In a control group B of five patients with manifest AP, sustained AF was induced by rapid atrial pacing during electrophysiological study and 12 mg of adenosine was administered.
The ECG and electrophysiologic features in the two groups were compared. All patients had a single manifest AP. The usual rate-slowing drugs used in atrial fibrillation are not effective, and digoxin and the nondihydropyridine calcium channel blockers eg, verapamil , diltiazem are contraindicated because they may increase the ventricular rate and cause ventricular fibrillation. If cardioversion is impossible, drugs that prolong the refractory period of the accessory connection should be used.
IV procainamide or amiodarone is preferred, but any class Ia, class Ic, or class III antiarrhythmic drug Drugs for Arrhythmias The need for treatment of arrhythmias depends on the symptoms and the seriousness of the arrhythmia. Do not give digoxin or nondihydropyridine calcium channel blockers eg, verapamil , diltiazem to patients with atrial fibrillation and Wolff-Parkinson-White syndrome because these drugs may trigger ventricular fibrillation.
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Arrhythmias and Conduction Disorders. Test your knowledge. The standard initial recommended dosage of adenosine is 6 mg, followed by a rapid saline flush.
In this article, the investigators found that 6 mg of adenosine converted Thus, paramedics and their medical directors should have pre-established protocols beginning with 6—12 mg. These protocol should conclude that a second 12 mg dose should be attempted if 12 mg is ineffective,. Treating Wide Complex Tachycardia Adenosine was initially considered useful in helping distinguish wide complex tachycardias due to aberrantly conducted PSVT vs. However, based on cases of patients deteriorating, many cautioned against trying this drug in any patient with wide complex tachycardia.
We now know that adenosine is safe and can help distinguish supraventricular arrhythmias from those originating in the ventricle for monomorphic wide complex tachycardias that are regular in rate and by definition, have the same QRS size and shape.
In the largest recent study of adenosine in wide complex tachycardias, patients were studied. Ninety percent of the SVTs responded to escalating doses of adenosine i. Only one patient with proven v tach responded to adenosine, and a second patient may have transiently slowed. The authors concluded that adenosine was safe as long as patients had regular monomorphic wide complexes and that adenosine was useful in helping distinguish between PSVT and v tach. Another thing is absolutely clear: Never give adenosine to a wide irregular tachycardia or a polymorphic multiple different QRS configurations tachycardia, such as Torsades de Pointes.
The side effects of adenosine are usually mild and transient, lasting just a few seconds. They include chest tightness, shortness of breath and a short sinus pause. Although more serious side effects can occur, such as hypotension, bradycardias and seizures, these side effects are rare in healthy patients with no underlying heart disease. Adenosine is contraindicated in patients who are likely to be harmed by its inappropriate use. Patients with irregular heart rates, especially atrial fibrillation, patients with PSVT mimics such as atrial flutter with conduction or sinus tachycardia in a dehydrated or stressed patient should never receive adenosine.
Adenosine should never be used in wide irregular tachycardias. Providers who are going to use adenosine must be experts in cardiac rhythm interpretation. They also must carefully review a rhythm strip prior to drug administration. Our recommended starting dosage is 12 mgs via IV push followed by a 10—20 cc rapid flush of saline.
References 1. Anti-Arrhytmic Drugs: Introduction. McGraw-Hill: New York. Antiarrhythmic Drugs. Ann Emerg Med.
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