Atrial tachycardia with block

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... 

The most commonly reported cardiac signs of toxicity are dysrhythmias, such as ventricular ectopic depolarization, second- and third-degree heart block, junctional tachycardia, atrial tachycardia with block, ventricular tachycardia, sinoatrial block, and sinus arrest. 

Lown B, Wyatt NF, Levine HD. Paroxysmal atrial tachycardia with block. Circulation 1960 21 129-43. 

Phenytoin (diphenylhydantoin, Dilantin) has been in use as an antiepileptic agent since 1938. Its ability to abolish ventricular tachycardia was noted much later. It is currently used in the treatment of several clinical arrhythmic disorders but especially in disorders induced by toxic dosage levels of digitalis, in ventricular tachycardia, and in atrial tachycardia with block. It is probably not effective in other types of atrial arrhythmias. 

B. With chronic intoxication, visual disturbances, weakness, sinus bradycardia, atrial fibrillation with slowed ventricular response rate or junctional escape rhythm, and ventricular arrhythmias (ventricular bigeminy or trigeminy, ventricular tachycardia, bidirectional tachycardia, and ventricular fibrillation) are common. Accelerated junctional tachycardia and paroxysmal atrial tachycardia with block are frequently seen. Hypokalemia and hypomagnesemia from chronic diuretic use may be evident and appear to worsen the tachyarrhythmias. 

May be difficult to differentiate atrial tachycardia with block from sinus arrhythmia with U waves... 

RED FLAG At toxic levels, digoxin may cause numerous arrhythmias, including paroxysmal atrial tachycardia with block, AV block, atrial and junctional tachyarrhythmias, and ventricular arrhythmias. 

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). 

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. 

Paroxysmal atrial tachycardia with Wenckebach (Mobitz type I) atrioventricular block has been reported in a patient with a serum digoxin concentration of 3.2 ng/ml (39) and in a patient who in error took three times the recommended dose (40). 

Spodick DH. Well concealed atrial tachycardia with Wenckebach (Mobitz 1) atrioventricular block digitalis toxicity. Am J Geriatr Cardiol 2001 10(1) 59. 

First degree, second degree (Mobitz type I), third degree AV junctional escape rhythms, junctional tachycardia Atrial arrhythmias with slowed AV conduction or AV block Particularly paroxysmal atrial tachycardia with AV block Sinus bradycardia... 

Digoxin Atrial tachycardia with AV block ventricular bigeminy and others DAD-related triggered activity (+T vagal tone) Antidigoxin antibodies Coexistence of abnormal impulses with abnormal sinus or AV nodal function... 

If a patient is over-digitalised, signs of toxicity will occur, which may include loss of appetite, nausea and vomiting, and bradycardia. These symptoms are often used as clinical indicators of toxicity, and a pulse rate of less than 60 bpm is usually considered to be an indication of over-treatment. Note that paroxysmal atrial tachycardia with AV block and junctional tachycardia can also occur as a result of digitalis toxicity. Other symptoms inelude visual disturbances, headache, drowsiness and occasionally diarrhoea. Death may result from cardiac arrhythmias. Patients treated for eardiac arrhythmias can therefore demonstrate arrhythmias when they are both under- as well as over-digitalised. 

The differential diagnosis of this regular narrow QRS complex rhythm with 1 1 AV relationship at such a short interval between R and P waves is essentially typical AV node reentrant tachycardia (AVNRT) vs. atrial tachycardia with a severe first degree AV block. The interval between each R wave and subsequent P wave appears fixed. An atrial or sinus tachycardia does not have this fixed relationship between R and subsequent P wave, and typically may display variation in the interval between them. Thus, from the EGMs this is most likely typical AVNRT. 

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. 

Drugs that block beta-1 receptors on the myocardium are one of the mainstays in arrhythmia treatment. Beta blockers are effective because they decrease the excitatory effects of the sympathetic nervous system and related catecholamines (norepinephrine and epinephrine) on the heart.5,28 This effect typically decreases cardiac automaticity and prolongs the effective refractory period, thus slowing heart rate.5 Beta blockers also slow down conduction through the myocardium, and are especially useful in controlling function of the atrioventricular node.21 Hence, these drugs are most effective in treating atrial tachycardias such as atrial fibrillation.23 Some ventricular arrhythmias may also respond to treatment with beta blockers. 

A-V junctional escape rhythms, junctional tachycardia atrial rhythms with slowed A-V conduction or A-V block... 

A 74-year-old man was to receive a combined sciatic nerve and psoas compartment block for a total hip arthroplasty the classic Labat s approach was used and 30 ml of 0.75% ropivacaine was injected over 1.5 minutes, after which he suddenly became unresponsive and developed tonic-clonic movements. Propofol was administered and the seizure resolved, but he developed sinus bradycardia with progressive lengthening of the QRS interval, which converted to nodal bradycardia. A ventricular escape rhythm at 20/minute with T wave inversion was treated with ephedrine 10 mg and adrenahne 0.1 mg, resulting in supraventricular tachycardia with transient atrial fibrillation. 

Three patients taking digoxin and either reserpine or whole root Rauwolfia serpentina developed arrhythmias, namely atrial tachyeardia with 4 1 Wenckebach irregular block, ventricular bigeminy and tachycardia, and atrial fibrillation. A large number of other patients received both drugs without problems. ... 

Oral Premature atrial, AV junctional and ventricular contractions paroxysmal atrial (supraventricular) tachycardia paroxysmal AV junctional rhythm atrial flutter paroxysmal and chronic atrial fibrillation established atrial fibrillation when therapy is appropriate paroxysmal ventricular tachycardia not associated with complete heart block maintenance therapy after electrical conversion of atrial fibrillation or flutter. Parenteral When oral therapy is not feasible or when rapid therapeutic effect is required. 

Verapamil IV- Do not administer concomitantly with IV -adrenergic blocking agents (within a few hours), because both may depress myocardial contractility and AV conduction ventricular tachycardia (VT), because use in patients with wide-complex VT (QRS 0.12 seconds or more) can result in marked hemodynamic deterioration and ventricular fibrillation atrial fibrillation or atrial flutter associated with an accessory bypass tract. 

The action potential duration and ERP of atrial muscle are both prolonged by propafenone. The electrophysiological effects persist beyond removal of the drug from the tissue. In patients with atrial flutter, fibrillation, or tachycardia, propafenone can slow the atrial rate, resulting in a change from 2 1 or 4 1 A-V block to 1 1 A-V conduction with a subsequent increase in the ventricular rate. 

Contraindications Atrial fibrillation or flutter associated with accessory conduction pathways, cardiogenic shock, CHF, second- or third-degree heart block, severe hypotension, sinus bradycardia, ventricular tachycardia, within several hours of IV beta-blocker therapy... 

Disturbances of cardiac rhythm (e.g., tachycardia, atrial fibrillation, ventricular flutter, and A-V or intraventricular block) are the most frequent causes of death. Thus, management of cardiac function is critical. If the patient survives the early phase, recovery without sequelae is probable, and vigorous resuscitative measures are important. A major clinical problem is determining when a patient is no longer in danger. Many patients with mild overdose have been hospitalized... 

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