Term Infant With Acute-Onset Tachycardia

A 2-day-old female term neonate with a giant omphalocele presents with acute-onset tachycardia.Prenatal course is complicated by gestational diabetes, iron-deficiency anemia, major depressive disorder, and hypothyroidism.Maternal medications are insulin glargine, metformin, sertraline, and levothyroxine.Prenatal laboratory study results are all normal.Prenatal imaging is notable for fetal giant omphalocele, intrauterine growth restriction, and a single umbilical artery. Fetal echocardiography shows normal cardiac anatomy.Born to a 32-year-old woman (gravida 1, para 0) at 39 weeks and 0 days by scheduled cesarean delivery, with rupture of membranes at delivery.Infant has good tone, respiratory effort, and a heart rate greater than 100 beats/min (bpm). The infant is directly placed on bubble continuous positive airway pressure (bCPAP) with a maximum fraction of inspired oxygen (FIO2) of 0.5, which is titrated to 0.3 before admission to the neonatal intensive care unit (NICU).Apgar scores are 8 and 9 at 1 and 5 minutes, respectively.Birth weight is 2940 g (26th percentile); length, 48 cm (27th percentile); and head circumference, 34.5 cm (70th percentile).A chest and abdominal radiograph obtained on admission shows normal lung fields, a Replogle tube terminating in the gastric body, and the presence of giant omphalocele overlying the abdomen (Figure 1). Over the first 36 hours, the infant remains hemodynamically stable and without respiratory distress. Pediatric surgery is consulted for comanagement of her giant omphalocele. At 48 hours of age, she undergoes peripherally inserted central catheter (PICC) placement to support long-term needs for parenteral nutrition. The initial radiograph after PICC placement shows migration of the PICC deep into the right atrium (Figure 2A). The PICC is subsequently retracted to the appropriate location (Figure 2B). After PICC placement, the infant develops acute tachycardia (Figure 2C).Temperature: 36.6 °CHeart rate: 198 to 220 bpm, occasionally as high as 270 bpmRespirations: 40 to 50 breaths/minBlood pressure: 87/63; mean, 70 mm HgOxygen saturation: 97% on bCPAP with a Positive End Expiratory Pressure (PEEP) of 5 mm Hg and FIO2 of 0.30Head: anterior fontanelle is soft, open, and flat; no scalp moldingFace: eyes are normally spaced and open spontaneouslyOropharynx: pink mucosa, intact palateRespiratory: lungs are clear to auscultation bilaterally with no retractionsCardiovascular: tachycardic; no murmur; lower-extremity pulses are equal and adequate; normal capillary refillAbdomen: abdomen is round and soft; giant omphalocele is present with an intact sac and umbilical cord cystGenitourinary: normal term female genitalia; patent anusNeurologic: awake, normal tone and strength, intermittent agitationSkin: pink, no rashesArterial blood gas: pH, 7.39; Pco2, 38 mm Hg; Pao2, 72 mm Hg; HCO3, 24 mmol/L; base excess, −1 mmol/LSerum lactate: 1.7 mmol/LSerum electrolytes: sodium, 137 mmol/L; potassium, 3.2 mmol/L; chloride, 108 mmol/L; CO2, 21 mmol/L; anion gap, 8 mmol/L; magnesium, 1.6 mg/dL; phosphate, 6.7 mg/dL; ionized calcium, 4.38 mg/dLAtrial flutterSinus tachycardia associated with acute painSupraventricular tachycardia (SVT)Ventricular tachycardiaOther reentrant tachycardiaAtrial flutter precipitated by PICC migrationThe infant receives one dose of fentanyl for pain control but remains tachycardic. A 12-lead electrocardiogram (ECG) is obtained, which reveals a narrow complex tachycardia with intermittent aberrant ventricular conduction, a heart rate of 230 bpm, and a QTc interval of 336 ms (Figure 3). With concern for SVT, vagal maneuvers are attempted by placement of ice on the infant’s face, which did not resolve the tachycardia. A repeat chest radiograph reveals PICC migration (Figure 4A); however, the infant remains tachycardic even after PICC retraction. A follow-up ECG shows narrow QRS tachycardia with a 2:1 conduction, regular rhythm with no aberration, an average heart rate of 200 bpm, PR interval of 68 ms, and QTc interval of 416 ms (Figure 4B). The infant remains hemodynamically stable during this time with intermittent desaturations.Due to prolonged and refractory tachycardia, adenosine 0.1 mg/kg is rapidly administered without response. An additional dose of adenosine 0.2 mg/kg is administered, which more clearly unmasks the presence of flutter waves (Figure 4C). The infant receives synchronized cardioversion with 1 J/kg with return to normal sinus rhythm. An echocardiogram, which is obtained to evaluate for tachycardia-induced cardiomyopathy, shows normal cardiac function and size. Throughout the remainder of her NICU course, she remains in normal sinus rhythm without recurrence of atrial flutter. The infant was weaned off respiratory support to room air on day of life 34, and she was discharged home on day of life 50 with a nasogastric tube.SVT is a broad category that comprises most cases of narrow complex tachycardia and indicates that the aberrant rhythm originates from above the bundle of His. Other aberrant rhythms may also present as narrow complex tachyarrhythmias, such as atrial flutter, atrial fibrillation, junctional tachycardias, and atrioventricular nodal reentrant tachycardia.1 Arrhythmias are a known complication of indwelling central line catheters. Migration after insertion is likely related to the extremity position during insertion (eg, abduction) and subsequent spontaneous movements of the extremity position after insertion (eg, flexion and extension).2 A pediatric retrospective case-control study found a 1% incidence of PICC-induced arrhythmia.3 While some cases occur during insertion, most occur after insertion and are atrial in origin.3 For this patient, placement of a deep PICC precipitated an atrial arrhythmia—specifically, atrial flutter—and its later migration back into the right atrium allowed for the persistence of the arrhythmia.In neonates, atrial flutter is generally hemodynamically well tolerated and presents with a mean atrial rate of 300 to 600 bpm and a mean ventricular rate of 180 to 220 bpm, which is consistent with the heart rate of the patient presented.1,4–6 The atrial rate is usually faster in a 2:1, 3:1, or 4:1 conduction pattern and can vary between the different conduction patterns, making the rhythm appear irregular.5 The patient likely initially had a variable conduction pattern, complicating the early identification of the arrhythmia, but ultimately appeared to have 2:1 conduction at the time of diagnosis. Atrial flutter may be challenging to discern from other tachyarrhythmias due to high ventricular rates that obscure P wave morphology. Adenosine, which transiently blocks the AV node, may slow the heart rate to more clearly unmask the P wave morphology, as in this patient, but is not a first-line treatment for atrial flutter.1,5,6 Atrial flutter is treated with synchronized cardioversion, 0.5 to 2 J/kg, or transesophageal atrial pacing. Unlike other tachyarrhythmias, recurrence in neonates after achievement of normal sinus rhythm is rare.1,4–6Alternatively, sinus tachycardia presents characteristically as an elevated heart rate, often >160 bpm in neonates, with normal morphology on ECG, and is often a response to stress or pain that resolves when the underlying cause is treated.1 Notably, this patient’s heart rate did not respond to fentanyl administration during the acute tachycardic episode. Other reentrant tachycardias, such as atrioventricular reentrant tachycardia (AVRT), present similarly to atrial flutter, with acute-onset and sustained tachycardia. AVRT can also be precipitated by the placement of deep central lines through the induction of Premature Atrial Contractions (PACs), which initiates the abnormal pathway.1 On ECG, AVRT also presents as a narrow complex tachycardia. Depending on the direction (antegrade or retrograde) of the accessory pathway, AVRT may induce visible delta waves (antegrade) or concealed delta waves (retrograde), making the rhythm difficult to distinguish from atrial flutter without slowing the rate with adenosine.1 In this case, atrial flutter became apparent after adenosine administration, and AVRT was ruled out. Ventricular tachycardia presents as a wide complex tachycardia on ECG, which this patient did not demonstrate.Atrial flutter is generally well tolerated in neonates and rarely causes hemodynamic instability. The ventricular rate is generally 180 to 220 bpm. It is important to assess for deep placement of central lines as a precipitating factor. After synchronized cardioversion with return to normal sinus rhythm, recurrence of atrial flutter is uncommon.American Board of Pediatrics Neonatal-Perinatal Content SpecificationUnderstand cardiac arrythmias.Recognize indications, management, and complications of medical technology (eg, central lines, gastronomy, tracheostomy, ostomy, ventriculoperitoneal shunt, extracorporeal membrane oxygenation).