Essential Hypertension Flashcards
What is hypertension?
Hypertension is defined by persistent elevation of BP in the systemic arterial circulation. It is a disease of ageing => due to age related stiffening (due to atherosclerosis) in large arteries.
Hypertension is the most important risk factor for premature death
What is essential hypertension?
Essential hypertension (aka primary hypertension) has no known cause.
Raised BP is a leading risk factor for which conditions?
Atrial fibrillation
Stroke
Myocardial infarction
End-stage kidney disease
Leading risk factor for death worldwide
What is considered to be a protective factor in women against hypertension?
Oestrogen - as women have lower BP than men until menopause.
Hypertension is most commonly seen in which ethnic group?
Black, African, African-Caribbean
What are the risk factors of hypertension?
- Weight
- Alcohol
- Recreational drugs
- Tobacco
- Exercise
- Stressors (work/personal)
- Family hx
- Pregnancy
- Adherence to anti-hypertensives
- Secondary causes e.g. renal artery stenosis, chronic kidney disease, primary hyperaldosteronism, acromegaly, thyroid disease, obstructive sleep apnoea etc
(see pg 1139 Kumar & Clarks for more)
What clinical examination are carried out in hypertension?
What are the aims of the clinical exam?
- Out of office BP level
- Asymptomatic organ damage : fundoscopy, palpations and auscultation
- Estimation of total cardiovascular risk
=> Look for signs of end organ damage i.e. retinal disease, heart failure, stroke and chronic kidney disease
=> Assess assoc. cardiovascular risk factor i.e. blood glucose, stigmata of hyperlipidaemia
=>Younger patients look for rarer secondary causes e.g. cushingoid features, acromegaly, renal masses
Which investigations are carried out for suspected BP?
To assess target organ disease:
- Urine reagent strip testing and ACR
- eGFR
- ECG
- CV risk i.e. lipids, HbA1c
- Secondary causes
What is the meaning of in office / out of office BP measurement?
In office BP : BP measured at by a healthcare professional in a GP surgery (primary care) or hospital out-patient department ; correct technique (seated position after 5mins of uninterrupted rest).
Out of office : Ambulatory (portable) measurement ; BP at home
What is the threshold BP values for hypertension in under 80 year olds (in office and home measurements)
and
over 80 year olds (in office and home measurements)?
Under 80 years : >140/90 (office) ; >135/85 (home)
Over 80 years : >160/90 (office) ; >150/85 (home)
What is the target BP values in the UK?
Under 80 years : <140/90mmHg
Over 80 years : <150/90mmHg
What is the correct way to measure blood pressure?
- Legs uncrossed, back supported and uninterrupted rest for 5 min
- Palpate pulse to ensure in sinus rhythm (in case of AF use auscultatory method).
- Record at least two readings at each sitting
What is the cause of isolated systolic hypertension?
What is the risk of subsequent widening pulse pressure (big difference between systolic and diastolic)?
- Age-Related arterial stiffening = systolic BP continues to rise in patients over 50 years whilst diastolic BP declines
- Aortic valve dysfunction can also result in isolated systolic hypertension (but usually found on auscultation or echo)
=> Widening pulse pressure leads to increased vascular damage.
What are the causes of a raised BP?
- Primary (essential) hypertension - 90% patients with no singular identifiable cause
- Polygenetics - each single gene only contributes a small amount to high BP levels but combined can attribute to 60% of high BP level.
- Environment - 40% effect on BP
DIET: High salt intake; low veggie & fruit intake; high saturated fat intake; high simple carbohydrates intake; excessive liquorice (inhibits enzyme that normally prevents cortisol from activating the mineralocorticoid receptor)
EXERCISE:
Lack of exercise increases risk of high BP ; cardio and strength training assoc. with low BP
Which drugs may raise BP?
- Alcohol
- Recreational drugs
- Oral contraceptive pill
- NSAID
- Corticosteroid
- Calcineurin inhibitors
- Vascular endothelial growth factor inhibitors
- Venlafaxine
What is the formula for BP?
BP = CO x SVR
CO = cardiac output SVR = systemic vascular resistance
What factors result in raised CO and SVR, thus raised BP?
Cardiac output:
Sympathetic nervous system activation (through renin); aldosterone; ADH => sodium/water retention
=> raised intravascular volume => raised preload (dependent on venous tone SNS via alpha 1 receptors)
=> raised Stroke volume (dependent on contractility SNS, catecholamines) => increased CO (SNS, catecholamines)
Systemic vascular resistance:
Direct innervation SNS via alpha 1 receptors
Circulating factors i.e. angiotensin II and catecholamines
Local factors i.e. angiotensin II, endothelin, Nitric oxide
What is resistant hypertension?
Uncontrolled BP despite 3 separate guideline recommended anti-hypertensives.
*Check adherence or causes of secondary hypertension
What are the most common causes of secondary hypertension?
Secondary hypertension = singular, identifiable cause which can be removed or reversed to normalise BP.
Common causes:
- Primary hyperaldosteronism (increased water/sodium retention)
- Obstructive sleep apnoea
- Obesity
*Last two causes due to sympathetic overdrive
What is the physiological response to circulating volumes in pregnancy?
How does pregnancy result in hypertension?
Physiological response to pregnancy: There is an increase in circulating volume => leading to significant vasodilation => low BP esp in 2nd trimester
However, sometimes there is a defect in placental formation or vascularity leading to hypertension or pre-eclampsia
What is the grading system and thresholds for hypertension?
Normal office BP: <130/80mmHg
High-normal office BP: 130-139 systolic ; 80-89 diastolic
Grade 1 hypertension:
Office BP: 140-149 systolic ; 90-99 diastolic
Daytime ambulatory/home BP: 135-149 systolic ; 85-94 diastolic
Grade 2 hypertension:
Office BP: 160-179 systolic ; 100-109 diastolic
Daytime ambulatory/home BP: 150-169 systolic ; 95-104 diastolic
Severe hypertension:
Office BP: >180/110mmHg
Daytime ambulatory/home BP: >170/105mmHg
Isolated systolic hypertension:
Office BP: >140 systolic ; <90 diastolic
Daytime ambulatory/home BP: >135 systolic ; <85 diastolic
Uncontrolled hypertension can lead to target organ damage.
The retina (retinopathy) is one example of hypertensive target organ damage. This is investigated using direct ophthalmoscope (fundpscopy) to see any hypertensive vascular changes.
What are the 3 grades of retinopathy?
*Images of fundoscopy on pg 1141 Kumar & Clark’s
- Mild: generalised arteriolar narrowing focal arteriolar narrowing, arteriovenous nicking => modest assoc. with cardiovascular & cerebral events
- Moderate: Haemorrhage (blot, dot or flame shaped haemorrhage), micro-aneurysm, cotton-wool spot, hard exudates => strong assoc. with cardiovascular & cerebral events
- Severe: signs of moderate retinopathy mentioned above + papilloedema (swelling of optic head) => strong assoc. with cardiovascular events, stroke and death
Uncontrolled hypertension can lead to target organ damage.
The heart is another example of hypertensive target organ damage.
What change is seen in the heart as a result of hypertension?
Which modalities help detect this change?
Hypertension leads to increase workload on the heart.
=> Initially, this leads to left ventricular remodelling (compensation) to reduce wall stress.
=> But eventually, this leads to a pathogenic left ventricular hypertrophy (LVH).
LVH = usually asymptomatic but sometimes ECG may detect changes (T-wave abnormalities).
- ECG recommended in all hypertensive patients (cheap & easy to use). ECG have low sensitivity but high specificity.
- Transthoracic echocardiography and cardiac MRI more sensitive and specific than ECG (more expensive, not easy access/training)
Uncontrolled hypertension can lead to target organ damage.
Kidney disease is both a cause and consequence of hypertension.
Early hypertensive kidney damage detectable through an increase is microalbuminuria on urine test strips or as an increased lab albumin:creatinine ratio.
Most anti-hypertensive drugs = nephrotoxic so GFR reduction by 10% okay in anti-hypertensive therapy. Follow up to ensure this doesn’t result in renal decline
Information card.
