Hypertension (HTN)
Introduction
- No definition (continuous variable)
- Trials show benefit of treating sustained ABPs > 140 / 90 mmHg
Essential HTN
- 95 % of all cases
2o HTN
Renal:
- Renal artery stenosis
- parenchymal disease (glomerulonephritis, pyelonephritis, polycystic kidney disease (PCKD), SLE, hydronephrosis)
Endocrine:
- excess CAs (phaeochromocytoma)
- excess mineralocorticoids (Conn’s, adrenal hyperplasia)
- excess glucocorticoids (Cushing’s, iatrogenic steroid treatment)
- excess hGH (acromegaly)
Drugs:
- Steroids
- NSAIDs
- OCP
Other:
- coarctation
- pre-eclampsia
- polycythaemia
- acute porphyria
- (Cushing’s reflex - increased BP as autoregulation of cerebral pressure in cases of raised ICP is lost)
Consequences of HTN
End-organ damage:
- Cerebrovascular: CVA (haemorrhagic or ischaemic)
- Cardiovascular: CAD(MI), LVH (CCF), aortic dilatation (AR, dissection)
- Renovascular: chronic renal failure (CRF)
- Retinopathy: grade 1 - 4
Malignant HTN
- Definition: severe uncontrolled HTN (with symptoms or acute end-organ damage)
- Symptoms: headache, visual disturbance, confusion (hypertensive encephalopathy)
- Acute end-organ damage: stroke (CVA), acute renal failure (ARF), aortic dissection, etc.
Malignant phase HTN
- Triad of: HTN, grade 4 retinopathy, progressive CRF
- Mortality: >50% @ 1year if untreated
Clinical Features of HTN
Target organ damage:
- LVH (displaced apex, stigmata of CCF)
- Fundal changes (hypertensive retinopathy, grade 1–4)
- Urinalysis: protein (renal failure), glucose (associated DM)
Aetiology:
- Endocrine: Cushingoid, acromegaly
- Coarctation: radiofemoral delay, ABP in both arms, ABP in arms / legs
- Renal: renal bruit (RAS), palpable kidneys (PCKD)
Management of Malignant HTN
- Admit
- Gradually decrease ABP (risk of CVA if too rapid)
- PO drugs where possible
- IV treatment if: hypertensive seizures / severe LVF / aortic dissection
> Sodium nitroprusside (potent vasodilator)
> Labetolol (beta-blocker with alpha activity
Investigations
Confirm ABP:
- Method: office measurement (>2 records @ each of several visits) or 24-hr ambulatory ABP
- ABP: optimal (<120/80), N (<130/85), high N (<140/90)
>Grade 1 (mild HTN) >140/90
>Grade 2 (moderate HTN) >160/100
>Grade 3 (severe HTN) >180/110
Routine Ix:
- Urine: protein, blood, glucose
- Bloods: U+Es, fasting lipids (total cholesterol, HDL cholesterol, TAGs), fasting glucose
- ECG: LVH
Further Ix:
- Bloods: TFTs, Ca2+
- CXR : cardiothoracic ration increased (big heart due to failure), coarctation signs (rib notching, etc)
Special Ix:
>Phaeochromocytoma: 24-hr urinary VMA (vanillylmandelic acid - metabolites of catecholamines) and catecholamines.
>Cushing’s: urinary free cortisol, low-dose dexamethasone suppression test.
>Conn’s: urinary K+, blood aldosterone.
>RAS: renal USS, renal DSA (digital subtraction angiography)
Management
NICE guidelines 2006
Threshold for intervention:
- ABP sustained >160/100* = treat all patients
- ABP sustained >140/90* = treat if end-organ damage, DM or 10 yrs CVS risk > 20 %
- Most patients = target ABP <140/85*
- DM / established CVS disease = target ABP <130/80*
* figures are 10/5 lower if using home or ambulatory measurements
Lifestyle:
- Diet: reduce sodium intake <100 mmol/day, reduce EtOH <21(14)U/wk, 5-7 portions/day fresh fruit & veg, less total or saturated fat, more fish
- Exercise: >30 mins aerobic exercise 3x per week
- Weight: reduce BMI <25
- Smoking: stop!
Antihypertensives (A-B-C-D algorithm - from NICE guidelines 2006):
These new guidelines were published as a result of the ASCOT study. This found a calcium channel blocker (amlodipine) +/- an ACE-Inhibitor (perindopril) significantly reduced risk of death (by any cause), cardiovascular death, stroke, total coronary events and new-onset diabetes, compared with a beta-blocker (atenolol) +/- a diuretic (bendroflumethiazide) combination.
For patients with newly diagnosed with hypertension:
- Step 1: [A] if <55yrs and not black (i.e. "high-renin HTN"), or [C or D] if >55yrs or black (i.e. "low-renin HTN")
- Step 2: [A + C] or [A or D]
- Step 3: [A] + C + D]
- Step 4: Consider 4th line drug, e.g. alpha-blocker, further diuretic therapy, beta-blocker & consider seeking specialist advice.
NB: Althoughbeta-blockers are now no longer preferred as routine initial therapy, still consider their use in younger patients, particularly women of childbearing age, those with intolerance/contraindication to ACE-I, or patients with an increased sympathetic drive.
Where:
A = ACE-I or ATII-blocker
B = beta-blocker
C = Ca2+ channel antagonist
D = thiazide diuretic
Addressing other risk factors
Primary prevention
- Aspirin (75 mg OD): if >50yrs with ABP <150/90, and any of: target organ damage / DM / 10yr CVS risk >20%
- Statin: if <80yrs with total cholesterol >3.5 mM and 10 yrs CVS risk > 20 %
Secondary prevention
- Aspirin: all patients
- Statin: if <80yrs with cholesterol >3.5 mM
Follow-up
- <6 monthly: weight, ABP urine check for proteinuria)
- Lifestyle advice
- Reinforce need for concordance with treatments
