4. essential hypertension

8/13/2019 4. Essential Hypertension

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Essential Hypertension


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Hypertension Hypertension is not a disease

It is an arbitrarily defined disorder to whichboth environmental and genetic factors

contribute

Major risk factor for:cerebrovascular disease

myocardial infarction

heart failure

peripheral vascular disease

renal failure


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This left ventricle is very thickened (slightly over 2 cm in

thickness), but the rest of the heart is not greatly enlarged.

This is typical for hypertensive heart disease. The

hypertension creates a greater pressure load on the heart to

induce the hypertrophy.


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The left ventricle is markedly thickened in this patient

with severe hypertension that was untreated for many

years. The myocardial fibers have undergone

hypertrophy.


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Blood pressure is a continuous variable

which fluctuates widely during the dayphysical stress

mental stress

The definition of hypertension has been

arbitrarily set as:

That blood pressure above which thebenefits of treatment outweigh the risks

in term of morbidity and mortality


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Blood Pressure

Exhibits a normal distribution within the

population

Increasing blood pressure is associated with

a progressive increase in the risk of stroke

and cardiovascular disease

Risk however rises exponentially and notlinearly with pressure


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At what blood pressure is a patient

hypertensive? BHS 140/90

JNC-VI 140/90 Opt


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In 95% of cases no cause can be found

In 5-10% a cause can be found

Chronic renal disease

Renal artery stenosis Endocrine disease, Cushings, Conns

Syndrome, Phaeochromocytoma, GRA


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Risks of Hypertension

The risk of hypertension is considerable

The 4thmost common cause of death world-wide

Directly and indirectly responsible for >20% of alldeaths

The risks of hypertension have been most

thoroughly determined by the Framingham Study -a longitudinal study performed in the USA


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Framingham Study

This study clearly demonstrated that therelative risk to a patient with a DBP of 99

mmHg compared to a DBP of 84 mm Hg

forStroke increases 4 fold

MI increases 2 times

The same was also found to be true forsystolic blood pressure

These pressure are common


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Despite the clear relationship between blood

pressure and morbidity the risk fromhypertension also depends on and increases

exponentially with other factors

Cigarette smoking Adds 20/10 mmHg

Diabetes mellitus 5-30 X increase MI

Renal disease

Male 2X risk

Hyperlipidaemia

Previous MI or stroke

Left ventricular hypertrophy 2X risk


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Control of blood pressure

Blood pressure is controlled by anintegrated system

Prime contributors to blood pressure are:

Cardiac output Stroke volume

Heart rate

Peripheral vascular resistance

Each of these factors can be manipulated by

drug therapy


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Sympathetic Nervous System

Sympathetic system activation produces

vasoconstriction

reflex tachycardia

increased cardiac output

In this way blood pressure is increased

The actions of the sympathetic system are

rapid and account for second to second

blood pressure control


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The renin-angiotensin-aldosterone system

The RAAS is pivotal in long-term BP

control

The RAAS is responsible for:maintenance of sodium balance

control of blood volume

control of blood pressure


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The RAAS is stimulated by:

fall in BP

fall in circulating volume

sodium depletion

Any of the above stimulate renin release

from the juxtaglomerular apparatus

Renin converts angiotensinogen to

angiotensin I

Angiotensin I is converted to angiotensin IIby angiotensin converting enzyme (ACE)


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Angiotensin II is a potent

vasoconstrictor

anti-natriuretic peptide

stimulator of aldosterone release from the

adrenal glands

Aldosterone is also a potent antinatriureticand antidiuretic peptide

Angiotensin II is also a potent hypertrophic

agent which stimulates myocyte and smoothmuscle hypertrophy in the arterioles


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Myocyte and smooth muscle hypertrophy:

are both poor prognostic indicators in patientswith hypertension

partially explain why hypertension and the risks

of hypertension persist in some patients despite

treatment

Both the sympathetic and RAAS are key

targets in the treatment of hypertension


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Aetiology of essential hypertension

The aetiology of hypertension is

Polygenic

Major genes

Poly genes

Polyfactorial

Environment Individual and Shared


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Likely causes:

Increased reactivity of resistance vesselsand resultant increase in peripheral

resistance

as a result of an hereditary defect of the smooth

muscle lining arterioles

A sodium homeostatic effect

In essential hypertension the kidneys are unable

to excrete appropriate amounts of sodium for

any given BP. As a result sodium and fluid are

retained and the BP increases


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Other factors

Age

Genetics and family history

Environment

Weight

Alcohol intake

Race


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AGE

BP tends to rise with age, possibly as a result of

decreased arterial compliance.

Hypertension in the elderly should be treated as

aggressively as in the young. They have more

to loseStudies such as EWPHE, Primary Care

Study,MRC Hypertension in the Older Adult,

SHEP, SYSTEUR and STOP-1 and 2 have

proven that treating both diastolic and systolichypertension in the elderly significantly reduces

stoke and MI.


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GENETICS

A history of hypertension tends to run in

families

The closest correlation exists between sibs

rather than parent and childIt is also possible that environmental factors

common to members of the family also have a

role in the development of hypertension


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Environment

Mental and physical stress both increase bloodpressure

However removing stress does nor necessarily

return blood pressure to normal values

True stress responders who have very high BPwhen they attend their doctor but low normal

pressures otherwise tend to be highly resistant

to treatment


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ALCOHOL

The most common cause oh hypertension in the

young ScotAffects 1% of the population

Small amounts of alcohol tend to decrease BP

Large amounts of alcohol tend to increase BPIf alcohol consumption is reduced BP will fall

over several days to weeks.

Average fall is small 5/3 mmHg

W i ht


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Weight

Obese patients have a higher BP

Up to 30% of hypertension is attributable in

part or wholly to obesity

If a patient loses weight BP will fall

In untreated patients a weight loss of 9Kg has

been reported to produce a fall in BP of 19/18mmHg

In treated patients a fall in BP of 30/21 mmHg

has been reported

Weight reduction is the most important non-

pharmacological measure available


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Birth Weight

Birth weight is also associated with the

development of hypertension in later life.

The lower the birth weight the higher thelikelihood of developing hypertension and

heart disease

Clearly in-utero factors affect health at alater stage.


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Race

Caucasians have a lower BP than black

populations living in the same environmentBlack populations living in rural Africa have a

lower BP than those living in towns

Reasons are not clearPossibly black populations are more susceptible

to stress when living in towns

Respond in different ways to changes in diet

Black populations are genetically selected to be

salt retainers and so are more sensitive to an

increase in dietary salt intake


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Secondary Hypertension

5-10% of all hypertension has an

identifiable cause

Removal of the cause does not guarantee

that the hypertension or risk will return to

normal Sustained hypertension produces end-organ

damage to blood vessels, heart and kidney

This type of damage tends to increase BPfurther and so a vicious self-propagating

cycle is established


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Causes for Secondary Hypertension

Renal disease

20% of resistant hypertensive patients

chronic pyelonephritis

renal artery stenosis

polycystic kidneys

Drug Induced

NSAIDs

Oral contraceptive

Corticosteroids


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The risks of hypertension

The risks of hypertension are well

recognised

Cerebrovascular disease

Thromboembolic

Intra cranial bleed

TIA

Cardiovascular disease

Myocardial infarction

Heart failure

Coronary artery disease


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Peripheral vascular disease

Renal failure


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A sustained increase in BP increases theload on the heart and blood vessels

This has two effects

Myocardial hypertrophySmooth muscle hypertrophy in the resistance

vessels

Hypertrophy of this type increases thestrength of the heart and vasculature

However it also reduces compliance


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Atheromatous disease


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Atheromatous disease

Sustained hypertension is associated with

accelerated atheromatous disease of the blood

vessels

Peripheral vascular disease

Coronary artery disease

Cerebrovascular diseaseRenal artery disease

The Heart

MIHeart failure

Angina


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Detection and Diagnosis

Initial assessment History

Office blood pressure

ABPM Abdominal ultrasound scan

Inpatient assessment

Assess risk Smoking

Diabetes

Previous pathology


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Hypertension

Medication for High Blood

Pressure Diuretics

Rid the body of excess fluids and salt

Beta-blockers

Reduce the heart rate and the work of theheart

Calcium antagonists

Reduce heart rate and relax blood vessels


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Hypertension


Pressure Angiotensin II receptor blockers(ACE)

Interfere with the bodies production of

angiotensin, a chemical that causes the

arteries to constrict (narrow)

Vasodialators

Cause the muscle in the wall of the blood

vessels to relax, allowing the vessel to

dialate (widen)


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Hypertension


Pressure Sympathetic nerve inhibitors

Sympathetic nerves go from the brain to all

parts of the body, including the arteries

Cause arteries to constrict raising bloodpressure

These drugs reduce blood pressure by

inhibiting these nerves from constricting

blood vessels


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Hypertension

Home Blood Pressure

Monitoring Mercury sphygmomanometer

Standard for BP monitoring

No calibration

May be bulky

Need a second person to use machine

May be difficult for hearing impaired or

patients with arthritis


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Hypertension

Home Blood Pressure

Monitoring Automatic equipment

Contained in one unit

Portable with easy-to-read digital display

Expensive, fragile

Must be calibrated

Requires careful cuff placement


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Thank you for attention!

4. essential hypertension

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