Atrial flutter mechanisms

Reentry mechanism Intranodal (AV node) reentry Extranodal reentry Reentrant tachyarrhythmia Atrial flutter Atrial fibrillation Ventricular tachycardia Ventricular fibrillation Conduction B/ocks ... 

The predominant mechanism of AF and atrial flutter is reentry, which is usually associated with organic heart disease that causes atrial distention (e.g., ischemia or infarction, hypertensive heart disease, valvular disorders). Additional associated disorders include acute pulmonary embolus and chronic lung disease, resulting in pulmonary hypertension and cor pulmonale and states of high adrenergic tone such as thyrotoxicosis, alcohol withdrawal, sepsis, or excessive physical exertion. 

Amiodarone is indicated for the suppression and prevention of documented life-threatening, recurrent, ventricular tachycardia or fibrillation when other agents have failed. Amiodarone is also used in the management of supraventricular tachyarrhythmias including paroxysmal atrial fibrillation and atrial flutter, ectopic or multifocal atrial tachycardia, junctional tachycardia, and paroxysmal reentrant supraventricular tachycardia when other agents have failed to suppress or prevent their recurrence. Amiodarone has also been used to treat wide-complex tachycardia of uncertain mechanism. 

Disopyramide, proprietary name Norpace, is used for maintenance of sinus rhythm in patients with atrial flutter and atrial fibrillation and for prevention of ventricular tachycardia and fibrillation. The mechanism of action of disopyramide is similar to that of quinidine, and the drug can be used as replacement therapy for quinidine when quinidine side effects are intolerable. 

It is generally accepted that the predominant mechanism of atrial fibrillation and atrial flutter is reentry. Atrial fibrillation appears to result from multiple atrial reentrant loops (or wavelets), and atrial flutter is due to a single, dominant reentrant substrate (counterclockwise circus movement around the tricuspid annulus). Atrial fibrillation or flutter usually occurs in association with forms of organic heart disease that causes atrial distension. Forms of heart disease that commonly lead to atrial stretch and precipitate atrial fibrillation or flutter include... 

Allessie MA, Lammers WJ, Bonke IM, Hollen J. Intra-atrial reentry as a mechanism for atrial flutter induced by acetylcholine and rapid pacing in the dog. Circulation 1984 70 123-35. 

Ibutilide Ibutilide (Corvert) is an blocker that in some systems also activates an inward Na current. The action-potential-prolonging effect of the drug may arise from either mechanism. Ibutilide is administered as a rapid infusion (1 mg over 10 minutes) for the immediate conversion of atrial fibrillation or flutter to sinus rhythm. The drug s efficacy rate is higher in patients with atrial flutter (50 to 70%) than in those with atrial fibrillation (30 to 50%). In atrial fibrillation, the conversion rate is lower in those in whom the arrhythmia has been present for weeks or months compared with those in whom it has been present for days. The major toxicity with ibutilide is torsade de pointes, which occurs in up to 6% of patients and requires immediate... 

UseAs sulfate for extrasystoles and atrial flutter, also for acute treatment. Not only Q. but also quinine are used in investigations of the mechanisms of multiple drug resistance of cancer cells against a series of chemotherapeutic agents. For biosynthesis, see Cinchona alkaloids. 

Atrial fibrillation For the prevention of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms and paroxysmal supraventricular tachycardias (PSVT), including atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, and other supraventricular tachycardias of unspecified mechanism associated with disabling symptoms in patients without structural heart disease. 

Altered rate of automatic discharge or abnormality of the mechanism by which an impulse is generated from a centre in the nodes or conducting tissue, is one cause of cardiac arrhythmia, e.g. atrial fibrillation, flutter or tachycardia. 

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