L8: Essential Hypertension Flashcards
How do you define hypertension?
An “artificial” concept i.e. a cut-off value applied to a risk continuum, the value can change and can be applied differently in different populations.
Definition of hypertension
- Sustained elevation of systolic and diastolic blood pressure (> 140/90 mmHg)
Causes of hypertension:
-Primary (idiopathic/essential): No identifiable cause
Secondary Hypertension, secondary to (can identify cause):
- renal disease (salt/H2O imbalance)
- adrenal tumours (aldosterone)
- aortic coarctation (narrowing of aorta)
- Steroids, Rx
Hypertension-related end organ disease
Infarction: thrombotic = ischaemic damage within the cerebral vessels
Examples of organ damage by hypertension
What has happened here?
Hypertensive Heart Disease
= Increased load causes concentric left ventricular hypertrophy
(increase in cell and muscle size in the heart) –> causes weakening of the heart and reduced contractility = Hypertensive Heart Disease ->can lead to heart failure
What has happened here?
How is BP regulated?
why must we understand factors that contribute to BP?
- To understand how BP drugs work
How is high BP arised from?
Essential Hypertension Prevalance + Cause
- unknown cause; ~ 90% of cases)
- Prevalence in urban-based populations increased by 20%
Risk Factors of Essential Hypertension
Depends on:
- BP cut off value (Usual value >140 and/or > 90 mmHg)
- Age (increases with age)
- Ethnic group (e.g. more common in African Americans)
Some potentially important factors for essential (primary) hypertension include:
Cause(s) of essential hypertension is still not known but genetic and environmental factors are believed to be important.
- Increased activity of hormonal system such as:
-Sympathetic nervous system (SNS)
-Renin-angiotensin-aldosterone system (RAA)
-Obesity/ Insulin resistance – can lead to inflammatory changes - Endothelial dysfunction – big impact on atherosclerosis development
-Capillary rarefaction – decrease in density of vessels, can have impact on vascular resistance
-Defect in vascular smooth muscle contraction/relaxation (vasodilator/vasoconstrictor agents)
-Defects in renal sodium handling (altered kidney function)
Why is treatment of hypertension important?
Reduction in blood pressure level reduces relative risk of consequences
A 5-mmHg reduction in diastolic BP for 5 years will:
- Reduce strokes by 42%
- Reduce MI by 16%
- Reduce vascular mortality by 21%
= significant reductions thus vital to reduce BP levels
What are the goals of anti-hypertensive therapy
- Adequate Blood Pressure Control (< 140/90 mmHg) (sometimes difficult to do this)
- Prevention of Target Organ Damage
- Controlling other cardiovascular risk factors
- No detrimental metabolic side-effects
Classification of Hypertension
This can impact care pathway (whether to use lifestyle measures or when to use antihypertensive drugs)
Care pathways briefly by NHS
Types of Hypertension treatment + Management
- Nonpharmacological (Life-style modification)
- Pharmacological treatment
- Surgical e.g. for Conn’s syndrome (adrenal gland increases in aldosterone)
Targets for lifestyle measures
In red shows reduction in BP
For stage 1 patients + 2,3 patients (alongside their pharmacological treatments)
Pharmacological treatment: major classes of antihypertensive drugs: (give examples of drugs)
- Renin inhibitors (not/rarely used)
- ACE inhibitors (first-line)
- Angiotensin II receptor blockers
- Calcium channel antagonists
- Diuretics (Na handling)(loop diuretics, thiazides, potassium sparing)
- Adrenergic (a1 /b1) receptor antagonists
- Drugs acting on sympathetic system
- Centrally acting a2 receptor agonists (rarely used for essential e.g. pregnancy)
- Other vasodilators (used for severe or resistant hypertension when other primary, first-line drugs are not effective.)
Key issues to consider in selecting drug therapy
- Essential vs secondary hypertension
- Evidence of efficacy
- Side effects of drug
- Drug interactions
- Individual demographics
- Coexisting diseases
- Quality of life
- Economic considerations
NICE guidelines regarding initiating antihypertensive treatment
If no sign of efficacy = step 2
still resistant = step 3
still resistant = step 4
Under 55: ace inhibtors/angiotensin receptor blocker
Ca channel blocker added if ACE inhibitor wasn’t effective
Drugs are usually added to the already existing prescription until one works
Over 55/ Caribbean/ African patient: Ca channel blocker prescribed first because limited activity of drugs against the RAAS pathway
Combined with diuretic if it doesn’t work
RAAS system
Aldosterone section = increase BP + inhibit H20 loss
Give examples of drugs that can be used to treat hypertension via targeting the renin-angiotensin system?
- Renin inhibitors (rarely used) e.g. Aliskiren (risk of stroke)
- ACE inhibitors (e.g. enalapril, ramipril)
Some side effects & contraindications:
- Hyperkaelemia
- Dry cough: decrease quality of life - ACE in lung + it breaks down bradykinin (thus high levels when ACE inhibitor present = irritation -> cough; patients offered ATII antagonists instead)
- Angioedema
- Contraindicated in pregnancy - Angiotensin 2 receptor (type 1) antagonists e.g. losartan, valsartan
