How to treat a 9-month-old infant with reentry tachycardia and mild left ventricular non-compaction on propranolol (propranolol), presenting with wheezing and a lower respiratory tract infection?

Management of Wheezing Lower Respiratory Tract Infection in an Infant with Reentry Tachycardia on Propranolol

For a 9-month-old infant with reentry tachycardia and mild left ventricular non-compaction on propranolol who presents with wheezing and lower respiratory tract infection with moderate retractions, a trial of short-acting inhaled bronchodilator (albuterol) with monitoring for clinical improvement is recommended while continuing propranolol therapy.

Initial Assessment and Considerations

• The infant has two concurrent conditions requiring careful management: reentry tachycardia with mild left ventricular non-compaction (being treated with propranolol) and a wheezing lower respiratory tract infection with moderate retractions 1
• Moderate retractions indicate significant respiratory distress requiring prompt intervention 1
• The presence of underlying cardiac condition (non-compaction) increases the risk for severe disease and warrants close monitoring 1
• Propranolol therapy should be continued as it is the mainstay treatment for reentry tachycardia in infants 2, 3

Treatment Approach

Bronchodilator Therapy

• Despite being on propranolol (a non-selective beta-blocker), a trial of short-acting inhaled bronchodilator (albuterol) is recommended for the wheezing lower respiratory tract infection 1
• Studies show that 55% of infants with recurrent wheeze respond to albuterol, and bronchodilator therapy can significantly improve airflow in patients with respiratory symptoms 1
• The American Thoracic Society recommends a trial of short-acting inhaled bronchodilator with monitoring to assess for clinical improvement in symptoms for infants with respiratory symptoms such as cough or wheeze 1
• Monitor closely for:
  • Clinical improvement in wheezing and retractions 1
  • Potential paradoxical response (worsening of symptoms) 1
  • Tachycardia, tremors, or oxygen desaturation as possible adverse effects 1

Corticosteroid Consideration

• For persistent symptoms despite bronchodilator therapy, a trial of inhaled corticosteroids may be considered 1
• The American Thoracic Society suggests a trial of inhaled corticosteroids with monitoring to assess for clinical improvement in symptoms for infants with chronic cough or recurrent wheezing 1
• A suggested duration for this trial would be 3 months 1

Special Considerations with Propranolol

• Continue propranolol therapy as it is effective in preventing recurrence in 70% of infants with supraventricular tachycardia 3
• Be aware that propranolol may potentially reduce the efficacy of bronchodilators due to its beta-blocking properties 4
• Monitor for signs of propranolol toxicity, particularly with respiratory distress, as bronchospasm has been reported with propranolol therapy in pediatric patients 4
• If severe bronchospasm develops that is unresponsive to bronchodilators, temporary reduction in propranolol dose may be considered while maintaining cardiac monitoring 4

Monitoring and Follow-up

• Close monitoring of respiratory status (work of breathing, oxygen saturation) and cardiac status (heart rate, signs of heart failure) is essential 1, 2
• If bronchospasm worsens or is unresponsive to bronchodilators, consider:
  • Oxygen supplementation if hypoxemia develops 1
  • Hospitalization for more intensive monitoring and treatment if respiratory distress increases 1
  • Isoproterenol may be used for severe bronchospasm in the setting of propranolol therapy, but this requires careful cardiac monitoring 4

Potential Pitfalls and Caveats

• Beta-blockers like propranolol can potentially worsen bronchospasm, requiring careful monitoring when treating respiratory symptoms 4
• Children with tracheobronchomalacia can have a paradoxical response to bronchodilator therapy (increased airway resistance) 1
• Propranolol should not be abruptly discontinued due to risk of rebound tachycardia 4
• Recognize that recurrent wheezing episodes may represent undiagnosed asthma, which would require long-term management considerations 5

By following this approach, you can effectively manage the acute respiratory symptoms while maintaining control of the cardiac condition in this complex infant patient.