Arrhythmias in Children

A Case-Based Approach

Vincent C. Thomas, Seshadri Balaji

• Editorial: Elsevier
• Año: 2021
• ISBN:
  9780323779081
• Categoría: Medicina
• Categoría: Cardiología

Pediatricarrhythmiaspresent numerous challenges topediatriccardiologists and other practitioners who seepediatricpatients, includingpediatricians, family physicians, emergency physicians, residents, fellows, and otherclinicians.Arrhythmias in Children: A Case-Based Approachfeaturespractical methods fordiagnosing and treating arrhythmias in these patients across all settings.Nearly three dozen real-worldscenarios are presented, followed by a discussion of the diagnosis, clinical thinking process involved, treatment options, expected outcomes, and how to manage anticipated and unanticipated outcomes. These practical, realisticcases provide a unique and engaging way of approaching these challenging patientscenarios.

• Uses a case-based approach for a full spectrum ofpediatricarrythmias in thenewborn, child, pre-teen, and teenager.
  
  

• Presents history and physical, differential diagnoses, tests to order, and practical plans of action.
  
  

• Includes a section on arrythmias in special circumstances.
  
  

• Models clinical thinking skills for a wide number of real-world patient situations.
  
  

• Reviews pertinent clinical guidelines, treatment, and follow up.
  
  

Section 1

Infant

Outline

Chapter 1. Newborn nursery infant that has bradycardia

Chapter 2. NICU infant noted to have extrasystoles on cardiac monitor

Chapter 3. Full-term infant noted to have persistent tachycardia

Chapter 4. 2-month-old presenting to the ER with tachycardia, fussy, unable to eat

Chapter 5. 4-month-old with extrasystoles on auscultation at pediatrician’s office

Chapter 6. 9-month-old with recurrent episodes of supraventricular tachycardia despite medical therapy

Chapter 1: Newborn nursery infant that has bradycardia

Abstract

This chapter reviews diagnosis and management of the newborn infant that presents with asymptomatic bradycardia. Bradycardia in newborns is commonly due to noncardiac or nonarrhythmic findings and usually does not require an extensive cardiac evaluation or workup. An electrocardiogram is most often recommended and demonstrates a finding of sinus bradycardia that may be influenced by a number of noncardiac factors including electrolytes, maternal medication use, and respiratory pauses. Patient clinical status is always paramount when deciding what actions to take. This is particularly true for patients with cardiac causes for bradycardia that may require intervention including the use of external cardiac pacing or temporary pacing via pacing wires.

Keywords

Bradycardia; Newborn; Pacing

Case

I’m calling from the newborn nursery and I’m the charge nurse on for today. I have a 1-day old newborn infant that on auscultation has a slow heart rate. I counted an average pulse rate of 90 beats per minute. The baby looks well and seems to be feeding OK. I’ve called the pediatrician and she’s coming to see the baby this afternoon after clinic, but she asked me to call you. Anything I should be worried about?

What am I thinking?

As with any arrhythmia, the first thing I think about is the clinical status of the patient. In this situation, is the bradycardia impacting the ability of this newborn to live—namely maintaining homeostatic metabolism, eating, and gaining weight? A patient who is not acidotic, able to feed, and is gaining an appropriate amount of weight is less of a concern for immediate intervention. Once I have established that the patient is clinically OK, I need to understand the rhythm and I will be looking for some form of tracing, best performed with a 15-lead ECG. The most common reason an electrophysiologist gets involved for bradycardia in a newborn is sinus bradycardia, which often is a sign of other issues rather than the diagnosis. As long as the patient is clinically stable, I have time to perform a work-up.

Differential diagnosis
Likely
Sinus bradycardia ⁃ Secondary to respiratory pauses or apnea ⁃ Secondary to maternally administered medications
Possible
Blocked premature atrial contractions Sinus bradycardia secondary to induced hypothermia
Rare
Congenital hypothyroidism (sinus bradycardia) Congenital heart block Long QT syndrome (sinus bradycardia, 2:1 atrioventricular block) Sick sinus syndrome or heterotaxy syndrome (left atrial isomerism) secondary to congenital heart disease

History and physical

History is paramount in the work-up of a newborn infant with bradycardia. While this may seem counterintuitive given the short history outside of the womb, the history should involve what occurred antenatally and in the immediate postnatal period. Foremost, what is the clinical status of the patient? This should always be the first concern in any arrhythmia case and should drive decision-making and actions. Any suggestion of instability due to bradycardia may require immediate action with the consultation of a pediatric cardiologist and preferably, a pediatric electrophysiologist. With a clinically stable patient, history questions may help with diagnostic considerations. Most cases of neonatal bradycardia are due to sinus bradycardia (see Fig. 1.1). Causes of sinus bradycardia can include respiratory-related issues such as apnea of prematurity and/or respiratory pauses. Sinus bradycardia could also be the result of medication given during or after delivery. Bradycardia during fetal life may suggest blood flow insufficiency from the placenta or underlying genetic predisposition such as congenital heart disease or Long QT syndrome. It may also suggest an underlying arrhythmia such as blocked atrial premature beats (see Figs. 1.2 and 1.3). The most common ectopic arrhythmia noted in the normal newborn is that of atrial premature beats. In the neonate with congenital heart block, there is a higher incidence of maternal lupus and this history should be elicited.

On physical examination, most neonates with stable bradycardia have no other significant changes to vital signs. Pauses in respiration leading to bradycardia should be monitored and documented. Any evidence for cyanosis or low oxygen saturation may suggest underlying congenital heart disease. Overall appearance should indicate adequate perfusion and no evidence for skin mottling in a clinically stable neonate. Cardiac murmurs in addition to an expected bradycardic rate may indicate possible congenital heart disease. Irregularity to the rhythm on auscultation may indicate blocked atrial premature beats.

Figure 1.1 Sinus bradycardia in an infant.The ECG demonstrates a bradycardic rhythm around 95 bpm in a newborn infant. There are clear p waves with 1:1 conduction and an appropriate vector for sinus bradycardia. This sinus bradycardia was due to maternal medications given before delivery.

Diagnostic testing

The primary test for bradycardia in the newborn is the electrocardiogram and should be the first test ordered. If bradycardia appears intermittently, the neonate should be placed on a form of continuous monitoring, preferably one with an ability to record the change in rhythm and can capture a single or multi-lead rhythm strip. If such a system does not exist in the hospital setting, a Holter monitor may act as a surrogate though requires time for interpretation and action would be delayed by at least 24 h. If there are clinical concerns for congenital heart disease, an echocardiogram should be performed to evaluate the cardiac anatomy. For concerns of congenital heart block, maternal lupus antibodies (anti-SSA, anti-SSB) can be measured. Congenital hypothyroidism is routinely checked in the newborn screen within the United States and should be assessed if there are concerns.

Figure 1.2 Blocked premature atrial contractions.The ECG demonstrates premature atrial beats (arrows) that lie within the T wave and are not conducted to the ventricle resulting in a reduced heart rate.

Figure 1.3 Long QT syndrome with 2:1 AV block in a newborn.The ECG demonstrates sinus rhythm with a severely prolonged QT interval that leads to 2:1 conduction of the sinus rate (arrowheads) and subsequent bradycardic ventricular rhythm. Findings of 2:1 conduction due to long QT syndrome in the newborn are very concerning and carry a poor prognosis.

Action plan

As stated previously, the clinical status of the patient is paramount to all arrhythmia management. In a scenario where the patient is clinically not doing well, immediate intervention is often required. Immediate consultation with cardiology is highly recommended. Suggested treatments may include the use of chronotropic medications (e.g., epinephrine, isoproterenol, atropine) or temporary pacing. Temporary pacing can be conducted with the transvenous placement of a temporary pacing lead in the right ventricle and connection with a temporary pacemaker. In emergent situations, temporary pacing can be conducted via defibrillator patch placement on standard hospital cardioverter defibrillators and should always be used with appropriate sedation as external pacing can be quite painful.

A few notes ab...