How to evaluate a patent ductus arteriosus (PDA) on transthoracic echocardiogram (TTE)?

From the Guidelines

When evaluating a patent ductus arteriosus (PDA) on transthoracic echocardiogram (TTE), the transducer position should be adjusted slightly superior and leftward from the standard short axis view to visualize the main pulmonary artery and its bifurcation, and color Doppler should be applied to demonstrate the flow direction and velocity through the PDA. To evaluate a PDA on TTE, the following steps should be taken:

• Adjust the transducer position to visualize the main pulmonary artery and its bifurcation
• Apply color Doppler to demonstrate the flow direction and velocity through the PDA, typically showing continuous left-to-right shunting from the aorta to the pulmonary artery 1
• Use pulsed wave and continuous wave Doppler to measure flow velocities and calculate the pressure gradient across the defect, which helps determine the degree of pulmonary hypertension
• Measure the size of the PDA at its narrowest point (usually the pulmonary end), as this dimension is critical for determining hemodynamic significance and treatment options
• Assess chamber sizes, particularly left atrial and left ventricular dimensions, to provide information about volume overload resulting from the left-to-right shunt This comprehensive evaluation helps determine whether the PDA requires intervention through medical management, catheter-based closure, or surgical ligation, as guided by the indications for intervention outlined in the ESC guidelines for the management of grown-up congenital heart disease 1. The use of TTE for evaluating PDA is supported by its widespread availability, reproducibility, safety, and painlessness, making it a valuable tool in the investigation of congenital heart disease 1. In cases where TTE is limited by poor acoustical windows or other technical difficulties, transesophageal echocardiography (TEE) and MRI may be used as alternative imaging modalities 1. Overall, the evaluation of a PDA on TTE should prioritize the use of color Doppler and pulsed wave and continuous wave Doppler to assess flow direction and velocity, as well as the measurement of PDA size and chamber dimensions to guide treatment decisions.

From the Research

Evaluating Patent Ductus Arteriosus (PDA) on Transthoracic Echocardiogram (TTE)

To evaluate a PDA on TTE, several key factors should be considered:

• The size of the PDA, which can be assessed by measuring the pulmonary end diameter in both the suprasternal and parasternal short-axis views 2
• The color flow width and extent, which can help determine the severity of the PDA 2
• The peak and end-diastolic Doppler gradients across the duct, which can provide information on the hemodynamic significance of the PDA 2
• The presence of diastolic flow reversal, which can indicate significant left-to-right shunting 2
• The left atrial dimensions and volume, which can be affected by the presence of a PDA 2
• The left ventricular sphericity index and volumes, which can provide information on the impact of the PDA on left ventricular function 2

Echocardiographic Predictors of PDA Closure

Several echocardiographic predictors can help determine the likelihood of successful PDA closure:

• A pulmonary end diameter cutoff point of >2.5mm from the suprasternal view and >2.61mm from the parasternal short-axis view can predict the likelihood of device closure 2
• The pulmonary end diameter measured from the suprasternal view is the most independent predictor of device closure 2
• Other factors such as left atrial volume, diastolic flow reversal, and left ventricular volumes can also provide valuable information on the hemodynamic significance of the PDA and the likelihood of successful closure 2

Simplified Approach to Echocardiography in Adult Patients with PDA

In adult patients with PDA, a simplified approach to echocardiography can be used:

• Basic echocardiographic assessment should include evaluation of the PDA size, location, and flow characteristics 3
• Assessment of left ventricular function, left atrial size, and pulmonary artery pressures can provide valuable information on the hemodynamic significance of the PDA 3
• Echocardiography can also be used to monitor the effectiveness of treatment and to detect any potential complications 3

Comparison of TTE and Computed Tomographic Angiography (CTA)

TTE and CTA can be used to assess the size of the pulmonary artery and its branches:

• There is a strong correlation and agreement between cardiac CTA and TTE for the assessment of the annulus and the size of the pulmonary artery and its branches 4
• TTE can provide accurate measurements of the main pulmonary valve annulus, main pulmonary artery, and branch pulmonary arteries, but may be limited by poor echogenic windows in some patients 4
• CTA can provide more accurate measurements in patients with poor echogenic windows, but may not be necessary in all cases 4