Breathlessness

may be present owing

to left

ventricular hypertrophy or cardiac failure

,

symptoms

of peripheral arterial vascular disease

suggest the

diagnosis of

atheromatous

renal artery stenosis

.

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Examination

Findings related to hypertension

Loud A2

S4

Forceful sustained apical impulse (heaving)

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Examination

Secondary causes

: Radio-femoral

delay (

coarctation

of the

aorta),

enlarged kidneys (polycystic kidney disease), abdominal bruits (renal artery stenosis) and the characteristic

facies

and habitus of Cushing's syndrome are all examples of physical signs that may help to identify causes of secondary

hypertension.

Risk factors

: Examination

may also reveal features of important risk factors such as central obesity and

hyperlipidaemia

(tendon

xanthomas

etc.).

Complications:

The

optic fundi are often

abnormal

and

there may be evidence of

generalised

atheroma or specific complications such as aortic aneurysm or peripheral vascular disease.

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Investigations

investigation of all

patients

Urinalysis for blood, protein and glucose

Blood urea, electrolytes and

creatinine

N.B.

Hypokalaemic

alkalosis may indicate primary

hyperaldosteronism

but is usually due to diuretic therapy

Blood glucose

Serum total and HDL cholesterol

12-lead ECG (left ventricular hypertrophy, coronary artery disease)

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investigation of selected patients

Chest X-ray

: to detect cardiomegaly, heart failure,

coarctation

of the aorta

Ambulatory BP recording

: to assess borderline or 'white coat' hypertension

Echocardiogram

: to detect or quantify left ventricular hypertrophy

& for the diagnosis

ofcoactation

of aorta

Renal ultrasound

: to detect possible renal disease

Renal angiography

: to detect or confirm presence of renal artery stenosis

Urinary

catecholamines

: to detect possible

phaeochromocytoma

Urinary cortisol and dexamethasone suppression test

: to detect possible Cushing's syndrome

Plasma renin activity and aldosterone

: to detect possible primary

aldosteronism

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Ambulatory blood pressure monitoring

Indirect automatic blood pressure measurements can

be made

over a 24-hour period using a measuring device

worn by

the patient.

they

are used to confirm the diagnosis

in those

patients with

‘white-coat’ hypertension

, i.e.

blood pressure

is completely normal at all stages

except

during

a clinical consultation

These devices may also be

used to

monitor the response of patients to drug treatment

and, in

particular, can be used to determine the adequacy of

24-hour

control with once-daily

medication

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Ambulatory blood pressure recordings seem to be

better predictors

of cardiovascular risk than clinic measurements.

Analysis of the diurnal variation in blood pressure

suggests that

those

hypertensives

with loss of the usual nocturnal

fall in

blood pressure (‘non-dippers’) have a worse

prognosis than

those who retain this pattern.

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Complications

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Blood vessels

In larger arteries (> 1 mm in diameter), the internal elastic lamina is thickened, smooth muscle is hypertrophied and fibrous tissue is deposited

.

In

smaller arteries (< 1 mm), hyaline arteriosclerosis

aortic aneurysm and aortic

dissection

Central nervous system

Stroke (due

to cerebral

haemorrhage

or

infarction).

Carotid atheroma and transient

ischaemic

attacks are more common in hypertensive patients.

Subarachnoid

haemorrhage

is also associated with hypertension.

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Hypertensive encephalopathy is a rare condition

characterised

by high BP and neurological symptoms, including transient disturbances of speech or vision,

paraesthesiae

, disorientation, fits and loss of consciousness.

Papilloedema

is common.

Retina

central retinal vein thrombosis

Hypertensive retinopathy

Grade I

Arteriolar thickening, tortuosity and increased reflectiveness ('silver wiring')

Grade 2

Grade 1 plus constriction of veins at arterial crossings ('

arteriovenous

nipping')

Grade 3

Grade 2 plus evidence of retinal

ischaemia

(flame-shaped or blot

haemorrhages

and 'cotton wool' exudates)

Grade 4

papilloedema

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Heart

coronary artery disease.

left

ventricular

hypertrophy

Atrial fibrillation

Diastolic dysfunction

LV failure.

Kidneys

Long-standing hypertension may cause proteinuria and progressive renal

failure

by damaging the renal vasculature.

'Malignant' or 'accelerated' phase hypertension

(Diastole>130

mmgh

)

This rare condition may complicate hypertension of any

aetiology

and is

characterised

by accelerated

microvascular

damage

and by intravascular thrombosis.

The

diagnosis is based on evidence of high BP and rapidly progressive end organ damage, such as

retinopathy

(grade 3 or 4),

renal dysfunction

(especially proteinuria) and/or

hypertensive encephalopathy

.

Left

ventricular failure may occur and, if this is untreated, death occurs within months.