cardio:hypertension:start []

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====== Module 4 – Hypertension ======

Hypertension is a chronic disorder of elevated arterial pressure.

Core Equation:
**MAP = CO × SVR**

All antihypertensive drugs lower blood pressure by modifying:

• Systemic Vascular Resistance (SVR)  
• Cardiac Output (CO)  
• Blood Volume  
• Sympathetic Tone  
• RAAS Activity  

Most chronic hypertension is primarily a disorder of increased SVR.

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===== Confirm True Hypertension =====

Before initiating therapy:

  * • Ensure correct cuff size and technique  
  * • Repeat readings on separate visits  
  * • Consider home or ambulatory monitoring  
  * • Assess medication adherence  
  * • Review contributing substances (NSAIDs, decongestants, stimulants, alcohol)  

If severe, resistant, or early-onset → evaluate for secondary causes.

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===== Mechanism-Based Antihypertensive Classes =====

==== 1. RAAS Blockade ====

  * • [[cardio:raas:acei|ACE Inhibitors]]  
  * • [[cardio:raas:arb|Angiotensin Receptor Blockers (ARBs)]]  
  * • [[cardio:raas:renin_inhibitors|Direct Renin Inhibitors]]  

Effect: ↓ Angiotensin II → ↓ SVR and ↓ aldosterone-mediated sodium retention

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==== 2. Calcium Channel Blockers ====

  * • [[cardio:ccb:dhp|Dihydropyridine Calcium Channel Blockers]]  
  * • [[cardio:ccb:non_dhp|Non-Dihydropyridine Calcium Channel Blockers]]  

DHP CCBs:
Primary arteriolar vasodilation (↓ SVR)

Non-DHP CCBs:
↓ Heart rate and ↓ contractility (↓ CO)

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==== 3. Diuretics ====

[[cardio:diuretics:start|Diuretics]]

[[cardio:diuretics:thiazide:start|Thiazide / Thiazide-Like]]
  * • [[cardio:diuretics:chlorthalidone|Chlorthalidone]]  
  * • [[cardio:diuretics:hydrochlorothiazide|Hydrochlorothiazide]]  
  * • [[cardio:diuretics:indapamide|Indapamide]]  

[[cardio:diuretics:loop|Loop Diuretics]]  
  *   - [[cardio:diuretics:furosemide|Furosemide]]  
  *   - [[cardio:diuretics:torsemide|Torsemide]]  

[[cardio:diuretics:mra|Mineralocorticoid Receptor Antagonists]]  
  *   - [[cardio:hf:spironolactone|Spironolactone]]  
  *   - [[cardio:hf:eplerenone|Eplerenone]]  

[[cardio:diuretics:enac|ENaC Inhibitors]]  
  *   - [[cardio:diuretics:amiloride|Amiloride]]  
  *   - [[cardio:diuretics:triamterene|Triamterene]]  

Effect: ↓ Sodium retention → ↓ plasma volume → long-term ↓ SVR

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==== 4. Sympathetic Modulation ====

[[cardio:beta_blockers:start|Beta-Blockers]]

Combined Alpha/Beta Blockade:
  * • [[cardio:beta_blockers:labetalol|Labetalol]]  
  * • [[cardio:beta_blockers:carvedilol|Carvedilol]]  

Central Alpha-2 Agonists:
  * • [[cardio:hypertension:clonidine|Clonidine]]  
  * • [[cardio:hypertension:methyldopa|Methyldopa]]  

Alpha-1 Blockade:
  * • [[cardio:alpha_blockers:start|Alpha-1 Blockers]]  

Effect: ↓ Sympathetic tone → ↓ CO and ↓ SVR

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==== 5. Direct Vasodilators ====

  * • [[cardio:hypertension:hydralazine|Hydralazine]]  
  * • [[cardio:hypertension:minoxidil|Minoxidil]]  

Potent arteriolar vasodilation  
Typically require a [[cardio:beta_blockers:start|Beta-Blocker]] and a [[cardio:diuretics:start|Diuretic]] to blunt reflex tachycardia and fluid retention

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===== Initial Treatment Strategy =====

Treatment intensity depends on how far the patient is from goal.

==== If BP <20/10 mmHg Above Goal ====

Start:
• ONE first-line class

Titrate to effect.

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==== If BP ≥20/10 mmHg Above Goal (Stage 2 Hypertension) ====

Start:
• TWO first-line agents from different classes

Preferred combinations:

• [[cardio:raas:acei|ACE Inhibitor]] or [[cardio:raas:arb|ARB]]  
  + [[cardio:ccb:dhp|DHP CCB]]

• [[cardio:raas:acei|ACE Inhibitor]] or [[cardio:raas:arb|ARB]]  
  + [[cardio:diuretics:thiazide_like|Thiazide-like Diuretic]]

Avoid:
• [[cardio:raas:acei|ACE Inhibitor]] + [[cardio:raas:arb|ARB]]

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===== Stepwise Escalation =====

==== Step 1: Single or Dual Therapy ====

Choose based on comorbidity:

CKD / Diabetes:
→ [[cardio:raas:acei|ACE Inhibitor]] or [[cardio:raas:arb|ARB]]

Black patient (without CKD):
→ [[cardio:diuretics:thiazide_like|Thiazide-like Diuretic]] or [[cardio:ccb:dhp|DHP CCB]]

Coronary artery disease:
→ [[cardio:beta_blockers:start|Beta-Blocker]]  
  + [[cardio:raas:acei|ACE Inhibitor]] or [[cardio:raas:arb|ARB]]

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==== Step 2: Triple Therapy Backbone ====

[[cardio:raas:acei|ACE Inhibitor]] or [[cardio:raas:arb|ARB]]  
+  
[[cardio:ccb:dhp|DHP CCB]]  
+  
[[cardio:diuretics:thiazide_like|Thiazide-like Diuretic]]

If reduced eGFR or significant volume overload:
→ Use a [[cardio:diuretics:loop|Loop Diuretic]]

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==== Step 3: Resistant Hypertension ====

Add:
• [[cardio:hf:spironolactone|Spironolactone]]  
• or [[cardio:hf:eplerenone|Eplerenone]]

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==== Step 4: Advanced / Specialist Tier ====

• [[cardio:beta_blockers:start|Beta-Blocker]]  
• [[cardio:hypertension:clonidine|Clonidine]]  
• [[cardio:hypertension:hydralazine|Hydralazine]]  
• [[cardio:hypertension:minoxidil|Minoxidil]]

Evaluate for secondary causes.

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===== Hypertensive Urgency vs Emergency =====

==== Hypertensive Urgency ====

  * • Severe BP elevation  
  * • No acute end-organ damage  
  * • Gradual reduction over 24–72 hours  

Oral agents:

  * • [[cardio:raas:captopril|Captopril]]  
  * • [[cardio:beta_blockers:labetalol|Labetalol]]  
  * • [[cardio:hypertension:clonidine|Clonidine]]  

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==== Hypertensive Emergency ====

  * • Severe BP elevation  
  * • Evidence of end-organ damage  
  * • Requires IV therapy and admission  

Common IV agents:

  * • [[cardio:ccb:nicardipine|Nicardipine]]  
  * • [[cardio:beta_blockers:labetalol|Labetalol]]  
  * • [[cardio:hypertension:nitroprusside|Nitroprusside]]  
  * • [[cardio:angina:nitroglycerin|Nitroglycerin]]

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===== Clinical Pearls =====

  * ✔ Most chronic hypertension is driven by increased SVR  
  * ✔ Most patients require ≥2 medications  
  * ✔ [[cardio:diuretics:chlorthalidone|Chlorthalidone]] often superior to HCTZ  
  * ✔ [[cardio:hf:spironolactone|Spironolactone]] is the most effective 4th-line agent  
  * ✔ Avoid combining [[cardio:raas:acei|ACE Inhibitor]] + [[cardio:raas:arb|ARB]]  
  * ✔ Treat physiology, not just numbers  

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Related:

→ [[cardio:raas:acei|ACE Inhibitors]]  
→ [[cardio:raas:arb|ARBs]]  
→ [[cardio:ccb:start|Calcium Channel Blockers]]  
→ [[cardio:diuretics:start|Diuretics]]  
→ [[cardio:beta_blockers:start|Beta-Blockers]]  
→ [[cardio:start|Return to CV Modules]]