Atrioventricular dissociation

The arrhythmias mainly observed are ventricular tachycardias, ventricular premature depolarizations and accelerated idioventricular rhythms as well as atrioventricular dissociation. 

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

Halothane has the highest blood/gas partition coefficient of the volatile anaesthetic agents and recovery from halothane anaesthesia is comparatively slow. It is pleasant to breathe and is second choice to sevoflurane for inhalational induction of anaesthesia. Halothane reduces cardiac output more than any of the other volatile anaesthetics. It sensitises the heart to the arrhythmic effects of catecholamines and hypercapnia arrhythmias are common, in particular atrioventricular dissociation, nodal rhythm and ventricular extrasystoles. Halothane can trigger malignant hyperthermia in those who are genetically predisposed (see p. 363). 

In adults, atrioventricular dissociation was common and in children atrial rhythm disturbances (1). In volunteers, atropine in doses of 1.6 mg/70 kg/minute causes episodes of nodal rhythm with absent P waves on the electrocardiogram (2) the episodes occurred before the heart rate had increased under the influence of the drug. In healthy men being anesthetized for dental surgery a dose of only 0.4 mg atropine intravenously 5 minutes before induction caused reductions in mean arterial pressure, stroke volume, and total peripheral resistance (3). 

Cardiac dysrhythmias are generally considered to be less frequent, or at least less severe, with enflurane than with halothane (5,6). However, caution in the use of adrenaline is advisable, especially in patients with cardiac disease or hjrperthyroidism. Isorhythmic atrioventricular dissociation was seen in 16 of 105 patients after the use of 1.0-1.5% enflurane (7). 

Chander S. Isorhythmic atrioventricular dissociation during enflurane anesthesia. South Med J 1982 75(8) 945-50. 

Veratrum poisoning can cause heartburn and vomiting, bradydysrhythmias, atrioventricular dissociation, and vasodilatation with hypotension (22,23). It can be fatal (24). 

Other cardiovascular effects include widening of the QRS complex, atrioventricular dissociation, heart block, sinus arrest, and cardiac arrest (23,24). 

Occasionally nodal rhythm, atrioventricular dissociation, and tachydysrhythmias (such as ventricular extra beats or even bigeminy) develop, but these usually occur in association with halothane. 

Symptoms of overdose include nausea, vomiting, transient visual or auditory deficits, drowsiness, and seizures followed by severe cardiac arrhythmias, shock, or cardiorespiratory arrest. Hypotension may be severe and intractable, producing metabolic acidosis and end-organ failure. Cardiac conduction disturbances include complete atrioventricular dissociation, QRS and QT prolongation, severe bradycardia, and ventricular fibrillation. Acute ingestions of 30-50 mg kg of chloroquine in adults and as little as 300 mg in children are potentially fatal. 

Ishikawa T, Imamura T, Koiwaya Y, Tanaka K, Atrioventricular dissociation and sinus arrest... 

Lillehei CW, Gott VL, Hodges PC, Long DM, Bakken EE (1960) Transistor pacemaker for treatment of complete atrioventricular dissociation. JAMA 172 2006-2010... 

Procainamide INa (primary) and IKr (secondary) blockade Slows conduction velocity and pacemaker rate prolongs action potential duration and dissociates from INa channel with intermediate kinetics direct depressant effects on sinoatrial (SA) and atrioventricular (AV) nodes Most atrial and ventricular arrhythmias drug of second choice for most sustained ventricular arrhythmias associated with acute myocardial infarction Oral, IV, IM eliminated by hepatic metabolism to /V-acetylprocainamide (NAPA see text) and renal elimination NAPA implicated in torsade de pointes in patients with renal failure Toxicity Hypotension long-term therapy produces reversible lupus-related symptoms... 

These alkaloids exhibited effects on cardiac rhythm quite like that seen ivith digitalis. Low doses induced slowdng without atrioventricular conduction dissociation. Larger doses might induce bigeminal rhythms (2 1 and 3 1 were seen). A prolongation of the PR interval was observed in... 

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