P0884 - Fascicular Ventricular Tachycardia in a Neonate

Ventricular arrhythmias may involve the fascicular system and have been seen in both structurally normal and abnormal hearts. The posterior fascicle is the most commonly affected region and accounts for about 90% of cases of idiopathic fascicular ventricular tachycardia. This tachycardia often occurs in the absence of structural disease. The mechanism of this tachycardia is believed to be localized reentry close to the fascicle of the left bundle branch.

Our case begins with a 6-day-old full-term healthy male, whose mother had an uncomplicated pregnancy, presenting to the hospital emergency room after concerns from PCP’s office for rapid heart rate. Family cardiac history was nonexistent. On physical examination, heart rate of 221 beats per minute with otherwise stable vitals was found. His exam was positive for tachycardia and jaundice.

A stat echocardiogram was obtained and showed a structurally normal heart with patent foramen ovale. Normal biventricular systolic function was noted along with tachycardia including heart rates of 220-230 beats per minute. Initial EKG was interpreted as borderline wide QRS complex indicative of either supraventricular tachycardia, an aberrant rhythm, or ventricular tachycardia. Afterwards, 3 doses of adenosine were administered. Heart rate initially dropped but rebounded. He was transferred out for escalation of care and cardioversion.

Multiple cardioversion attempts were made with no resolution of tachyarrhythmia. He was started on a procainamide infusion without successful resolution. It was not until he was initiated on verapamil was there resolution of his tachycardia. He was subsequently transferred to neonatal intensive care for jaundice and elevated bilirubinemia. He was treated with light therapy but his value continued to rise and he was prepared for exchange transfusion with sepsis evaluation which found free air under the diaphragm. Exploratory laparotomy was performed where he was found to have a perforation of his cecum in a section showing areas of necrotic bowel. He was diagnosed with necrotizing enterocolitis.

Children can often tolerate rapid ventricular rates for many hours, but this condition should be treated as it can deteriorate into hypotension and ventricular fibrillation. In a hemodynamically stable patient, the drugs of choice for treatment include amiodarone, procainamide, or lidocaine. If the patient is hemodynamically unstable, they require DC cardioversion.

In this specific monomorphic ventricular tachycardia of fascicular ventricular tachycardia, treatment options involve verapamil which is contraindicated in neonates due to life-threatening cardiovascular collapse. Despite use of this medication, 20% of patients will still have breakthrough episodes. In those cases, alternate anti-arrhythmic medication or ablation should be considered. Ablation can be safely accomplished in pediatric infants weighing greater than 15 kg. Studies have shown a success rate of 72% with a recurrence rate of 18%. A common approach has been medical management until ablation can be attempted.