Neonatal Echo HemodynamicsExperimental

Ventricular outputs and SVC flow

Flow [mL/kg/min] = VTI [cm] x π x (d [cm] / 2)^2 x HR [beats/min] / weight [kg]
LV output: d = aortic valve diameter, VTI = aortic VTI
RV output: d = pulmonary valve diameter, VTI = pulmonary VTI
SVC flow:  d = (maximal + minimal SVC diameter) / 2, VTI = SVC VTI

• SVC method: Kluckow M, Evans N. Superior vena cava flow in newborn infants: a novel marker of systemic blood flow. Arch Dis Child Fetal Neonatal Ed 2000;82(3):F182-F187. doi:10.1136/fn.82.3.f182. The full text could not be retrieved; the formula is quoted from a later paper describing the standard Kluckow method: “SVC flow = (SVC VTI × (π × (mean SVC diameter²/4) × heart rate)/body weight”, mean of minimal and maximal M-mode diameters (Miletin et al., Front Pediatr 2021, doi:10.3389/fped.2021.661698).
• Normal data (Kluckow 2000 abstract): 14 infants >36 weeks, median SVC flow 76 mL/kg/min on day 1 and 93 on day 2; 25 uncomplicated infants <30 weeks, median 62 at 5 h rising to 86 at 48 h; lowest values 30 at 5 h rising to 46 by 48 h. Intra- and interobserver variability 8.1% and 14%. With a closed duct, SVC flow averaged 37% of LV output.
• Low SVC flow <41 mL/kg/min: Osborn DA, Evans N, Kluckow M. Arch Dis Child Fetal Neonatal Ed 2004;89(2):F168-F173 (abstract: “low SVC flow (< 41 ml/kg/min)”, infants <30 weeks, first day). doi:10.1136/adc.2002.023796. Kluckow and Evans 2000 (doi:10.1136/fn.82.3.f188) described low flow as below the range in well preterm babies. Some later studies use <40. This page flags low flow only for infants born <30 weeks at ≤48 h of age.
• Error propagation: diameter is squared, so ±10% in diameter gives about −19% / +21% in flow; the range is shown under each flow.
• Shunts: a left-to-right PDA adds to LV output and an atrial shunt adds to RV output, so neither equals systemic flow when a shunt is present. SVC flow is not affected by these shunts (the reason it was proposed).

PDA severity score (El-Khuffash 2015)

Score = (GA [weeks] x -1.304) + (PDA diameter [mm] x 0.781)
      + (LV output [mL/kg/min] x 0.008) + (PDA Vmax [m/s] x -1.065)
      + (LV a' [cm/s] x -0.470) + 41

High risk of chronic lung disease or death: score ≥ 5

• El-Khuffash A, James AT, Corcoran JD, et al. A patent ductus arteriosus severity score predicts chronic lung disease or death before discharge. J Pediatr 2015;167(6):1354-1361.e2. doi:10.1016/j.jpeds.2015.09.028. Abstract: 141 infants <29 weeks, echo on day 2; five variables (gestation at birth, PDA diameter, maximum flow velocity, LV output, LV a′); range 0 (low risk) to 13 (high risk); AUC 0.92; cut-off 5: sensitivity 92%, specificity 87%.
• The J Pediatr full text was not retrieved. The coefficients are quoted verbatim, identically, from two open-access papers: the PDA RCT protocol by El-Khuffash et al. (HRB Open Res 2021, doi:10.12688/hrbopenres.13140.1; “where 41 is the constant of the formula”, echo at 36–48 h, score ≥5.0 high risk) and a 2025 cohort applying the score (Mullaly et al., BMJ Paediatr Open 2025, doi:10.1136/bmjpo-2025-003347; gestation at birth, birth weight for LV output).
• Guards on this page: GA at birth <29 weeks, scan at 24–48 h (day 2), PDA present. Outside these, no score is shown. The group is decided on the unrounded score.

Iowa PDA score (shunt volume)

Total = sum of the 7 items (0 to 14)
<6   low-volume shunt
6-8  moderate-volume shunt
≥9   high-volume shunt ("above 8")

• Source of the table: Brandt C, Mat HD, Bischoff AR, McNamara PJ, Rios DR. Association of low shunt burden from PDA and adverse outcomes in premature infants. J Perinatol 2026;46(3):364-369 (online 2025). doi:10.1038/s41372-025-02437-4. Table 1, “Determination of PDA status on TNE, low-volume shunt score <6”, retrieved from the open-access full text (PMC12628839) and quoted verbatim above. Cohort: infants born <30 weeks with TNE in the first postnatal week, University of Iowa, 2018–2023.
• Categories: Mifflin J, Makoni M, Chatmethakul T, McNamara PJ, Bischoff AR. Cerebral and intestinal Doppler patterns according to PDA shunt characteristics in preterm infants. J Perinatol 2026;46(3):349-357 (online 2025). doi:10.1038/s41372-025-02505-9: “maximum possible score of 14 points. A score below 6 indicates a low-volume … Scores between 6 and 8 indicate moderate shunting, where medical therapy may be warranted, while scores above 8 denote high-volume shunts” (infants <32 weeks, <40 days). Mifflin’s text lists “LVO” among the items (its supplementary table could not be read), whereas Brandt’s table uses LVO:RVO, as do the descriptions in Battersby 2026 (“left to right ventricular output ratio”) and Int J Pediatr 2025 (doi:10.1155/ijpe/5558870); this page follows the Brandt table. A later Iowa analysis used “high-volume shunt (score ≥ 9)” (Hobson et al., J Pediatr 2025, doi:10.1016/j.jpeds.2025.114965, abstract). In the Iowa early-screening programme the treatment threshold was a score ≥6 (Battersby et al., Arch Dis Child Fetal Neonatal Ed 2026, doi:10.1136/archdischild-2025-330266, summarising Giesinger et al., Semin Perinatol 2023, doi:10.1016/j.semperi.2023.151721).
• Original version: Rios DR, de Freitas Martins F, El-Khuffash A, Weisz DE, Giesinger RE, McNamara PJ. Early role of the atrial-level communication in premature infants with patent ductus arteriosus. J Am Soc Echocardiogr 2021;34(4):423-432.e1. doi:10.1016/j.echo.2020.11.008 (author manuscript PMC8026594, Appendix 2). Same E, IVRT, D wave and LA:Ao rows; LVO (mL/min/kg) <250 / 250–430 / >430 instead of LVO:RVO; reversal forward 0 / reversed 2; “Total score = [# total points] + [PDA diameter ÷ weight at echo]” (continuous, not banded); “a score of ≥ 6 signifying a presumed hsPDA”. Infants <32 weeks, first postnatal week. The authors state it “has not been formally validated”. The page shows this version as a secondary line only; the middle bands of that table (“45–80” etc.) are read as inclusive, as in the 2025 table.
• Guards on this page: PDA present with an exclusive or predominantly left-to-right shunt; born <32 weeks; 12 h to 40 days of age (the earliest Iowa screening was at 12–18 h; the oldest cohort was <40 days). Outside these, no score is shown. Each item is scored on the unrounded value. LVO:RVO comes from the LV and RV outputs above; heart rate and weight cancel in the ratio.
• Not verified: the score has no published derivation or validation statistics (sensitivity, specificity) against an outcome; it is an expert-consensus composite. No published worked example was found; the tests use hand-built cases and an independent Python implementation.

Post-ligation LV output (Jain 2012), cited context

Jain A, Sahni M, El-Khuffash A, et al. Use of targeted neonatal echocardiography to prevent postoperative cardiorespiratory instability after patent ductus arteriosus ligation. J Pediatr 2012;160(4):584-589.e1. doi:10.1016/j.jpeds.2011.09.027. Abstract: LV output <200 mL/kg/min at 1 hour after PDA ligation was a sensitive predictor of systemic hypotension and need for inotropes, and was used to start milrinone in the second epoch. The marker is shown only when the post-ligation box is ticked; it is not a treatment rule.

TAPSE z-score by gestational age (Koestenberger 2011)

Predicted TAPSE [cm] = -0.471 + 0.036 x GA [weeks + days/7]
z = (TAPSE [cm] - predicted) / 0.065          0.065 cm = residual SD
-2 to +2 SD range = predicted -/+ 0.130 cm

• Koestenberger M, Nagel B, Ravekes W, et al. Systolic right ventricular function in preterm and term neonates: reference values of the tricuspid annular plane systolic excursion (TAPSE) in 258 patients and calculation of z-score values. Neonatology 2011;100(1):85-92. doi:10.1159/000322006. Read in full text: the regression equation and residual SD (Results) and Table 1 (observed and predicted mean ±2 SD for each week). 258 neonates (134 male), 25+0 to 40+6 weeks, 530–4,200 g, echo within 48 h after birth. TAPSE rose linearly with gestation (r = 0.93); gestational age alone explained 85.9% of the variance (86.3% with birth weight); no sex difference. M-mode from the apical four-chamber view with the cursor at the lateral tricuspid annulus, 5 beats averaged.
• Reference population: appropriate for gestational age only. Excluded: small for gestational age, malformations, suspected infection or sepsis, suspected pulmonary hypertension, inotropes, asphyxia, intubation and ventilation, a significant PDA shunt (the paper’s example: >1.5 mm in preterm infants <1,500 g) or a bidirectional shunt, and preterm infants who later developed BPD. Below 28 weeks, nasal CPAP with up to 30% oxygen was accepted.
• Guards on this page: gestational age 25+0 to 40+6 weeks and a scan at 48 h of age or less; outside these no z-score is shown, only the published values. It is a reference at birth: it was not tested in preterm infants scanned weeks later (for example at 36 weeks postmenstrual age). The page adds a caution when the PDA entered above is of a kind the cohort excluded.
• Week labels: Table 1 rows “26” to “41” are the 26th to 41st week of gestation (row 26 = 25+0 to 25+6). The equation reproduces the predicted column at mid-week (25.5 weeks gives 0.447 cm, printed 0.45; 39.5 weeks gives 0.951, printed 0.95), so gestational age enters as completed weeks plus days/7. The observed means were 0.44 cm (−2 to +2 SD 0.30–0.59) in the 26th week and 1.03 cm (0.85–1.21) in the 41st week.
• Koestenberger M, Ravekes W, Everett AD, et al. Right ventricular function in infants, children and adolescents: reference values of the tricuspid annular plane systolic excursion (TAPSE) in 640 healthy patients and calculation of z score values. J Am Soc Echocardiogr 2009;22(6):715-719. doi:10.1016/j.echo.2009.03.026. Read in full text. Table 1, neonates 0–30 days (n = 41): mean 0.91 cm, −2 to +2 SD 0.68–1.15, −3 to +3 SD 0.56–1.26 cm. The paper gives bounds by age group and charts; it prints no z-score equation, so it is shown for context only.
• Jain A, et al. J Am Soc Echocardiogr 2014;27(12):1293-1304. doi:10.1016/j.echo.2014.08.018. Term newborns at 15 and 35 h: normative RV data and Z scores. [unverified] Its TAPSE equations have not been checked against the paper and are not used here.

Not verified on this page

• Normal ranges for LV and RV output are not shown (no primary source retrieved).
• The El-Khuffash PDA score and SVC formula were checked against secondary open-access quotations, not the original full texts. The Iowa PDA score table was checked against the original open-access full texts (Brandt 2025; Rios 2021).
• TAPSE z-score: the equation and residual SD were checked against the Koestenberger 2011 full text, and the The equation reproduces the Table 1 predicted column at every week (within its 2-decimal printing). In Table 1 the printed predicted +2 SD for the 32nd and 37th weeks (0.80 and 0.98 cm) is 0.007 cm above predicted + 2 × 0.065 (0.793 and 0.973); the page uses the printed equation and SD. Not independently verified.
• Other “Iowa” scores: a “modified Iowa PDA score” is named in Hobson et al. 2025 (abstract only; modifications not described there) and is not implemented separately.