Atrial tachycardia

Is characterized by the presence of three or more atrial premature beats, and an atrial rate of between 140 and 250 BPM (Fig. 6.19). P waves, best seen in leads II or Vi are sometime present and usually hidden in the preceding T waves. The rhythm is regular. Atrial Tachycardia can also cause loss of atrial kick and a reduced cardiac output if sustained. 

Caffeine and other stimulants Physical/emotional stress Hypoxia 

The contribution of atrial contraction before ventricular systole that increases ventricular ejection efficiency. 

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Cardiac glycosides have a small ratio of toxic to therapeutic concentration. Possible adverse effects are nausea, vomiting, abdominal pain, diarrhoea, fatigue, headache, drowsiness, colour vision disturbances, sinus bradycardia, premature ventricular complexes, AV-block, bigeminy, atrial tachycardia with AV-Block, ventricular fibrillation. There are several mechanisms relevant for their toxic action (Table 2). 

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... 

Abnormal initiation of electrical impulses occurs as a result of abnormal automaticity. If the automaticity of the SA node increases, this results in an increased rate of generation of impulses and a rapid heart rate (sinus tachycardia). If other cardiac fibers become abnormally automatic, such that the rate of initiation of spontaneous impulses exceeds that of the SA node, other types of tachyarrhythmias may occur. Many cardiac fibers possess the capability for automaticity, including the atrial tissue, the AV node, the Purkinje fibers, and the ventricular tissue. In addition, fibers with the capability of initiating and conducting electrical impulses are present in the pulmonary veins. Abnormal atrial automaticity may result in premature atrial contractions or may precipitate atrial tachycardia or atrial fibrillation (AF) abnormal AV nodal automaticity may result in junctional tachycardia (the AV node is also sometimes referred to as the AV junction). Abnormal automaticity in the ventricles may result in ventricular premature depolarizations (VPDs) or may precipitate ventricular tachycardia (VT) or ventricular fibrillation (VF). In addition, abnormal automaticity originating from the pulmonary veins is a precipitant of AF. 

In a patient who has had attacks of paroxysmal atrial tachycardia, an ideal prophylactic drug is... 

Common supraventricular tachycardias requiring drug treatment are atrial fibrillation (AF) or atrial flutter, paroxysmal supraventricular tachycardia (PSVT), and automatic atrial tachycardias. Other common supraventricular arrhythmias that usually do not require drug therapy are not discussed in this chapter (e.g., premature atrial complexes, wandering atrial pacemaker, sinus arrhythmia, sinus tachycardia). 

Automatic atrial tachycardias such as multifocal atrial tachycardia appear to arise from supraventricular foci with enhanced automatic properties. Severe pulmonary disease is the underlying precipitating disorder in 60% to 80% of patients. 

Type II drugs include /Tadrenergic antagonists clinically relevant mechanisms result from their antiadrenergic actions. /3- Blockers are most useful in tachycardias in which nodal tissues are abnormally automatic or are a portion of a reentrant loop. These agents are also helpful in slowing ventricular response in atrial tachycardias (e.g., AF) by their effects on the AV node. 

If tachycardia persists, the need for additional treatment is determined by symptoms. Patients with asymptomatic atrial tachycardia and relatively slow ventricular response usually require no drug therapy. 

Cardiovascular manifestations include hypertension and cardiac arrhythmias (e.g., heart block, atrial flutter, paroxysmal atrial tachycardia, ventricular fibrillation, and digitalis-induced arrhythmias). In severe hypokalemia (serum concentration <2.5 mEq/L), ECG effects include ST-segment depression or flattening, T-wave inversion, and U-wave elevation. 

Atrial natriuretic peptide (ANP), 5 186-187 Atrial tachycardia, 5 101, 104, 108 Atrioventricular node, 5 80 Atromid-S, 5 145-146... 

Procainamide is intended for treating paroxysmal atrial tachycardia, atrial fibrillation, prematnre ventricular contraction, and ventricnlar tachycardia. For qnickly reaching therapeutic concentrations, parentemal introdnction of procainamide is preferred over cynidine. Synonyms of this drng are amidoprocaine, cardiorythmine, novocainamide, pronestyl, and others. 

PABA para-amino benzoic acid PAT paroxysmal atrial tachycardia pc after eating (Latin post cibum )... 

The clinical uses of these drugs are associated with their potent vasoconstrictor action. They are used to restore or maintain blood pressure during spinal anesthesia and certain other hypotensive states. The reflex bradycardia induced by their rapid intravenous injection has been used to terminate attacks of paroxysmal atrial tachycardia. Phenylephrine is commonly used as a nasal decongestant, although occasional nasal mucosal... 

Procainamide is an effective antiarrhythmic agent when given in sufficient doses at relatively short (3-4 hours) dosage intervals. Procainamide is useful in the treatment of premature atrial contractions, paroxysmal atrial tachycardia, and atrial fibrillation of recent onset. Procainamide is only moderately effective in converting atrial flutter or chronic atrial fibrillation to sinus rhythm, although it has... 

Procainamide Atrial tachycardia, ventricular tachycardia Premature ventricular contractions... 

Verapamil is useful for slowing the ventricular response to atrial tachyarrhythmias, such as atrial flutter and fibrillation. Verapamil is also effective in arrhythmias supported by enhanced automaticity, such as ectopic atrial tachycardia and idiopathic left ventricular tachycardia. 

Rapid loading dose for the management and treatment of CHF control ofventricular rate In patients with atrial fibrillation-, treatment and prevention of recurrent paroxysmal atrial tachycardia PO Initially, 0.5-0.75 mg, additional doses of 0.125-0.375 mg at 6-to8-hr intervals. Range 0.75-1.25 mg. IV 0.6-1 mg. 

Maintenance dosage for CHF control of ventricular rate in patients with atrial fibrillation treatment and prevention of recurrent paroxysmal atrial tachycardia PO, IV... 

Maintenance of normal sinus rhythm after conversion of atrial fibrillation or flutter, prevention of premature atrial, AV, and ventricular contractions paroxysmal atrial tachycardia paroxysmal AV functional rhythm atrial fibrillation atrial flatter paroxysmal ventricular tachycardia not associated with complete heart block PO 100-600 mg q4-6h. (Long-acting) 324-972 mg q8-12h. IV 200-400 mg. 

Vomiting is common in patients with digitalis overdose. Hyperkalemia may be caused by acute digitalis overdose or severe poisoning, whereas hypokalemia may be present in patients as a result of long-term diuretic treatment. (Digitalis does not cause hypokalemia.) A variety of cardiac rhythm disturbances may occur, including sinus bradycardia, AV block, atrial tachycardia with block, accelerated junctional rhythm, premature ventricular beats, bidirectional ventricular tachycardia, and other ventricular arrhythmias. 

Unifocal or multiform ventricular premature contractions, ventricular tachycardia, atrioventricular dissociation, accelerated junctional rhythm, and atrial tachycardia with block... 

Digitoxin and related drugs are used as cardiac stimulants, causing a positive inotropic effect. Thus, they increase the strength and intensity of the contractions and so are used in the treatment of heart failure. Because they slow the electrical conduction between atria and ventricles, they can also be used in the treatment of atrial fibrillation, atrial tachycardia, and atrial flu ter. 

In addition to vomiting and diarrhea, severe toxicity can occur with erroneous or intentional overdoses. These include cardiac arrythmias and atrial tachycardia with atrial-ventricular (AV) block. These effects are due to increased intracellular calcium. Hyperkalemia also occurs. Disturbances of cognitive function, including visual disturbances, delirium, and convulsion are also adverse effects resulting from neuronal effects. 

Sun, H., Gaspo, R., Eeblanc, N., and Nattel, S. (1998). Cellular Mechanisms of Atrial Contractile Dysfunction Caused by Sustained Atrial Tachycardia. Circulation 98(7) 719—27. 

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