Hypertension Flashcards
Definition of hypertension
a blood pressure which is associated with significant cardiovascular risk and treatment is beneficial
Major varieties of hypertension
primary/central (95%) - no single obvious cause
secondary - some other medical condition which causes it
Causes of secondary hypertension
renal disease, renovascular disease Conn's syndrome, Cushing's syndrome hyperthyroidism phaeochromocytoma pregnancy drugs - NSAIDs, corticosteroids, sympathomimetics
Which organ is the main control of BP?
kidneys
Conn’s syndrome
excess aldosterone produced
causes increased sodium retention and therefore increased BP
Cushing’s syndrome
excess corticosteroids
sodium retention, augment sympathetic NS
Hyperthyroidism
excess thyroid hormone increases SNS
Phaeochromocytoma
young p
severely hypertensive
tumour secreting NA and adrenaline
Causes of primary hypertension
obesity insulin resistance XS alcohol genetics - activity of RAAS environment fetal programming eg. low birth weight salt sensitivity age ethnicity
How does obesity cause hypertension?
production of
How does insulin resistance cause hypertension?
metabolic syndrome, resistant to insulin
type II diabetes
Goals of treatment
and why?
control BP with as few side effects as possible
generally no symptoms of hypertension (if benefits outweigh SEs)
keep SBP <140; DBP <80
reduction in CV damage, preservation of renal function, limitation or reversal of LV hypertrophy, prevention of THD, reduction in mortality due to stroke and MI
Drugs used to treat hypertension
ACEIs AT1 receptor antagonists calcium channel blockers diuretics alpha-blockers beta-blockers centrally acting antihypertensives
How do ACEIs treat hypertension?
inhibits conversion of angiotensin I to II
prevent vasoconstriction - reduces TPR
prevents production of aldosterone - reduces sodium and water retention
Side effect of ACEIs
potentiate bradykinin - cough
hyperkalaemia - increased K
severe first dose hypotension
What is contraindicated with ACEIs?
and why?
renovascular diease - bilateral renal artery stenosis
BP is very RAAS-dependent
ACEIs cause substantial drop in BP
potentially causing kidney failure
pregnancy - angiotensin II involved in vascular and renal development of fetus
What are ACEIs effective for (besides hypertenstion)?
prevention of diabetic nephropathy - slows down renal damage
therefore ACEIs are best choice for ps with diabetes and hypertension
How do AT1 receptor anntagonists treat hypertension?
block action of angiotensin II at AT1 receptor
therefore prevents vasoconstriction and production of aldosterone
Why might AT1 receptor antagonists be preferred over ACEIs?
they are less likely to cause a cough
How do calcium channel blockers treat hypertension?
they are vasodilators
inhibit voltage operated Ca2+ channles on vascular smooth muscle - leads to vasodilation and reduction in BP
Types of calcium channel blockers and their predominant effect
rate-limiting: cardiac tissue (IHD) eg. verapamil
DHPs: vascular smooth muscle eg. amlodipine
Contraindication of rate-limiting CCBs
heart failure
How do diuretics treat hypertension?
act on kidney inhibit Na+/Cl- transporter in distal convoluted tubule prevention of Na and water retention reduction in circulating volume (vasodilators)
Example of diuretics used for hypertension
thiazide-like eg. indapamide
moderate diuretics
Side effects of diuretics (thiazide-like agents)
hypokalaemia
postural hypertension
impaired glucose control - worsen diabetes
alter lipid profile (diabetogenic)
How do alpha-blockers treat hypertension?
competitive receptor antagonists of α1-adrenoceptors on vascular smooth muscle
vasodilation
Why are alpha-blockers last choice anti-hypertensives?
many side effects such as posturlal hypotension
Which beta blockers are and are not preferred?
and why?
+ atenolol - β1 selective
- propranolol - β nonselective
How do beta blockers treat hypertension?
unclear
reduction in sympathetic drive to the heart, reducing cardiac output
reduction in sympathetically evoked renin release
What are beta blockers contraindicated with?
asthma
caution with COPD
Side effects of beta blockers and why does this occur?
cold extremities and fatigue (find exercise more difficult)
blockade of peripheral β2-adrenoceptors opposes vasodilatation to skeletal muscle
bronchospasm - not selective
Side effects of calcium channel blockers
peripheral oedema - dilate arterioles
postural hypotension
constipation
How do you treat hypertension?
lifestyle - reduce CV risk: alcohol, BMI, caffeine, fat and salt, increase fruit and oily fish, exercise, smoking (doesn’t cause but makes worse)
further measurements before diagnosis
Guidelines for treating hypertension
ACD
hypertension and type 2 diabetes -> ACEI/ATRA -> + CCB/diuretic
<55 and non-black -> ACEI/ATRA -> + CCB/diuretic
>55 or black -> CCB -> + ACEI/ATRA/diuretic
3rd step: take all three
4th: referral/spironolactone/alpha or beta blocker
What should be prescribed to a p wih hypertension and IHD?
beta blockers
Why does treatment differ for those <55 and non-black?
BP more renin dependent controlled
How do centrally acting antihypertensives work?
and give an example and how it works
decrease sympathetic output from central cardiovascular control centres in the medulla
alpha-methyl dopa: false substrate leading to an anolgue of noradrenaline acting at central α2-adrenoceptors
Benefits and disadvantages of alpha-methyl dopa
+ safe in pregnancy
- widespread side effects
- no advantages over other antihypertensive agents
