Pathology of Hypertension Flashcards
Definition of hypertension
Disorder in which the level of sustained arterial pressure is higher than expected for the age, sex, and race of the individual
Accepted value of hypertension and flaw?
Greater than 140/90 mmHg
But there is normal variation in BP and around 25% of the population have unknown hypertension
Cautions when taking and interpreting BP readings?
Normal variation in individuals at different times of day - REPEAT measurements
WHITE COAT hypertension - nervousness of having BP reading taken
Two types of BP, in relation to variation?
Stable - not much variation (more effective remodelling than in labile)
Labile - great variation in readings at different times (likely to be worse in terms of complications)
What does hypertension CAUSE?
Cardiac failure
Hypertension is a risk factor for?
Cerebral haemorrhage
Atheroma; also, increased rate of progression of that atheroma
Renal failure
Sudden cardiac death
Where are when is hypertension more common?
Higher in Black populations
If there is a familial tendency
Rises with age
Types of classification of hypertension?
According to cause (aetiological):
Primary
Secondary
According to consequences (clinicopathological):
Benign
Malignant
How can BP change?
Changes in CO due to changes in:
HR
Contractility (SV)
Blood volume (SV)
Changes in TPR due to:
Vasoconstrictors, e.g: Ang. II and catecholamines (adrenaline, noradrenaline)
Vasodilators, e.g: NO, certain prostaglandins
What do SBP and DBP mean?
SBP - peak BP that coincides with left ventricular ejection
DBP - baseline below which BP does not fall and coincides with left ventricular relaxation
What are the resistance arteries?
Arterioles contribute most to TPR
Main regulation of the RAAS system?
Mainly, renal blood flow (kidneys and brain auto-regulate blood flow)
If BP decreases, renin is released
Function of Ang. II?
First bio-active component of the RAAS system:
Vasoconstrictor
Aldosterone (mineralocorticosteroid) release causes Na+ and water retention to increase blood volume
Reason for which RAAS system activity may be high?
Due to polymorphisms in renin, etc
May contribute to familial hypertension
What is primary hypertension?
Majority (90%) of cases have NO OBVIOUS CAUSE
Genetic factors are strongly implicated - from twin studies
How can protein intake affect BP?
Increased protein intake, increases renal blood flow so more RAAS activity
What is salt-sensitive hypertension?
Where an increase in dietary salt increases BP (controlled by a reduced salt diet) - due to genetic polymorphisms
NOT ALL PRIMARY HYPERTENSIVES ARE SALT-SENSITIVE
What type of hypertension is normally salt-sensitive?
Hypertension secondary to renal disease
What is secondary hypertension?
Underlying disease is implicated, e.g: Renal disease (most common secondary cause) Endocrine disease Aortic disease Renal artery stenosis Drug therapy
Renal causes of secondary hypertension?
Any renal disease, e.g: diabetic renal disease (almost all diabetics become hypertensive) Renal artery stenosis Acute/chronic glomerulonephritis Chronic pyelonephritis Cystic diseases Interstitial nephritis
How do renal disease cause hypertension?
Reduced renal blood flow so excess renin release
Salt and water overload increase blood volume
Endorcrine causes of hypertension?
Adrenal gland hyperfunction/tumours:
Conn’s Syndrome (primary aldosteronism) - excess aldosterone
Cushing’s syndrome - excess corticosteroid
…adrenal cortex responsible for these two
Phaeochromocytoma - tumour of adrenal medulla leading to excess noradrenaline
How does coarctation of the aorta cause hypertension?
Congenital narrowing of segments of the aorta (increase in resistance)
Example of drugs which cause hypertension?
Corticosteroids
