Treatment of hypertension

Question 1

Why is hypertension set at 140/90?

Answer 1

Data shows that at a mean diastolic of 91, the relative risk of stroke and coronary heart disease becomes 1.00, as opposed to 0.5 at a mean diastolic of 84

Question 2

What is essential (primary) hypertension?

Answer 2

Hypertension with an unknown medical cause

Question 3

What is secondary hypertension?

Answer 3

Hypertension with an identifiable medical cause e.g hormonal abnormalities, Cushing’s syndrome, genetic conditions, vascular causes, drugs (contraceptive pill), pregnancy

Question 4

What can essential hypertension be caused by?

Answer 4

• Genetic pre-disposition and environmental factors are proposed to cause essential hypertension through many mechanisms:
  
  • Increased sympathetic nervous system activity
  • Increased RAAS
  • Obesity/insulin resistance
  • Endothelial dysfunction
  • Defect in vascular smooth muscle contraction
  • Defects in renal-Na handling, increased salt intake
  • Age
  • Ethnicity

Question 5

How can essential hypertension be treated?

Answer 5

• Non-pharmacological (lifestyle changes)
  
  • Quit smoking
  • Weight control
  • Eat less salt
  • Regular exercise
  • Reduce alcohol intake
  • Behavioural therapies
• Pharmacological treatments

Question 6

How can ACE inhibitors and Angiotensin II receptor blockers treat hypertension?

Answer 6

• ACEi (ACE inhibitors) prevent the production of AngII
• ARB - competitive agonists at AT1 receptors, preventing the binding of AngII, therefore leading to less aldosterone production, leading to lower blood volume and cardiac output, and also prevent vasoconstriction.

Question 7

What are the side effects of ACEi?

Answer 7

• Angiotensin- converting enzyme also breaks down bradykinin (a substance associated with inflammation that stimulates sensory nerves)
• ACEi decreases bradykinin breakdown
• High levels of bradykinin can cause dry cough- non-compliance issue as patients may then stop taking the medication
• Due to raised bradykinin levels stimulating sensory nerves
• Can cause angioedema (swelling under skin) often around lips → can prevent bleeding
• If patient is non-compliant, they may be prescribed another hypertensive drug

Question 8

How do Ca channel blockers treat hypertension?

Answer 8

• Voltage-dependent Ca2+ channel blockers e.g. dihydropyridines (amlodipine) target VGCCs in vascular smooth muscle cells = Vascular selective - relates to the tissue selectivity of drugs.
• Reduce Ca, meaning there are fewer calcium- calmodulin complexes, therefore MLCK is not being activated, so myosin and actin interactions are being prevented, preventing the vascular smooth muscular contraction, leading to vasodilation of blood vessels

Question 9

How do diuretics treat hypertension?

Answer 9

• Increase Na and H2O excretion from kidneys
• Doing this reduces blood volume, reducing CO, reducing blood pressure
• They also produce vasodilation, decreasing TPR

Question 10

How do drugs decrease sympathetic nervous system activity to treat hypertension?

Answer 10

• CNS: alpha 2 adrenoceptor agonists- prevent reuptake of neurotransmitter in synaptic cleft e.g. clonidine
• Adrenoceptor blockers - alpha 1 blockers, causes relaxation of vascular smooth muscle e.g. prazosin and beta 1 blockers - reduces CO and renin release e.g. atenolol, bisoprolol

Question 11

What must be considered when deciding what medication to use?

Answer 11

• Essential vs Secondary hypertension
• Evidence of efficacy
• Side effects of drug
• Drug interactions
• Individual demographics
• Co-existing diseases
• Quality of life
• Economic considerations

Question 12

What are the four steps for treating hypertension when you’re not treating hypertension for those age <55 and not of black African or African-Caribbean family origin according to NICE guidelines?

Answer 12

Step 1: ACEi or ARB
Step 2 : ACEi or ARB + CCB or thiazide-like diuretic
Step 3 : ACEi or ARB + CCB + thiazide-like diuretic
Step 4 : Confirm resistant hypertension - confirm elevated BP with ABPM or HBPM, consider expert advice or add low-dose spironolactone if blood potassium level is < or = 4.5 mmol/l or an alpha or beta blocker is blood potassium level is >4.5mmol/l

Question 13

What are the four steps of treating hypertension if aged 55 or over, or of black African or African- Caribbean family origin (any age)?

Answer 13

Step 1 - CCb
Step 2 - CCB + ACEi/ ARB or thiazide-like diuretic
Step 3 - ACEi or ARB + CCB + thiazide-like diuretic
Step 4 : Confirm resistant hypertension - confirm elevated BP with ABPM or HBPM, consider expert advice or add low-dose spironolactone if blood potassium level is < or = 4.5 mmol/l or an alpha or beta blocker if blood potassium level is >4.5mmol/l