Adenosine supraventricular arrhythmias

Adenosine (Adenocard) is an endogenous nucleoside that is a product of the metabolism of adenosine triphosphate. It is used for the rapid termination of supraventricular arrhythmias following rapid bolus dosing. 

Belardinelli et al. 1989, 1995 Shryock and Belardinelli 1997). The depressant effects of adenosine on A-V nodal cells through activation of A( receptors and IK ado explains the clinical efficacy of adenosine to terminate certain forms of supraventricular arrhythmias (DiMarco et al. 1983, 1984, 1990). 

Adenosine is the treatment of choice for diagnosis and reversal of supraventricular arrhythmias. Verapamil is an alternative for the management of narrow complex tachycardias. Amiodarone is the most effective drug at reversing atrial fibrillation, and in prevention of ventricular arrhythmias, but has several adverse effects. 

Adenosine Negative chronotropic effect Hypersensitivity Effect on sinus node of denervated heart Life-threatening asystole (>0.5 min) may occur if used to treat supraventricular arrhythmia or stress testing... 

ADENOSINE Adenosine (adenocard) is a nucleoside that is administered as a rapid intravenous bolus for the acute termination of reentrant supraventricular arrhythmias. Rare cases of ventricular tachycardia in patients with otherwise normal hearts are thought to be DAD-mediated and can be terminated by adenosine. Adenosine also has been used to produce controlled hypotension during some surgical procedures and in the diagnosis of coronary artery disease. 

Supraventricular bradycardia is treated by implantation of a pacemaker device or has been treated pharmacologically with atropine. Supraventricular paroxysmal tachycardia is treated with aj marine or praj marine. Supraventricular tachyarrhythmias or AV reentrant arrhythmia typically can be terminated using adenosine. 

The answer is e. (Hardman, pp 858-874.) Because verapamil, a Ca channel blocker, has a selective depressing action on AV nodal tissue, it is an ideal drug for both immediate and prophylactic therapy of supraventricular tachycardia (SVT). Nifedipine, another Ca channel blocker, has little effect on SAT Lidocaine and adenosine are parenteral drugs with short ha If-lives and, thus, are not suitable for prophylactic therapy. Procainamide is more suitable for ventricular arrhythmias and has the potential for serious adverse reactions with long-term use. 

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. 

As noted above, the antiarrhythmic drugs can modify impulse generation and conduction. More than a dozen such drugs that are potentially useful in treating arrhythmias are currently available. However, only a limited number of these agents are clinically beneficial in the treatment of selected arrhythmias. For example, the acute termination of ventricular tachycardia by lidocaine or supraventricular tachycardia by adenosine or verapamil are examples in which antiarrhythmic therapy results in decreased morbidity. In contrast, many of the antiarrhythmic agents are now known to have lethal proarrhythmic actions, that is, to cause arrhythmias. 

Rankin AC, Oldroyd KG, Chong E, Dow JW, Rae AP, Cobbe SM. Adenosine or adenosine triphosphate for supraventricular tachycardias Comparative double-blind randomized study in patients with spontaneous or inducible arrhythmias. Am Heart J 1990 119(2 Pt l) 316-23. 

In acute overdose, peak serum levels > 100 pg ml may be predictive of arrhythmias and seizures. The use of sustained-release formulations and the presence of pharmacobezors in the gut may make it difficult to determine peak serum levels. Sinus tachycardia is the most common cardiac sign of theophylline toxicity. Ventricular and supraventricular tachycardia, ectopic beats, hypotension, and cardiac arrest may occur. Metabolic acidosis, hypokalemia, hypercalcemia, and hyperglycemia may be seen. Tremulousness and agitation frequently occur. Intractable seizures may occur in severe intoxications, probably secondary to adenosine receptor antagonism in the brain. Onset of seizures is a poor prognostic indicator. Persistent vomiting is commonly seen and may interfere with attempts at therapy. 

Adenosine is most useful in the therapy of supraventricular tachycardias such as Wolff-Parkinson-White syndrome. It is not effective against normal atrial arrhythmias such as atrial flutter and atrial fibrillation. 

Ertan C, Atar I, Gulmez O, Atar A, Ozgul A, Aydinalp A, MUderrisoglu H, Ozin B. Adenosine-induced ventricular arrhythmias in patients with supraventricular tachycardias. Ann Noninvasive Electro-cardiol 2008 13(4) 386-90. 

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