Overview
Definition:
Patent ductus arteriosus (PDA) is a congenital heart defect where the ductus arteriosus, a blood vessel connecting the aorta and pulmonary artery, fails to close after birth
In term infants, a hemodynamically significant PDA can lead to increased pulmonary blood flow and left ventricular volume overload, affecting cardiopulmonary function.
Epidemiology:
PDA is one of the most common congenital heart defects, occurring in approximately 0.05-0.1% of live births
While more prevalent in premature infants, it can also be present and significant in term infants, especially in specific circumstances like prematurity-associated conditions or genetic syndromes.
Clinical Significance:
A hemodynamically significant PDA in term infants can cause respiratory distress, poor feeding, failure to thrive, and potentially lead to pulmonary hypertension and congestive heart failure
Early recognition and appropriate management are crucial to prevent long-term sequelae and improve outcomes.
Clinical Presentation
Symptoms:
Infants may present with tachypnea
Recurrent lower respiratory tract infections
Poor feeding and weight gain
Bounding peripheral pulses
Widened pulse pressure
Palpable thrill over the precordium.
Signs:
A continuous, machinery-like murmur heard best at the left upper sternal border (infraclavicular region)
A bounding pulse
Signs of heart failure: hepatomegaly, peripheral edema
Poor peripheral perfusion.
Diagnostic Criteria:
Diagnosis is primarily based on clinical examination and confirmed by echocardiography
Echocardiographic criteria include visualization of the ductus arteriosus, assessment of shunt direction and magnitude (left-to-right shunt), and evaluation of cardiac chamber sizes and pulmonary artery pressures.
Diagnostic Approach
History Taking:
Detailed antenatal history for maternal infections or drug exposure
Birth history: gestational age, Apgar scores, need for resuscitation
Postnatal history: onset and progression of respiratory symptoms, feeding difficulties, presence of murmurs noted by primary caregiver or during routine check-ups.
Physical Examination:
Systematic cardiovascular examination focusing on heart rate, rhythm, murmurs (character, location, radiation), peripheral pulses (strength, character), and signs of heart failure (respiratory effort, liver size, edema).
Investigations:
Echocardiography is the gold standard for diagnosis, assessing ductal anatomy, flow, and hemodynamic significance
Chest X-ray may show cardiomegaly and increased pulmonary vascular markings
Electrocardiogram (ECG) can reveal left ventricular hypertrophy or strain in severe cases.
Differential Diagnosis:
Conditions to consider include other causes of murmurs in neonates like ventricular septal defect (VSD), atrial septal defect (ASD), peripheral pulmonary stenosis, and aortopulmonary window
Differentiating factors include murmur characteristics and echocardiographic findings.
When To Treat
Indications For Intervention:
Treatment is indicated for PDA in term infants when it is hemodynamically significant and causing symptoms or complications
Hemodynamic significance is defined by echocardiographic evidence of a left-to-right shunt leading to left atrial or left ventricular volume overload, or pulmonary hypertension.
Timing Of Intervention:
The timing depends on the infant's clinical status
Urgent intervention may be needed in infants with signs of severe heart failure or respiratory compromise
Elective intervention may be planned for infants with less severe symptoms but evidence of progressive cardiac enlargement or pulmonary hypertension.
Conservative Management:
In asymptomatic term infants with a small PDA or one that is likely to close spontaneously, conservative management with close monitoring may be considered
This involves regular clinical assessments and serial echocardiograms to track ductal patency and hemodynamic impact
Sometimes, fluid restriction and judicious use of diuretics can manage mild symptoms temporarily.
Management
Medical Management:
Pharmacological closure is typically reserved for premature infants
In term infants, medical management focuses on supportive care and managing symptoms of heart failure
This includes diuretics (e.g., furosemide) to reduce fluid overload, and optimizing feeding to ensure adequate growth
Fluid restriction may be necessary.
Pharmacological Agents For Closure:
While indomethacin and ibuprofen are commonly used for PDA closure in premature infants, their efficacy and safety profile in term infants with significant PDA is less established and not typically the first line of treatment
Their use would be guided by expert opinion and specific clinical scenarios, often reserved for cases where surgical intervention carries high risk.
Surgical Management:
Surgical ligation or division of the PDA is indicated when medical management fails to control symptoms or when the PDA is large and causes significant hemodynamic compromise
This is typically performed via thoracotomy
Percutaneous device closure via cardiac catheterization is an alternative in select term infants, particularly older ones with suitable anatomy.
Supportive Care:
Nursing care includes meticulous fluid balance monitoring, respiratory support as needed (e.g., oxygen, CPAP), and optimizing nutritional intake to promote catch-up growth
Continuous cardiac monitoring for arrhythmias or signs of decompensation is essential.
Complications
Early Complications:
Heart failure exacerbation
Pulmonary edema
Persistent pulmonary hypertension
Arrhythmias
Increased risk of infection.
Late Complications:
Pulmonary arterial hypertension
Eisenmenger syndrome (rare in term infants unless uncorrected for a prolonged period)
Growth retardation
Recurrent pulmonary infections.
Prevention Strategies:
Prompt diagnosis and appropriate intervention based on hemodynamic significance
Effective management of heart failure symptoms
Careful fluid balance and respiratory support
Regular follow-up to monitor for recurrence or development of complications.
Key Points
Exam Focus:
Distinguishing hemodynamically significant PDA from incidental murmurs
Recognizing signs of heart failure in neonates
Indications for medical vs
surgical/device closure in term infants
Echocardiographic assessment of PDA significance.
Clinical Pearls:
A continuous murmur at the left upper sternal border in a term infant warrants thorough evaluation for PDA
Do not underestimate the impact of a PDA, even in term infants
always assess hemodynamic significance
Consider surgical or device closure if medical management is ineffective or infant is deteriorating.
Common Mistakes:
Over-reliance on murmur characteristics without echocardiographic confirmation
Treating asymptomatic, hemodynamically insignificant PDAs
Delaying intervention in symptomatic infants, leading to irreversible pulmonary vascular changes.