Fibrillation atrial

Is the most commonly encountered arrhythmia. Atrial Fibrillation (AF) increases in incidence with age. It is caused by multiple electrical triggers (multiple ectopic foci) occurring in the atria (Fig. 6.20), most commonly occurring around the region of the pulmonary veins. 

As a result of these multiple triggers the atrial rate becomes very high, up to 600 BPM. Fortunately, not all of these impulses are conducted to the ventricles as this would be haemodynamically catastrophic. A ventricular rate below 100 BPM is termed controlled AF , whereas a ventricular response of more than 100 BPM is termed uncontrolled or fast AF, which may cause damaging haemodynamic changes. 

The high atrial rate causes the atria to librillate rapidly this in turn means the atria cannot fill adequately before anptying. This subsequently results in a loss of atrial kick and a reduction in cardiac output. There is also the risk of clot formation as the atria do not anpty adequately. Potential clots could migrate to other parts of the body with serious consequences, such as stroke. 

The ECG characteristics of AF are best seen in the rhythm strip on the ECG (usually lead 11 or Vi) (Figs. 6.21 and 6.22). The rhythm is irregularly irregular, this is because there is no repeated pattern to the irregularity. 

The other primary feature of AF is the complete absence of P waves and the presence of a chaotic baseline consisting of fibrillatory or f waves (Fig. 6.21). There are three main types of Atrial Fibrillation, comprised of  

More than 50% of patients with cerebral embolism have atrial fibrillation. In the majority of these patients, the underlying cardiac disease is nonvalvular. The risk of ischemic stroke and atrial fibrillation increases with age, reaching a cumulative risk of 35% during a patient s lifetime. Combined results from several randomized trials show that warfarin reduces the risk of stroke in patients with nonrheumatic atrial fibrillation by 68% (to 1.4% per year), with an excess incidence of major hemorrhage (including intracranial) of only 0.3% per year. 

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Reentry mechanism Intranodal (AV node) reentry Extranodal reentry Reentrant tachyarrhythmia Atrial flutter Atrial fibrillation Ventricular tachycardia Ventricular fibrillation Conduction B/ocks ... 

QuinidJne. Quinidine, an alkaloid obtained from cinchona bark (Sinchona sp.), is the dextrorotatory stereoisomer of quinine [130-95-0] (see Alkaloids). The first use of quinidine for the treatment of atrial fibrillation was reported in 1918 (12). The sulfate, gluconate, and polygalacturonate salts are used in clinical practice. The dmg is given mainly by the oral (po) route, rarely by the intravenous (iv) route of adniinistration. It is the most frequentiy prescribed po antiarrhythmic agent in the United States. The clinical uses of quinidine include suppression of atrial and ventricular extrasystoles and serious ventricular arrhythmias (1 3). 

Dlgltoxin. Digitoxin is a cardiac glycoside obtained from Digitalis purpurea. Digitoxin is indicated in the treatment of atrial flutter, atrial fibrillation, and supraventricular tachycardia. Its electrophysiologic and adverse effects are similar to those described for digoxin (87). 

Verapamil. Verapamil hydrochloride (see Table 1) is a synthetic papaverine [58-74-2] C2qH2 N04, derivative that was originally studied as a smooth muscle relaxant. It was later found to have properties of a new class of dmgs that inhibited transmembrane calcium movements. It is a (+),(—) racemic mixture. The (+)-isomer has local anesthetic properties and may exert effects on the fast sodium channel and slow phase 0 depolarization of the action potential. The (—)-isomer affects the slow calcium channel. Verapamil is an effective antiarrhythmic agent for supraventricular AV nodal reentrant arrhythmias (V1-2) and for controlling the ventricular response to atrial fibrillation (1,2,71—73). 

Newly developed class III drugs comprise dofetilide, a specific Ik, blocker, and ibutilide, which blocks IKl and activates the slow iNa- Both drugs lack hemodynamic side effects. These drugs are scheduled for the treatment of atrial fibrillation and atrial flutter. As with class HI drugs, they can induce torsade de pointes arrhythmia. 

The most common arrhythmia in humans is atrial fibrillation. Because of the lack of rhythmic atrial activation, irregular ventricular rhythms and thromboembolism result. There are two possible therapeutic goals ... 

Coumarin is also widely used for long-term anticoagulation in chronic atrial fibrillation (particularly to avoid cardioembolic strokes), to prevent DVT or PE in patients with chronic hypercoagulability (e.g., congenital AT or protein C deficiency), or to prevent... 

Cardiac arrhythmia with a rapid and irregular activity in different areas within the upper chambers (atria) of the heart is also known as atrial fibrillation. 

The clinical indications of cardiac glycosides are tachyarrhythmic atrial fibrillation or flutter, as well as... 

Kvl.5 In human atria, the Kvl.5 presents the ultrarapid delayed rectifier that contributes to the repolarization in the early phase of cardiac action potential. Selective blockers of Kvl.5 channels could be potentially beneficial in the treatment of atrial fibrillation because blocking Kvl. 5 could delay repolarization and prolong refractoriness selectively in cardiac myocytes. Examples for Kvl.5 blockers include AVE0118, S9947, and analogs of diphenyl phosphine oxide (DPO). 

The cardiotonics are used to treat HF and atrial fibrillation. Atrial fibrillation is a cardiac arrhythmia characterized by rapid contractions of the atrial myocardium, resulting in an irregular and often rapid ventricular rate. See Chapter 40 for more information on various arrhythmias and treatment. 

Atrial fibrillation Irregular and rapid atrial contraction, resulting in a quivering of the atria and causing an irregular and inefficient ventricular contraction... 

The uses of the antiarrhythmic drug are given in the Summaiy Drug Table Antiarrhythmic Drug3. In general these drugp are used to prevent and treat cardiac arrhythmias, such as premature ventricular contractions (PVCs), ventricular tachycardia (VT), premature atrial contractions (PACs), paroxysmal atrial tachycardia (PAT), atrial fibrillation, and atrial flutter. Some of the antiarrhythmic dru are used for other... 

Prevention and treatment of atrial fibrillation with embolization... 

Systemic anaphylaxis in man is frequently accompanied by electrocardiographic alterations ischemic ST waves, arrhythmias and atrial fibrillation [6-11]. Anaphylactic reactions after insect stings can lead to coronary spasm or acute myocardial infarction [12, 13]. Myocardial infarction can also occur as a consequence of idiopathic... 

Fontana L Paroxysmal atrial fibrillation after insect sting. J Allergy Clin Immunol 1996 98 759. 24... 

Expert opinion is a source, frequently elicited by survey, that is used to obtain information where no or few data are available. For example, in our experience with a multicountry evaluation of health care resource utilization in atrial fibrillation, very few country-specific published data were available on this subject. Thus the decision-analytic model was supplemented with data from a physician expert panel survey to determine initial management approach (rate control vs. cardioversion) first-, second-, and third-line agents doses and durations of therapy type and frequency of studies that would be performed to initiate and monitor therapy type and frequency of adverse events, by body system and the resources used to manage them place of treatment and adverse consequences of lack of atrial fibrillation control and cost of these consequences, for example, stroke, congestive heart failure. This method may also be used in testing the robustness of the analysis [30]. 

Singh S, Singh B, Reda D, et al. [Abdellatif M]. Comparison of sotalol vs. amio-darone in maintaining stability of sinus rhythm in subjects with atrial Fibrillation (Sotalol-Amiodarone Atrial Fibrillation Effectiveness Trial [SAFE-T]). Am J Cardiol 2003 92 468-72. 

The Heparin in Acute Embolic Stroke Trial (HAEST) was a multicenter, randomized trial of the effect of LMWH (dalteparin 100 lU/kg sc twice daily) or aspirin (160 mg once daily) for the acute treatment of 449 patients with ischemic stroke and atrial fibrillation (AF). The primary outcome was the rate of recurrent stroke within 14 days. No difference in rates of early recurrence (8.5% dalteparin treated vs. 7.5% aspirin treated) or good 3-month functional outcome was found. The frequency of early slCH was 2.7% on dalteparin versus 1.8% on aspirin. 

Berge E, Abdelnoor M, Nakstad PH, Sandset PM, on behalf of the Haest Study Group. Low molecular-weight heparin versus aspirin in patients with acute ischemic stroke and atrial fibrillation a double blind randomised study. Lancet 2000 335 1205-1210. 

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