Atrial ectopic beats

As with most data for reboxetine, this information primarily comes from summary papers rather than primary sources (473, 474). With this caveat, the adverse-effect profile of reboxetine is consistent with its pharmacology as an NSRI. Thus, it is similar to that of desipramine and maprotiline but without the risk of serious CNS (i.e., seizures, delirium) or cardiac (i.e., conduction disturbances) toxicity. The most common adverse effects of reboxetine are dry mouth, constipation, urinary hesitancy, increased sweating, insomnia, tachycardia, and vertigo. Whereas the first three adverse effects are commonly called anticholinergic, they are well known to occur with sympathomimetic drugs as well. In other words, these effects can be either the result of decreased cholinergic tone or increased sympathetic tone, although they tend to be more severe with the former than the latter. In contrast to TCAs, reboxetine does not directly interfere with intracardiac conduction. The tachycardia produced by reboxetine, however, can be associated with occasional atrial or ventricular ectopic beats in elderly patients. 

Haissaguerre M, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998 339(I0) 659 666. 

This occurs in otherwise healthy individuals, who possess an anomalous (accessory) atrioventricular pathway they often experience attacks of paroxj mal AV re-entrant tachycardia or atrial fibrillation. Drugs that both suppress the initiating ectopic beats and delay conduction through the accessory pathway are used to prevent attacks e.g. flecainide, sotalol or amiodarone. Verapamil and digoxin may increase conduction through the anomalous pathway and should not be used. Electrical conversion may be needed to restore sinus rhythm when the ventricular rate is very rapid. Radiofrequency ablation of aberrant pathways will almost certainly provide a cure. 

P-ARK An enzyme that phosphoylates the occupied form of a G-protein coupled receptor, e.g. the 6-adrenoceptor, leading to uncoupling of that receptor and desensitization. ARMI age-related memory impairment, arrhythmia (dysrhythmia) An abnormality of heart rhythm or rate of heartbeat, usually caused by disturbance of the electrical impulses and their conduction within the heart. They include ectopic beats (isolated irregular beats), tachycardias (too fast a heartbeat), bradycardias (too slow a heartbeat) and atrial flutter and ventricular fibrillation. Arthus reaction A severe local inflammatory response, a skin reaction characterized by erythema, oedema, necrosis, local haemorrhage. A type III hypersensitivity reaction. Arunlakshana and Schild plot See Schild plot, ascites fluid The fluid that accumulates in the peritoneal cavity during certain pathological conditions, aspiration The withdrawal of fluid or tissue from the body by suction. 

Chen SA, Hsieh MH, Tai CT, et al. Initiation of atrial fibrillation by ectopic beats originating from the pulmonary veins Electrophysiologic characteristics, pharmacologic responses and the effects of radiofrequency ablation. Circulation 1999 80 1527-1535. 

FIGURE 6.1 Initiation of atrial fibrillation (AF) with ectopic beats arising from the left superior pulmonary vein (PV). Shown are three surface leads (I, aVF, and VI), five intracardiac electrograms form the coronary sinus (CS prox to CS distal) and five electrograms from a catheter in the left superior PV (PV1 through PV5). After a sinus beat, a premature PV potential appears on PV3, which initiates AF (arrow). 

This common arrhythmia involves multiple ectopic foci of atrial cells creating a chaotic movement of impulses through the atria. The ventricular response is rapid (100-150 beats per minute) and irreguiar. 

Digoxin (see p. 158) shortens the refractory period in atrial and ventricular myocardial cells while prolonging the effective refractory period and diminishing conduction velocity in Purkinje fibers. Digoxin is used to control the ventricular response rate in atrial fibrillation and flutter. At toxic concentrations, digoxin causes ectopic ventricular beats that may result in ventricular tachycardia and fibrillation. [Note This arrhythmia is usually treated with lidocaine or phenytoin.]... 

Paroxysmal atrial tachycardia occurs with a sudden onset of 140-220 beats/minute, which may cease abruptly. The focus is ectopic—it can be anywhere in the atrium. 

Atrial Three or more consecutive ectopic atrial beats at 150 to 250 beats/minute rarely exceeds 250 beats/ minute... 

From a single ectopic focus or multiple atrial fod that supersede the SA node as pacemaker for one or more beats. 

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