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Hypertension

From Mediwikis

Persistently elevated blood pressure. Sustained hypertension is a major risk factor for heart disease, stroke, aortic aneurysm and chronic kidney disease.

Definitions

  • Stage 1: Clinic blood pressure between 140/90 and 160/100. Home monitoring above 135/85.
  • Stage 2: Clinic blood pressure between 160/100 and 180/. Home monitoring above 150/95
  • Severe hypertension: Clinic blood pressure above 180/110 (either systolic or diastolic criteria)

Causes

  • Essential - >90% of cases; No known cause
  • Secondary hypertension
    • Renal artery stenosis or co-arctation of the aorta
    • Hormonal abnormalities eg: Hyperaldosteronism, phaeochromocytoma, etc
    • Drugs
    • Pre-eclampsia

Measuring Blood Pressure

For a guide to measuring blood pressure in the clinic, see Blood Pressure and Pulses Measurement.

  • Must be measured with the patient relaxed, sat at rest, with the sphymomanometer at the same level as the heart.
  • Measure both arms- use higher reading if > 20 mmHg difference
  • Hypertension is only confirmed after home monitoring (with the exception of severe hypertension as above)

Investigations

Investigate any features suggestive of organ failure (cardiac, renal, retinopathy)

Management[1]

Lifestyle

  • Reduction in alcohol consumption if excessive drinking
  • Reduce consumption of caffeine
  • Keep dietary sodium low
  • Smoking cessation assistance

Pharmacological Therapies

A = ACE inhibitor (ARBs can be used if ACEi not tolerated); B = Beta blocker; C = Calcium channel blocker; D = diuretic

  1. A or C
    1. For patients aged <55, first-line treatment for essential hypertension is an ACE inhibitor.
    2. For patients >55 or black people of African/Caribbean origin, first line is Calcium channel Blockers (CCBs)
  2. A + C
  3. A + C + D
  4. A + C + D + Beta blocker or Alpha blocker

ACE inhibitors

  • ↓Angiotensin II (a powerful vasoconstrictor) → lower arteriolar resistance and increased venous capacity
  • ↓Aldosterone → less reabsorption of water and NaCl from renal tubule → ↓BP
  • ↑Bradykinin (vasodilation ↓TRP)

Angiotensin II antagonists

  • Inhibition of angiontensin II and therefore causing vasodilation and ↓aldosterone

Calcium Channel Blockers

Rate-limiting or non rate-limiting; good in hypertension and heart failure

Act on many different areas → vasodilation, ↓cardiac contractility, (some ↓heart rate)

  • Examples of non rate-limiting CCBs - amlodipine (usually first line; commonly causes ankle swelling), Nifedipine
  • Rate-limitiing CCBs include: Diltiazem and Verapamil- cardioselective

α-adrenoreceptor antagonists

  • Causes vasodilation ↓TPR and venous pressure
  • ↓LDL, VLDL, TGA ↑HDL therefore reduces the chance of coronary artery

Hydraizine

  • Interacts with inositol triphosphate in vascular smooth muscle ↓TPR and BP

Minoxidil

  • Activates smooth muscle ATP sensitive K+ channels causing hyperpolarisation and hence vasodilation

sodium nitroprusside

  • Decomposes in to NO ↑ cGMP- vasodilation

References

  1. https://www.nice.org.uk/guidance/cg127