Introduction

Umbilical venous catheter (UVC) is commonly used in the Neonatal Intensive Care Unit (NICU) as a tool for the administration of fluids, nutrition, and medications.^1)-(4) Ideally, UVC should be located just outside the heart, at the junction of the inferior vena cava and right atrium. ⁽² Chest and abdomen radiography is the most common method to confirm the position of the catheter, but ultrasound has also been used, with favorable outcomes.¹ - ²⁾ UVC complications usually result from catheter malposition and include pericardial effusion and cardiac tamponade, pleural effusion, thrombosis, endocarditis, infections, and cardiac arrythmia, among others.² - ⁴

Tachyarrhythmia is a well-known potential complication of central venous catheter (CVC) placement in adults. However, only a few cases have been reported in neonates.¹

Clinical case

A boy with 1250 g (90^th percentile) and 27+5 weeks of gestational age was born by vaginal delivery after a spontaneous preterm birth, with incomplete lung maturation. Apgar score was 5/8/10 (at 1, 5, and 10 minutes, respectively). After birth, he required resuscitation measures with positive pressure ventilation and endotracheal ventilation. At NICU, surfactant was administered, and the patient started to receive caffeine citrate and empiric antibiotics. Since the mean arterial blood pressure (MABP) was low (19 mmHg), peripheric dopamine infusion was administered, with favorable outcome. An umbilical arterial catheter (UAC) and UVC were inserted to the length of 12.8 cm and 7.4 cm, respectively. Easy bleeding was noted during the procedure, and the newborn suddenly developed tachycardia immediately after UVC insertion, with a heart rate of 300-320 beats/minute. Since chest radiography was not an immediate option at the moment, UVC and UAC were pulled back, but tachycardia persisted. The patient maintained hemodynamic and respiratory stability and good peripheral perfusion. An echocardiogram and electrocardiogram (ECG; Figure 1) were performed, excluding cardiac tamponade. MABP remained stable. After consulting with the Pediatric Cardiology, supraventricular tachycardia was confirmed. Because the patient was a premature neonate on the first day of life, vagal maneuvers with crushed ice were not initiated to avoid thermal instability. Alternatively, adenosine was administered at the dose of 50 mcg/kg, with a resulting heart rate of 200 beats/minute and reestablishment of the sinus rhythm. Both central lines were pulled out. After the event, the patient remained in NICU, with no additional cardiovascular complications or sequelae. Since no accessory pathway was found, the exact cause of this event remained unknown.

Discussion/conclusions

Atrial flutter and supraventricular tachycardia (SVT) are the most common arrhythmias found. However, atrial flutter is not frequent in the neonatal period.^1,2,4 Since the therapeutic attitude comprises synchronized cardioversion in atrial flutter and adenosine in SVT, prompt distinction of these conditions is of great relevance.^1,4 Atrial flutter consists of regular rapid atrial rate of 240-360 beats/min and regular rhythm with sawtooth pattern of P waves and narrow QRS in ECG (in the absence of aberrant pathways). SVT also has a narrow QRS but is characterized by regular R-R interval, rates of 260-300 beats/min, and absence of P waves.³

Reasons for CVC migration include contraction of the umbilical stump and changes in the size of the abdomen, recurrent movement of the affected limb or head, and routine flushing or handling of the catheters by medical or nursing staff.^1,2 In most cases, arrhythmia occurs at the time of catheter insertion but may also happen hours or even days later.¹ Therefore, imaging assessment to confirm the position of the catheter should not be delayed.¹ Proposed mechanisms for the development of arrhythmia associated with central lines include premature atrial beat, induced when the catheter tip touches the endocardium and triggers SVT in the presence of an accessory pathway, and mechanical distortion of the atria, predisposing for a reentry pathway.^1,2

The most effective treatment for SVT depends on the overall cardiovascular status and may include cardiovascular resuscitation in severe cases, and synchronized cardioversion in hemodynamically unstable patients.^3,5) Vagal maneuvers and intravenous adenosine may be used in hemodynamically stable patients.^1,3,5 Vagal maneuvers, such as placing crushed ice over the face for a few minutes or oropharyngeal suction, may buy some time while adenosine is being prepared, but their use in neonates is controversial.³ Adenosine starting dose should be 0.05-0.1 mg/kg, until a maximum of 0.3 mg/kg.⁶ Although withdrawal of the catheter tip is important, most cases also require medical therapy to induce reversion to sinus rhythm.¹

With this case, the authors aimed to raise awareness of tachyarrhythmia as a potential and serious complication of CVC in neonates and for the importance of checking the position of the catheter. Prompt diagnosis of the type of arrhythmia is also crucial to define an early and adequate therapeutic strategy.