docnikki
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A 72-year-old man reports one month of episodic palpitations. He is not short of breath. The patient has a past medical history of stable angina and hypertension. A physical examination performed during the episode of palpitations shows a blood pressure 160/90 mm Hg, normal jugular venous pressure, and irregularly irregular heart sounds with a heart rate of 82/min. Mild bibasilar crackles are present. Echocardiography shows mild to moderate left ventricular hypertrophy and an ejection fraction of 50%.
Which of the following is true concerning this patient?
(A) Antiarrhythmic agents should be started first.
(B) Anticoagulation must be done only prior to cardioversion.
(C) Chronic coumadin should be started for every patient with atrial fibrillation.
(D) A beta-blocker, calcium-channel blocker, or digoxin should be started prior to using to lC and lA agents, as well as dofetilide.
(E) Amiodarone has the same efficacy rate in maintaining sinus rhythm after conversion of atrial fibrillation as other antiarrhythmic agents.
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| sandra
Forum Guru
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hey doc, are these step 2 qs?
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| farnsworth
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D
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| dr.wad
Forum Senior
Topics: 3
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yes D .....
class lA as disopyramide and class lc astecainide may increase atrioventricular conductions >>>>proarrhythmias.
so ccb , bb or digoxin should be given before.
not A >>>antiarrhythmics should be given after anticoagulats .
not B>>> anticoagulants should be given before and after cardioversion because the atrium may regain its contractility 4 weeks after cardioversion
not C >>> because in lone AF ( pt with AF without any other risk factor should not be given coumadin.
not E >>> actually i dont know if this correct or wrong ( just by exclusion i rule it out  )
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| docnikki
Forum Guru
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Great!
In the absence of severe cardiovascular compromise, slowing of ventricular rate becomes the initial therapeutic goal. This may be most rapidly accomplished with beta-adrenergic blockers and/or calcium-channel blockers. Both slow conduction within the AV node. Conversion to sinus rhythm with antiarrhythmic medications may then be attempted.
Patients who have had atrial fibrillation for >48 hours should be anticoagulated for 3 to 4 consecutive weeks before electrical or chemical cardioversion. Both pharmacological and electrical conversion of atrial fibrillation to sinus rhythm are associated with transient atrial stunning or electromechanical dissociation, in which the return of effective atrial mechanical function lags behind sinus activity for as long as 7 days. Recognition of this phenomenon supports the need for maintaining effective anticoagulation (INR 2 to 3) for at least 3 to 4 weeks after conversion. For patients with paroxysmal atrial fibrillation, anticoagulation should be maintained until a stable sinus rhythm has been present for several months. This can be maintained indefinitely if sinus rhythm cannot be maintained despite antiarrhythmic therapy and if the patient has a high risk for stroke, such as hypertension, mitral valve disease, heart failure, or diabetes. Even in the absence of these risk factors, patients above the age of 60 have an increased risk for stroke, and anticoagulation with warfarin should be considered. Younger patients without any of these risk factors can be maintained on aspirin alone.
Antiarrhythmic medications in either oral or intravenous form are modestly effective in restoring sinus rhythm. When antiarrhythmic agents, such as those in class lA (quinidine, procainamide, or disopyramide) or the flecainide-like agents (type 1C), are used, it is important to increase AV node refractoriness prior to administering such drugs. They have a vagolytic effect and speed up the heart rate.
Amiodarone has the highest efficacy rate in maintaining sinus rhythm after conversion of atrial fibrillation and also the lowest incidence of proarrhythmia (1 to 2% compared with 5 to 10% for other agents). Amiodarone is particularly effective in those with left ventricular dysfunction and has a much better efficacy in the setting of left ventricular dysfunction.
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