Atrial fibrillation digitalis

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). 

Homestam, B., Jerling, M., Karlsson, M.O., and Held, P. DAAf Trial Group, Intravenously administered digoxin in patients with acute atrial fibrillation a population pharmacokinetic/pharmacodynamic analysis based on the digitalis in acute atrial fibrillation trial, Eur.. Clin. Pharmacol., 58, 747-755, 2003. 

Atrial flutter Digitalis slows the heart normal sinus rhythm may appear. Often, flutter is converted to atrial fibrillation with a slow ventricular rate. 

Electrical cardioversion It may be desirable to reduce the dose of digoxin for 1 to 2 days prior to electrical cardioversion of atrial fibrillation to avoid the induction of ventricular arrhythmias, but physicians must consider the consequences of increasing the ventricular response if digoxin is withdrawn. If digitalis toxicity is suspected, delay elective cardioversion. If it is not prudent to delay cardioversion, select the lowest possible energy level to avoid provoking ventricular arrhythmias. Lab test abnormalities Periodically assess serum electrolytes and renal function (serum creatinine concentrations) the frequency of assessments will depend on the clinical setting. 

Although quinidine often is successful in producing normal sinus rhythm, its administration in the presence of a rapid atrial rate (flutter and possibly atrial fibrillation) can lead to a further and dangerous increase in the ventricular rate secondary to inhibition of basal vagal tone upon the A-V node. For this reason, digitalis should be used before quinidine when one is attempting to convert atrial flutter or atrial fibrillation to normal sinus rhythm... 

Propranolol alone or in conjunction with digitalis can help control the ventricular rate in patients with atrial flutter or atrial fibrillation. Patients with supraventricular extrasystoles and intermittent paroxysms of atrial fibrillation may benefit from (3-receptor blockade with propranolol. 

Digitalis is the drug of choice in atrial fibrillation for controlling ventricular rate. Its effect is due to the prolongation of the refractory period of the conducting tissue. The dose in so adjusted as to maintain the ventricular rate of 60 to 80 beats per minute at rest and approximately 100 beats per minute during light exercise. 

Digitalis (DIGOXIN) 0.25-0.5 mg IV for paroxysmal supraventricular tachycardia (PSVT), atrial flutter and atrial fibrillation... 

Give digitalis if systolic dysfunction with third heart sound or atrial fibrillation is present... 

Digoxin is indicated in patients with heart failure and atrial fibrillation. It is also most helpful in patients with a dilated heart and third heart sound. It is usually given only when diuretics and ACE inhibitors have failed to control symptoms. Only about 50% of patients with normal sinus rhythm (usually those with documented systolic dysfunction) will have relief of heart failure from digitalis. Better results are obtained in patients with atrial fibrillation. If the decision is made to use a cardiac glycoside, digoxin is the one chosen in most cases (and the only one available in the USA). When symptoms are mild, slow loading (digitalization) with 0.125-0.25 mg per day is safer and just as effective as the rapid method (0.5-0.75 mg every 8 hours for three doses, followed by 0.125-0.25 mg per day). 

Digitalis should be avoided in the therapy of arrhythmias associated with Wolff-Parkinson-White syndrome because it increases the probability of conduction of arrhythmic atrial impulses through the alternative rapidly conducting atrioventricular pathway. It is explicitly contraindicated in patients with Wolff-Parkinson-White syndrome and atrial fibrillation (see Chapter 14 Agents Used in Cardiac Arrhythmias). 

Approximately 25% of all patients with hypertrophic cardiomyopathy (HCM) have latent left ventricular outflow obstruction with an intraventricular gradient (I). Pathophysiologic features are asymmetric hypertrophy of the septum and a systolic anterior movement of the anterior leaflet. Medical treatment includes betablockers, and calcium antagonists of the verapamil type. Approximately 5— 10% of the patients with outflow obstruction are refractory to such negative inotropic therapy (2). Positive inotropic drugs such as digitalis or sympathomimetics are strictly contraindicated. In the presence of atrial fibrillation, anticoagulation therapy should be started. Since endocarditis is more common in patients with HCM because of turbulence in the left ventricle, prophylactic antibiotics should be administered for periods of potential bacteraemia. 

Digitalis glycosides augment contractile force and are likewise used in severe forms of insuf ciency, specifically in the presence of concomitant atrial fibrillation. Because of the narrow margin of safety, the digoxin dose must be adjusted individually in each patient. 

Digitalis can cause supraventricular extra beats or tachycardia. The combination of such dysrhythmias with atrioventricular block is particularly suggestive of digitalis toxicity and carries a high mortality rate (3,36). Rarely atrial fibrillation (37) and atrial flutter (38) may be attributed to digitalis toxicity. The frequency of atrioventricular nodal block is mentioned above. 

There have been many studies of the long-term efficacy of digitalis in patients in heart failure in sinus rhythm and also in patients with atrial fibrillation. These have been reviewed (SEDA-4, 123) (SEDA-14, 145) (SEDA-18, 196). The following is a brief resume. 

It produced a small reduction in hospitalizations due to heart failure (nine per 1000 patients-years) balanced by a significant increase in deaths from presumed dysrhythmias. Digitalis is therefore indicated for a small number of patients who have severe heart failure associated with sinus rhythm after treatment with diuretics, vasodilators, beta-blockers, and spironolactone. It remains the drug of first choice in patients with heart failure accompanied by fast atrial fibrillation, especially if due to myocardial or mitral valve disease. A trial of withdrawal of digitalis therapy can be considered in some cases (as noted in point 3 above). 

If the plasma digitalis concentration is below the target range in a patient whose condition is stable (for example atrial fibrillation with a ventricular rate of 80/minute) digitalis can usually be withdrawn safely. 

A placebo-controUed study of the use of propafenone 450-600 mg orally, either alone or in combination with digoxin, has been carried out in 176 patients with atrial fibrillation a further 70 patients were given digitalis plus quinidine (12). There were no significant differences across the groups in terms of percentage conversion to sinus rhjThm,... 

Digitalis glycosides are positive inotropic agents used in the management of patients with congestive heart failure. They control ventricular rate in supraventricular arrhythmias including atrial fibrillation and atrial flutter. 

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