Pathology of Hypertension Flashcards
what is hypertension?
= high blood pressure
- when the level of sustained arterial pressure is higher than expected for the age, sex and race of the individual
what blood pressure would be classed as hypertensive?
blood pressure of > 140/90
why is important to repeat a blood pressure measurement?
as there is normal variation in individuals at different times of the day
what are the 2 types of hypertension?
1) white coat hypertension
2) stable or labile hypertension
when does white coat hypertension arise?
patient feels anxiety in a medical environment causing an abnormally high blood pressure
what does labile hypertension mean?
blood pressure that fluctuates abruptly & repeatedly from normal to high.
e.g. due to emotional stress.
what can hypertension cause?
cardiac failure
what 4 things is hypertension a risk factor for?
1) cerebral haemorrhage
2) atheroma
3) renal failure
4) sudden cardiac death
in what type of populations is hypertension higher or lower?
Higher
= in black populations
Lower
= in South Pacific
what 2 non-modifiable factors influence hypertension?
1) familial tendency
2) rises with age
what 2 ways can you classify hypertension?
1) according to cause
2) according to consequence
what are the 2 branches of ‘according to cause’ classification of hypertension?
1) primary
2) secondary
what are the 2 branches of ‘according to consequence’ classification of hypertension?
1) bening
2) malignant
what is the relationship between blood pressure, cardiac output and peripheral resistance?
Blood pressure = cardiac output x peripheral resistance
what 3 things affect cardiac output?
1) heart rate
2) contractility
3) blood volume
what 2 things affect peripheral resistance?
1) constrictors
2) dilators
give examples of constrictors and dilators, that are part of peripheral resistance?
1) constrictors
e. g. angiotensin II
e. g. catecholamines
2) dilators
e. g. nitric oxide
e. g. prostaglandins
once renin is release from the kidney, what does it combine with to form angiotensin I?
combines with angiotensinogen.
what enzyme converts angiotensin I into angiotensin II?
ACE = angiotensin converting enzyme (lungs).
what 2 things can angiotensin II do?
1) release aldosterone
2) vasoconstriction
what does the release of aldosterone cause?
salt & fluid retention
what causes primary hypertension?
= no obvious cause
- genetic factors (twin studies)
- salt intake
- protein intake
- renin, angiotensin system
- sympathetic activity (BP = TPR x CO)
in salt sensitive hypertension, what does an increase in dietary salts do to the BP?
increases BP
what sort of genetic factor influences salt sensitive hypertension?
genetic polymorphisms
what sort of renal disease is usually salt sensitive?
renal disease 2y hypertension
what are the 5 possible causes of secondary hypertension?
1) renal disease
2) endocrine disease
3) aortic disease
4) renal artery stenosis
5) drug therapy
what sort of renal diseases can cause secondary hypertension?
- renal artery stenosis
- acute or chronic glomerulonephritis
- chronic pyelonephritis
- cystic diseases
- interstitial nephritis
what are the consequences of renal diseases?
= reduced renal blood flow
= excess renin release
= salt and water overload
what are 4 possible endocrine diseases that could cause secondary hypertension?
- what do each of these causes do?
1) adrenal gland hyperfunction
= tumours
2) Conn’s syndrome
= excess aldosterone
3) Cushing’s syndrome
= excess corticoid steroids
4) Phaecochromocytoma
= excess noradrenaline
what are 2 other possible secondary causes?
1) coarctation of the aorta
= congenital narrowing of segments of the aorta
2) drugs
= including corticosteroids
what are the 2 branches of causes of hypertension according to consequence?
1) benign hypertension
2) malignant (accelerated) hypertension
what is benign hypertension a cause of?
= serous life threatening morbidity
True or False.
Bening hypertension is asymptomatic.
True
what does benign hypertension eventually cause?
- left ventricular hypertrophy
- congestive cardiac failure
- increases atheroma
- increases aneurysm (excessive swelling of wall of artery) rupture = aortic dissection, berry aneurysms
- renal disease
hypertension causes left ventricular hypertrophy. what does this do to the heart?
1) increased LV load
2) poor perfusion
3) interstitial fibrosis
4) micro-infarcts
5) diastolic dysfunction
what does this ventricular hypertrophy cause?
= sudden cardiac death
- arrhythmias & poor perfusion
= cardiac failure
what is a sub-arachnoid haemorrhage?
= an uncommon type of stroke caused by bleeding on the surface of the brain
i.e. rupture of berry aneurysm
in benign hypertension, how is the risk of MI doubled?
for every 10mmHg of diastolic pressure above 85
in benign hypertension, how is the risk of stroke doubled?
for every 8mmHg of diastolic pressure above 85
in microvascular injury, what is affected and in what way?
1) blood vessel wall changes
- small arteries & arterioles
2) retina & kidney
3) thickening of media (smooth muscle)
4) hyaline arteriosclerosis
- plasma proteins forced into vessel wall (cf ageing)
in malignant hypertension, what is the diastolic pressure?
> 130/140
what can a malignant hypertension develop from?
1) primary hypertension
2) secondary hypertension
3) arise de-novo
what does malignant hypertension do the cerebrum?
= cerebral oedema
- seen as papilloaedema
what else does malignant hypertension do?
1) acute renal failure
2) acute heart faire
3) headache and cerebral haemorrhage
4) blood vessels show fibrinoid necrosis & endarteritis proliferans of their walls
what does pregnancy associated hypertension cause?
= increased maternal and fatal morbidity & mortality
what serious thing can pregnancy associated hypertension & proteinuria cause?
= pre-eclampsia
- resolves following birth
what is hypertension secondary to?
1) silent renal or systemic disease
