Table 3.
Echocardiographic parameters used in the evaluation of hemodynamically significant patent ductus arteriosus
| Parameter | Variable | Effect of HSPDA | Threshold value |
|---|---|---|---|
| Direct evaluation of PDA | |||
| Size | PDA diameter (mm) | Increases | Small: <1.5 mm Moderate: 1.5-2 mm Large: ≥2 mm |
| PDA diameter: Left pulmonary artery diameter (on the first 4 days) | Increases | Small: <0.5 mm Moderate: 0.5- 1 mm ~Large: ≥1mm | |
| PDA diameter index (mm/ kg) | Increases | >1.4 | |
| Flow pattern | End-diastolic: peak systolic flow rate ratio in the shunt in PDA | Decreases | <0.5 |
| Indirect markers of the shunt volume | |||
| Increased pulmonary blood flow | Left atrium: Aortic root ratio | Increases | >15 |
| Left ventricular end-diastolic diameter: Aortic root ratio | Increases | >2.1 | |
| Early and late diastolic flow ratio in the mitral valve | Increases | >1 | |
| Left ventricular isovolumetric relaxation time (ms) | Decreases | <35 | |
| Left ventricular output (mL/kg/min) | Increases | >314 | |
| LPA mean antegrade flow rate (cm/s) | Increases | >42 | |
| LPA end-diastolic antegrade flow rate (cm/s) | Increases | >20 | |
| Decreased systemic blood flow | Diastolic flow patttern in systemic arteries (descending aorta, celiac, superior mesenteric, middle cerebral) | Decreases | Small: Antegrade diastolic flow Moderate: Absence of diastolic flow Large: Retrograde diastolic flow |
| Left ventricular output/ | Increases | >4 | |
| Superior vena cava flow rate | |||
HSPDA: hemodynamically significat PDA; PDA: patent ductus arteriosus; LPA: left pulmonary artery