Hypertension Flashcards
What is hypertension?
Sustained increase in blood pressure
What are the stages of hypertension?
Stage 1
Stage 2
Severe
What is stage 1 hypertension?
Blood pressure of 140/90mmHg or above
What is stage 2 hypertension?
Blood pressure of 160/100mmHg or above
What is severe hypertension?
Blood pressure of 180/110mmHg or above
How does blood pressure measured at home differ to blood pressure measured in clinic?
Slightly lower at home
What are the types of hypertension?
Primary hypertension
Secondary hypertension
Which type of hypertension is more common - primary or secondary?
Primary by far
What is another term for primary hypertension?
Essential hypertension
What is the difference between primary and secondary hypertension?
Primary - unknown cause
Secondary - cause can be defined
What factors contribute to primary hypertension?
Genetic factors - hypertension runs in families
Environmental factors
What are some of the causes of secondary hypertension?
Renovascular disease
Chronic kidney disease
Hyperaldosteronism
Cushing’s syndrome
How does renovascular disease lead to secondary hypertension?
Renal artery stenosis
fall in perfusion pressure of kidney
release of renin
How does the release of renin lead to secondary hypertension?
Activation of RAAS
increases blood volume, TPR
and hence blood pressure
How does renal parenchymal disease lead to secondary hypertension?
Early stage - loss of local vasodilators
Late stage - inadequate filtration, more Na+ and water retention
How does loss of local vasodilators lead to secondary hypertension?
Vasoconstriction of afferent arteriole
Decreased GFR
Increased Na+ retention, water reabsorption
Increased blood volume, blood pressure
What are the adrenal causes of secondary hypertension?
Conn’s syndrome
Cushing’s syndrome
Phaeochromocytoma
How does Conn’s syndrome lead to secondary hypertension?
Adrenal adenoma
secretes aldosterone - hyperaldosteronism
How does hyperaldosteronism lead to secondary hypertension?
Increased retention of Na+, water
Increased blood volume, blood pressure
What else does Conn’s syndrome lead to? How?
Hypokalaemia
Aldosterone gives activation of apical K+ channel
K+ diffuses out, loss of K+
How does Cushing’s syndrome lead to secondary hypertension?
Excess secretion of cortisol
binds to aldosterone receptors at high concs.
How does phaeochromocytoma lead to secondary hypertension?
Secretes catecholamines - adrenaline and noradrenaline
Increased sympathetic activity
What does hypertension lead to damage of?
Heart
Vasculature
What are some of the complications of hypertension?
LV hypertrophy
MI
Heart failure
Aortic aneurysm
Coronary artery disease
Stroke
Retinopathy
Chronic kidney failure
How does hypertension lead to LV hypertrophy?
Increased pressure in arteries, afterload
LV has to contract harder, generate more pressure
In order to push blood into arteries
What can LV hypertrophy lead to? How?
Heart failure - diastolic
Reduced filling of left ventricle
Reduced EDV, SV, CO
How does hypertension lead to myocardial ischaemia, infarction?
Increased pressure in arteries, afterload
Heart has to contract harder, generate higher pressures
To push blood into arteries
Requires more oxygen
Making it more susceptible to ischaemia, infarction
How does hypertension lead to retinopathy, aneurysm, stroke, renal failure?
Arteries become damaged
Are weakened
More prone to atherosclerosis
Why are arteries more prone to atherosclerosis with hypertension?
High pressure damages arterial walls
Get inflammatory response
Deposition of fat, calcium
How is secondary hypertension treated?
Treat primary cause
What are the two approaches to treating primary hypertension?
Non-pharmacological
Pharmacological
What does the non-pharmacological approach of treating primary hypertension involve?
Improving diet - reduce Na+, alcohol intake
Increasing exercise
What is a disadvantage of non-pharmacological approaches to treating primary hypertension?
Limited effect
What are the groups of drugs used to treat primary hypertension?
RAAS blockers
Vasodilators
Calcium ion channel blockers
Beta blockers
What are some examples of RAAS blockers?
ACE inhibitors
Angiotensin 2 receptor antagonists
How do ACE inhibitors work?
Prevent ACE converting angiotensin 1 into angiotensin 2
Prevent breakdown of bradykinin
What are the effects of ACE inhibitors?
Vasodilation by bradykinin
Reduced sodium, water reabsoprtion
Reduced release of aldosterone from adrenal cortex
What is an example of an ACE inhibitor?
Captopril
What are the effects of angiotensin 2 receptor antagonists?
Reduced vasoconstriction
Reduced sodium, water retention
Reduced aldosterone release from adrenal cortex
What are some examples of vasodilators?
Calcium ion channel blockers
A1 receptor blockers
How do calcium ion channel blockers cause vasodilation?
Prevent calcium ion entry into smooth muscle cells
Reduced smooth muscle cell contraction
How do angiotensin 2 receptors antagonists work?
Prevent angiotensin 2 binding to its receptor
How do A1 adrenoceptor antagonists cause vasodilation?
Prevent noradrenaline binding to A1 adrenoceptors on vascular smooth muscle cells and causing vasoconstriction
What is a side effect of A1 adrenoceptor antagonists? Why?
Postural hypotension
block baroreceptor reflex from causing vasoconstriction
What causes postural hypotension?
Standing up
Gravity draws blood down to blood vessels in legs
Reduced venous return, filling, SV, CO, maBP
What responds to postural hypotension? How?
Baroreceptor reflex
Increased sympathetic output
Increases heart rate, force of contraction, SV, CO
Peripheral vasoconstriction, increases TPR
Increasing maBP
What are some examples of diuretics?
Thiazide
Aldosterone antagonists
How do thiazide diuretics work?
Inhibit Na+ Cl- co-transporter on apical domain of cells
in distal tubule
What is the effect of thiazide diuretics?
Reduced sodium and water retention
reduced blood volume, blood pressure
What is an example of an aldosterone antagonist?
Spironolactone
How do beta blockers work?
Block B1 adrenoceptors in heart
Reduce heart rate, force of contraction
Are beta blockers commonly used to treat hypertension?
No
When would beta blockers be used to treat hypertension?
Hypertension with a previous MI
