Hypertension

Overview – Hypertension

Hypertension is a persistently elevated arterial blood pressure that significantly increases the risk of stroke, myocardial infarction, heart failure, chronic kidney disease, and peripheral vascular disease. It is often asymptomatic but is a major modifiable risk factor for cardiovascular and end-organ complications. This article outlines the definitions, causes, diagnostic workup, and management of hypertension, tailored to final-year medical students preparing for clinical application.

Definition

• Hypertension (HTN):
  • Systolic BP ≥ 140 mmHg and/or
  • Diastolic BP ≥ 90 mmHg
  • Requires 3 separate readings over 6 months for formal diagnosis
• Stage-based classification (Adults):

Aetiology

Primary (Essential) Hypertension – 95%

• Idiopathic and multifactorial
• Common risk factors:
  • Family history, high salt/cholesterol intake
  • Obesity, diabetes mellitus, smoking
  • Excess alcohol, stress, increasing age
• Subtypes:
  • Isolated Diastolic Hypertension: Often older males
  • Isolated Systolic Hypertension:
    • Young adults → ↑ Cardiac output (sympathetic overactivity)
    • Elderly → ↓ Arterial compliance (vascular stiffening)

Secondary Hypertension – 5%

• Cardiac causes: Coarctation of aorta, hypervolaemia
• Renal causes: CKD, glomerulonephritis, renal artery stenosis
• Endocrine causes: Cushing’s, acromegaly, pheochromocytoma, thyroid dysfunction
• Neurologic causes: Raised intracranial pressure, sleep apnoea, acute stress
• Pregnancy-related: Pre-eclampsia – placental ischaemia leads to vasoconstrictive mediators

Pathophysiology

• Hypertension increases afterload, requiring the heart to work harder
• Chronic elevation → left ventricular hypertrophy, impaired relaxation, reduced cardiac output
• Accelerated vascular damage → arteriosclerosis, microangiopathy, and end-organ damage
• Baroreceptor reflex: Acts to correct acute BP drops but is reset in chronic HTN

Clinical Features

• Symptoms: Often asymptomatic
  • If severe: Headache, dizziness, visual disturbance, nausea, vomiting
• Signs:
  • Features of underlying cause: goitre (thyroid), abdominal masses (adrenal or renal), signs of CKD
  • Fundoscopy: hypertensive retinopathy (e.g., papilloedema)
  • Cardiovascular: displaced apex beat, murmurs
  • Renal bruit in renal artery stenosis

Investigations

• Diagnosis:
  • 3 elevated readings over 6 months
  • Confirm with home or ambulatory monitoring, especially in “white coat” HTN
  • Standing BP:
    • Diastolic ↑ on standing → Essential HTN
    • Diastolic ↓ on standing → Secondary HTN
• Workup:
  • FBC – rule out polycythaemia
  • UEC – assess renal function, electrolyte status
  • Lipid profile – assess cardiovascular risk
  • Urinalysis – proteinuria or haematuria (renal disease)
  • BSL – diabetes screening
  • ECG – evidence of LVH or ischaemia

Management

Lifestyle Changes

• Weight loss
• Smoking cessation
• Salt/alcohol reduction
• Low-fat diet
• Regular aerobic exercise

Pharmacological Management

• Initiate if BP >160/100 mmHg (Stage 2)
• Stepwise approach:
  1. Monotherapy, then combine if needed
     • ACE inhibitors (Perindopril) or ARBs (Candesartan)
     • Calcium channel blockers (Amlodipine, Nifedipine)
     • Thiazide diuretics (Hydrochlorothiazide)
     • Beta-blockers (Carvedilol, Atenolol) – only if IHD or heart failure
  2. Therapeutic target:
     • <140/90 mmHg general population
     • <130/80 mmHg in diabetics
• Mechanisms of Action:
  • Diuretics: Reduce blood volume → ↓ Preload
  • Sympatholytics: ↓ HR and contractility → ↓ Cardiac output
  • Vasodilators: ↓ Peripheral resistance → ↓ Afterload
  • Renin-Angiotensin-Aldosterone System blockers: ↓ Vasoconstriction, ↓ fluid retention

Complications

Malignant (Accelerated) Hypertension

• Rapid ↑ in BP >200/120 mmHg
• May cause:
  • Retinopathy (e.g., haemorrhages, papilloedema)
  • Acute renal injury (creatinine rise)
  • Cerebral symptoms (confusion, seizures)
• Management:
  • Gradual BP reduction over 24–36 hours
  • Target <150/90 mmHg
  • Avoid overly rapid correction → ischaemia risk

Long-Term Complications

• Cardiac: LV hypertrophy, heart failure, coronary artery disease
• Renal: Nephrosclerosis, progressive CKD
• Cerebral: Intracerebral haemorrhage, vascular dementia
• Vascular: Aneurysms, aortic dissection
• Ophthalmic: Hypertensive retinopathy

Summary – Hypertension

Hypertension is a major cause of cardiovascular morbidity and mortality worldwide. It is typically asymptomatic, but leads to significant long-term complications if untreated. Accurate diagnosis, regular monitoring, and targeted therapy—starting with lifestyle modifications and progressing to pharmacological agents—are essential to preventing end-organ damage. For a broader context, see our Cardiovascular Overview page.