Atrial flutter cardioversion

Atrial flutter cardioversion o Same as atrial fibrillation... 

Duration of atrial fibrillation/atrial flutter >48 h or unknown, o Electrical or chemical cardioversion in a patient without adequate anticoagulation may cause embolization of atrial thrombi. 

Resynchronize after each cardioversion ° Paroxysmal SVT and atrial flutter often respond to lower energy doses (may start with 50J)... 

Ibutilide is approved for the chemical cardioversion of recent-onset atrial fibrillation and atrial flutter. Ibutilide appears to be more effective in terminating atrial flutter than atrial fibrillation. It can also lower the defibrilla-... 

Supraventricular tachycardia is the major arrhythmia indication for verapamil. Adenosine or verapamil are preferred over older treatments (propranolol, digoxin, edrophonium, vasoconstrictor agents, and cardioversion) for termination. Verapamil can also reduce the ventricular rate in atrial fibrillation and flutter. It only rarely converts atrial flutter and fibrillation to sinus rhythm. Verapamil is occasionally useful in ventricular arrhythmias. However, intravenous verapamil in a patient with sustained ventricular tachycardia can cause hemodynamic collapse. 

Arnold AZ, et al. Role of prophylactic anticoagulation for direct current cardioversion in patients with atrial fibrillation or atrial flutter. J Am Coll Cardiol 1992 19(4) 851-855. 

Therapeutic uses Quinidine is used in the treatment of a wide variety of arrhythmias, including atrial, AV junctional, and ventricular tachyarrhythmias. Quinidine is used to maintain sinus rhythm after direct current cardioversion of atrial flutter or fibrillation and to prevent frequent ventricular tachycardia. 

FIGURE 6-1. Algorithm for the treatment of atrial fibrillation (AF) and atrial flutter. °lf AF <48 hours, anticoagulation prior to cardioversion is unnecessary may consider transesophageal echocardiogram (TEE) if patient has risk factors for stroke. Ablation may be considered for patients who fail or do not tolerate one antiarrhythmic drug (AAD). Chronic antithrombotic therapy should be considered in all patients with AF and risk factors for stroke regardless of whether or not they remain in sinus rhythm. (BB, 8-blocker CCB, calcium channel blocker p.e., verapamil or diltiazem] DCC, direct-current cardioversion.)... 

Atrial flutter, benefiting by the vagus nerve action of shortening the refractory period of the atrial muscle so that flutter is converted to fibrillation (in which state the ventricular rate is more readily controlled). Electrical cardioversion is preferred. 

Conversion of atrial fibrillation and flutter In a crossover, placebo-controlled study in 16 patients with recent onset atrial fibrillation, cardioversion was achieved in two of six patients who received dofetilide 8 micrograms/kg and in two of nine who received 12 micrograms/kg (41). None cardioverted with placebo. However, the average duration of atrial fibrillation was 35 days in those who cardioverted with dofetilide and 83 days in those who did not. The authors concluded that dofetilide had only limited effect in cardioverting atrial fibrillation of moderate duration. 

In a double-bhnd, placebo-controlled study in 325 patients with atrial fibrillation or flutter cardioversion, rates for dofetilide 125, 250, and 500 micrograms bd were 6.1, 9.8, and 30% respectively, compared with 1.2% with placebo (45). The probabihties of remaining in sinus rhythm at 1 year with dofetihde 125, 250, and 500 micrograms bd were 0.40, 0.37, and 0.58 respectively, and 0.25 for placebo. 

The adverse effects of a single oral dose of propafenone for cardioversion of recent-onset atrial fibrillation have been evaluated in a systematic review (18). The adverse effects were transient dysrhythmias (atrial flutter, bradycardia, pauses, and junctional rhythm), reversible widening of the QRS complex, transient hypotension, and mild non-cardiac effects (nausea, headache, gastrointestinal disturbances, dizziness, and paresthesia). 

FIGURE 17-6. Algorithm for the treatment of atrial fibrillation and atrial flutter. Sx = symptoms AVN = AV node DCC = direct-current cardioversion CCB = calcium channel antagonist (verapamil or diltiazem) BB = jS-blocker ASA = aspirin OHD = organic heart disease AADs = antiarrhythmic drugs INR = international normalized ratio MVD = mitral valve disease CHF = congestive heart failure HTN = hypertension DM = diabetes mellitus. 

There are several exceptions to this recommended process of anticoagulation. In patients with atrial fibrillation of less than 48 hours duration, anticoagulation prior to cardioversion probably is not necessary because there has not been sufficient time to form atrial thrombi. However, in most presentations of atrial fibrillation, the exact time of onset is unclear. In the past, patients with atrial flutter were felt to be at low risk for stroke, but current consensus recommendations... 

IBUTILIDE Ibutilide (corvert) is an blocker that may also activate 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 is higher in patients with atrial flutter (50-70%) than in those with atrial fibrillation (30-50%). 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 torsades de pointes, which occurs in up to 6% of patients and requires immediate cardioversion in up to one-third of these. The drug undergoes extensive first-pass metabohsm and so is not used oraUy. It is ehminated by hepatic metabohsm with a tj of 2-12 hours (mean, 6 hours). 

When intravenous ibutilide 2 mg was used for cardioversion of atrial fibrillation or flutter in 70 patients taking long-term amiodarone the QT interval was further prolonged (iiom 371 to 479 milliseconds). However, only one patient had an episode of non-sustained torsade de pointes. Ibutilide was effective within 30 minutes of infusion in 39% of patients with atrial flutter, and 54% of patients with fibrillation. Both amiodarone and ibutilide are class III antiarrhythmics and prolong the QT interval, with the consequent risk of torsade de pointes. The manufacturer recommends that they should not be used concurrently. However, the authors of the above report suggest that ibutilide may be useful for cardioversion in those already taking amiodarone. Combined use should be very well monitored. 

The increase in QTc interval after intravenous ibutilide 2 mg was less in patients treated with propafenone (5 patients) or flecainide (1 patient) than in 85 other patients who had taken ibutilide alone (34 versus 65 milliseconds). The effect appeared to be dose-related, with higher propafenone doses causing the largest attenuation in the ibutilide-induced QT prolongation. The efficacy of ibutilide was unaltered. In a further study, 71 patients with atrial fibrillation or atrial flutter receiving either propafenone 300 to 900 mg daily or flecainide 100 to 300 mg daily underwent cardioversion with a single intravenous dose of ibutilide 1 mg over 10 minutes, followed if necessary by a further dose after an interval of 10 minutes. Torsade de pointes occurred in one patient with profound sinus node suppression after cardioversion, but the mean ibutilide-induced QTc interval was attenuated (20 + 54 milliseconds compared to reported range of 47 to 90 milliseconds) without a decrease in efficacy. However, the authors note that the risk of sustained torsade de pointes in this study appears to be similar to that seen in other studies of ibutilide. ... 

Another use for defibrillators is to shock either atrial flutter or fibrillation, which are abnormally rapid atrial rhythms. These atrial rhythms are much less likely to spontaneously proceed rapidly to death than ventricular arrhythmias. Using electrical shock to treat rapid heart arrhythmias other than VF is usually referred to as cardioversion and hence some users refer to the tachycardia treatment devices as cardioverter—defibrillators. Cardiovertor and defibrillator treatment is different from pacemaker treatment (discussed elsewhere in this book) because a pacemaker stimulates a slowly beating heart and uses much weaker shocks. Pacemaking increases the rate of the relatively healthy heart, which increases blood flow. 

If patient hemodynamically unstable and with atrial flutter of 48 hours or less, immediate synchronized electrical cardioversion... 

With atrial flutter of more than 48 hours, anticoagulation therapy before and after cardioversion... 

In synchronized cardioversion, an electric current is delivered to the heart to correct an arrhythmia. This procedure may be done electively in a stable patient with recurrent atrial fibrillation or urgently in an unstable patient with such arrhythmias as PSVT, atrial flutter, atrial fibrillation, and VT with a pulse. 

If the patient is hemodynamically unstable and atrial flutter has lasted 48 hours or less, synchronized electrical cardioversion or coimtershock should be performed right away. 

If atrial flutter has lasted more than 48 horns, electrical cardioversion won t he performed unless the patient is adequately anticoagulated because of the increased risk of thromboembolism. 

Arruodarone is used in chronic ventricular arrhythmias in atrial fibrillation it both slows the ventricular response and may restore sinus rhythm it may be used to maintain sinus rhythm after cardioversion for atrial fibrillation or flutter. Amiodarone should no longer be used for the management of reentrant supraventricular tachycardias associated with the Wolff-Parkinson-White syndrome as radiofrequency ablation is preferable. 

Dofetilide has a small positive inotropic effect in animal hearts (15,33). In a double-blind, placebo-controlled study of oral dofetilide 125, 250, or 500 mg bd for the maintenance of sinus rhythm after cardioversion of sustained atrial fibrillation or flutter in 201 patients, there were small changes in echocardiographic measures of atrial contractility, but no changes in stroke volume or cardiac output (34). 

In a comparison of intravenous dofetihde (8 micrograms/kg n = 48), amiodarone (5mg/kg n=50), or placebo (n = 52) in converting atrial fibrillation or flutter to sinus rhythm in 150 patients, two patients given dofetilide had non-sustained ventricular tachycardias four had torsade de pointes, in one case requiring electrical cardioversion (53). 

DeCara JM, PoUak A, Dubrey S, Falk RH. Positive atrial inotropic effect of dofetilide after cardioversion of atrial fibrillation or flutter. Am J Cardiol 2000 86(6) 685-8. 

Murdock DK, Schumock GT, Kaliebe J, et al. Clinical and case comparison of ibutilide and direct-current cardioversion for atrial fibrillation and flutter. Am J Cardiol 2000 85 503-506. 

Gosselink ATM, Crijns HJM, VanGelderIC, et al. Low-dose amiodarone for maintenance of sinus rhythm after cardioversion of atrial fibrillation or flutter. JAMA 1992 267 3289-3292. 

Cardiovascular One case of torsade de pointes was observed in a series of 160 patients taking dofetilide, mean dose 428 mg/dose, for chemical cardioversion of atrial fibrillation or flutter, 50 of whom were also taking magnesium sulfate in an attempt to improve the chance of success [54 ]. The addition of magnesium sulfate resulted in a 107% increase in success rate. However, the patient with the dysrhythmia did not receive magnesium sulfate. 

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