Value and limitations of adenosine in the diagnosis and treatment of narrow and broad complex tachycardias.

Abstract

SUMMARY The diagnostic and therapeutic potential of intravenous adenosine was studied in 64 patients during 92 episodes of regular sustained tachycardia. In 40 patients who had narrow complex tachycardias (QRS <0-12 s) adenosine (2-5-25 mg) restored sinus rhythm in 25 with junctional tachycardias (46 of 48 episodes) and produced atrioventricular block to reveal atrial or sinus tachycardia in 15. In 24 patients with broad complex tachycardias (QRS > 0 12 s) adenosine terminated the tachycardias in six patients and revealed atrial or sinus arrhythmias in four. The tachycardias persisted in 14 patients despite doses up to 20 mg, but adenosine allowed the diagnosis of ventricular tachycardia with retrograde atrial activation in two patients by producing transient ventriculoatrial dissociation. Diagnosis based on adenosine induced atrioventricular nodal block was correct in all patients with narrow complex tachycardias and in 92% of those with broad complex tachycardias, compared with correct electrocardiographic diagnoses in 90% and 75% respectively. Adenosine gave diagnostic information additional to the electrocardiogram in 25%. The response to adenosine in broad complex tachycardias identified those of supraventricular origin with 90% sensitivity, 93% specificity, and 92% predictive accuracy. Adenosine restored sinus rhythm in all patients with junctional reentrant tachycardias, but in 10 (35%) the arrhythmias recurred within two minutes. Symptomatic side effects (dyspnoea, chest pain, flushing, headache) were reported by 40 (63%) patients and, although transient, were severe in 23 (36%). There were ventricular pauses ofover 2 s in 16% of patients, the longest pause being 6*1 s.Adenosine is ofvalue in the diagnosis and treatment of narrow and broad complex tachycardias, but its use is limited by symptomatic side effects, a tenfold range in minimal effective dosage, occasional action at sites other than the atrioventricular node, and early recurrence of arrhythmia.Adenosine is a naturally occurring, rapidly metabolised compound that produces transient atrioventricular nodal block in humans when injected intravenously.' It can terminate reentrant supraventricular tachycardias that involve the atrioventricular node,' while in tachycardias of atrial origin it may be of diagnostic value, because adenosine induced atrioventricular block slows the ventricular rate and reveals the unaffected atrial arrhythmia.2 Such diagnostic and therapeutic effects of adenosine should be of most value in broad complex Requests for reprints to Dr A C Rankin,

Part 8: Advanced Life Support

“…350 Adenosine Adenosine may aid in diagnosing VT, but it will not terminate it (LOE 4). 351,352 Calcium Channel Blockers The evidence for the use of calcium channel blockers in VT is conflicting, with most studies opposing their use (LOE 4), 353354,355 but 1 study supported the use as long as coronary disease was not present (LOE 5). 356 …”

“…Five studies involving more than 300 patients (LOE 4) 351,352,[373][374][375] demonstrated that adenosine could safely be administered in regular wide-complex tachycardia: it converted wide-complex tachycardia secondary to supraventricular tachycardia to normal sinus rhythm, but rarely terminated VT. One small study showed poor rates of conversion to sinus rhythm in patients known to have VT (LOE 4). 344 No patient in these trials had serious adverse events; however, there are case reports in patients with irregular wide-complex tachycardia (generally pre-excited atrial fibrillation) in whom VF was precipitated by adenosine (LOE 4).…”

Adenosine-induced non-sustained polymorphic ventricular tachycardia

“…Premature isolated atrial and ventricular complexes are often observed after adenosine-induced termination of tachycardias' 1 '. The rare occurrence of short runs of ventricular tachycardias has been quoted' 2 ' 31 , but no serious consequences of this proarrhythmic effect have been reported' 4 '. Despite extensive research on the cardiac and cardiovascular effects of adenosine 13 ', the pathophysiological mechanism of the premature ventricular contractions that develop after adenosine-induced termination of a supraventricular tachycardia remains unknown.…”

Adenosine: An Effective and Safe Antiarrhythmic Drug in Pediatrics

“…Therefore it might be expected that the drug exerts almost no antiarrhythmic effects on primary atrial tachyarrhythmias (i.e., atrial fibrillation and atrial flutter) as well as intraatrial reentrant and automatic atrial tachycardia [58,77]. Termination of atrial flutter and focal atrial tachycardia, however, has occasionally been reported [60,66,77]. It has been shown that adenosine is capable of terminating sinus node reentrant tachycardia and atrial tachycardia owing to triggered activity.…”