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Difficulty: EasyPediatric Cardiovascular Disorders

A 5-day-old female neonate, born prematurely at 28 weeks gestation, is evaluated in the neonatal intensive care unit for increasing respiratory distress. Over the past 12 hours, she has developed worsening tachypnea and an increased need for supplemental oxygen. Vital signs show a heart rate of 168/min, respiratory rate of 72/min, and blood pressure of 55/25 mm Hg. Physical examination reveals bounding peripheral pulses in all four extremities and a hyperactive precordium. Cardiac auscultation demonstrates a prominent, continuous, "machine-like" murmur heard best at the left second intercostal space. Echocardiography confirms a patent vascular connection between the descending aorta and the main pulmonary artery with left-to-right shunting. Which of the following is the most appropriate initial pharmacologic intervention to close this defect?

  1. Intravenous indomethacinAnswer
  2. B
    Continuous alprostadil infusion
  3. C
    Intravenous furosemide therapy
  4. D
    Empiric intravenous ampicillin and gentamicin
  5. E
    Nebulized levalbuterol therapy

Answer

Intravenous indomethacin
This premature infant presents with classic signs of a hemodynamically significant patent ductus arteriosus (PDA). The classic physical exam findings include a continuous "machine-like" murmur best heard in the left infraclavicular area and bounding peripheral pulses (due to a widened pulse pressure from diastolic runoff into the pulmonary circulation). The persistent left-to-right shunting causes pulmonary overcirculation, manifesting as tachypnea and increasing oxygen requirements. The most appropriate initial pharmacologic intervention to close a symptomatic PDA in a premature infant is a cyclooxygenase (COX) inhibitor, such as intravenous indomethacin or ibuprofen. These medications decrease the synthesis of prostaglandins, which are responsible for maintaining ductal patency, thereby promoting closure of the vessel.

Step-by-Step Solution

1
Analyze the clinical presentation.
The patient is a premature infant presenting with bounding pulses, a wide pulse pressure (55/25 mm Hg), and a continuous "machine-like" murmur.
These findings are highly specific and classic for a Patent Ductus Arteriosus (PDA).
2
Identify the pathophysiology causing the patient's deterioration.
The PDA is allowing oxygenated blood to shunt from the high-pressure aorta to the lower-pressure pulmonary artery (left-to-right shunt).
This leads to pulmonary overcirculation, resulting in cardiogenic pulmonary edema, tachypnea, and increased oxygen requirements.
3
Determine the pharmacological mechanism required to manage the condition.
Prostaglandins (specifically PGE2) are responsible for keeping the ductus arteriosus open; therefore, inhibiting prostaglandin synthesis will promote closure.
Definitive management requires structural closure of the defect rather than just treating the symptoms of heart failure.
4
Select the appropriate medication based on the mechanism.
A cyclooxygenase (COX) inhibitor should be administered.
Intravenous indomethacin or ibuprofen is the standard first-line pharmacologic therapy to close a PDA in a premature infant.

Key Concept

Premature infants presenting with a continuous "machine-like" murmur, bounding pulses, and signs of heart failure should be suspected of having a Patent Ductus Arteriosus (PDA). The first-line pharmacologic treatment to induce closure is a COX inhibitor such as indomethacin or ibuprofen.

Alternative Method

If pharmacologic therapy with indomethacin or ibuprofen fails, or if it is contraindicated (e.g., active bleeding, severe thrombocytopenia, or necrotizing enterocolitis), the alternative definitive management is procedural closure via surgical ligation or transcatheter device closure.
Estimated Time:1m 0s
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Pediatric Cardiovascular Disorders

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