This EKG comes courtesy of Dr. Pilat.
A 5 month old boy presented to the ED with intermittent fast heart rate observed by the mother. No change in the level of activity or alertness, normal feeding, no SOB or any other additional complaints. No recent illness. Physical exam revealed a well-appearing, well-nourished baby boy, smiling, playful, active, good eye contact, normal work of breathing, no retractions, lungs CTA b/l, tachycardia, abdomen soft NT/ND, normal skin color and temperature, no cyanosis, capillary refill<2 sec.
V/S: P – recorded at triage as 148, R 28, BP 85/59
The EKG is below.
1. What does the EKG demonstrate?
2. How would you manage this baby?
The EKG demonstrates a regular narrow complex tachycardia at a rate of approximately 220 with absent P waves. This is consistent with SVT.
Infants in SVT can be managed with vagal maneuvers. If they are unsuccessful, give adenosine 0.1 mg/kg.
This patient received 3 doses of adenosine (0.1, 0.2, 0.2) and then converted.
The post-conversion EKG (below) shows a sinus rhythm with tall P waves (best seen in leads II, III, aVF, V1 and V2) consistent with right atrial enlargement. There is also a short PR interval with a delta wave (best seen in leads V4-V6) consistent with pre-excitation.
This patient had Ebstein’s anomaly. This is a congenital malformation of the tricuspid valve where the valve is located “too low” in the right ventricle. This results in the upper portion of the right ventricle effectively becoming part of the right atrium (known as “atrialization of the right ventricle”). The functional portion of the right ventricle is very small. Most patients with Ebstein’s anomaly also have tricuspid regurgitation and an atrial septal defect.
Patients with Ebstein’s anomaly often present with cyanosis and signs of right-sided heart failure. They are also at risk for arrhythmias including narrow complex SVT, wide complex tachycardia, a-flutter, a-fib, v-tach and sudden cardiac death.
The abnormal tricuspid valve results in direct muscle connection from the right atrium to the right ventricle. This can serve as an accessory pathway which puts the patient at risk for pre-excitation arrhythmias (WPW). 10-25% of patients with Ebstein’s anomaly will have WPW.
Management of arrhythmias in patients with Ebstein’s anomaly is the same as in the general population.
This patient was admitted to the hospital and seen by pediatric cardiology. Her echo showed mild to moderate tricuspid regurgitation, normal RV pressure, dilated right atrium.
She was started on propranolol and discharged home.
(Attenhofer Jost, et al. Ebstein’s Anomaly. Circulation. 2007;115:277-285)
(Loomba et al, Association of Atrial Tachycarrhythmias with Atrial Septal Defect, Ebstein’s Anomaly and Fontan Patients. Expert Review of Cardiovascular Therapy 2011;9:887.)