hypertension Flashcards
what is pre-hypertension?
Systolic 130-139, Diastolic: 85-89
how should prehypertension treated?
- Lifestyle modification should be encouraged
* Don’t give drugs unless they have compelling indications e.g. diabetes
what is the goal blood pressure for people with prehypertension?
<130/80
what is isolated systolic hypertension?
Systolic >140mmHg, diastolic <90mmHg (systolic high, diastolic normal)
how do you treat isolated systolic hypertension?
- Lifestyle interventions are the first stage of successful treatment
- Drug treatment recommended if lifestyle changes aren’t effective
which is more serious - hypertension or isolated systolic hypertension?
hypertension
unless theyre elderly, then isolated systolic hypertension is more serious
define hypotension
systolic blood pressure (SBP) <90mmHg or diastolic less than 60mmHg
what is another name for postural hypotension?
orthostatic hypotension
when is postural hypotension present?
if SBP decrease in standing >20 mmHg or DBP >10 mmHg when associated with dizziness/fainting
who commonly experiences hypotension?
elderly esp diabetics
what can cause hypotension?
drugs e.g. antihypertensives (diuretics, vasodilators), some psychotrophic drugs, alcohol
what are the 3 main categories of symptoms associated with hypotension?
CNS effects
Muscle effects
Heart effects
what are the CNS effects that occur with hypotension?
dizziness, impaired cognition (esp in elderly), lethargy, fatigue, visual disturbance (e.g. blurred vision, tunnel vision, ‘greying out’ colour deficits) bc of hypoperfusion of the brain
what are the muscle effects that occur with hypotension?
paracervical (upper back) ache, general fatigue
what are the heart effects that occur with hypotension?
angina (bc of hypoperfusion of heart esp during exercise)
define hypertension
Present if systolic is persistently >140 and diastolic persistently >90mmHg
how should you prepare to take a blood pressure?
- Repeated measurements need to be taken on separate days.
- Seat them quietly for 5 mins, properly prepare and position.
- Caffeine, exercise and smoking should be avoided for 30mins before
- Appropriate-sized cuff should be use
when should 24 hour ambulatory BP monitoring be used?
Borderline/suspected ‘White Coat’ effect
why do you have to measure bp to diagnose hypertension?
rarely has any symptoms
why does systolic blood pressure increase with age?
loss of compliance of arteries –> loss of elastin + collagen
what is primary hypertension and what % of hypertension cases does it make up?
90-95% of cases. No obvious underlying cause. Strong familial trend
what are the causes of secondary hypertension?
- renal or renovascular disease
- endocrine disease;
Phaeochomocytoma (tumour of chromaffin cells)
Cushings syndrome (adrenal cortical tumour)
Conn’s syndrome (hypersecretion of aldosterone)
Acromegaly and hypothyroidism - coarctation of the aorta
- Iatrogenic – hormonal/oral contraceptive, NSAIDs
- Thyroid (either hypo or hyper) or parathyroid disease
what are the framingham studies?
A classical epidemiology study on the long-term effects of hypertension
• Big cohort of people who hadn’t developed CVD or had a stroke/MI and they were monitored over a long period to identify the major CVD risk factors
what were the results of the framingham studies?
elevated arterial blood pressure is a major cause of premature vascular disease leading to stroke, coronary heart disease, renal impairment and peripheral vascular disease
how does concentric hypertrophy happen?
- high diastolic pressure in the aorta - more work for the heart to push blood through the aortic valve
- increase symp output to the heart
- increase HR (tachycardia)
- heart muscle thickens over time to produce a higher end systolic pressure - also decreases ventricular diameter
what is concentric hypertrophy?
heart wall thickens and the lumen diameter is decreased
why does ischaemia damage occur in concentric hypertrophy?
- hypertrophied cardiac muscle has a poor blood supply
- ischaemia damage happens esp after exercise or other cardiac death
what is eccentric hypertrophy?
whole ventricle enlarges (wall may or may not increase in thickness too)
what causes eccentric hypertrophy
Happens in conditions that cause increase in preload (not systemic hypertension) e.g. mitral regurgitation
how can eccentric hypertrophy lead to heart failure?
Enlarged heart = weaker force of contraction bc of Laplace’s Law –> reduces SV –> increased residual volume –> makes larger heart –> weaker heart –> heart failure
why don’t anaerobic exercise regimes reduce ventricular volume?
- raise BP by compressing vessels in the contracting muscles
- leads to cardiac remodelling and a healthy form of concentric hypertrophy where the ventricular volume isnt reduced
what effect does aerobic training have on the heart?
increases preload
healthy eccentric remodelling bc heart gradually increases in size to accommodate increased venous return
what blood vessels are particularly sensitive to chronic hypertension?
retinal blood vessels
what are signs of damage to the retinal blood vessels caused by hypertension?
- arteriolar narrowing where arterioles and venules cross - silver/copper wire arterioles
- haemorrahges in the retinal capillaries
what are silver/copper wire arterioles?
manifestation of arteriolar narrowing where arterioles and venules cross - the centre of swollen arterioles shines bc of reflected light
how do retinal capillary haemorrhages appear in an opthalamoscope?
Blot and flame haemorrhages
‘Cotton wool spots’
In severe cases - swelling of the optic disc (papilledema, or optic disc edema)
what do diabetes and hypertension cause?
frequent haemorrhage of the retinal capillaries until eventually severe sight loss occurs (unless treated)
what are the possible causes of hypertension?
- overactivity of the sympathetic nervous system
- impaired production of NO
- elevated renin release
- reduced atrial natriuretic
how does overactivity of the sympathetic nervous system cause hypertension?
- SNS controls systemic vascular resistance
- SNS increases SVR
- BP = SVR x CO - increase in SVR with no increase in CO means increased BP
what can cause overactivity of the SNS?
- Vasomotor control system is found in the medulla of the brainstem
- Local hypoxia in the brainstem caused by sclerosis/narrowing of arteries can cause overstimulation of the SNS –> chronic hypertension
what effect does NO have?
- diffuses into smooth muscle under the endothelium and relaxes it
- balances the vasoconstrictor effects of angiotensin and noradrenaline
what can decrease NO production?
• Endothelial injury by free radicals or pro-inflammatory cytokines can decrease NO production
why does impaired production of NO cause hypertension?
causes vasoconstriction and therefore a raised SVR
what effect does ANP have?
o Dilation of the glomerular afferent arterioles
o Constriction of the efferent arterioles
o Relaxes the mesangial cells that line the glomerulus
• Increases pressure in the glomerular capillaries –> increases GFR –> increases water excretion
name potassium rich foods
most vegetables, beans, potatoes, leafy greens, most fruits esp. bananas and avocados
define hyponatremia
if ECF sodium (inc blood plasma) is below 135mmol/L
why is hyponatremia serious
bc it affects AP production and can cause brain swelling
what are symptoms of mild hyponatremia?
loss of energy and fatigue; confusion; muscle weakness
what are symptoms of severe hyponatremia?
nausea and vomiting, headache, spasms, restlessness and irritability, seizures, coma (all bc of brain swelling)
how can diabetes cause hypertension?
Suspected that diabetes damages the endothelium and reduces NO production
what is leptin?
hormone from fat cells which increases satiety in normal individuals and maintains body weight
how is leptin affected in obese people?
obese people have increased leptin but decreased sensitivity to it – ‘ponderostat’ control is set too high.
how does leptin lead to hypertension?
o High leptin levels produce overstimulation of SNS – esp supply to the kidney directly stimulates excess renin release
how does hyperinsulinamia lead to hypertension?
o Hyperinsulinaemia can damage endothelial walls and decrease NO production –> increases SVR and induces hypertension
what is stage 1 hypertension?
where blood pressure is 140/90 mmHg or higher
what is stage 2 hypertension?
where blood pressure is 160/100 mmHg or higher
what lifestyle changes should a person with hypertension made?
lose weight
• Moderate exercise without weight loss is often v effective
• Diet rich in vegetables and low in sugar
• Low salt diet is advisable bc it helps lower BP in salt-sensitive individuals and does no harm in others
how would you treat someone <55 years old for hypertension?
antihypertensive treatment with ACE inhibitor or a low-cost angiotensin-II receptor blocker (ARB) - Don’t combine the 2 to treat hypertension
o If ACE-inhibitor isn’t tolerated then offer low-cost ARB
how would you treat someone >55 years or of African/Caribbean origin?
offer calcium channel blocker
if CCB not suitable then offer thiazide like diuretic
why might a calcium channel blocker not be suitable?
bc of oedema, intolerance or evidence of heart failure/risk of heart failure
name thiazide like diuretics
chlortalidone (12.5–25.0 mg once daily) or indapamide
why are beta blockers no longer a preferred initial therapy for hypertension?
bc of risk of developing diabetes
which group of people are beta blockers considered as a treatment for?
considered in younger people, particularly
o People with intolerance to ACE inhibitors and ARBs
o Women of child-bearing potential
o People with increased sympathetic drive
if a second drug is needed with beta blockers, what should be given and why?
add a CCB not a thiazide-like diuretic to reduce risk of diabetes
when is step 2 treatment given?
when step 1 doesnt control blood pressure
what is step 2 treatment for hypertension?
- CCB in combination with either an ACE inhibitor or an ARB
- If CCB isn’t suitable then give thiazide-like diuretic
- For black people of African or Caribbean family origin, consider an ARB in preference to an ACE inhibitor, in combination with a CCB
what is step 3 treatment for hypertension?
give a 3-drug combination of ACE inhibitor, angiotensin II receptor blocker, CCB and thiazide-like diuretic
what is resistant hypertension
If BP remains at higher than 140/90 mmHg
what is step 4 treatment for hypertension?
Consider adding a fourth antihypertensive drug and/or seeking expert advice
