CVS 5 Control Of Blood Pressure+ Hypertension Flashcards
Normal range of blood pressure
Systolic - 90-120
Diastolic - 60-80
BP in stage 1 hypertension
Clinical: >140/90 mmHg
Home: >135/85 mmHg
BP in stage 2 hypertension
Clinical: >160/100 mmHg
Home: >150/95
BP in severe hypertension
> 180 systolic or > 110 diastolic
Difference in the changes of the stages of hypertension
+ 20 systolic: - normal 90-120
- stage 1 140
- stage 2 160
- severe 180
+ 10 diastolic: - normal 60-80
- stage 1 90
- stage 2 100
- severe 110
diagnosis of hypertension
pt with clinical BP >140/90 should have 24 hour ambulatory blood pressure or home readings
What should you do if clinical blood pressure reading in >180/120?
- assess for target organ damage
- if there is damage, start drug treatment without ABPM
- if no damage, confirm diagnosis: repeated clinical BP in 7 days OR ABPM + clinical review in 7 days
Blood pressure screening
- every 5 years
- more often in borderline cases
- every year in pts with type 2 diabetes
What should all patients with a new diagnosis of hypertension have?
- urine albumin:creatiine ratio
- urine dipstick
- bloods HbA1c, U&Es, lipids
- fundus exam
- ECG
- QRISK score
Modifiable risk factors of hypertension
- excess weight
- excess dietary salt intake
- lack of physical activity
- excessive alcohol intake
- stress
Non-modifiable risk factors of hypertension
- increasing age
- family history
- ethnicity
- gender: BP higher in men up to age 65, then women higher >65
Causes of primary hypertension
Idiopathic - Unknown
Causes of secondary hypertension
ROPED
- Renal disease e.g. renal artery stenosis
- Obesity
- Pregnancy induced or Pre-eclampsia
- Endocrine e.g. Cushing’s syndrome, hyperaldosteronism
- Drugs e.g. alcohol, steroids, NSAIDS, oestrogen
what is the most common cause of secondary hypertension?
renal disease e.g. renal artery stenosis
diagnosis of renal artery stenosis
duplex USS
MR or CT angiogram
What is the most common endocrine condition that can cause hypertension?
hyperaldosteronism
(Conn’s syndrome)
What organs should be assessed by clinical history + physical exam in relation to hypertension?
Brain
Eyes
Heart
Kidneys
Arteries
Life style management of hypertension
- regular exercise
- healthy diet
- reduce salt + caffeine intake
- reduce alcohol
- smoking cessation
Hypertension management for:
- type 2 diabetics (regardless of age)
- under 55
- step 1: ACEi or ARB
- **step 2 **: add CCB or thiazide like diuretic
- step 3: add the other one (ACEi/ARB + CCB + thiazide like diuretic)
- step 4 if K+ <4.5mmol/L: spironolactone
- step 4 if K+ >4.5mmol/L: alpha blocker or beta blocker
Hypertension management for:
- over 55 years old
- black African or African-Caribbean family origin (regardless of age)
- step 1: CCB
- step 2: add ACEi/ARB or thiazide like diuretic
- step 3: add the other one (CCB + ACEi/ARB + thiazide like diuretic
- step 4 if K+ is <4.5mmol/L: spironolactone
- step 4 if K+ is >4.5mmol/L: alpha blocker or beta blocker
What controls short term regulation of blood pressure?
Baroreceptors reflexes
Why can baroreceptors only work in short term regulation of BP?
Threshold for baroreceptor firing resets
So not long term
Where are baroreceptors located?
Carotid sinus
Aortic arch
What are the neurohumoral pathways that control blood pressure?
1- renin-angiotensin-aldosterone-system
2- sympathetic nervous system
3- anti diuretic hormone
4- atrial natriuretic peptide
Where is renin released from?
Granular cells of juxaglomerular apparatus (JGA) in kidney
What is renin release stimulated by?
- decreased NaCl delivery to distal convoluted tubule
- decreased kidney perfusion
- sympathetic stimulation of JGA
What is kidney perfusion detected by?
Baroreceptors in afferent arteriole to kidney
What can a decrease in kidney perfusion be due to?
Renal artery stenosis
Decrease circulating volume
What is the pathway in RAAS?
Angiotensinogen > angiotensin I > angiotensin II
renin. ACE
What is angiotensinogen produced by?
Liver
What type of receptor is angiotensin receptor 1/2?
G protein coupled receptor
Action of angiotensin II
- increases BP
- vasoconstriction of arterioles
- increased Na+ reabsorption at kidney
- stimulates sympathetic NS to release more NA
- acts on hypothalamus to increase thirst + increase ADH release
- aldosterone release from adrenal cortex
Where is aldosterone released from?
Adrenal cortex
Zona glomerulosa
Action of aldosterone on kidney
- increased expression of Na/K ATPase > increased Na reabsorption > H2O follows - H2O reabsorption
- activates apical Na+ and K+ channels
ACE action on bradykinin
Breaks down bradykinin into peptide fragments
Function of bradykinin
Vasodilator
Why do ACE inhibitors cause dry coughs?
Prevent breakdown of bradykinin
Build up bradykinin cause cough
What is the sympathetic nervous system stimulated by for regulating BP?
RAAS directly (AngII)
A decrease in BP
What do high levels of sympathetic stimulation cause?
- Decreased renal blood flow by vasoconstriction of afferent arterioles
- stimulates renin release from JGA - ^ AngII levels > ^ aldosterone
- activates apical NHE + basolateral Na/K ATPase
All cause increased Na + fluid reabsorption > ^ BP
Where is ADH released from?
Posterior pituitary
What stimulates ADH release?
Severe hypovalaemia
Increase in plasma osmolarity
What does ADH do?
- increase water reabsorption
- increase Na+ reabsorption
- vasoconstiction
Increased BP
How does ADH cause increase water reabsorption?
- insertion of aquaporins into collecting duct of kidney nephron
- forms concentrated urine
What do atrial natriuretic peptides do?
Promotes Na+ excretion > water follows > decreased BP
How does ANP promote Na+ excretion?
Inhibits Na+ reabsorption
Stimulates vasodilation of afferent arterioles
Where are atrial natriuretic peptides synthesised + stored?
Atrial myocytes
Where are atrial natriuretic peptides released from?
In response to what?
Atrial cells
In response to stretch (increased BP)
What inhibits atrial natriuretic peptides?
Decreased filling of heart due to low BP > less stretching > ANP release inhibited > increased BP
What is dopamine made from?
L-DOPA
Effects of dopamine
Vasodilatation
Increased renal blood flow
Decreased reabsorption of NaCl
What do prostaglandin act as?
Vasodilators
Buffers to excessive vasoconstriction by SNS + RAAS
Examples of a1 receptor blockers
Doxazosin
Examples of L-type Ca2+ channel blockers
Verapamil
Nifedipine
Adrenal causes of secondary hypertension
- conn’s syndrome
- cushing’s syndrome
- phaeochromocytoma
What is Conn’s syndrome
Aldosterone secreting adenoma
What is Cushing’s syndrome?
How does it cause secondary hypertension?
- Excess secretion of cortisol from Zona fasiculata
- at high levels, acts on aldosterone receptors > Na+ and H2O retention
What is a phaeochromocytoma?
Tumour of adrenal medulla
Secretes catecholamines (NA + adrenaline)
Triad of symptoms for phaeochromocytoma
- episodic headache
- sweating
- tachycardia
(Patients often do not have all three)
what is the most common symptoms of phaeochromocytoma?
Sustained or paroxysmal hypertension
Treatment of phaeochromocytoma
- resection
- before surgery a + B blockers are needed phenoxybenzamine 10mg od/bd
Diagnosis of phaeochromocytoma
- 24 hour urine collection
- Abdominal CT or MRI to detect tumours
. - confirmed by measuring urinary + plasma fractionated metanephrines
What drug is most commonly used during treatment of phaeochromocytoma?
Phenoxybenzamine
(alpha blocker)
What is the target blood pressure for those <80 on treatment?
<140 systolic
<90 diastolic
What is the target blood pressure for those >80 on treatment?
<150 systolic
<90 diastolic
What is accelerated/malignant hypertension?
BP >180/120 with retinal haemorrhages or papilloedema
IV options in hypertensive emergency
- sodium nitroprusside - vasodilator
- labetalol - B blocker
- glyceryl trinitrate - vasodilator
- nicardipine - CCB
- esmolol - B blocker
What are the two ways patients can present in hypertensive crisis?
- emergency: high BP associated with a critical event e.g. encephalopathy, pulmonary oedema, MI, AKI
- urgency: high BP without critical illness but may include malignant hypertension
What is the aim of therapy for hypertensive crisis:
- emergency
- urgency
To reduce diastolic BP to 110mmHg:
- in 3-12 hours for emergency
- in 24 hours for urgency then to 100mg in 48-72 hours
What is the safest treatment for most patientsof hypertensive urgency?
- nifedipine 20mg MR BD + amlodipine10mg OD for three days
- continue amlodipine 10mg OD after
What is a hypertensive emergency?
High BP with assocaited critical event
e.g. MI, AKI, pulmonary oedema, encephalopathy
What is hypertensive urgency?
High BP without critical event
But may include malignant hypertension