====== 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. -------------------------------------------------------------------- ===== 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. -------------------------------------------------------------------- ===== 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 -------------------------------------------------------------------- ==== 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) -------------------------------------------------------------------- ==== 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 -------------------------------------------------------------------- ==== 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 -------------------------------------------------------------------- ==== 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 -------------------------------------------------------------------- ===== 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. ---- ==== 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]] -------------------------------------------------------------------- ===== 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]] ---- ==== 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]] ---- ==== Step 3: Resistant Hypertension ==== Add: • [[cardio:hf:spironolactone|Spironolactone]] • or [[cardio:hf:eplerenone|Eplerenone]] ---- ==== 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. -------------------------------------------------------------------- ===== 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]] ---- ==== 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]] -------------------------------------------------------------------- ===== 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 -------------------------------------------------------------------- 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]]