Atrial flutter treatment

Dlgltoxin. Digitoxin is a cardiac glycoside obtained from Digitalis purpurea. Digitoxin is indicated in the treatment of atrial flutter, atrial fibrillation, and supraventricular tachycardia. Its electrophysiologic and adverse effects are similar to those described for digoxin (87). 

Newly developed class III drugs comprise dofetilide, a specific Ik, blocker, and ibutilide, which blocks IKl and activates the slow iNa- Both drugs lack hemodynamic side effects. These drugs are scheduled for the treatment of atrial fibrillation and atrial flutter. As with class HI drugs, they can induce torsade de pointes arrhythmia. 

Common supraventricular tachycardias requiring drug treatment are atrial fibrillation (AF) or atrial flutter, paroxysmal supraventricular tachycardia (PSVT), and automatic atrial tachycardias. Other common supraventricular arrhythmias that usually do not require drug therapy are not discussed in this chapter (e.g., premature atrial complexes, wandering atrial pacemaker, sinus arrhythmia, sinus tachycardia). 

The desired outcome depends on the underlying arrhythmia. For example, the ultimate treatment goals of treating AF or atrial flutter are restoring sinus rhythm, preventing thromboembolic complications, and preventing further recurrences. 

Indications. Verapamil is used as an antiarrhythmic drug in supraventricular tachyarrhythmias. In atrial flutter or fibrillation, it is effective in reducing ventricular rate by virtue of inhibiting AV-conduction. Verapamil is also employed in the prophylaxis of angina pectoris attacks (p. 308) and the treatment of hypertension (p. 312). Adverse effects Because of verapamil s effects on the sinus node, a drop in blood pressure fails to evoke a reflex tachycardia Heart rate hardly changes bradycardia may even develop. AV-block and myocardial insufficiency can occur. Patients frequently complain of constipation. 

Procainamide is an effective antiarrhythmic agent when given in sufficient doses at relatively short (3-4 hours) dosage intervals. Procainamide is useful in the treatment of premature atrial contractions, paroxysmal atrial tachycardia, and atrial fibrillation of recent onset. Procainamide is only moderately effective in converting atrial flutter or chronic atrial fibrillation to sinus rhythm, although it has... 

Dofetilide is approved for the treatment of atrial fibrillation and atrial flutter. Because of the lack of significant hemodynamic effects, dofetilide may be useful in patients with CHF who are in need of therapy for supraventricular tachyarrhythmias. Dofetilide is not indicated for use in the setting of ventricular arrhythmias. 

It is indicated in tachyarrhythmias associated with WPW syndrome, atrial flutter and fibrillation, paroxysmal tachyarrhythmias not responding to other agents. Ventricular tachycardia and ventricular arrhythmia refractory to other treatment. 

This drug is only approved for oral administration in some countries. It is effective for conversion of atrial flutter or fibrillation or ischaemia-induced ventricular arrhythmias. It has significant anticholinergic properties (10% of the potency of atropine) that can offset its direct depressant effects on sinus and AV nodes. It has a pronounced negative inotropic effect and should be administered with caution to patients with a history of congestive heart failure. For acute treatment of perioperative arrhythmias it is given intravenously 0.2 mg-kg-1 over 10-15 min, then 0.2 mg-kg-1 over the next 45 min and a maintenance infusion of 0.4 mg-kg-l-h-1. 

This agent also has some class lA and class II effects. It is effective for the treatment of ventricular and supraventricular tachycardias (AV nodal and accessory pathway re-entry, atrial flutter and fibrillation). Propafenone is useful in converting recent-onset atrial fibrillation or flutter to sinus rhythm, and for terminating paroxysmal supraventricular tachycardia. Its pro-ariythmic and myocardial depressant effects limit its use, especially in patients with poor ventricular function. 

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. 

Quinidine is used for the maintenance of normal sinus rhythm in patients with atrial flutter or fibrillation. It is also used occasionally to treat patients with ventricular tachycardia. Because of its cardiac and extracardiac side effects, its use has decreased considerably in recent years and is now largely restricted to patients with normal (but arrhythmic) hearts. In randomized, controlled clinical trials, quinidine-treated patients are twice as likely to remain in normal sinus rhythm compared with controls. However, drug treatment was associated with a twofold to threefold increase in mortality. 

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. 

In a subsequent investigation by the author (3) arylated furan- and thiophenecarbox-amides, (III), were prepared and were effective in the treatment of atrial fibrillation or atrial flutters. 

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.)... 

It is doubtful whether this differs in its origins or sequelae from atrial fibrillation. The ventricular rate is usually faster (typically, half an atrial rate of 300, where 2 1 block is present), which is too fast to leave without treatment. Since, similarly, the patient is unlikely to have been in this rhythm for a prolonged period, there is less likelihood that atrial thrombus has accumulated. Conversion without prior anticoagulation may occasionally be considered safe but anticoagulation is usually also needed. Patients should not be left in chronic atrial flutter, and DC conversion will usually restore either sinus rhythm or result in atrial fibrillation. The latter is treated as above. Patients who fail to convert, or who revert to atrial flutter should be referred for consideration of radiofrequency ablation that is highly effective and may remove the cause of the atrial flutter > 80% of cases. 

There is some anecdotal evidence that atrioventricular nodal blockade with verapamil or a beta-blocker can also be effective. However, in two cases the addition of a beta-blocker (either atenolol or metoprolol) to treatment with class I antidysrhythmic drugs (cibenzoline in one case and flecainide in the other) did not prevent the occurrence of atrial flutter with a 1 1 response (47). However, the author suggested that in these cases, although the beta-blockers had not suppressed the dysrhythmia, they had at least improved the patient s tolerance of it. In both cases the uses of class I antidysrhythmic drugs was contraindicated by virtue of structural damage, in the first case due to mitral valvular disease and in the second due to an ischemic cardiomyopathy. 

Calcium channel blockers can worsen myasthenic syndromes. Myasthenia gravis can deteriorate with oral verapamil (58). A patient with Lambert-Eaton syndrome and a small-cell carcinoma of the lung developed respiratory failure within hours of starting treatment with verapamil for atrial flutter, and required assisted ventilation (59). Only after verapamil had been withdrawn did breathing improve. Verapamil affects calcium channels in nerve membranes in animals, but the experimental concentrations used exceeded those found in clinical practice (59). Thus, the evidence for a drug-related effect is circumstantial. In another case, diltiazem triggered Lambert-Eaton syndrome, which improved with drug withdrawal (60). 

MackstaUer LL, Marcus FI. Rapid ventricular response due to treatment of atrial flutter or fibrillation with Class I antiarrhythmic drugs. Arm Noninvasive Electrocardiol 2000 5 101. ... 

Kawabata M, Hirao K, Horikawa T, Suzuki K, Motokawa K, Suzuki F, Azegami K, Hiejima K. Syncope in patients with atrial flutter during treatment with class Ic antiarrhythmic drugs. J Electrocardiol 2001 34(l) 65-72. 

The safety of oral propafenone in the treatment of dysrhythmias has been studied retrospectively in infants and children (40). There were significant electrophysiolo-gical adverse effects and prodysrhythmia in 15 of 772 patients (1.9%). These included sinus node dysfunction in four, complete atrioventricular block in two, aggravation of supraventricular tachycardia in two, acceleration of ventricular rate during atrial flutter in one, ventricular prodysrhythmia in five, and unexplained sjmcope in one. Cardiac arrest or sudden death occurred in five patients (0.6%) two had a supraventricular tachycardia due to Wolff-Parkinson-White syndrome the other three had structural heart disease. Adverse cardiac events were more common in the presence of structural heart disease and there was no difference between patients with supraventricular and ventricular dysrhythmias. 

Adenosine is the treatment of choice for PSVT. It slows the conduction and interrupts the re-entry pathways through the atrioventricular node, restoring dysrhythmia to NSR. Adenosine is not effective in treating other atrial arrhythmias such as atrial flutter or atrial fibrillation or in treating ventricular arrhythmias. Adenosine is rapidly degraded... 

Verapamil, proprietaiy name Calan, is a calcium channel blocker that is effective in the treatment of various cardiovascular disorders, including angina (classical and variant), arrhythmias (paroxysmal supraventricular tachycardia), atrial flutter, atrial fibrillation, hypertrophic cardiomyopathy (idiopathic hypertrophic subaortic stenosis), hypertension, congestive heart failure, and Raynaud s phenomenon, along with the preservation of ischemic myocardium and the treatment of migraine headaches. 

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. 

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