Clinical and Electrocardiographic Features of Common Arrhythmias
| Rhythm | Atrial Rate | Features | Carotid Sinus Massage | Precipitating Conditions | Initial Treatment |
|---|---|---|---|---|---|
| Narrow QRS complex | |||||
| Atrial premature beats | — | P wave abnormal; QRS width normal | — | Can be normal or due to anxiety, CHF, hypoxia, caffeine, abnormal electrolytes (↓K+↓Mg2+) | Remove precipitating cause; if symptomatic: beta blocker |
| Sinus tachycardia | 100-160 | Normal P wave contour | Rate gradually slows | Fever, anxiety, dehydration, pain, CHF, hyperthyroidism, COPD | Remove precipitating cause; if symptomatic: beta blocker |
| AV nodal tachycardia (reentrant) | 120-250 | Absent or retrograde P wave | Abruptly converts to sinus rhythm (or no effect) | Can occur in healthy individuals | Vagal maneuvers; if unsuccessful: adenosine, verapamil, beta blocker, cardioversion (100-200 J). To prevent recurrence: beta blocker, verapamil, diltiazem, digoxin, class IC agent, or catheter ablation |
| Atrial tachycardia | 130-200 | P contour different from sinus P wave; AV block may occur; automatic form shows “warm-up” in rate in first several beats | AV block may ↑ | Digitalis toxicity; pulmonary disease; scars from prior cardiac surgery | If digitalis toxic: hold digoxin, correct [K+] In absence of digoxin toxicity: slow rate with beta blocker, verapamil, or diltiazem; can attempt conversion with IV procainamide or amiodarone; if unsuccessful, proceed to cardioversion or catheter ablation |
Atrial flutter Atrial fibrillation | 260-300 >350 | “Sawtooth” flutter waves; 2:1, 4:1 block No discrete P; irregularly spaced QRS | ↑AV block with ↓ventricular rate ↓Ventricular rate | Mitral valve disease, hypertension, pulmonary embolism, pericarditis, post-cardiac surgery, hyperthyroidism; obstructive lung disease, EtOH, idiopathic |
|
| Multifocal atrial tachycardia | 100-150 | More than three different P wave shapes with varying PR intervals | No effect | Severe respiratory insufficiency | Treat underlying lung disease; verapamil or diltiazem may be used to slow ventricular rate; class IC agents or amiodarone may ↓ episodes |
| Wide QRS Complex | |||||
| Ventricular premature beats | Fully compensatory pause between normal beats | No effect | CAD, MI, CHF, hypoxia, hypokalemia, digitalis toxicity, prolonged QT interval (congenital or drug-related) | May not require therapy; if needed for symptomatic suppression, use beta blocker | |
| Ventricular tachycardia | QRS rate 100-250; slightly irregular rate | No effect | If unstable: electrical conversion/defibrillation (≥200 J monophasic, or 100 J biphasic) Otherwise: acute (IV): amiodarone, lidocaine, procainamide; chronic management: usually ICD Pts without structural heart disease (e.g., focal outflow tract ventricular tachycardia) may respond to beta blockers or verapamil | ||
| Accelerated idioventricular rhythm (AIVR) | Gradual onset and offset; QRS rate 40-120 | Acute MI, myocarditis | Usually none; for symptoms, use atropine or atrial pacing | ||
| Ventricular fibrillation | Erratic electrical activity | No effect | Immediate defibrillation | ||
| Torsade de pointes | Ventricular tachycardia with sinusoidal oscillations of QRS height | No effect | Prolonged QT interval (congenital or drug-related) | IV magnesium (1- to 2-g bolus); overdrive pacing; isoproterenol for bradycardia-dependent torsades (unless CAD present); lidocaine Drugs that prolong QT interval are contraindicated | |
| Supraventricular tachycardias with aberrant ventricular conduction | P wave typical of the supraventricular rhythm; wide QRS complex due to conduction through partially refractory pathways | Etiologies of the respective supraventricular rhythms listed above; atrial fibrillation with rapid, wide QRS may be due to preexcitation (WPW) | Same as treatment of respective supraventricular rhythm; if ventricular rate rapid (>200), treat as WPW (see text) | ||
aAntiarrhythmic drug groups listed in Table 123-2.
Abbreviations: CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; EtOH, ethyl alcohol; ICD, implantable cardioverter defibrillator; NSR, normal sinus rhythm; WPW, Wolff-Parkinson-White.