Hypertension (HTN)

• Background    

  

  Causes

  Primary causes:
  • Essential HTN (i.e. idiopathic). Commonest cause.
  • Non-pathologically raised during pain or anxiety (including white coat HTN). However, this may suggest underlying problem so consider following up.
  Kidney diseases (80% of secondary HTN):
  • Chronic kidney disease.
  • Renal artery stenosis: due to atherosclerosis or fibromuscular dysplasia. Latter most commonly occurs in young women, but even then essential HTN is still commoner.
  Endocrine:
  • Conn's
  • Cushing's
  • Pheochromocytoma
  • Acromegaly
  • Hyperparathyroidism
  Other:
  • Obstructive sleep apnoea
  • Pregnancy or pre-eclampsia.
  • Coarctation of the aorta.
  Medication: CE-LESS ('see less'):
  • Cyclosporin
  • Estrogen (OCP)
  • Liquorice
  • EPO
  • Steroids
  • Sympathomimetics: α-agonists, dopamine agonists, cocaine, amphetamines, and nasal decongestants such as ephedrine.

• Signs and symptoms

  Symptoms of HTN itself are rare, and occur only in severe disease. They include headache and blurred vision.
  Symptoms suggesting secondary cause:
  • Postural ↓BP
  • Palpitations
  • Sweating
  Only notable sign is hypertensive retinopathy, though this is rare. Graded 1-4:
  1. Silver wiring and tortuosity.
  2. AV nipping.
  3. Cotton wool spots and flame haemorrhages.
  4. Papilloedema.

• Investigations

  Measuring BP

  Clinic BP readings:
  • Can be automated or manual. Always use manual if patient has arrhythmia.
  • Should be done seated and in both arms.
  • Repeat measurement if ↑BP (to confirm) or if there is >15 mmHg difference between arms.
  • Arm with highest reading counts, but within that arm the lowest measurement counts.
  • Confirm ↑BP with ABPM.
  Ambulatory BP monitoring (ABPM):
  • ≥2 measures per hour during waking hours.
  • Ultimately uses average of ≥14 measures.
  • Don't use in AF.
  Home BP monitoring (HBPM) if ABPM declined:
  • 2 consecutive measures 1 minute apart each time, once AM and once PM.
  • Measurements over 4-7 days, with final result discarding first day and averaging the rest.
  • Don't use in AF.

  Other investigations

  Check for organ effects including:
  • Eyes
  • Heart: check for LVF on ECG. CXR and echo are optional.
  • Kidney: urine dip (blood and proteinuria), U+E, protein:creatinine ratio.
  Calculate 10 year CVD risk by checking glucose and lipids, and using clinic BP measurement.
  If age <40, investigate underlying causes, remembering that essential HTN is still the commonest cause even in this group:
  • Renal artery stenosis: ↑renin, kidney duplex USS, MR angiography (if you suspect fibromuscular dysplasia).
  • CKD: urinalysis, ↑renin, U&E, USS (might show small kidneys).
  • Endocrine: metadrenalines, cortisol, renin/aldosterone, Ca2+.

• Management

  Stages of HTN

  • Treatment thresholds are expressed as systolic/diastolic BP, but systolic BP is the determinant of whether treatment is indicated (i.e. even if the diastolic BP is below the threshold). This reflects the fact that systolic BP is more strongly associated with heart disease than diastolic BP.
  • At every stage, offer lifestyle advice: Na+ restriction, and reduce weight, smoking, and alcohol.

  Stage 1

  Clinic BP ≥140/90 and A/HBPM ≥135/85. Medication indications:
  • Age <80: >10% 10 yr risk of CVD, established CVD, kidney disease, diabetes, or end organ damage. If age <60, 'consider' even without any of these additional risk factors.
  • Age >80: BP >150/90.
  In contrast to NICE, US and European guidelines recommend offering medication if high risk from BP ≥130/80, and medication for all at ≥140/90.

  Stage 2

  Clinic BP ≥160/100 and A/HBPM ≥150/95:
  • Medication for all.

  Severe

  Clinic BP ≥180 systolic or ≥120 diastolic:
  • Start medication immediately but still do ABPM to confirm.
  • Same day specialist care if hypertensive crisis.

  Stepwise medical treatment

  Step 1. ACE inhibitor (ACEi) or angiotensin receptor blocker (ARB) or calcium channel blocker (CCB):
  • ACEi/ARB if <55 years old and non-black, or diabetic (any age any race, ARB if black). Switch to ARB if ACEi causes cough.
  • Calcium channel blocker (CCB) if >55 years old and non-diabetic, or black any age non-diabetic. 2nd line if not tolerated (oedema) or contraindicated (CHF): thiazide-like diuretic.
  • Common drug choices: lisinopril (ACEi), losartan (ARB), amlodipine (CCB).
  Step 2. ACEi/ARB + CCB:
  • ARB not ACEi if black.
  • Thiazide-like diuretic is an alternative 2nd agent
  Step 3. ACEi/ARB + CCB + thiazide-like diuretic:
  • Thiazide-like (chlorthalidone or indapamide) is preferred to thiazide (bendroflumethiazide or hydrochlorothiazide), though can stay on the latter if already controlled on this.
  Step 4. Diagnose resistant hypertension, consider spironolactone:
  • Confirm BP using A/HBPM, check for postural hypotension, check adherence.
  • Spironolactone if K+ ≤4.5, α-blocker or β-blocker if K+ >4.5.
  BP targets:
  • <80 years old: 140/90 (or 135/85 on ABPM).
  • ≥80 years old: 150/90 (or 145/85 on ABPM).
  • In contrast to NICE, US and European guidelines recommend 130/80 for almost all (except 140/80 if ≥65 years old in European guidelines).

  Other considerations

  • Monitor BP annually in clinic. Use A/HBPM if white-coat HTN. Use standing BP if orthostatic.
  • HTN during pregnancy: labetalol, methyldopa, nifedipine.

• Complications and prognosis

  • All major cardiovascular diseases: MI, stroke, PVD, HF, AF.
  • Hypertensive crisis.
  • Aortic aneurysm ± dissection.
  • Hypertensive nephropathy (aka nephrosclerosis).

• Hypertensive crisis

  Definiton

  • Sudden ↑BP and end organ damage.
  • Aka accelerated hypertension or malignant hypertension when retinal hemorrhage or papilloedema is present.

  End organ effects

  • Acute kidney injury.
  • Encephalopathy: headache, visual impairment, seizures.
  • Microangiopathic haemolytic anaemia.
  • HF and pulmonary oedema.

  Signs

  • Papilloedema
  • Retinal haemorrhage.

  Management

  • Labetalol IV or nitroprusside IV.
  • If there is no end organ damage, ↑↑BP is not a hypertensive crisis and does not require rapid control. However, adjustment (or introduction) of anti-hypertensives may be needed if persistent.