What are the signs of Patent Ductus Arteriosus (PDA)?

Signs of Patent Ductus Arteriosus (PDA)

The classic sign of a moderate to large PDA is a continuous "machinery-type" murmur heard best at the left infraclavicular area, accompanied by bounding pulses and wide pulse pressure. 1

Clinical Examination Findings

Cardiovascular Signs

• Continuous machinery murmur: Best heard at the left infraclavicular area in moderate to large PDAs 1
• Systolic murmur only: When pulmonary arterial hypertension (PAH) is present, the continuous murmur may disappear and only a systolic component remains 1
• Bounding peripheral pulses: Increased pulse amplitude due to left-to-right shunting 1
• Wide pulse pressure: Present when the PDA is large with significant left-to-right shunt 1

Signs of Eisenmenger Physiology (Large, Nonrestrictive PDA)

• Differential cyanosis: Lower extremities are cyanotic while upper extremities remain pink (unoxygenated blood from the ductus enters the aorta distal to the left subclavian artery) 1
• Differential clubbing: Clubbing in the lower extremities, sometimes including the left arm 1
• Absence of continuous murmur: The machinery murmur disappears with development of Eisenmenger syndrome 1

Symptoms Related to Shunt Size

• Small PDA: Generally asymptomatic with normal left ventricle and normal pulmonary artery pressure 1
• Moderate PDA with LV volume overload: Shortness of breath, easy fatigability, and potential left heart failure 1
• Moderate PDA with predominant PAH: Right heart failure symptoms with pressure-overloaded right ventricle 1

Diagnostic Findings

Electrocardiogram

• Normal ECG: If the ductus is small 1
• Left atrial enlargement and LV hypertrophy: With moderate left-to-right shunt 1
• RV hypertrophy: Present when PAH develops 1

Chest X-Ray

• Cardiomegaly: Variable, depending on shunt size 1
• Increased pulmonary vascular markings: Reflects the magnitude of left-to-right shunt 1
• Prominent proximal pulmonary artery segment: Indicates elevated pulmonary artery pressure 1
• Enlarged left atrium and left ventricle: Due to volume overload from left-to-right shunt 1
• Ductal calcification: Important to identify in adults as it increases surgical risk 1

Echocardiographic Signs

• Direct visualization of PDA: Color Doppler in parasternal short-axis view is diagnostic 1
• Left ventricular volume overload: Dilated left atrium and left ventricle 1, 2
• Elevated pulmonary artery pressure: Estimated by transpulmonary gradient measurement with continuous-wave Doppler 1
• Right heart changes: When PAH is present 1

Clinical Pitfalls

Differential diagnosis on physical examination includes aortopulmonary collateral, coronary arteriovenous fistula, ruptured sinus of Valsalva, and VSD with associated aortic regurgitation. 1 Wide pulse pressure must be distinguished from other causes such as aortic insufficiency and hyperthyroidism. 1

In patients with significant elevation of pulmonary vascular resistance, echocardiography may not be diagnostic, requiring cardiac catheterization to evaluate shunt direction, pulmonary vascular resistance, and vascular bed reactivity. 1

Silent duct (very small PDA with no murmur) requires no intervention. 1