Table 1 Proposed staging system (adapted from McNamara and Hellman, unpublished clinical triaging system for ligation of a patent ductus arteriosus (PDA)) for determining the magnitude of the haemodynamically significant ductus arteriosus (HSDA), which is based on clinical and echocardiographic criteria
C1AsymptomaticE1No evidence of ductal flow on two-dimensional or Doppler interrogation
C2MildE2Small non-significant ductus arteriosus
    Oxygenation difficulty (OI <6)    Transductal diameter <1.5 mm
    Occasional (<6) episodes of oxygen desaturation,    Restrictive continuous transductal flow (DA Vmax >2.0 m/s)
        bradycardia or apnoea    No signs of left heart volume loading (eg, mitral regurgitant jet >2.0 m/s
    Need for respiratory support (nCPAP) or mechanical        or LA:Ao ratio >1.5:1)
        ventilation (MAP <8)    No signs of left heart pressure loading (eg, E/A ratio >1.0 or IVRT >50)
    Feeding intolerance (>20% gastric aspirates)    Normal end-organ (eg, superior mesenteric, middle cerebral) arterial
    Radiologic evidence of increased pulmonary vascularity        diastolic flow
C3ModerateE3Moderate HSDA
    Oxygenation difficulty (OI 7–14)    Transductal diameter 1.5–3.0 mm
    Frequent (hourly) episodes of oxygen desaturation,    Unrestrictive pulsatile transductal flow (DA Vmax<2.0 m/s)
        bradycardia or apnoea    Mild-moderate left heart volume loading (eg, LA:Ao ratio 1.5 to 2:1)
    Increasing ventilation requirements (MAP 9–12)    Mild-moderate left heart pressure loading (eg, E/A ratio >1.0 or
    Inability to feed due to marked abdominal distension        IVRT 50–60)
        or emesis    Decreased or absent diastolic flow in superior mesenteric artery,
    Oliguria with mild elevation in plasma creatinine        Middle cerebral artery or renal artery
    Systemic hypotension (low mean or diastolic BP) requiring
        a single cardiotropic agent
    Radiological evidence of cardiomegaly or pulmonary
    Mild metabolic acidosis (pH 7.1–7.25 and/or
        base deficit −7 to −12.0)
C4SevereE4Large HSDA
    Oxygenation difficulty (OI >15)    Transductal diameter >3.0 mm
    High ventilation requirements (MAP >12) or need for    Unrestrictive pulsatile transductal flow
        high-frequency modes of ventilation    Severe left heart volume loading (eg, LA:Ao ratio >2:1, mitral regurgitant
    Profound or recurrent pulmonary haemorrhage        jet >2.0 m/s)
     “NEC-like” abdominal distension with tenderness    Severe left heart pressure loading (eg, E/A ratio >1.5 or IVRT >60)
        or erythema    Reversal of end-diastolic flow in superior mesenteric artery, middle
    Acute renal failure        cerebral artery or renal artery
    Haemodynamic instability requiring >1 cardiotropic agent
    Moderate-severe metabolic acidosis (pH<7.1) or
        base deficit >−12.0
  • BP, blood pressure; DA Vmax, ductus arteriosus peak velocity; E/A, early passive to late atrial contractile phase of transmitral filling ratio; IVRT, isovolumic relaxation time; LA: Ao ratio, left atrium to aortic ratio; MAP, mean airway pressure; nCPAP, nasal continuous positive airway pressure; NEC, necrotising enterocolitis; OI, oxygenation index.

  • Patients should be assigned both a clinical and echocardiography stage (eg, neonate with severe oxygenation failure, pulmonary haemorrhage and a 3.2 mm unrestrictive left-to-right shunt will be C4-E4 class HSDA).

  • Detailed discussion of the echocardiography parameters is beyond the scope of this perspective.