What is the recommended management for an adult patient presenting with patent ductus arteriosus (PDA)?

Diagnosis of Adult Patent Ductus Arteriosus

Primary Diagnostic Modality

Transthoracic echocardiography with color Doppler in the parasternal short-axis view is the definitive diagnostic test for PDA in adults, directly visualizing the ductus and characterizing hemodynamic significance. 1, 2

Clinical Examination Findings

The physical examination provides critical diagnostic clues that should prompt echocardiographic evaluation:

• Continuous "machinery-type" murmur heard best at the left infraclavicular area and left upper sternal border is the classic finding in moderate to large PDA with preserved left-to-right shunting 2, 3
• Bounding peripheral pulses with wide pulse pressure indicate significant left-to-right shunting and increased stroke volume 2, 3
• Laterally and inferiorly displaced apex beat reflects left ventricular volume overload from chronic shunting 2

Critical pitfall: When pulmonary arterial hypertension develops, the continuous murmur may disappear and only a systolic component remains, potentially leading to misdiagnosis 2. Always maintain high clinical suspicion even with atypical auscultatory findings.

Hemodynamic Classification System

The European Society of Cardiology classification system guides diagnostic assessment and management decisions 2:

Small PDA

• No left ventricular volume overload (normal LV size and function) 2
• Normal pulmonary artery pressure 2
• Generally asymptomatic 2
• Continuous machinery murmur may be present 2

Moderate PDA

Two distinct presentations exist 2:

Predominant LV volume overload:

• Large/dilated left ventricle with normal or reduced function 2
• Left heart failure symptoms (dyspnea, fatigue) 2
• Elevated pulmonary artery pressure but not yet Eisenmenger physiology 2

Pulmonary arterial hypertension:

• Elevated pulmonary artery pressure approaching systemic levels 2
• May have only systolic murmur 2

Large PDA (Eisenmenger Physiology)

• Differential cyanosis and clubbing affecting lower extremities (and sometimes left arm) is pathognomonic 2
• Differential hypoxemia with lower oxygen saturation in feet compared to right hand indicates right-to-left shunting at the ductal level 2, 4
• Severe, irreversible pulmonary vascular disease with shunt reversal 2

Critical diagnostic step: Always measure oxygen saturation in all four extremities when evaluating suspected PDA to detect differential cyanosis 3, 4. Consider ambulatory pulse oximetry in addition to resting measurements to detect dynamic shunt reversal 4.

Echocardiographic Assessment

Echocardiography provides comprehensive diagnostic information 1, 2, 5:

Direct Visualization

• Color Doppler in parasternal short-axis view directly visualizes the PDA and shunt direction 1, 2, 3
• Assess ductus size and morphology 5

Hemodynamic Assessment

• Continuous-wave Doppler measurement of transpulmonary gradient estimates pulmonary artery pressure 1, 2, 3
• Evaluate left atrial and left ventricular chamber size to assess volume overload 2, 3
• Assess right ventricular size and function to evaluate pressure overload 2
• Determine shunt direction and magnitude 2

Important limitation: In cases of significant elevation of pulmonary vascular resistance with Eisenmenger physiology, echocardiography may not be diagnostic, and the PDA may not be visualized despite large size 1, 6.

Electrocardiographic Findings

ECG findings correlate with hemodynamic severity 2, 3:

• Normal ECG if the ductus is small 2, 3
• Left atrial enlargement and LV hypertrophy with moderate left-to-right shunt 2, 3
• RV hypertrophy when pulmonary arterial hypertension develops 2, 3

Chest Radiography

Radiographic findings reflect shunt magnitude 1, 2, 3:

• Cardiomegaly (variable, depending on shunt size) 2, 3
• Increased pulmonary vascular markings reflecting magnitude of left-to-right shunt 2, 3
• Prominent pulmonary artery segment indicating elevated pulmonary artery pressure 1
• Enlarged left atrium and left ventricle due to volume overload 1
• Look for calcification in the region of the ductus, as calcified ductus increases surgical risk 1

Cardiac Catheterization Indications

Invasive hemodynamic assessment is NOT routinely required but has specific indications 1, 4:

• When pulmonary artery pressure appears high on echocardiography to accurately measure pulmonary vascular resistance 2, 4
• To determine operability when PAP >2/3 systemic pressure or PVR >2/3 systemic vascular resistance 2, 4
• To assess reactivity of the pulmonary vascular bed in patients with pulmonary hypertension 1, 4
• To determine size and shape of ductus for potential catheter-based closure 1

Differential Diagnosis

The differential diagnosis on physical examination includes 1, 3:

• Aortopulmonary collateral 1
• Coronary arteriovenous fistula (may have similar continuous murmur) 1
• Ruptured sinus of Valsalva 1
• VSD with associated aortic regurgitation 1

Echocardiography and/or angiography should differentiate all these conditions 1.

Advanced Imaging

CT or MRI of the chest are usually not necessary to diagnose PDA 1. However, CT may incidentally detect PDA in adults being evaluated for other conditions 6, and can be useful when echocardiographic windows are inadequate.