Hypertension & Hypertensive Emergencies

Definition & Epidemiology

  • Hypertension (HTN): persistent \text{SBP}\,\ge 140\,\text{mmHg} and/or \text{DBP}\,\ge 90\,\text{mmHg} on \ge 2 occasions.
  • Normal: 120! -!129/80! -!84\,\text{mmHg}.
  • Malaysia: ≈1 in 3 adults (29.2 %) hypertensive; ↑ risk of MI, HF, stroke, CKD.

Risk Factors

  • Modifiable: smoking / alcohol, obesity, high Na⁺ intake, stress, sedentary life.
  • Non-modifiable: age, male sex, family history, ethnicity.

Classification of Blood Pressure (Clinic)

  • Optimal: <120/80
  • Normal: 120! -!129/80! -!84
  • At-risk: 130! -!139/85! -!89
  • Stage 1: 140! -!159/90! -!99
  • Stage 2: 160! -!179/100! -!109
  • Stage 3: \ge180/\ge110
  • Isolated systolic HTN (ISH): \text{SBP}\,\ge140 with \text{DBP}<90.

Pathophysiology (Primary HTN)

  • Short-term BP control: baroreceptor reflex → sympathetic activation ↑HR, ↑SVR.
  • Long-term: RAAS, ADH, thirst → Na⁺/water retention ↑blood volume.

Secondary HTN (Key Causes)

  • Renovascular: renal artery stenosis → RAAS.
  • Endocrine: pheochromocytoma (↑catecholamines); Conn’s (↑aldosterone).
  • Others: coarctation of aorta, CKD, drugs (NSAIDs, OCP, cocaine, etc.).

Diagnosis & Initial Assessment

  • Measure both arms; average ≥2 readings after 1 min rest; verify with home/ambulatory BP (elevated if >135/85).
  • Evaluate: history (risk factors, secondary causes, TOD), physical (fundus, pulses, cardiomegaly), labs (FBC, glucose, renal, lipids, urinalysis, ECG).
  • Identify TOD/TOC: LVH, retinopathy, proteinuria, stroke, HF.

Management: Non-Pharmacological

  • Weight loss: ↓\approx1\,\text{mmHg} SBP per 1\,\text{kg}.
  • Na⁺ restriction: <2\,\text{g} Na⁺ (≈5\,\text{g} salt) daily.
  • Healthy diet (fruits/veg, low-fat dairy): ↓11/6\,\text{mmHg}.
  • Physical activity: ≥150 min/week aerobic/resistance.
  • Limit alcohol <2 drinks/day; stop smoking.
  • ↑Dietary K⁺ (if renal fxn normal).

Management: Pharmacological

  • Start drugs if: Stage 2, or Stage 1 with medium/high CV risk; consider after 3-6 mo lifestyle trial for low-risk Stage 1.
  • First-line monotherapy: ACEI, ARB, CCB, thiazide.
  • β-blocker reserved for younger pts, intolerance to ACEI/ARB, or ↑sympathetic drive.
  • If uncontrolled: maximize dose, switch class, or add 2nd drug (combo first-line for Stage 2 / high-risk).
  • Targets: <140/90 (<130/80 high risk; <150/90 if ≥80 y).
  • Refer if severe >180/110, resistant, secondary suspicion, TOD, pregnancy, age <30.

Severe HTN & Hypertensive Crisis

  • Severe HTN: BP >180/110.
    • Urgency: no acute TOD.
    • Emergency: acute TOD (HF, ACS, aortic dissection, encephalopathy, AKI, ICH, etc.).
  • Common triggers: poorly controlled essential HTN, renal disease, endocrine tumors, drugs, pregnancy.

Hypertensive Emergency – Goals

  • Admit ICU; IV therapy.
  • General aim: ↓MAP 10! -!25\% within minutes-hours, but not <160/90 (except specific conditions).
  • Condition-specific targets:
    • Aortic dissection: ↓BP ≤120/80 & HR

IV Drug Options (Key Points)

  • Labetalol: rapid, 3-6 h; avoid in HF.
  • Nicardipine: titratable CCB; avoid in acute HF.
  • Nitroprusside: potent; risk cyanide toxicity, avoid ↑ICP.
  • Nitroglycerine/Isosorbide: ACS & pulmonary edema.
  • Hydralazine: pregnancy; avoid in ACS/dissection/stroke.
  • Esmolol: short-acting β-blocker (surgery, tachyarrhythmia).

Long-Term Complications (Target-Organ Damage)

  • Eye: hypertensive retinopathy (KWB grades 1-4) → vision loss.
  • Heart: LVH → stiff ventricle → HF, arrhythmia, ischemia.
  • Kidney: hypertensive nephropathy – CKD with \text{eGFR}<60, proteinuria.
  • Vessels: CAD, stroke (ischemic/hemorrhagic), peripheral artery disease.