Patent Ductus Arteriosus in Children
Introduction to Patent Ductus Arteriosus
Patent Ductus Arteriosus (PDA) is a congenital heart defect characterized by the persistence of the ductus arteriosus, a fetal blood vessel connecting the pulmonary artery to the proximal descending aorta. Normally, this vessel closes shortly after birth, but in PDA, it remains open, allowing abnormal blood flow between the aorta and pulmonary artery.
PDA accounts for 5-10% of all congenital heart diseases. It is more common in premature infants and has a higher incidence in females compared to males (2:1 ratio). The significance of a PDA depends on its size and the patient's age, with potential consequences ranging from asymptomatic to severe heart failure.
Embryology of Patent Ductus Arteriosus
The ductus arteriosus is a vital fetal structure that diverts blood away from the non-functioning fetal lungs:
- Develops from the left 6th aortic arch during embryonic development
- Maintained patent in utero by low oxygen tension and circulating prostaglandins, particularly prostaglandin E2 (PGE2)
- Normally begins to close within 10-15 hours after birth due to:
- Increased oxygen tension
- Decreased circulating prostaglandins
- Increased sensitivity to oxygen
- Functional closure typically occurs within 24-48 hours after birth
- Anatomical closure is usually complete within 2-3 weeks
Failure of this normal closure process results in a PDA. Factors influencing closure include gestational age, genetic factors, and environmental influences.
Classification of Patent Ductus Arteriosus
PDAs can be classified based on several criteria:
1. By Size:
- Small: <1.5 mm
- Moderate: 1.5-3 mm
- Large: >3 mm
2. By Hemodynamic Significance:
- Hemodynamically insignificant: No cardiac enlargement or pulmonary overcirculation
- Hemodynamically significant: Causes left heart volume overload and pulmonary overcirculation
3. Krichenko Classification (based on angiographic appearance):
- Type A (Conical): Narrowing at pulmonary end
- Type B (Window): Short and wide
- Type C (Tubular): Narrow with no constrictions
- Type D (Complex): Multiple constrictions
- Type E (Elongated): Elongated with remote constriction
This classification is particularly useful for planning transcatheter closure procedures.
Clinical Presentation of Patent Ductus Arteriosus
The clinical presentation of PDA varies widely depending on the size of the ductus and the patient's age:
Premature Infants:
- Respiratory distress
- Difficulty weaning from mechanical ventilation
- Pulmonary edema
- Systemic hypoperfusion
- Metabolic acidosis
Term Infants and Children:
- Often asymptomatic with small PDAs
- Characteristic continuous "machinery" murmur, best heard at the left infraclavicular area
- Bounding peripheral pulses
- Wide pulse pressure
- Symptoms of heart failure in large PDAs: tachypnea, poor feeding, failure to thrive
Adults:
- May be asymptomatic if PDA is small
- Exercise intolerance
- Dyspnea on exertion
- Palpitations
- Signs of left heart volume overload
- Risk of endarteritis
- Eisenmenger syndrome in long-standing large PDAs
Diagnosis of Patent Ductus Arteriosus
Diagnosis of PDA involves a combination of clinical examination and diagnostic tests:
Physical Examination:
- Continuous "machinery" murmur at the left infraclavicular area
- Bounding peripheral pulses
- Wide pulse pressure
- Hyperactive precordium in large PDAs
Diagnostic Tests:
- Chest X-ray:
- Cardiomegaly and increased pulmonary vascular markings in significant PDAs
- Possible visualization of the ductus in some cases
- Electrocardiogram (ECG):
- May be normal in small PDAs
- Left ventricular hypertrophy in larger PDAs
- Left atrial enlargement in chronic cases
- Echocardiography: Gold standard for diagnosis
- 2D imaging to visualize the ductus
- Color Doppler to demonstrate flow through the PDA
- Assessment of left heart volume overload
- Estimation of pulmonary artery pressure
- Cardiac CT or MRI: May be useful in complex cases or for detailed anatomical assessment
- Cardiac Catheterization:
- Rarely needed for diagnosis
- Used to assess pulmonary vascular resistance in adults with long-standing PDAs
- Often performed as part of transcatheter closure procedures
Management of Patent Ductus Arteriosus
Management of PDA depends on the patient's age, size of the ductus, and associated symptoms:
Premature Infants:
- Conservative management: Fluid restriction, diuretics, ventilatory support
- Pharmacological closure:
- Indomethacin or ibuprofen (COX inhibitors)
- Acetaminophen as an alternative
- Surgical ligation: If medical management fails or is contraindicated
Term Infants and Children:
- Observation: For very small, asymptomatic PDAs
- Transcatheter closure: Preferred method for most PDAs
- Devices: Amplatzer Duct Occluder, coils for smaller PDAs
- Generally performed after 6 months of age and >5 kg weight
- Surgical closure: For very large PDAs or when anatomy is unfavorable for device closure
Adults:
- Transcatheter closure: First-line treatment for most adult PDAs
- Surgical closure: For very large PDAs or unfavorable anatomy
- Medical management: For patients with irreversible pulmonary hypertension (Eisenmenger syndrome)
Indications for Closure:
- Any symptomatic PDA
- Asymptomatic PDA with left heart volume overload
- Prevention of endarteritis/endocarditis
- Before development of pulmonary vascular disease
Complications of Patent Ductus Arteriosus
Untreated PDAs can lead to several complications:
- Congestive Heart Failure: Due to left heart volume overload
- Pulmonary Hypertension: From chronic pulmonary overcirculation
- Eisenmenger Syndrome: Irreversible pulmonary hypertension leading to right-to-left shunting
- Endarteritis/Endocarditis: Risk is higher in uncorrected PDAs
- Aneurysm of the Ductus: Rare but potentially life-threatening
- Recurrent Respiratory Infections: Due to pulmonary overcirculation
Complications related to treatment:
- Device embolization: In transcatheter closure
- Residual shunt: More common with surgical ligation in premature infants
- Left pulmonary artery stenosis: From device protrusion or surgical clip
- Vocal cord paralysis: Due to recurrent laryngeal nerve injury during surgery
Prognosis of Patent Ductus Arteriosus
The prognosis for patients with PDA is generally excellent with timely intervention:
- Small PDAs: Excellent prognosis, may close spontaneously
- Successfully closed PDAs: Normal life expectancy in most cases
- Premature infants: Prognosis depends on other complications of prematurity
Factors affecting prognosis:
- Size of the PDA
- Age at diagnosis and intervention
- Presence of pulmonary hypertension
- Associated cardiac or non-cardiac anomalies
Long-term follow-up is recommended, especially for patients who underwent closure later in life or those with residual shunts or pulmonary hypertension.
Patent Ductus Arteriosus in Children
- What is a patent ductus arteriosus (PDA)?
A persistent opening between the aorta and pulmonary artery that normally closes shortly after birth - At what gestational age does the ductus arteriosus typically close in full-term infants?
Within 24-48 hours after birth - What percentage of congenital heart defects are PDAs?
Approximately 5-10% - Which gender is more commonly affected by PDA?
Females (2:1 ratio compared to males) - What is the primary function of the ductus arteriosus in fetal circulation?
To divert blood away from the non-functioning fetal lungs - Which prostaglandin is responsible for keeping the ductus arteriosus open in utero?
Prostaglandin E2 - What is the characteristic murmur associated with a PDA?
Continuous "machinery" murmur best heard in the left infraclavicular area - Which diagnostic test is considered the gold standard for diagnosing a PDA?
Echocardiogram - What complication can occur in untreated large PDAs?
Congestive heart failure and pulmonary hypertension - Which medication is commonly used to promote closure of a PDA in premature infants?
Indomethacin or ibuprofen - What is the success rate of medical closure of PDA in premature infants?
Approximately 70-80% - At what age is elective closure of a PDA typically recommended in full-term infants?
Between 6-12 months of age - What is the preferred method of PDA closure in children over 5-10 kg?
Transcatheter device closure - Which surgical approach is most commonly used for PDA ligation?
Left thoracotomy - What is the mortality rate for surgical PDA ligation in children?
Less than 1% - Which genetic syndrome is associated with a higher incidence of PDA?
Char syndrome - What is the risk of recurrence of PDA in offspring if a parent has a PDA?
Approximately 3-4% - Which cardiac chamber is typically enlarged in patients with a significant PDA?
Left atrium and left ventricle - What ECG finding is common in patients with a large PDA?
Left ventricular hypertrophy - Which complication can occur immediately after device closure of a PDA?
Device embolization - What is the long-term survival rate for patients who have undergone PDA closure?
Nearly normal life expectancy - Which imaging modality can be used to assess PDA size and morphology if echocardiography is inadequate?
CT angiography or MRI - What is the name of the classification system used to describe PDA morphology?
Krichenko classification - Which type of PDA in the Krichenko classification is most suitable for device closure?
Type A (conical) - What is the recommended follow-up interval for patients after PDA closure?
Annual follow-up for the first few years, then every 3-5 years - Which medication might be prescribed for patients with a PDA and pulmonary hypertension?
Sildenafil or other pulmonary vasodilators - What is the recommended antibiotic prophylaxis duration after device closure of a PDA?
6 months - Which condition in premature infants is associated with an increased incidence of PDA?
Respiratory distress syndrome - What is the potential risk of pregnancy in women with an unrepaired large PDA?
Increased risk of heart failure and pulmonary hypertension - Which type of PDA device is commonly used for transcatheter closure?
Amplatzer Duct Occluder
