Patent Ductus Arteriosus
Patient presentation:
J.R. a 2-month-old female is being seen for evaluation of poor feeding. She is in no apparent acute distress. Mom reports that J.R. has difficulty with feeding and “seems to get short of breath at times.” She is concerned that the baby seems to be losing weight and is excessively tired.
Assessment:
General- J.R.’s weight is below average for age and length. She is alert at this time and does not appear to be in any acute distress.
Respiratory- RR 41, auscultation reveals crackles in bilateral bases.
Cardiac- Patient is afebrile and has 3+ peripheral pulses. Auscultation reveals a HR of 140 with a continuous grade 3 machinery type murmur that is best heard in the left upper sternal border.
Diagnosis:
Echocardiogram confirms a mild patent ductus arteriosus.
Patent Ductus Arteriosus (PDA): During fetal circulation the PDA allows blood to shunt from the pulmonary artery to the aorta bypassing the pulmonary bed (R to L, pulmonary vascular resistance > systemic vascular resistance – in utero). At birth the placenta is removed and systemic vascular resistance rises, with pulmonary vasodilation and increased PaO2 the pulmonary vascular resistance drops creating a reversal L to R blood flow through the PDA. Changes in vascular resistance, in addition to a decrease in circulating prostaglandin (vasodilatory effect) should stimulate the beginning of PDA constriction within the first few hours of life. Complete closure is typically noted between 15 hrs – 2weeks of life. PDA is the failure of closure of the ductus arteriosus. Symptoms vary based on the degree of left to right shunting, from absent to severe CHF with the potential to develop irreversible pulmonary hypertension.
Treatment:
Medical management of symptoms includes Lasix® and digoxin. A lower serum digoxin level is appropriate for management of mild CHF, and a loading does is not required. An oral daily dose of 10 mcg/kg of digoxin is appropriate in addition to Lasix® PO 2mg/kg daily. Lowest therapeutic dose recommended due to mild presentation. Patient requires frequent monitoring of cardiorespiratory status, growth, and serum digoxin levels by pediatric cardiologist.
Outcome:
Medical management can be successful until the patient becomes an ideal surgical candidate, up to 2 years old. If medical management becomes unsuccessful, immediate surgical intervention is necessary. The minimum weight requirement for surgery is greater than 6 kg. PDA closure is recommended even if asymptomatic by the age of 2yrs. due to the risk of developing subacute bacterial endocarditis.
More on PDA:
The incidence of PDA is greatest among preterm babies; in these cases a prostaglandin inhibitor can often successfully close the PDA. Indomethacin is usually given intravenously as multiple doses that range between 0.1 and 0.2 mg/kg per dose administered at 12-to 24-hour intervals. Ibuprofen can also be used with an initial dose of 10 mg/kg followed by two additional doses of 5 mg/kg given at 24 hour intervals. This course of treatment is not successful in term infants. In full term cases the incidence is greater in females and increases if born at higher altitudes vs sea level. Congenital Rubella is also linked to an increase likelihood of PDA. Management in term cases will be further explained in the treatment section.
Case created by Jaime Records, 2011.