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, pain, anemia, dehydration, 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 |
Focal 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 or ablation | 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 adenosine; if unsuccessful, consider cardioversion; for long-term suppression, consider class I or III antiarrhythmic 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; atypical atrial flutter usually arises from atrial scars |
Atrial flutter may respond to rapid atrial pacing, and radio frequency ablation highly effective to prevent recurrences; consider ablation for recurrences of atrial fibrillation, especially if class IC or class III agents fail to control |
Multifocal atrial tachycardia | 100-150 | At least three distinct 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 | Monomorphic: myocardial scar (e.g., prior MI, sarcoid), ARVC, idiopathic outflow tract tachycardias Polymorphic: Myocardial ischemia, hypertrophic cardiomyopathy, electrolyte disturbances, drug toxicities, genetic arrhythmia syndromes (see torsade de pointes below) | If unstable: electrical conversion/defibrillation (≥200 J monophasic, or ≥100 J biphasic) Otherwise: acute (IV): amiodarone, procainamide, lidocaine; 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 occur in preexcitation (WPW) | Same as treatment of respective supraventricular rhythm; if ventricular rate rapid (>200), treat as WPW (see text) |
a Antiarrhythmic drug groups listed in Table 125-2 Commonly Used Antiarrhythmic Drugs.
Abbreviations: ARVC, arrhythmogenic right ventricular cardiomyopathy; CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; EtOH, ethyl alcohol; ICD, implantable cardioverter defibrillator; NSR, normal sinus rhythm; WPW, Wolff-Parkinson-White.