Intravenous Adenocard (adenosine injection) is indicated for the following.Conversion to sinus rhythm of paroxysmal supraventricular tachycardia (PSVT), including that associated with accessory bypass tracts (Wolff-Parkinson-White Syndrome).

When clinically advisable, appropriate vagal maneuvers (e.g., Valsalva maneuver), should be attempted prior to Adenocard administration.It is important to be sure the Adenocard solution actually reaches the systemic circulation (see DOSAGE AND ADMINISTRATION).Adenocard does not convert atrial flutter, atrial fibrillation, or ventricular tachycardia to normal sinus rhythm.

In the presence of atrial flutter or atrial fibrillation, a transient modest slowing of ventricular response may occur immediately following Adenocard administration.

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Paroxysmal supraventricular tachycardia -- An episodic form of supraventricular tachycardia, with abrupt onset and termination.

Wolff-Parkinson-White Syndrome -- A form of ventricular pre-excitation characterized by a short PR interval and a long QRS interval with a delta wave. In this syndrome, atrial impulse conducts to the HEART VENTRICLES via an accessory pathway located between the wall of the right or left atria and the ventricles, known as the bundle of Kent. The inherited form can be caused by mutation of PRKAG2 gene encoding a gamma-2 regulatory subunit of AMP-activated protein kinase.

Atrial Flutter -- Rapid, irregular atrial contractions caused by a block of electrical impulse conduction in the right atrium and a reentrant wave front traveling up the inter-atrial septum and down the right atrial free wall or vice versa. Unlike ATRIAL FIBRILLATION which is caused by abnormal impulse generation, typical atrial flutter is caused by abnormal impulse conduction. As in atrial fibrillation, patients with atrial flutter cannot effectively pump blood into the lower chambers of the heart (HEART VENTRICLES).

Atrial Fibrillation -- Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation.

Tachycardia, Ventricular -- An abnormally rapid ventricular rhythm usually in excess of 150 beats per minute. It is generated within the ventricle below the BUNDLE OF HIS, either as autonomic impulse formation or reentrant impulse conduction. Depending on the etiology, onset of ventricular tachycardia can be paroxysmal (sudden) or nonparoxysmal, its wide QRS complexes can be uniform or polymorphic, and the ventricular beating may be independent of the atrial beating (AV dissociation).

Intravenous Adenocard (adenosine injection) is contraindicated in:Second- or third-degree A-V block (except in patients with a functioning artificial pacemaker).Sinus node disease, such as sick sinus syndrome or symptomatic bradycardia (except in patients with a functioning artificial pacemaker).Known hypersensitivity to adenosine.

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Disease -- A definite pathologic process with a characteristic set of signs and symptoms. It may affect the whole body or any of its parts, and its etiology, pathology, and prognosis may be known or unknown.

Sick Sinus Syndrome -- A condition caused by dysfunctions related to the SINOATRIAL NODE including impulse generation (CARDIAC SINUS ARREST) and impulse conduction (SINOATRIAL EXIT BLOCK). It is characterized by persistent BRADYCARDIA, chronic ATRIAL FIBRILLATION, and failure to resume sinus rhythm following CARDIOVERSION. This syndrome can be congenital or acquired, particularly after surgical correction for heart defects.

Hypersensitivity -- Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.

Adenocard (adenosine injection) exerts its effect by decreasing conduction through the A-V node and may produce a short lasting first-, second- or third-degree heart block.

Appropriate therapy should be instituted as needed.

Patients who develop high-level block on one dose of Adenocard should not be given additional doses.

Because of the very short half-life of adenosine, these effects are generally self-limiting.Transient or prolonged episodes of asystole have been reported with fatal outcomes in some cases.

Rarely, ventricular fibrillation has been reported following Adenocard administration, including both resuscitated and fatal events.

In most instances, these cases were associated with the concomitant use of digoxin and, less frequently with digoxin and verapamil.

Although no causal relationship or drug-drug interaction has been established, Adenocard should be used with caution in patients receiving digoxin or digoxin and verapamil in combination.

Appropriate resuscitative measures should be available.