I
HYPERTENSION
a n o t h e r d i s o r d e r , s u c h a s
H o d g k i n ’s d i s -
e a s e
o r
m a l a r i a
.
i n w h i c h t h e s p l e e n h a s
b e c o m
e e n l a r g e d .
S i g n s o f h y p e r s p l e n i s m i n c l u d e
a n a e -
m i a
a n d
t h r o m b o c y t o p e n i a
( d e f i c i e n c y o f
p l a t e l e t s ) . T h e r e m a y a l s o b e d e c r e a s e d
r e s i s t a n c e t o i n f e c t i o n . P r i m a r y h y p e r -
s p l e n i s m
i s
t r e a t e d
w i t h
s p l e n e c t o m y
( r e m o v a l
o f t h e s p l e e n ) . T r e a t m e n t
o f
s e c o n d a r y
h y p e r s p l e n i s m
i s
a i m e d
a t
c o n t r o l o f t h e c a u s e .
h y p e rte n s io n
P e r s i s t e n t l y
r a i s e d
b l o o d p r e s s u r e
( t h e
p r e s s u r e o f b l o o d i n t h e m a i n a r t e r i e s ) .
B l o o d p r e s s u r e g o e s u p t e m p o r a r i l y a s a
n o r m a l r e s p o n s e t o s t r e s s a n d p h y s i c a l
a c t i v i t y , a n d i t r i s e s n a t u r a l l y w i t h i n -
c r e a s i n g a g e a n d w e i g h t . A p e r s o n w i t h
h y p e r t e n s i o n , h o w e v e r , h a s p e r s i s t e n t l y
h i g h b l o o d p r e s s u r e e v e n w h e n a t r e s t .
B e c a u s e t h e c o n d i t i o n i t s e l f c a u s e s n o
s y m p t o m s ,
a
l a r g e
n u m b e r
o f p e o p l e
h a v e h y p e r t e n s i o n w i t h o u t r e a l i z i n g i t ;
h o w e v e r ,
b e c a u s e
h y p e r t e n s i o n
c a u s e s
t h e r i s k o f d e v e l o p i n g s e r i o u s c a r d i o -
v a s c u l a r
d i s o r d e r s
t o
i n c r e a s e ,
r e g u l a r
m e d i c a l c h e c k s a r e a d v i s e d i n o r d e r t o
d e t e c t t h e c o n d i t i o n a t a n e a r l y s t a g e .
H y p e r t e n s i o n i s v e r y c o m
m o n , p a r t i c u -
l a r l y
i n
m e n ,
a n d
i t s
i n c i d e n c e
i s
h i g h e s t i n t h e m i d d l e - a g e d a n d e l d e r l y .
B l o o d
p r e s s u r e
i s
m e a s u r e d
a s
t w o
v a l u e s ,
e a c h
e x p r e s s e d
a s
m i l l i m e t r e s
( m m )
o f
m e r c u r y
( c h e m
i c a l
s y m b o l
H g )
o r m m H g . T h e s y s t o l i c v a l u e
( t h e
h i g h e r
v a l u e )
i s
t h e
p r e s s u r e
w h e n
b l o o d s u r g e s
i n t o
t h e
a o r t a f r o m
t h e
h e a r t ; t h e d i a s t o l i c v a l u e i s t h e p r e s s u r e
w h e n
t h e
v e n t r i c l e s
( l o w e r
c h a m b e r s
o f t h e
h e a r t )
r e l a x
b e t w e e n
b e a t s .
A
b l o o d
p r e s s u r e
c o n s i s t e n t l y
e x c e e d i n g
a b o u t
1 4 0 m m H g
( s y s t o l i c )
a n d
9 0
m m H g
( d i a s t o l i c )
a t r e s t i s d e f i n e d a s
h y p e r t e n s i o n .
SYMPTOMS AND COMPLICATIONS
H y p e r t e n s i o n
i s
u s u a l l y
s y m p t o m l e s s ,
a n d g e n e r a l l y
g o e s
u n d i s c o v e r e d u n t i l
d e t e c t e d
d u r i n g
a
r o u t i n e
p h y s i c a l
e x a m i n a t i o n . H o w e v e r , i f i t i s s e v e r e o r
a c c e l e r a t e d
( s e e
m a l i g n a n t h y p e r t e n s i o n
)
i t m a y c a u s e h e a d a c h e s , b r e a t h l e s s n e s s ,
a n d v i s u a l d i s t u r b a n c e s . T h e c o n d i t i o n
p u t s
c o n s i d e r a b l e
s t r a i n
o n
t h e
h e a r t
a n d b l o o d v e s s e l s , i n c r e a s i n g t h e r i s k o f
s t r o k e , c o r o n a r y a r t e r y d i s e a s e ,
a n d
h e a r t
f a i l u r e
.
H y p e r t e n s i o n m a y e v e n t u a l l y l e a d
t o k i d n e y d a m a g e a n d
r e t i n o p a t h y
( d a m -
a g e t o t h e r e t i n a a t t h e b a c k o f t h e e y e ) .
CAUSES
I n
m a n y
c a s e s ,
t h e r e
i s
n o
o b v i o u s
c a u s e ,
i n w h i c h
c a s e t h e
c o n d i t i o n i s
HYPERTENSION
Hypertension (high blood pressure)
affects ten to 20 per cent of adults in
the UK. It is diagnosed if a person’s
resting
b l o o d p r e s s u r e
is persistently
raised. Blood pressure is expressed
by two values - the systolic and
diastolic pressures - and measured in
millimetres of mercury.
Although hypertension rarely causes
symptoms, it is a serious condition.
It may cause excessive strain on the
arteries. Left untreated, it increases the
risk of stroke and other disorders. In
many cases there is no obvious cause
for hypertension, but in some people
there is a specific cause, such as a
kidney disorder, pregnancy, or the use
of oral contraceptives. Hypertension
is linked to obesity and, in some
people, to a high salt intake. Smoking
compounds the risks ofthe condition.
Stress and hypertension
Acute stress or pain act on the nervous system,
causing blood vessels to constrict and the heart
to work harder. Both lead to a brief rise in blood
pressure. Hence, pressure should be measured
when a person is relaxed. It is possible (but
unproven) that frequent stress may eventually
cause hypertension.
F a t ty
d e p o s i t s
C o n t r a c t e d
m u s c l e
Ml
A r t e r y w a ll
Atheroma
Hypertension and
atherosclerosis, in
which arteries are
narrowed byfatty
deposits called
atheroma (left), are
closely linked both
to each other and
to obesity.
Constriction
Factors such as
nicotine in tobacco
cause constricted
arteries (left) and
a short-term rise
in blood pressure
that may worsen
hypertension.
Blood pressure
Variation in blood pressure
In any population, blood pressure varies over a wide range
in the same way as height. Many people are considered to
be hypertensive because they are at the top end of this
range (see above). In obese people, the range is similarly
wide but shifted towards the top end: hence, more obese
people are hypertensive.
COMMON FACTORS AND PREVENTIVE MEASURES
Factors
associated with
essential
hypertension
• Age (incidence higher in the elderly)
• Family history ofthe condition
• Gender (incidence higher in men than in women)
Factors that may
aggravate
hypertension
• Smoking • Obesity • Excess alcohol intake
• Diabetes mellitus • High salt intake
Self-help and
treatment
• Regular screening ofblood pressure is important for early
diagnosis and can help to prevent complications.
Sufferers from essential hypertension should:
Reduce weight; Not smoke; Reduce or stop alcohol intake
Reduce salt intake; Take regular exercise; Learn relaxation.
Antihypertensive drugs, prescribed by a doctor, can usually
keep high blood pressure under control.
H
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