ATRIAL FLUTTER &

ATRIAL FIBRILLATION

MUHAMMAD ALIPEDIATRIC CARDIOLOGY

DIVISION

ATRIAL FLUTTER

Description• The pacemaker lies in an ectopic focus, and “circus

movement” in the atrium is the mechanism of this arrhythmia. Atrial flutter is characterized by an atrial rate (F wave with “sawtooth” configuration) of about 300 beats/minute, a ventricular response with varying degrees of block (e.g., 2:1, 3:1, 4:1), and normal QRS complexes

Causes

• Possible causes are structural heart disease with dilated atria, myocarditis, previous surgery involving atria (the Mustard or Senning procedure, Fontan operation, or atrial septal defect repair), and digitalis toxicity

Significance• The ventricular rate determines eventual cardiac output;

a too-rapid ventricular rate may decrease cardiac output. Atrial flutter usually suggests a significant cardiac pathology.

Management

• Digitalization is provided if the arrhythmia is not the result of digitalis toxicity; digitalis increases the AV block and thereby slows the ventricular rate. Propranolol (1 to 4 mg/kg per day orally in three or four doses) may be added to digoxin

• Recent reports suggest that amiodarone may be more effective than digoxin in treating atrial flutter. One can start with a trial of digoxin and, if digoxin fails, progress to amiodarone

• Electric cardioversion may be required. Digitalis should be discontinued for at least 48 hours before cardioversion. Anticoagulation with warfarin is recommended before cardioversion to prevent embolization

• Rapid atrial pacing with a catheter in the esophagus or the right atrium can be effective when cardioversion is contraindicated (e.g., digitalized patients)

• Quinidine may prevent recurrence.

ATRIAL FIBRILLATION

Description• The mechanism of this arrhythmia is “circus movement,”

as in atrial flutter. Atrial fibrillation is characterized by an extremely fast atrial rate (f wave at a rate of 350 to 600 beats/minute) and an irregularly irregular ventricular response with normal QRS complexes

Causes

• Atrial fibrillation usually is associated with structural heart disease, including dilated atria; myocarditis; digitalis toxicity; or previous intra-atrial surgery

Significance

• The rapid ventricular rate, in addition to the loss of coordinated contraction of the atria and ventricles, decreases the cardiac output, as occurs in atrial tachycardia.

• Atrial fibrillation usually suggests a significant cardiac pathology.

Management • AF > 48 hours, anticoagulation warfarin for 3 weeks to prevent

systemic embolization of atrial thrombus. Anticoagulation is continued for 4 weeks after the restoration of sinus rhythm. If cardioversion cannot be delayed, heparin should be started, with subsequent oral anticoagulation

• Digoxin is provided to slow the ventricular rate. Propranolol (1 to 4

mg/kg per day orally in three or four doses) may be added

• As a pharmacologic means of conversion, class I antiarrhythmic agents (e.g., quinidine, procainamide, flecainide) and the class III agent amiodarone may be used

• In patients with chronic atrial fibrillation, anticoagulation with warfarin should be considered to reduce the incidence of thromboembolism

• Quinidine may prevent recurrence.

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