Hypertension Flashcards
Hypertension definition
The blood pressure above which the benefits of treatment outweigh the risks in terms of morbidity and mortality
usually: >140/>90
Causes of hypertension
RENAL DISEASE:
Chronic renal disease, Renal artery stenosis, fibromuscular dysplasia, polycystic kidneys
DRUG INDUCED:
NSAIDs, OCP, corticosteroids, cocaine
PREGNANCY:
pre-eclampsia
ENDOCRINE:
Conn’s syndrome, Cushing’s disease, hypo/hyperthyroidism, acromegaly
VASCULAR:
coarctation of the aorta
SLEEP APNOEA
- 90 - 95% of cases = primary hypertension
- no cause can be found
Factors increasing the risk of morbidity from hypertension
Smoking, Diabetes mellitus, Renal disease, Male, Hyperlipidaemia, Previous MI or stroke, Left ventricular hypertrophy
Possible hereditary causes of hypertension
Hereditary defect of smooth muscle lining arterioles = ^reactivity of resistance vessels = ^TPR
Sodium homeostatic effect - kidneys are unable to excrete appropriate amounts of sodium for a given BP. sodium and therefore fluid are retained.
hypertension risk factors
Age, Environment (mental and physical stress), Weight, Birth weight, Diet, Alcohol intake, Sodium intake, Race
End-organ damage
Damage in major organs fed by the circulatory system due to hypertension
e.g. brain, eye, blood vessels, kidney, heart
Outcomes of untreated hypertension
end-organ damage
BRAIN: stroke
EYE: retinopathy
BLOOD VESSELS: peripheral vascular disease
KIDNEY: renal disease
HEART: left ventricular hypertrophy, congestive heart failure, coronary heart disease, myocardial infarction
EWPHE and SHEP
Studies that found that treating both diastolic and systolic hypertension in the elderly significantly reduces stroke and MI
The Stepped Approach to treatment of hypertension
Uses low doses of several drugs,
A new medication is added to current therapy until target BP is achieved.
This minimises adverse effects and maximises patient compliance
BHS target Blood Pressure
<80yrs, ABPM = <130/85 mmHg
> 80yrs, ABPM = <145/85 mmHg
Stage 1 Hypertension
<80yrs,
ABPM >135/85
One/ more of the following:
- Target organ damage,
- CV disease,
- Renal disease,
- Diabetes,
- 10yr CV risk equivalent to 20% or greater.
Stage 2 Hypertension
ABPM >150/90 mmHg
Criteria for anti-hypertensive drug therapy
Stage 1 or 2 hypertension
Step 1 Treatment
<55 (not women of child-bearing age):
ACE inhibitor OR Angiotensin II receptor blocker (ARB)
> 55/ Afro-Caribbean:
Calcium-channel blocker
Step 2 Treatment
Add thiazide-like diuretic
Step 3 Treatment
ACEI or ARB
+ calcium channel blocker
+ thiazise-like diuretic
Step 4 (resistant hypertension) treatment
CONSIDER:
- further diuretic therapy
- higher dose thiazide-like diuretic treatment
- beta-blocker
*Monitoring drug treatment
Calcium channel antagonists/blockers (CCBs)
mechanism
VASODILATORS: e.g. amlodipine, felodipine
Block L-type calcium channels in smooth muscle around large and small arteries (relaxes muscle)
= reduced TPR
RATE LIMITING: e.g. veramapil, diltiazem
Block L-type calcium channels in myocardium (reduces contractility) and the SA and AV nodes (reduces conduction velocity and therefore HR)
= reduced CO
Strengths of calcium channel antagonists
Compliance is high,
Can be used in women of child bearing age,
Rarely cause postural hypotension,
Most benefit elderly w/ systolic hypertension.
Contraindications of calcium channel antagonists
RATE-LIMITING:
Acute MI
Heart failure
Bradycardia
VASODILATING:
Acute MI
IHD + Angina
Thiazide-type diuretics
mechanism
Increases urinary excretion of sodium
Strengths of Thiazide-type diuretics
Can be used in combination with any other anti-hypertensive agents,
Proven benefit in stroke and MI reduction,
Adverse drug reactions not common
Weaknesses of Thiazide-type diuretics
Full antihypertensive effect may take weeks,
Adverse drug reactions include gout and impotence
Angiotensin Converting Enzyme (ACE) Inhibitors
mechanism
Competitively inhibit angiotensin converting enzyme
↓Vasoconstriction = ↓BP =↓Cardiac workload
↓ADH + Aldosterone release = ↑diuresis
Contraindications of ACEIs
Renal failure
Renal artery stenosis
Hyperkalaemia
*(ACEIs = ↑K+)
Treatment of hypertension before and during pregnancy
PRE-PREGNANCY:
methyldopa, CCBs, beta-blockers
DURING PREGNANCY:
add thiazide-like diuretic and/or amlodipine (CCB)
**ACEI and ARB = teratogenic
Angiotensin II antagonists/
Angiotensin receptor blockers (ARBs)
Block the actions of angiotensin II,
Advantage over ACEIs = no cough.
Methyldopa
Acts on CNS alpha adrenoceptors,
decreases central sympathetic outflow
Strengths of methyldopa
Mainly used in the treatment of hypertension in pregnancy
Methyldopa ADRs
Sedation and drowsiness,
Dry mouth and nasal congestion,
Orthostatic (postural) hypotension.
CCB ADRs
Ankle oedema
Flushing
Headache
Vasodilating only:
Reflex tachycardia
ACEI ADRs
Cough
First dose hypotension
Renal impairment
