18 Failure of adenosine to terminate supraventricular tachycardia in neonates

Adenosine and pediatric supraventricular tachycardia in the emergency department: multicenter study and review

STUDY OBJECTIVE

To determine the frequency of successful cardioversion and the adverse effects of adenosine treatment in pediatric emergency department patients with supraventricular tachycardia (SVT).

METHODS

This was a multicenter descriptive study with both prospective (convenience sample) and retrospective (chart review) patient entry. The setting was 7 urban pediatric EDs with a yearly census range of 22,000 to 70,000 visits. Pediatric patients 18 years of age and younger who received intravenous adenosine for presumed SVT were eligible.

RESULTS

Six investigators from 7 pediatric EDs entered 82 patients with 98 presumed SVT episodes (52 prospective and 46 retrospective) into the study. Twenty-five episodes occurred in children younger than 1 year of age. Eight patients had congenital heart disease, 59 had a history of SVT, 43 were taking cardiac medications (digoxin in 27), 13 had a history of asthma, and 25 presented in compensated cardiogenic shock. A total of 193 intravenous doses of adenosine were administered; doses were classified as low (<.1 mg/kg [n=18]), medium (.1 to <.2 mg/kg [n=116]), or high (>/=.2 mg/kg [n=59]). The dose range was.03 to.5 mg/kg, and only 2 doses were higher than.3 mg/kg. A total of 95 patient-events were determined to be SVT, all but 5 of which were atrioventricular (AV) node-dependent; 3 events were ventricular tachycardia. The overall cardioversion success rate of adenosine was 72% (71/98), and that for AV node-dependent SVT was 79% (71/90). Cardioversion was successful for 4 patient-events at a low dose, 44 at a medium dose, and 23 at a high dose of adenosine. Adverse effects occurred in 22 patients, and no patient had bronchospasm or hemodynamically significant arrhythmia.

CONCLUSION

Intravenous administration of adenosine led to successful cardioversion in 72% of pediatric ED patient-events that were presumed to be SVT. A dose range of.1 to.3 mg/kg was found to be most effective. Adenosine was not associated with significant adverse effects.

Recognition and management of childhood cardiac arrhythmias

Cardiac arrhythmias are common in children, but most of them are benign and do not signify underlying heart disease. However, the main tachyarrhythmias (SVT and VT) can cause cardiovascular collapse, and should therefore be treated promptly. Drug treatment is generally effective and is appropriate in stable patients. DC shock is the treatment of choice in patients with compromised circulation. There is a wide array of antiarrhythmic drugs and though they are generally safe, most of them have the potential for serious adverse effects. Hence, there is a need to exercise caution and balanced judgement in prescribing them. It is perhaps best for the general duty paediatric staff to be familiar with a select few, and stick to them if possible. Management of most cases of cardiac arrhythmia in children is within the competence of non-cardiologist paediatric staff. But in some instances cardiology referral will be required, either for further investigations, for decision regarding longterm drug therapy, or for more technical management modalities.

Management of infants, children, and adolescents with paroxysmal supraventricular tachycardia

Several acceptable options are available for the successful management of children either with an acute PSVT episode or with ongoing episodes. These options include the "no treatment" management approach. Although an example of an algorithm used in one center is provided for this Medical Progress article, other algorithms also are successfully practiced among pediatric cardiologists together with primary care pediatricians. Current and ongoing updated data related to the important factors of presenting symptoms, natural history, results of the treatment options, and the risk/ benefit ratios of the treatment options are essential when one is choosing the specific management approach.