Essential Hypertension

1. Definition & Epidemiology

Essential (Primary) Hypertension = persistent elevation of blood pressure without an identifiable secondary cause.

  • Accounts for ~90–95% of all hypertension cases.
  • Defined (UK / Europe – European Society of Cardiology / European Society of Hypertension 2023):
    • Clinic BP ≥140/90 mmHg
    • Home BP ≥135/85 mmHg
    • ABPM 24-h mean ≥130/80 mmHg
  • US definition (American College of Cardiology / American Heart Association):
    • ≥130/80 mmHg

2. Pathophysiology 

Essential hypertension is multifactorial – interaction of genetic predisposition + environmental factors.

A. Core Haemodynamic Equation—>BP=CO×SVR

Early disease → ↑ Cardiac output
Established disease → ↑ Systemic vascular resistance (arteriolar remodeling)

 

B. Mechanisms Involved

1️⃣ Genetic Factors

  • Polygenic inheritance
  • RAAS polymorphisms
  • Sodium transporter abnormalities

2️⃣ Renin–Angiotensin–Aldosterone System (RAAS)

4

  • Renin → Angiotensin I → Angiotensin II
  • Ang II causes:
    • Vasoconstriction
    • Aldosterone release
    • Sodium retention
    • Vascular remodeling

Some patients have low-renin hypertension (common in elderly, Black ethnicity).

 

3️⃣ Sympathetic Overactivity

  • Increased heart rate
  • Increased peripheral resistance
  • Linked to obesity, stress

4️⃣ Endothelial Dysfunction

  • ↓ Nitric oxide
  • ↑ Endothelin
  • Increased vascular stiffness

5️⃣ Sodium Sensitivity

  • Impaired natriuresis
  • Shift in pressure-natriuresis curve

📌 Seen commonly in:

  • Elderly
  • Afro-Caribbean populations
  • CKD

6️⃣ Vascular Remodeling

  • Media hypertrophy
  • Narrowed lumen
  • Increased SVR
  • Hyaline arteriolosclerosis

3. Risk Factors

Non-modifiable

  • Age
  • Family history
  • Ethnicity
  • Male sex (earlier onset)

Modifiable

  • Obesity
  • High salt intake
  • Alcohol
  • Sedentary lifestyle
  • Smoking
  • Stress
  • Insulin resistance

 

4. Clinical Features

Usually asymptomatic.

Symptoms (if severe):

  • Headache
  • Dizziness
  • Blurred vision
  • Epistaxis

Signs:

  • Elevated BP
  • Retinopathy
  • LVH
  • S4 gallop

5. Diagnosis (NICE Approach)

Step 1: Clinic BP

≥140/90 → confirm with ABPM or HBPM

Step 2: ABPM Criteria

  • Daytime average ≥135/85

6. Investigations 

A. Baseline Tests

  • U&E (CKD)
  • FBC (anaemia, polycythaemia)
  • HbA1c
  • Lipid profile
  • Urine ACR
  • ECG (LVH)

B. Optional

  • Echocardiography
  • Fundoscopy

 

7. Target Organ Damage

1️⃣ Heart

  • LVH
  • HFpEF
  • IHD

2️⃣ Brain

  • Stroke
  • TIA
  • Vascular dementia

3️⃣ Kidney

  • Hypertensive nephropathy
  • Proteinuria

4️⃣ Eye

  • AV nicking
  • Cotton wool spots
  • Flame hemorrhages
  • Papilloedema (malignant HTN)

 

8. Classification of Hypertension

Stage

Clinic BP

Stage 1

140–159 / 90–99

Stage 2

≥160 / ≥100

Severe

≥180 / ≥120

 

9. Management – NICE Stepwise 

Lifestyle (for all)—Lifestyle measures may reduce SBP by up to 20 mmHg cumulatively.

Intervention

Target / Recommendation

Approx SBP Reduction

Mechanism

Weight Reduction

BMI 18.5–24.9 kg/m² 

1 kg weight loss ≈ 1 mmHg ↓ SBP

~5–20 mmHg (dose-dependent)

↓ Sympathetic tone 

↓ RAAS activation 

↓ Insulin resistance

Salt Restriction

<6 g salt/day (~2.4 g sodium)

↓ 4–6 mmHg

Improved natriuresis 

↓ Plasma volume 

↓ Vascular stiffness

DASH Diet

High fruit & veg 

Whole grains 

Low saturated fat 

High K⁺, Ca²⁺, Mg²⁺ 

Low sodium

↓ 8–14 mmHg

↑ Potassium → vasodilation 

Improved endothelial function 

↓ Oxidative stress

Physical Activity

≥150 min/week moderate aerobic exercise 

(e.g., brisk walking)

↓ 4–9 mmHg

↑ Nitric oxide 

↓ Sympathetic activity 

Improved arterial compliance

Alcohol Reduction

≤14 units/week (UK guidance) 

Spread over ≥3 days

↓ 2–4 mmHg

↓ Sympathetic drive 

↓ Cortisol & catecholamines

Smoking Cessation

Complete cessation

Minimal chronic BP change 

(acute BP spike with smoking)

↓ Acute catecholamine surges

Pharmacological Treatment (NICE Algorithm)

1️⃣ When to Treat? (Initiation Thresholds – UK Exam Priority)

Start drug therapy if:

✅ Stage 1 Hypertension (140–159 / 90–99)

Treat IF:

  • Age <80 AND
  • One of the following:
    • Target organ damage
    • Established CVD
    • CKD
    • Diabetes
    • 10-year QRISK ≥10%

Otherwise → lifestyle only.

 

✅ Stage 2 Hypertension (≥160 / ≥100)

Treat all patients regardless of risk.

 

✅ Severe Hypertension (≥180 / ≥120)

Treat urgently.

 

2️⃣ Target Blood Pressure (Very Common MRCP Question)

🎯 NICE Targets

Age

Clinic Target

<80 years

<140/90

≥80 years

<150/90

Home/ABPM target:

  • <135/85 (<80 yrs)
  • <145/85 (≥80 yrs)

 

🎯 ESC 2023 Targets 

  • Aim <140/90 initially
  • If tolerated → <130/80
  • Avoid <120 systolic routinely

 

Special Targets

Condition

Target

Diabetes

<140/90 (consider <130/80 if tolerated)

CKD with proteinuria

<130/80

IHD

<130/80 if tolerated

Frail elderly

Individualised

Don’t overtreat elderly → risk of falls.

Age <55 years:
→ ACE inhibitor (e.g., Ramipril)

Age ≥55 OR Black ethnicity:
→ CCB (e.g., Amlodipine)

Why?

Younger patients:

  • High renin → RAAS driven

Older/Black:

  • Low renin → Volume/vascular resistance driven

Stepwise Escalation

  1. A or C
  2. A + C
  3. A + C + D (thiazide-like diuretic e.g., Indapamide)
  4. Add:
    • Spironolactone (if K <4.5)
    • Alpha blocker
    • Beta blocker

Most patients require ≥2 drugs.

Why combination works:

  • Targets different mechanisms
  • Lower dose → fewer side effects

Preferred combinations:

  • ACEi + CCB (evidence strongest)
  • ACEi + thiazide

Avoid:

  • ACEi + ARB (no benefit, ↑ renal risk)

6️⃣ Monitoring After Starting Therapy

Check:

  • U&E 1–2 weeks after ACEi/ARB/diuretic
  • Creatinine rise acceptable up to 30%
  • Potassium <5.5 usually acceptable

Follow-up:

  • Every 4 weeks until controlled
  • Then 6–12 monthly

10. Special Situations

  • Diabetes-ACEi/ARB preferred.
  • CKD-ACEi first line (proteinuria).
  • IHD-Beta blockers + ACEi.
  • Pregnancy

Use:

  • Labetalol
  • Nifedipine
  • Methyldopa

Avoid ACEi/ARB.

 

11. Resistant Hypertension

Definition:
BP uncontrolled on ≥3 drugs including diuretic.

Causes:

  • Non-adherence
  • White coat
  • Secondary causes
  • OSA

Investigate:

  • Renin/aldosterone ratio
  • Renal artery Doppler
  • Sleep study

12. Complications

  • Stroke
  • MI
  • HF
  • CKD
  • Aortic dissection

14. Prognosis

Untreated → progressive organ damage.
Treatment reduces:

  • Stroke risk by ~40%
  • MI risk by ~20–25%