Not-so-typical typical atrioventricular nodal re-entrant tachycardia in an adolescent

Dysrhythmias are commonly encountered in the Emergency Department (ED). Timely management and recognition of dysrhythmia in the ED is essential and crucial. Physicians working in the ED should be familiar with atypical presentation of common dysrhythmias. This case report illustrates atrioventricular nodal re-entrant tachycardia (AVNRT) with an unusually slow heart rate in an adolescent. A 16-year-old male presented to the ED twice for palpitations. His electrocardiograms showed narrow complex tachycardia with absent P waves. Electrophysiology studies confirmed typical slow-fast AVNRT which was treated successfully with radiofrequency ablation of the slow pathway. Diagnosing rare dysrhythmias or common dysrhythmias which manifest atypically can be challenging for non-cardiologists. Although AVNRT generally occurs with a heart rate of >130 bpm, emergency physicians should be aware that AVNRT can take place with a relatively slower rate in both the elderly and young.

Utilizing the Cool-Down Phenomenon to Differentiate Supraventricular Tachycardias in a Patient with COVID-19 Infection

A 63-year-old male patient with a history of hypertension, diabetes mellitus type 2, prostate cancer and class two obesity was admitted for encephalopathy. During his hospital stay he developed narrow complex tachycardia and it was difficult to definitively diagnose the underlying arrhythmia. Observation of the cool down phenomenon on telemetry strip allowed us to make the diagnosis of atrial tachycardia and elegantly rule out other causes. We report this interesting case of narrow complex tachycardia.

Incessant Automatic Atrial Tachycardia in a Neonate Successfully Treated with Nadolol and Closely Spaced Doses of Flecainide: A Case Report

Supraventricular tachyarrhythmia (SVT) is the most common type of arrhythmia in childhood. Management can be challenging with an associated risk of mortality. A female neonate was diagnosed with episodes of SVT, controlled antenatally with digoxin. Flecainide was commenced prophylactically at birth. Despite treatment, the infant developed a narrow complex tachycardia at 5 days of age. The electrocardiogram features were suggestive of either re-entry tachycardia or of automatic atrial tachycardia (AAT). Following several unsuccessful treatments, a wide complex tachycardia developed. A transesophageal electrophysiological study led to a diagnosis of AAT. Stable sinus rhythm was finally achieved through increasing daily administrations of flecainide up to six times a day, in association with nadolol. The shortening of intervals to this extent has never been reported before and supports the evidence of a personal, age-specific variability in pharmacokinetics of flecainide. Larger studies are needed to better define the appropriate dose and timing of administration.