Treatment of Hypertension Flashcards
How is blood pressure regulated by the body?
Blood pressure is the pressure exerted by blood on blood vessels Short term regulation: Baroreceptors Sympathetic and parasympathetic outflow Long term: Hormonal control of total body sodium: -Control of blood volume via ECFV Degree of vasoconstriction MABP= CO x TPR MABP- mean arterial blood pressure Co- cardiac output TPR- total peripheral resistance
How hypertension defined by the NICE guidelines?
Hypertension is defined according to increased risk: 140/90 mm Hg NICE guidelines Stage 1 hypertension ≥ 140/90 Stage 2 hypertension ≥ 160/100 Severe hypertension ≥ 180/110
What is hypertension a risk factor for?
Hypertension is a risk factor for: Stroke, ischemic heart disease Left ventricular hypertrophy, heart failure Renal failure Retinopathy
What are the causes of secondary hypertension?
Secondary (identifiable cause, <10%):
Renal disease
Vascular- e.g. renal artery stenosis
Hormonal- e.g. Conn’s syndrome, Cushing’s syndrome (too much cortisol)
Monogenic genetic diseases e.g. Liddle’s
Primary or essential (unknown cause, >90%)
Genetic pre-disposition and environmental factors are proposed to cause essential hypertension through many mechanisms
What are the possible mechanisms and risk factors for essential hypertension?
Possible mechanisms and risk factors:
Increased sympathetic and risk factors
Increased renin-angiotensin-aldosterone system (RAAS)
Endothelial dysfunction
Defect in vascular smooth muscle contraction
Defects in renal Na handling, increased salt intake
Obesity/ insulin resistance
Age (increases with age)
Ethnicity e.g. more common in Afro-Caribbean groups
Family history
Why treat hypertension?
Risk reduction e.g. 5mmHg drop in diastolic BP for 5 years
Reduce strokes by 42%
Reduce vascular mortality by 21%
Goals of anti-hypertensive treatment:
Adequate blood pressure control- < 140/90 mmHg, alter relative risk
Prevention of target organ damage
Controlling other cardiovascular risk factors
Treatment pathways:
Non-pharmacological; life-style modifications
Pharmacological treatment
Surgical (if known cause e.g. Conn’s syndrome)
What lifestyle changes can reduce hypertension?
Quit smoking Weight control Eat less salt Regular exercise Reduce alcohol intake Behavioural therapies e.g. CBT (cognitive behavioural therapy)
How is hypertension treated pharmacologically?
Major Classes of Anti-hypertensive Drugs ACE inhibitors Angiotensin II receptor blockers Diuretics Drugs acting on Sympathetic Nervous System Vasodilators
What are the side effects of ACE inhibitors and AT1 receptor blockers?
Side effects: ACEi
Cough (common) due to decrease in bradykinin breakdown
Angioedema (rare but serious)
Side effects: both ACEi and ARBs:
Hyperkalaemia from the opposition of aldosterone
Decrease in vasoconstriction and aldosterone secretion to reduce blood pressure
What do diuretics do and how do they affect BP?
Increase in sodium water excretion
Reduce blood volume -> reduces CO -> reduce BP (BP= CO x TPR)
What are the sympathetic neural effects on CVS?
b1- increase HR and contractility -> increase CO-> increase BP a1- vasoconstriction-> TRP-> increase BP Beta blockers (b1 blockers e.g. atenolol)- reduction in CO and renin release
How do K channel openers vasodilate?
Arterioles normally have significant smooth muscle tone- scope for relaxation
Increased out K current
Hyperpolarisation
Reduced VGCC activity
Reduced [Ca]I
Less MLCK activity -> increased relaxation (vasodilatation)
How do voltage-dependent Ca2+ channel blockers vasodilate?
Arterioles normally have significant sooth muscle tone- scope for relaxation
Block VGCC activity in VSMCs
Reduced [Ca]I
Less MLCK activity-> increased relaxation (vasodilatation)
How do you decide which drugs to use?
Key issues to consider in selecting Drug Therapy: Essential vs. secondary hypertension Evidence of efficacy Side effects of drug Drug interactions Individual demographics CO-existing diseases Quality of life Economic considerations Complicated- so there are guidelines: NICE- National Institute for Health and Clinical Excellence
