Essential HTN First-Line
Thiazides, CCBs, ACEi / ARBs (Black patients: CCBs or Thiazides first-line)
Class IA Antiarrhythmics
Quinidine, Procainamide, Disopyramide (prolongs AP duration & QT interval)
Class IC Antiarrhythmics
Flecainide, Propafenone (profound 0-phase slowing; contraindicated post-MI)
Amiodarone Toxicities
Pulmonary fibrosis, Thyroid (hypo/hyper), Liver toxicity, Blue skin, Corneal deposits
First-Line Antihypertensive Drug Classes
Evidence-based selection based on patient comorbidities and demographic profiles:
| Drug Class | Representative Agents | Compelling Indications | Key Adverse Effects & Contraindications |
|---|---|---|---|
| ACE Inhibitors | Lisinopril, Enalapril, Ramipril | CKD with proteinuria, Diabetes, HFrEF, post-MI | Dry cough (bradykinin), Angioedema, Hyperkalemia. Absolutely CONTRAINDICATED in pregnancy! |
| Angiotensin Receptor Blockers (ARBs) | Losartan, Valsartan | Same as ACEi; alternative if ACEi-induced cough occurs | Hyperkalemia, renal impairment; contraindicated in pregnancy |
| Dihydropyridine CCBs | Amlodipine, Nifedipine | Isolated systolic HTN, elderly, Black patients | Peripheral dependent ankle edema, flushing, headache |
| Non-Dihydropyridine CCBs | Diltiazem, Verapamil | Atrial fibrillation rate control, angina | Bradycardia, AV block, Constipation (verapamil); avoid in HFrEF (negative inotrope) |
| Thiazide Diuretics | Chlorthalidone, HCTZ | First-line essential HTN, osteoporosis (retains calcium) | Hypokalemia, Hyponatremia, Hyperuricemia (gout), Hypercalcemia, Hyperglycemia |
Vaughan Williams Antiarrhythmic Classification
Categorized by primary electrophysiologic ion channel blockade:
| Class | Primary Mechanism of Action | Representative Agents | Electrophysiologic Effect on Action Potential |
|---|---|---|---|
| Class IA | Moderate Na+ block + K+ channel block | Quinidine, Procainamide, Disopyramide ("Double Quarter Pounder") | Prolongs action potential duration & QT interval (risk of Torsades) |
| Class IB | Weak Na+ block (fast on-off) | Lidocaine, Mexiletine ("with Lettuce & Tomato") | Shortens action potential duration; best for ischemic ventricular arrhythmias |
| Class IC | Potent Na+ block (slow dissociation) | Flecainide, Propafenone ("More Fries Please") | Markedly prolongs QRS duration; CONTRAINDICATED in structural heart disease (CAST trial) |
| Class II | β-Adrenergic Blockade | Metoprolol, Esmolol, Atenolol | Decreases SA/AV nodal automaticity; prolongs PR interval |
| Class III | K+ Channel Blockade | Amiodarone, Sotalol, Dofetilide, Ibutilide | Markedly prolongs Phase 3 repolarization and QT interval |
| Class IV | L-type Ca2+ Channel Blockade | Diltiazem, Verapamil | Slows AV nodal conduction velocity; prolongs PR interval |
COMLEX / OMM Integration
NBOME High-Yield Correlate
Cardiovascular Sympathetic Innervation & OMT
- Autonomic Innervation: Pre-ganglionic sympathetic neurons arise from
T1–T5.
- Right vs Left Sympathetics: Right sympathetic chain predominantly innervates the SA node (atrial tachyarrhythmias); left sympathetic chain innervates the AV node and ventricles (ventricular ectopic beats and ischemia).
Board Traps & Common Distractors
- Trap: Using Flecainide or Propafenone (Class IC) in a patient with a history of prior myocardial infarction or structural heart disease. The Cardiac Arrhythmia Suppression Trial (CAST) showed increased lethal proarrhythmic mortality in structural CAD.
- Trap: Combining Verapamil with a Beta-Blocker. Concurrent use causes profound additive negative inotropy and dromotropy, precipitating severe bradycardia, complete heart block, and cardiogenic shock.