Intravenous adenosine therapy accelerating rate of paroxysmal supraventricular tachycardia

Proarrhythmic effects of adenosine: a review of the literature

Adenosine is widely used as an antiarrhythmic agent for the investigation and management of both narrow complex and, less often, broad complex tachycardias. Over the past 10 years or so, reports of severe bradycardias and tachyarrhythmias being induced by this agent have appeared in the literature. As adenosine is increasingly used in emergency departments and indeed outside the hospital setting, a greater awareness of these potential problems is important. In this paper the evidence for such effects is summarised, and the mechanisms involved discussed.

Proarrhythmic effects of adenosine: one decade of clinical data

In 1989, adenosine was introduced into the American clinical setting as an antiarrhythmic drug for the acute management of reentrant supraventricular tachycardia involving the atrioventricular node. During this decade of use, evidence for proarrhythmic effects of the drug have been documented. In addition to the mostly benign transient episodes of atrial fibrillation, several cases of life-threatening ventricular arrhythmias induced by adenosine have been reported. This article summarizes the proarrhythmic effects of adenosine as they were reported in the literature as well as data from the manufacturer files. The causes of these adverse effects of adenosine are analyzed, and factors to be considered before using the drug are discussed.

Use of adenosine in patients hospitalized in a university medical center

PURPOSE

Adenosine is a useful agent for the diagnosis and termination of tachycardias. The purpose of this study was to identify the rhythms for which adenosine is prescribed in hospitalized adults and to identify the reasons for its misuse.

PATIENTS AND METHODS

Data were collected from the medical records of 100 patients who received intravenous adenosine while hospitalized at a university medical center. The characteristics of the patients, rhythms treated with adenosine, and dosages of adenosine were analyzed. In addition, internal medicine house officers were administered a questionnaire referring to an electrocardiogram of atrial fibrillation with a rapid ventricular response.

RESULTS

The arrhythmias for which adenosine was administered consisted of regular, narrow-QRS complex tachycardias in 33% of patients; atrial fibrillation in 32% of patients; regular, wide-QRS complex tachycardias in 23% of patients; atrial flutter in 10% of patients, and multifocal atrial tachycardia in 2% of patients. The mean (+/-SD) number of doses of adenosine given to each patient was 1.6+/-0.8, and the mean dose of adenosine was 7.8+/-2.8 mg. Internal medicine house officers prescribed 70% of the doses of adenosine and were as likely to use it for patients with atrial fibrillation as were surgical house officers. There was a 2% incidence of proarrhythmia, including asystole and polymorphic ventricular tachycardia. Thirty-one percent of the 100 house officers in our survey misdiagnosed a 12-lead electrocardiogram of rapid atrial fibrillation as paroxysmal supraventricular tachycardia, suggesting that adenosine may have been misused for atrial fibrillation because of errors in rhythm diagnosis. Only 5% of those who correctly diagnosed atrial fibrillation also answered that adenosine would be likely to terminate the arrhythmia, suggesting that a misunderstanding that adenosine terminates atrial fibrillation is not a common reason for its misuse.

CONCLUSIONS

Approximately 40% of hospitalized adults who are treated with adenosine receive the medication unnecessarily for atrial fibrillation or atrial flutter, and this misuse results in unnecessary expenses and risks of adverse effects. The primary reason that adenosine is misused for atrial fibrillation is the inability to recognize that rhythm on an electrocardiogram. House officers need additional education on the electrocardiographic recognition of atrial fibrillation.

Life-threatening alterations in heart rate after the use of adenosine in atrial flutter

Adenosine has become the preferred treatment for common types of supraventricular tachycardia because it is extremely effective and rarely associated with with serious side effects. It has also been advocated as an intervention for diagnostic use to assess uncommon types of tachycardia. Evidence is shown in this report that adenosine was associated with dangerous worsening of arrhythmia in patients with atrial flutter. In two patients, adenosine precipitated acceleration of ventricular response, in one case necessitating emergent cardioversion. Both patients had atrial flutter with 2 to 1 atrioventricular block that evolved into 1 to 1 atrioventricular conduction. In three other patients, adenosine was associated with prolonged bradyasystole and hypotension. In each of the five patients, adenosine was given in a standard fashion (6 or 12 mg). In summary, adenosine should be recognized as a potentially dangerous intervention in patients with atrial flutter. If it is used for diagnostic purposes, resuscitative equipment should be readily available.

Intravenous adenosine as first-line prehospital management of narrow-complex tachycardias by EMS personnel without direct physician control

This study was conducted to evaluate the safety and efficacy of intravenous adenosine therapy for prehospital treatment of narrow-complex tachycardias with a presumptive field diagnosis of paroxysmal supraventricular tachycardia (PSVT) by paramedics without direct physician control. A ten-month prospective case series was designed in an urban EMS system that has paramedics operating under standing orders before physician radio contact. All patients with PSVT field diagnosis were included. Diagnosis of PSVT was made by regular, narrow-complex tachycardia with a heart rate greater than 160 beats/min by field ECG. Interpretation was performed solely by paramedics; ECG transmission was not available. In hemodynamically stable patients, vagal maneuvers were followed by intravenous placement and administration of adenosine was recommended by the manufacturer. If three adenosine boluses failed to convert the arrhythmia, patients were monitored and transported, with electrical cardioversion available. Data collection included demographic, history, medications, vital signs, and EGG tracings. Of 14 included patients, 31 were correctly diagnosed with PSVT (75.6%), with mean ventricular rate of 205 beats/min (SD 7 beats/min); one had sinus tachycardia; nine had atrial fibrillation (AF) (22%). Of the 31 cases correctly diagnosed as PSVT, 28 converted to sinus rhythm after adenosine (90.3%). Of those converted, 16 required a single dose (57.1%), nine required one additional dose (32.1%), and three required two additional doses (10.8%). None reverted to PSVT after adenosine conversion during the study period (conversion to arrival at emergency department). No significant difference in length of asystolic pause or in outcome was detected between the true PSVT cases and the AF cases receiving adenosine.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory failure following adenosine administration

Adenosine is frequently administered to convert the rhythm of patients with paroxysmal supraventricular tachycardia to sinus rhythm. Adverse reactions are common after its administration, but these have been short-lived because adenosine has a half-life of less than 10 seconds. This report describes a 54-year-old male patient with chronic obstructive pulmonary disease who presented with paroxysmal supraventricular tachycardia at 200 beats/min. A 12-mg bolus injection of adenosine aggravated mild bronchospasm and produced respiratory failure. The patient subsequently required ventilatory support for 9 days. The presence of bronchoconstriction should be considered as a possible contraindication to the administration of intravenous adenosine.

Acceleration of the ventricular response in paroxysmal lone atrial fibrillation following the injection of adenosine

Treatment of a patient with new onset atrial fibrillation with intravenous adenosine was followed by transient but significant acceleration of the ventricular rate. This unexpected response to adenosine can be explained by a predominating increase in sympathetic discharge relative to the drug's direct atrial ventricular nodal-blocking action.