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If you are looking to estimate significance of the left to right PDA - one of the most used score has been the Iowa PDA score. Here is the calculator below. A value ≥ 6 is considered indicating echocardiographic signs of hemodynamics significance.
Important references / publications outlining the score:
This article presents a very important Table outlining the methodology to obtain the measurements (Appendix 1)
Of note, according to this publication, the authors will use Acetaminophen as their primary intention for acceleration of ductal closure. Followed by NSAIDs if remains significant.
Pulmonary vein D wave
Pulmonary vein D wave
Mitral E wave
Mitral E wave
E wave is 0.85 m/s (85 cm/s).
E wave is 0.46 m/s (46 cm/sec) and A-wave is 0.72 m/s.
In a large left-to-right patent ductus arteriosus (PDA), increased pulmonary venous return and left atrial (LA) volume overload significantly impact mitral inflow dynamics, particularly the E-wave (early passive filling phase of the left ventricle). During ventricular systole, the mitral valve remains closed, while continuous pulmonary venous return leads to progressive LA filling. In the presence of a large PDA, excess pulmonary blood flow results in elevated LA pressure, reducing the LV-LA pressure gradient needed for mitral valve opening. When the mitral valve opens, the E-wave velocity increases, reflecting a rapid "gush" of blood into the LV due to high preload (high LA pressure). This augmented early diastolic filling can mimic restrictive physiology in severe cases, characterized by shortened IVRT, increased E/A ratio, and shortened deceleration time due to elevated LA pressures.
Other considerations:
E/A Ratio: Often increased due to the disproportionately higher E-wave compared to A-wave.
Deceleration Time (DT): May be shortened due to elevated left atrial pressures, resulting in rapid equilibration of LA-LV pressures. The pattern of shortened IVRT and increased E-wave velocity is a hallmark of significant left heart volume overload, commonly seen in large left to right PDAs with significant shunt volume.
Isovolumetric relaxation time
Isovolumetric relaxation time
IVRT is obtained at the intersection of the inflow and the outflow in Colour-Doppler in the Apical 5 Chamber view. Here we see the swirling of blood flow from the inflow at mitral valve (red) and eventually looping up in the LV cavity to the LVOT in blue. The Cursor must be placed at the intersection.
Arrow indicating the intersection where to put the cursor.
The red arrow indicates the brief period of isovolumetric relaxation time. Prior, we can appreciate the negative deflection of the blood flow velocity going towards the outflow tract in systole. Following the IVRT, we can appreciate the blood flow velocity of the passive early left ventricular filling at the opening of the mitral valve.
IVRT of 39.61 msec
With a large left-to-right patent ductus arteriosus (PDA), the increased pulmonary venous return and left atrial (LA) volume overload have notable effects on isovolumic relaxation time (IVRT). The IVRT (Isovolumic Relaxation Time) shortens due to increased left atrial pressure and higher left ventricular (LV) preload. Elevated left atrial pressure reduces the pressure gradient required for the LV to relax to below LA pressure, thereby shortening IVRT. The rapid diastolic filling from the increased pulmonary venous return contributes to early LV filling.
LA:Ao ratio
LA:Ao ratio
Aorta diameter should be measured at the closure of the valve (leading edge ot leading edge). It can be measured at the onset or end of valve closure. LA is measured at the peak of ventricular systole, when the LA is most filled (closed mitral valve).
Because of the high pulmonary venous return, eventually the LA dilates relative to the Aorta. The LA/Ao ratio will start increasing above 1.5 (threshold described by Dr N. Silverman). This ratio may increase because of high LA diameter and/or small Ao diameter (pay attention to not miss a hypoplastic aortic arch, bicuspid aortic valve or coarctation!).
Beware that the LA may not dilate if there is a large inter-atrial shunt that decompresses the left atrium into the right atrium.
silverman-et-al-1974-echocardiographic-assessment-of-ductus-arteriosus-shunt-in-premature-infants.pdf
PW-Doppler must be obtained with the line of interrogation parallel to the LVOT-Aorta.
Ideally you would want the best and least angulation with the LVOT to obtain your PW-Doppler with here a VTI estimated at 0.150 meter.
With a large left-to-right patent ductus arteriosus (PDA), left ventricular output (LVO) is typically increased due to the significant volume overload on the left heart. Here’s why:
Increased Pulmonary Blood Flow → Increased Pulmonary Venous Return
The left-to-right shunt directs a portion of the systemic output back into the pulmonary circulation, leading to excessive pulmonary venous return to the left atrium (LA).
This results in elevated left atrial pressures and increased preload for the left ventricle (LV).
Increased LV Stroke Volume and Cardiac Output
Due to the increased preload, the LV must accommodate a higher volume of blood, leading to increased stroke volume and, consequently, an elevated left ventricular output (LVO).
The Frank-Starling mechanism contributes to increased contractility, maintaining a high cardiac output.
Key Echocardiographic Findings:
Key Echocardiographic Findings:
Increased LVO (measured via LVOT VTI and diameter)
Elevated E-wave velocity due to high preload
Shortened IVRT and deceleration time
Increased left atrial and LV dimensions (LA dilation, LVEDD increase)
PLAX view with anterior sweep visualizing the RVOT.
VTI here is 19.4 cm or 0.194 meter. The PAAT is 103 msec and RVET is 315 msec.
We locally measure the RVOT in the PLAX = 0.77 cm (RVOT).
Occasially, views in the PLAX are obstructed, and if the view is clearer in PSAX you can alternatively used this view to measure RVOT. Here: 0.77 cm (RVOT) in PSAX
Doppler flow reversal
Doppler flow reversal
Significant retrograde flow in diastole (middle cerebral artery) in an infant with a large ductus arteriosus (left to right) and diastolic steal.
Retrograde holodiastolic flow in the post-ductal descending aorta by PW Doppler from the suprasternal view.
Retrograde holodiastolic flow in the post-ductal descending aorta by PW Doppler from the subcostal view.
Retrograde holodiastolic flow in the celiac artery by PW Doppler from the subcostal view.
Retrograde holodiastolic flow in the anterior cerebral artery by PW Doppler from the transfontanelar view.
Retrograde holodiastolic flow in the middle cerebral artery by PW Doppler from the transfontanelar view.
Diameter of the PDA
Diameter of the PDA
Diameter 0.22 cm (2.2 mm)
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