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.

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.

• • ACE Inhibitors
• • Angiotensin Receptor Blockers (ARBs)
• • Direct Renin Inhibitors

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

• • Dihydropyridine Calcium Channel Blockers
• • Non-Dihydropyridine Calcium Channel Blockers

DHP CCBs: Primary arteriolar vasodilation (↓ SVR)

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

Diuretics

Thiazide / Thiazide-Like

• • Chlorthalidone
• • Hydrochlorothiazide
• • Indapamide

Loop Diuretics

• - Furosemide
• - Torsemide

Mineralocorticoid Receptor Antagonists

• - Spironolactone
• - Eplerenone

ENaC Inhibitors

• - Amiloride
• - Triamterene

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

Beta-Blockers

Combined Alpha/Beta Blockade:

• • Labetalol
• • Carvedilol

Central Alpha-2 Agonists:

• • Clonidine
• • Methyldopa

Alpha-1 Blockade:

• • Alpha-1 Blockers

Effect: ↓ Sympathetic tone → ↓ CO and ↓ SVR

• • Hydralazine
• • Minoxidil

Potent arteriolar vasodilation Typically require a Beta-Blocker and a Diuretic to blunt reflex tachycardia and fluid retention

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

Start: • ONE first-line class

Titrate to effect.

Start: • TWO first-line agents from different classes

Preferred combinations:

• ACE Inhibitor or ARB + DHP CCB

• ACE Inhibitor or ARB + Thiazide-like Diuretic

Avoid: • ACE Inhibitor + ARB

Choose based on comorbidity:

CKD / Diabetes: → ACE Inhibitor or ARB

Black patient (without CKD): → Thiazide-like Diuretic or DHP CCB

Coronary artery disease: → Beta-Blocker + ACE Inhibitor or ARB

ACE Inhibitor or ARB + DHP CCB + Thiazide-like Diuretic

If reduced eGFR or significant volume overload: → Use a Loop Diuretic

Add: • Spironolactone • or Eplerenone

• Beta-Blocker • Clonidine • Hydralazine • Minoxidil

Evaluate for secondary causes.

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

Oral agents:

• • Captopril
• • Labetalol
• • Clonidine

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

Common IV agents:

• • Nicardipine
• • Labetalol
• • Nitroprusside
• • Nitroglycerin

• ✔ Most chronic hypertension is driven by increased SVR
• ✔ Most patients require ≥2 medications
• ✔ Chlorthalidone often superior to HCTZ
• ✔ Spironolactone is the most effective 4th-line agent
• ✔ Avoid combining ACE Inhibitor + ARB
• ✔ Treat physiology, not just numbers

Related:

→ ACE Inhibitors → ARBs → Calcium Channel Blockers → Diuretics → Beta-Blockers → Return to CV Modules