Spectral Doppler waveforms in systemic arteries and physiological significance of a patent ductus arteriosus

A Novel Patent Ductus Arteriosus Severity Score to Predict Clinical Outcomes in Premature Neonates

Background: Patent Ductus Arteriosus (PDA) in premature neonates has been associated with comorbidities including chronic lung disease (CLD), and death. However, the treatment of PDA remains controversial. There have been several echocardiographic variables previously used to determine the hemodynamic significance of PDA but their utility in early prediction of clinical outcomes is not well studied. Objective: The objective of our study was to evaluate the use of a severity scoring system incorporating markers of systemic under perfusion, pulmonary over perfusion and left ventricular (LV) function in predicting clinical outcomes in premature neonates. Methods: It is a single center prospective observational study involving newborns < 32 weeks’ gestation. An echocardiogram was done within seven days of life to measure variables previously known to predict severity of shunting in PDA including pulmonary perfusion index (PPI). Predictors of CLD/death were identified using multivariate logistic regression. A severity score was derived and its ability to predict clinical outcomes was tested using a receiver operating characteristic curve. Results: We studied 98 infants with a mean (SD) gestation of 28.9 ± 1.91 weeks and birth weight of 1228.06 ± 318.94 g, respectively. We identified five echocardiographic variables along with gestational age that was independently associated with the outcome variable (PPI, LV output, Superior Mesenteric Artery [SMA] Velocity Time Integral [VTI], Peak diastolic flow velocity in Pulmonary Vein [PV Vd], and reversal of flow in diastole in descending aorta [DFR]). The range of severity score was 0 (low risk) to 12 (high risk). A higher score was associated with the primary outcome variable of CLD/death (7.5 [1.2] vs. 3.6 [1.5], p < 0.001). Our severity score had an area under the curve of 0.97 (95% CI 0.93−0.99, p < 0.001) for predicting CLD/death. Conclusion: Our new PDA severity score of 5.5 has a sensitivity and specificity of 94% and 93%, and positive and negative predictive values of 94% and 93%, respectively.

The often forgotten systemic effects of ductus arteriosus: impact on decision-making and future trials

Respiratory symptomatology and echocardiographic features of pulmonary circulation exclusively guide therapy for a hemodynamically significant patent ductus arteriosus in preterm infants. Interrogations of systemic artery Doppler or the exploration of their links with respective end organ symptomatology is not routine practice. This brief report shows the relevance of 'systemic' symptoms and the assessment of 'systemic hypo-perfusion' (and their resolution with physiologically appropriate therapy) in decision-making. Future trials should include this often-ignored aspect in study designs and/or post-hoc analysis.

Relationship of Patent Ductus Arteriosus Echocardiographic Markers With Descending Aorta Diastolic Flow

OBJECTIVES

To characterize the relationship of echocardiographic markers of left heart overload and flow in peripheral major end-organ vessels (eg, celiac artery) with the presence of reversed holodiastolic flow in the descending aorta, considered a surrogate marker of an increased transductal shunt volume, in preterm patients with a patent ductus arteriosus (PDA).

METHODS

This work was a retrospective study of data from echocardiography performed to investigate the hemodynamic significance of a PDA in preterm patients. We studied differences in echocardiographic markers of the PDA shunt volume according to patterns of flow in the postductal descending aorta (no PDA, PDA with antegrade diastolic flow, and PDA with reversed diastolic flow). The strength of the association between each echocardiographic marker and the presence of aortic holodiastolic flow reversal was investigated.

RESULTS

We studied 137 patients with a median (interquartile range) birth weight of 850 (694-1030) g and a median gestational age of 25 (24-27) weeks. Among patients with a PDA (113), those with diastolic flow reversal in the descending aorta (44) presented had increased echocardiographic markers representative of the shunt volume (increased left ventricular output, left atrial-to-aortic ratio, pulmonary vein D wave, and shorter isovolumic relaxation time) compared to those with aortic antegrade diastolic flow. A positive, albeit weak, correlation between diastolic flow reversal and shunt volume echocardiographic markers was found. Abnormal diastolic flow in the celiac artery had the strongest correlation (R²  = 0.24).

CONCLUSIONS

In preterm patients with a PDA, echocardiographic markers of the shunt volume were more abnormal in patients with reversed diastolic flow in the descending aorta. These data support the assumption that variance in these markers are related to the shunt volume, which needs consideration when adjudicating hemodynamic significance.

Effects of Patent Ductus Arteriosus on Organ Blood Flow in Infants Born Very Preterm: A Prospective Study with Serial Echocardiography

OBJECTIVE

To characterize the effects of a patent ductus arteriosus (PDA) on different organ blood flows in infants born preterm.

STUDY DESIGN

Infants born preterm at ≤30 weeks of gestational age had daily echocardiography and Doppler assessments of middle cerebral artery, celiac artery, superior mesenteric (SMA), and renal arteries (RA) during the first postnatal week. Abnormal organ blood flow was defined as either reverse or absent diastolic flow, abnormally low mean or systolic velocities, or abnormally high pulsatility or resistance index.

RESULTS

Twenty-five infants born very preterm (gestational age 27.0 ± 2.1 weeks) were enrolled. PDA presence at time of measurement increased the risk of abnormal organ blood flows (39% vs 8%, P < .001). Ductal diameter and left atrium-to-aortic root (LA/Ao) ratio correlated positively with resistance index (celiac artery, SMA, RA), and negatively with mean velocity (ductal diameter: SMA, RA; LA/Ao ratio: RA). A PDA >2.0 mm, LA/Ao ratio >1.4, and their combination were associated with 8.0 (95% CI 1.6-39.4)-, 6.7 (1.3-34.7)-, and 38.2 (3.2-455.5)-fold increase in risk of abnormal organ blood flow index, respectively. Abnormal descending aorta flow was detected in only 2% of measurements.

CONCLUSIONS

Ductal size >2.0 mm and LA/Ao >1.4, especially in combination, are associated with a greater risk of abnormal organ blood flows. We suggest that Doppler assessment of the renal and superior mesenteric arteries are more likely to detect systemic hypoperfusion than the descending aorta.

Early prediction of spontaneous Patent Ductus Arteriosus (PDA) closure and PDA-associated outcomes: a prospective cohort investigation

BACKGROUND

Patent ductus arteriosus (PDA), the most commonly diagnosed cardiovascular condition in preterm infants, is associated with increased mortality and harmful long-term outcomes (chronic lung disease, neurodevelopmental delay). Although pharmacologic and/or interventional treatments to close PDA likely benefit some infants, widespread routine treatment of all preterm infants with PDA may not improve outcomes. Most PDAs close spontaneously by 44-weeks postmenstrual age; treatment is increasingly controversial, varying markedly between institutions and providers. Because treatment detriments may outweigh benefits, especially in infants destined for early, spontaneous PDA closure, the relevant unanswered clinical question is not whether to treat all preterm infants with PDA, but whom to treat (and when). Clinicians cannot currently predict in the first month which infants are at highest risk for persistent PDA, nor which combination of clinical risk factors, echocardiographic measurements, and biomarkers best predict PDA-associated harm.

METHODS

Prospective cohort of untreated infants with PDA (n=450) will be used to predict spontaneous ductal closure timing. Clinical measures, serum (brain natriuretic peptide, N-terminal pro-brain natriuretic peptide) and urine (neutrophil gelatinase-associated lipocalin, heart-type fatty acid-binding protein) biomarkers, and echocardiographic variables collected during each of first 4 postnatal weeks will be analyzed to identify those associated with long-term impairment. Myocardial deformation imaging and tissue Doppler imaging, innovative echocardiographic techniques, will facilitate quantitative evaluation of myocardial performance. Aim1 will estimate probability of spontaneous PDA closure and predict timing of ductal closure using echocardiographic, biomarker, and clinical predictors. Aim2 will specify which echocardiographic predictors and biomarkers are associated with mortality and respiratory illness severity at 36-weeks postmenstrual age. Aim3 will identify which echocardiographic predictors and biomarkers are associated with 22 to 26-month neurodevelopmental delay. Models will be validated in a separate cohort of infants (n=225) enrolled subsequent to primary study cohort.

DISCUSSION

The current study will make significant contributions to scientific knowledge and effective PDA management. Study results will reduce unnecessary and harmful overtreatment of infants with a high probability of early spontaneous PDA closure and facilitate development of outcomes-focused trials to examine effectiveness of PDA closure in "high-risk" infants most likely to receive benefit.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03782610. Registered 20 December 2018.

Retrograde lower body arterial reservoir discharge underlies rapid reversal of ductus arteriosus shunting after early cord clamping at birth in preterm lambs

Arterial reservoir (“windkessel”) function, whereby a part of left ventricular (LV) output is stored in elastic arteries during systole and discharged in diastole, is a well-established physiological phenomenon. However, its role in rapid reversal (to left-to-right) and a systolic-to-diastolic shift of shunting across the ductus arteriosus after birth is unknown. To address this question, ductal and aortic isthmus flows were measured with high-fidelity transit-time probes in six anesthetized preterm fetal lambs before and after cord clamping and subsequent early mechanical ventilation and for 30 min postbirth. Descending aortic flow was calculated as the sum of isthmus and ductal flows. Left-to-right ductal flow profiles were related to those of the isthmus and descending aorta, with upper body arterial reservoir discharge indicated by forward diastolic isthmus flow, and retrograde lower body arterial reservoir discharge by negative diastolic descending aortic flow. Left-to-right ductal shunting appeared immediately after cord clamping ( P < 0.001), due entirely to newly emergent retrograde lower body reservoir discharge, and rose with ventilation via increased lower body reservoir discharge ( P < 0.005), supplemented by upper body reservoir discharge after 45 s ( P < 0.025) and LV systolic flow after 3 min ( P = 0.025). The contribution of lower body reservoir discharge to left-to-right ductal shunting fell to 55 ± 8% at ≥15 min ( P < 0.001) but remained higher ( P < 0.002) than LV systolic flow (33 ± 8%) or upper body reservoir discharge (12 ± 5%). These results suggest that retrograde lower body arterial reservoir discharge plays a key role in rapid reversal and a systolic-to-diastolic shift of ductal shunting after cord clamping and early ventilation at birth.

A Hemodynamically Significant Patent Ductus Arteriosus Does Not Affect Cerebral or Renal Tissue Oxygenation in Preterm Infants

BACKGROUND

Patent ductus arteriosus (PDA) is common in preterm infants and is associated with significant morbidity. To determine whether the PDA is hemodynamically significant (HSDA), several echocardiographic parameters have been suggested, including retrograde diastolic blood flow in the descending aorta (Dao).

OBJECTIVE

To assess the impact of an HSDA, including retrograde diastolic flow in the Dao, on regional tissue oxygen saturation (rSO2) and extraction measured by near-infrared spectroscopy (NIRS).

METHODS

This is a prospective observational cohort study in which we included preterm infants (GA <32 weeks) who underwent echocardiographic screening because of clinical signs of an HSDA within 2 weeks after birth. We measured cerebral and renal rSO2 on the day of echocardiography. HSDA was diagnosed if left-to-right shunting through the PDA was accompanied by left atrial-to-aortic root ratio >1.4 and/or left pulmonary artery end-diastolic flow velocity >0.2 m/s and/or retrograde diastolic blood flow in the Dao.

RESULTS

Forty-nine infants were included, with a median GA of 27.6 weeks (IQR: 26.1-29.0), birth weight of 980 g (IQR: 800-1,200), and postnatal age of 77 h (IQR: 70-107). Infants with a closed duct (n = 11), a non-HSDA (n = 18), and an HSDA (n = 20) had similar cerebral and renal NIRS measurements. Retrograde diastolic blood flow in the Dao, present in 11 infants with PDA, also did not affect cerebral and renal NIRS measurements.

CONCLUSION

In preterm infants with clinical signs of an HSDA within 2 weeks after birth, cerebral and renal oxygen saturation and extraction are not affected by an HSDA or by retrograde diastolic blood flow in the Dao.

Necrotizing enterocolitis in infants with ductal-dependent congenital heart disease

OBJECTIVE

Infants with congenital heart disease (CHD) receiving prostaglandins (PGEs) may be at an increased risk for necrotizing enterocolitis (NEC). Enteral feeding may further increase the risk of NEC in these patients. We evaluated the incidence of NEC and its association with enteral feeding in infants with ductal-dependent CHD.

STUDY DESIGN

We examined a cohort of infants with CHD receiving PGE in neonatal intensive care units managed by the Pediatrix Medical Group (Sunrise, FL) between 1997 and 2010. We used logistic regression to evaluate the association between NEC and enteral feeding, as well as other risk factors, including antacid medications, inotropic and ventilator support, and anatomic characteristics, controlling for gestational age.

RESULTS

We identified 6,710 infants with ductal-dependent CHD receiving PGE for 17,158 infant days. NEC occurred in 21 of the 6,710 (0.3%) infants, of whom 12/21 (57%) were < 37 weeks gestational age. The incidence of NEC was 1.2/1,000 infant days while on enteral feeds versus 0.4/1,000 infant days while not on enteral feeds (p = 0.27). Enteral feeding was not associated with a statistically significant increased odds of NEC on the day of diagnosis (odds ratio [OR] 2.08; 95% confidence interval [CI] 0.38, 11.7). Risk factors associated with a significant increased odds of NEC included a diagnosis of single-ventricle heart defect (OR 2.82; 95% CI 1.23, 6.49), although the overall risk in this population remained low (8/1,631, 0.5%).

CONCLUSION

The incidence of NEC in our cohort of infants with ductal-dependent CHD on PGE therapy was low and did not increase with enteral feeding.

Indomethacin vs ibuprofen: comparison of efficacy in the setting of conservative therapeutic approach

Indomethacin has been the mainstay for medical closure of patent ductus arteriosus. With its discontinuation, many units shifted to the use ibuprofen. We compared the therapeutic efficacy (successful closure, a priori defined as complete closure or >50% reduction in size) and the impact of the two drugs on neonatal morbidities. Two time epochs were analysed (IV indomethacin, January 2008 to November 2010, and IV ibuprofen lysine, November 2010 to September 2013). Demographic, clinical and echocardiographic data was compared. A total of 101 infants formed the study population, 58 (57.4%, indomethacin epoch) and 43 (42.6%, ibuprofen epoch). The gestational age, birth weight and postnatal age at initial treatment respectively were comparable [26 ± 1.8 vs 26.5 ± 1.9 weeks, 806 ± 183 vs 862 ± 234 g and median 12 (6, 17) vs 11 days (8, 18)]. Successful closure was significantly higher in the indomethacin group [26 (45%) vs 6 (14%), p < 0.01]. The incidence of bronchopulmonary dysplasia (BPD) and discharge in oxygen was comparable. Four infants (all in the ibuprofen group) developed pulmonary hypertension; one required pulmonary vasodilator therapy. Posttreatment serum creatinine was significantly lower in the ibuprofen group. Mortality was higher during the indomethacin epoch. On univariate analysis, the choice of the drug and higher gestational age were associated with successful closure.

CONCLUSION

Indomethacin was more efficacious for ductal closure although did not impact outcomes. Use of staging schema may help understand 'need to treat' and refine therapy.

Patent ductus arteriosus ligation and adverse outcomes: causality or bias?

Observational studies have associated patent ductus arteriosus (PDA) ligation in preterm infants with increased chronic lung disease (CLD), retinopathy of prematurity, and neurodevelopmental impairment at long-term follow-up. Although the biological rationale for this association is incompletely understood, there is an emerging secular trend toward a permissive approach to the PDA. However, insufficient adjustment for postnatal, pre-ligation confounders, such as intraventricular hemorrhage and the duration and intensity of mechanical ventilation, suggests the presence of residual bias due to confounding by indication, and obliges caution in interpreting the ligation-morbidity relationship. A period of conservative management after failure of medical PDA closure may be considered to reduce the number of infants treated with surgery. Increased mortality and CLD in infants with persistent symptomatic PDA suggests that surgical ligation remains an important treatment modality for preterm infants.

PDA ligation and health outcomes: a meta-analysis

BACKGROUND AND OBJECTIVE

Patent ductus arteriosus (PDA) ligation has been variably associated with neonatal morbidities and neurodevelopmental impairment (NDI). The objective was to systematically review and meta-analyze the impact of PDA ligation in preterm infants at <32 weeks' gestation on the risk of mortality, severe neonatal morbidities, and NDI in early childhood.

METHODS

Medline, Embase, Cochrane Central Register of Controlled Trials, Education Resources Information Centre (ERIC), Cumulative Index to Nursing and Allied Health (CINAHL), PsycINFO, and the Dissertation database were searched (1947 through August 2013). Risk of bias was assessed by using the Newcastle-Ottawa Scale and the Cochrane Risk of Bias tool. Meta-analyses were performed by using a random-effects model. Unadjusted and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were pooled when appropriate.

RESULTS

Thirty-nine cohort studies and 1 randomized controlled trial were included. Nearly all cohort studies had at least moderate risk of bias mainly due to failure to adjust for survival bias and important postnatal preligation confounders such as ventilator dependence, intraventricular hemorrhage, and sepsis. Compared with medical treatment, surgical ligation was associated with increases in NDI (aOR: 1.54; 95% CI: 1.01-2.33), chronic lung disease (aOR: 2.51; 95% CI: 1.98-3.18), and severe retinopathy of prematurity (aOR: 2.23; 95% CI: 1.62-3.08) but with a reduction in mortality (aOR: 0.54; 95% CI: 0.38-0.77). There was no difference in the composite outcome of death or NDI in early childhood (aOR: 0.95; 95% CI: 0.58-1.57).

CONCLUSIONS

Surgical ligation of PDA is associated with reduced mortality, but surviving infants are at increased risk of NDI. However, there is a lack of studies addressing survival bias and confounding by indication.

Plasma C-terminal pro-endothelin-1 and the natriuretic pro-peptides NT-proBNP and MR-proANP in very preterm infants with patent ductus arteriosus

BACKGROUND

In very preterm infants, clinical decision-making, such as closing a patent ductus arteriosus (PDA), may be aided by measuring circulating natriuretic and endothelial pro-peptides.

OBJECTIVES

To investigate the association between perinatal characteristics, PDA echocardiography and plasma concentrations of stable pro-peptides of B-type natriuretic peptide (NT-proBNP), atrial natriuretic peptide (MR-proANP) and endothelin-1 (CT-proET-1).

METHODS

A prospective, cross-sectional, single-center study was performed in 66 infants who were less than 32 weeks of gestational age. Pro-peptide concentrations were determined at birth and at day 2-3 of life.

RESULTS

Plasma concentrations of all 3 pro-peptides increased on average 2- to 5-fold from birth to day 2-3 of life. NT-proBNP and MR-proANP were closely related at birth and at day 2-3 (Rs 0.902 and 0.897, respectively, p < 0.001), whereas CT-proET-1 was related to NT-proBNP and MR-proANP at birth (Rs 0.478 and 0.460, respectively, p < 0.001) but not at day 2-3. Birth weight was negatively related to all 3 pro-peptides at birth (p < 0.01); however, preeclampsia and compromised placental perfusion were associated with elevated NT-proBNP and MR-proANP concentrations at birth. At day 2-3, MR-proANP and NT-proBNP correlated significantly with the ductal diameter (Rs 0.416 and 0.415, respectively, both p = 0.011), whereas CT-proET-1 correlated with the left atrium/aorta ratio (Rs 0.506, p = 0.027). CT-proET-1 was elevated in infants with treated compared to untreated PDA [median (5-95% range) 388 (272-723) vs. 303 (152-422) pmol/l, p = 0.011], but not NT-proBNP or MR-proANP.

CONCLUSION

CT-proET-1 is a promising predictor in determining the need for PDA intervention.

Urinary NT-proBNP, NGAL, and H-FABP may predict hemodynamic relevance of patent ductus arteriosus in very low birth weight infants

BACKGROUND

Hemodynamically significant patent ductus arteriosus (hsPDA) is the most common functional cardiovascular disease in preterm infants. The necessity to treat hsPDA can neither be derived solely from clinical nor from echocardiographic criteria.

OBJECTIVE

The aim of this study was to establish non-invasive parameters which can differentiate hsPDA from non-hsPDA.

METHODS

Urinary protein levels of NT-proBNP, NGAL, and H-FABP were measured and correlated with the necessity of therapy for PDA. In 37 neonates (<1,500 g), urinary protein concentrations were tested on days 0, 2, and 7 by ELISA methodology. Of 37 infants, 12 required therapeutic interventions according to current treatment standards.

RESULTS

Infants receiving an intervention for PDA showed significantly higher levels of pro-BNP, NGAL, and H-FABP at all time points except for NT-proBNP on day 0. Infants requiring a second or third course of ibuprofen had significantly higher levels of H-FABP and NGAL. In all samples, the concentration of the three proteins correlated positively with each other.

CONCLUSIONS

The present study shows that measurement of urinary proteins is a powerful and non-invasive method to quantify the effect of PDA on systemic perfusion in preterm infants. Furthermore, NGAL and H-FABP may be used to indicate the necessity of pharmacological or surgical treatment of PDA.