Diastolic left ventricular function in preterm infants with a patent ductus arteriosus: a serial Doppler echocardiography study

The effect of heart rate on systolic and diastolic time intervals and cardiac function in stable and sick preterm infants

BACKGROUND

Diastolic function includes relaxation and filling of the heart and is dependent on heart rate (HR) and time spent in either systole (St) or diastole (Dt). The St/Dt ratio increases as HR increased and is a marker of overall cardiac function in children with heart failure. The aim of this study is to describe cardiac cycle events in preterm infants.

METHODS

Cardiac ultrasounds of preterm infants <32 weeks were retrospectively reviewed for cardiac cycle events from Tissue Doppler images and grouped by clinical indication of the scan as stable or as clinical deterioration with significant illness.

RESULTS

412 scans in 201 preterm infants were analyzed. St/Dt ratio increased with increasing HR. St increased from 50 to 54 % of the cardiac cycle length with shortened diastolic duration. Isovolumetric contraction and relaxation remained unchanged at 9 and 12 % of the cardiac cycle respectively. Mean St, Dt and St/Dt ratio in stable infants were 195(19) msec, Dt 175(24) msec and 1.13 (0.16) respectively. Sick infants without cardiovascular medications showed a significantly shorter St and lower St/Dt ratio. Cardiovascular medications increased isovolumetric times, Dt, and early diastolic duration.

CONCLUSION

Reference values for cardiac cycle durations and St/Dt ratio are presented. Preterm hearts adapt to higher HR by shifting towards systole and shortened early diastole by optimising its force frequency relationship and enhanced relaxation. The St/Dt ratio was altered in preterm infants with significant illness. This simple ultrasound marker could be tested in further studies that investigate cardiovascular medications in preterm infants.

Serial tissue Doppler imaging in the evaluation of bronchopulmonary dysplasia-associated pulmonary hypertension among extremely preterm infants: a prospective observational study

Objectives

To evaluate serial tissue Doppler cardiac imaging (TDI) in the evolution of bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) among extremely preterm infants.

Design

Prospective observational study.

Setting

Single-center, tertiary-level neonatal intensive care unit.

Patients

Infant born <28 weeks gestation.

Main outcome measures

Utility of TDI in the early diagnosis and prediction of BPD-PH and optimal timing for screening of BPD-PH.

Results

A total of 79 infants were included. Of them, 17 (23%) had BPD-PH. The mean gestational age was 25.9 ± 1.1 weeks, and mean birth weight was 830 ± 174 g. The BPD-PH group had a high incidence of hemodynamically significant patent ductus arteriosus (83% vs. 56%, p < 0.018), longer oxygen days (96.16 ± 68.09 vs. 59.35 ± 52.1, p < 0.008), and prolonged hospital stay (133.8 ± 45.9 vs. 106.5 ± 37.9 days, p < 0.005). The left ventricular eccentricity index (0.99 ± 0.1 vs. 1.1 ± 0.7, p < 0.01) and the ratio of acceleration time to right ventricular ejection time showed a statistically significant trend from 33 weeks (0.24 ± 0.05 vs. 0.28 ± 0.05, p < 0.05). At 33 weeks, the BPD-PH group showed prolonged isovolumetric contraction time (27.84 ± 5.5 vs. 22.77 ± 4, p < 0.001), prolonged isovolumetric relaxation time (40.3 ± 7.1 vs. 34.9 ± 5.3, p < 0.003), and abnormal myocardial performance index (0.39 ± 0.05 vs. 0.32 ± 0.03, p < 0.001). These differences persisted at 36 weeks after conceptional gestational age.

Conclusions

TDI parameters are sensitive in the early evolution of BPD-PH. Diagnostic accuracy can be increased by combining the TDI parameters with conventional echocardiographic parameters. BPD-PH can be recognizable as early as 33-34 weeks of gestation.

The association between patterns of early respiratory disease and diastolic dysfunction in preterm infants

BACKGROUND

This study aims to determine the association between clinical patterns of early respiratory disease and diastolic dysfunction in preterm infants.

METHODS

Preterm infants <29 weeks' gestation underwent cardiac ultrasounds around day 7 and 14-21. Respiratory dysfunction patterns were classified as stable (ST), respiratory deterioration (RD) or early persistent respiratory dysfunction (EPRD) according to oxygen need. Diastolic dysfunction was diagnosed using a multi-parameter approach including left atrial strain (LASR) to help differentiate between cardiac or pulmonary pathophysiology.

RESULTS

98 infants (mean 27 weeks) were included. The prevalence of ST, RD and EPRD was 53%, 21% and 26% respectively. Diastolic dysfunction was more prevalent in the RD and EPRD groups with patent ductus arteriosus and significant growth restriction as risk factors. Not all infants with a PDA developed diastolic dysfunction. LASR was lower in the EPDR group.

CONCLUSION

Respiratory dysfunction patterns are associated with diastolic dysfunction in preterm infants.

Echocardiography algorithms to assess high left atrial pressure and grade diastolic function in preterm infants

BACKGROUND

Relaxation, restoring forces, myocardial stiffness and atrial function determine left ventricular (LV) diastolic function. This study aims to provide a comprehensive assessment of diastolic function in preterm infants using conventional echocardiography and speckle tracking imaging and determine the diagnostic accuracy of various algorithms to detect high left atrial pressure (LAP).

METHODS

Preterm infants received an echocardiogram 1 week after birth and diastolic reference values were derived from the outer percentiles of stable preterm infants. Impaired relaxation, LV stiffness and high LAP were defined by using algorithms where at least half of the parameters were outside the normal range. Diastolic function was graded using the 2016 American Society of Echocardiography algorithm and expanded with the EA ratio and left atrial strain. The diagnostic accuracy of various algorithms to detect high LAP was determined with sensitivity analysis.

RESULTS

We studied 146 infants (59 stable) with a mean of 27(1) weeks gestation. Impaired relaxation, LV stiffness and high LAP were found in 8%, 7%, and 14% of infants. The patent ductus arteriosus was a contributing factor to high LAP and LV stiffness, not impaired relaxation. Diagnostic accuracy improved from 90% to 96% and sensitivity from 40% to 90% by adding left atrial strain to the 2016 algorithm.

CONCLUSION

Various grades of diastolic dysfunction could be appreciated in preterm infants using a multi-parameter approach. Adding left atrial strain improved sensitivity to detect infants with high LAP.

Diastolic ventricular function in persistent pulmonary hypertension of the newborn

Background

Persistent pulmonary hypertension of the newborn (PPHN) is usually considered a consequence of impaired pulmonary circulation. However, little is known regarding the role of cardiac dysfunction in PPHN. In this study, we hypothesized that the tolerance for pulmonary hypertension in newborn infants depends on the biventricular function. The aim of this study is to evaluate biventricular cardiac performance by using Tissue Doppler Imaging (TDI) in an healthy newborn infants with asymptomatic pulmonary hypertension and in newborn infants with PPHN.

Methods

Right and left cardiac function were investigated using conventional imaging and TDI in 10 newborn infants with PPHN ("PPHN") and 10 asymptomatic healthy newborn infants ("asymptomatic PH").

Results

Systolic pulmonary artery pressure (PAP) as assessed by TDI and the mean systolic velocity of the right ventricular (RV) free wall were similar in both groups. The isovolumic relaxation time of the right ventricle at the tricuspid annulus was significantly longer in the "PPHN" than in the "asymptomatic PH" group (53 ± 14 ms vs. 14 ± 4 ms, respectively; p < 0.05). Left ventricular (LV) function was normal in both groups with a systolic velocity (S'LV) at the LV free wall groups (6 ± 0.5 cm/s vs. 8.3 ± 5.7 cm/s, p > 0.05).

Conclusion

The present results suggest that high PAP with or without respiratory failure is not associated with altered right systolic ventricular function and does not affect LV function in newborn infants. PPHN is characterized by a marked right diastolic ventricular dysfunction. These data suggest that the hypoxic respiratory failure in PPHN results, at least in part, from diastolic RV dysfunction and right to left shunting across the foramen ovale. We propose that the severity of the respiratory failure is more related to the RV diastolic dysfunction than the pulmonary artery pressure.

Left ventricular function before and after percutaneous patent ductus arteriosus closure in preterm infants

BACKGROUND

Definitive closure of the patent ductus arteriosus (PDA) is associated with significant changes in the loading conditions of the left ventricle (LV), which may lead to cardiovascular and respiratory instability. The objective of the study was to evaluate targeted neonatal echocardiography (TnECHO) characteristics and the clinical course of preterm infants ≤2 kg undergoing percutaneous PDA closure.

METHODS

Retrospective cohort study of prospectively acquired pre- and post-closure TnECHOs to assess hemodynamic changes. Cardiorespiratory parameters in the first 24 h following PDA closure were also evaluated.

RESULTS

Fifty patients were included with a mean age of 30.6 ± 9.6 days and weight of 1188 ± 280 g. LV global longitudinal strain decreased from -20.6 ± 2.6 to -14.9 ± 2.9% (p < 0.001) after 1 h. There was a decrease in LV volume loading, left ventricular output, LV systolic and diastolic parameters. Cardiorespiratory instability occurred in 24 (48%) [oxygenation failure in 44%] but systolic hypotension and/or need for cardiovascular medications was only seen in 6 (12%). Patients with instability had worse baseline respiratory severity score and lower post-closure early diastolic strain rates.

CONCLUSIONS

Percutaneous PDA closure leads to a reduction in echocardiography markers of LV systolic/diastolic function. Post-closure cardiorespiratory instability is characterized primarily by oxygenation failure and may relate to impaired diastolic performance.

IMPACT

Percutaneous patent ductus arteriosus closure leads to a reduction in echocardiography markers of left ventricular volume loading, cardiac output, and left ventricular systolic/diastolic function. Post-procedural cardiorespiratory instability is characterized primarily by oxygenation failure. Post-procedural cardiorespiratory instability may relate to impaired diastolic performance.

Short-term ventriculo-arterial coupling and myocardial work efficiency in preterm infants undergoing percutaneous patent ductus arteriosus closure

Definitive closure of a patent ductus arteriosus (PDA) causes significant changes in loading conditions of the left ventricle (LV) which can lead to cardiorespiratory instability including hypotension, low cardiac output, oxygenation, and ventilation impairment. Physiological insights of the adaptation of the LV can be gained by looking at ventriculo-arterial coupling (VAC) and myocardial work-energetics. We conducted a retrospective cohort study of preterm infants with echocardiographic assessment of VAC parameters, including end-systolic and arterial elastance (EES , EA ), and myocardial work indices derived from longitudinal strain analysis before and 1-h after percutaneous PDA closure. A total of 35 patients were included with mean [±SD] age at intervention of 30.8 ± 9.9 days and median [IQR] weight of 1130 [995, 1318] grams. There was a reduction in preload and stroke volume, an increase in EA (38.6 ± 11.4 vs. 60 ± 15.1 mmHg/ml/kg, p < 0.001) and in EES (72 [61.5, 109.8] vs. 91.6 [72.2, 125.2] mmHg/ml/kg, p = 0.003) post-closure. Myocardial work indices reduced after PDA closure, including global work efficiency (93.9 ± 2.3 vs. 91.1 ± 3.6%, p < 0.001). A total of 17 (48.6%) patients developed post-closure instability which was associated with younger age, lower preload, and higher EA and EES . Percutaneous PDA closure is associated with major short-term changes in VAC and myocardium energetics, which may provide novel insights on the physiology of PDA closure and on the differential vulnerability to changes in loading conditions.

Spontaneous Closure of the Ductus Arteriosus in Preterm Infants: A Systematic Review

The optimal management strategy for patent ductus arteriosus in preterm infants remains a topic of debate. Available evidence for a treatment strategy might be biased by the delayed spontaneous closure of the ductus arteriosus in preterm infants, which appears to depend on patient characteristics. We performed a systematic review of all literature on PDA studies to collect patient characteristics and reported numbers of patients with a ductus arteriosus and spontaneous closure. Spontaneous closure rates showed a high variability but were lowest in studies that only included preterm infants with gestational ages below 28 weeks or birth weights below 1,000 g (34% on day 4; 41% on day 7) compared to studies that also included infants with higher gestational ages or higher birth weights (up to 55% on day 3 and 78% on day 7). The probability of spontaneous closure of the ductus arteriosus keeps increasing until at least 1 week after birth which favors delayed treatment of only those infants that do not show spontaneous closure. Better prediction of the spontaneous closure of the ductus arteriosus in the individual newborn is a key factor to find the optimal management strategy for PDA in preterm infants.

Left Ventricular Diastolic Dysfunction and Diastolic Heart Failure in Preterm Infants

Diastolic dysfunction is primarily an echocardiographic diagnosis. Its clinical counterpart is diastolic heart failure, where the heart has difficulty to fill at normal pressure and the patient develops signs of pulmonary edema. Although diastolic dysfunction is common in adults, limited information is available in preterm infants. The aim of this study is to explore left ventricular diastolic dysfunction and diastolic heart failure in preterm infants and describe clinical manifestations in this population. This is a retrospective observational study in preterm infants < 30 weeks' gestation who received an echocardiography in the first 4 weeks after birth. Diastolic dysfunction was graded using a population-specific adapted version of the adult recommendations for the evaluation of left ventricular diastolic function by echocardiography. Left ventricular diastolic dysfunction was absent, indeterminate, and definite in 82%, 14%, and 4% of the 168 echocardiograms analyzed, and is associated with increased respiratory signs and respiratory deterioration at 48 h before echocardiogram. In seven infants, diastolic heart failure was diagnosed with both ultrasound and clinical signs. The cumulative risk of diastolic dysfunction increased with the increasing postnatal age and a patent ductus arteriosus. Evidence of left ventricular diastolic dysfunction on echocardiography is relatively common in preterm infants, while the left ventricular diastolic heart failure is less frequent. Prolonged exposure to volume load was the most common cause.

Application of NPE in the assessment of a patent ductus arteriosus

In many preterm infants, the ductus arteriosus remains patent beyond the first few days of life. This prolonged patency is associated with numerous adverse outcomes, but the extent to which these adverse outcomes are attributable to the hemodynamic consequences of ductal patency, if at all, has not been established. Different treatment strategies have failed to improve short-term outcomes, with a paucity of data on the correct diagnostic and pathophysiological assessment of the patent ductus arteriosus (PDA) in association with long-term outcomes. Echocardiography is the selected method of choice for detecting a PDA, assessing the impact on the preterm circulation and monitoring treatment response. PDA in a preterm infant can result in pulmonary overcirculation and systemic hypoperfusion, Therefore, echocardiographic assessment should include evaluation of PDA characteristics, indices of pulmonary overcirculation with left heart loading conditions, and indices of systemic hypoperfusion. In this review, we provide an evidence-based overview of the current and emerging ultrasound measurements available to identify and monitor a PDA in the preterm infant. We offer indications and limitations for using Neonatologist Performed Echocardiography to optimize the management of a neonate with a PDA.

Early signs that predict later haemodynamically significant patent ductus arteriosus

OBJECTIVE

Our aim was to determine the optimal cut-off values, sensitivity, specificity, and diagnostic power of 12 echocardiographic parameters on the second day of life to predict subsequent ductal patency.

METHODS

We evaluated preterm infants, born at ⩽32 weeks of gestation, starting on their second day of life, and they were evaluated every other day until ductal closure or until there were clinical signs of re-opening. We measured transductal diameter; pulmonary arterial diastolic flow; retrograde aortic diastolic flow; pulsatility index of the left pulmonary artery and descending aorta; left atrium and ventricle/aortic root ratio; left ventricular output; left ventricular flow velocity time integral; mitral early/late diastolic flow; and superior caval vein diameter and flow as well as performed receiver operating curve analysis.

RESULTS

Transductal diameter (>1.5 mm); pulmonary arterial diastolic flow (>25.6 cm/second); presence of retrograde aortic diastolic flow; ductal diameter by body weight (>1.07 mm/kg); left pulmonary arterial pulsatility index (⩽0.71); and left ventricle to aortic root ratio (>2.2) displayed high sensitivity and specificity (p0.9). Parameters with moderate sensitivity and specificity were as follows: left atrial to aortic root ratio; left ventricular output; left ventricular flow velocity time integral; and mitral early/late diastolic flow ratio (p0.05) had low diagnostic value.

CONCLUSION

Left pulmonary arterial pulsatility index, left ventricle/aortic root ratio, and ductal diameter by body weight are useful adjuncts offering a broader outlook for predicting ductal patency.

Systolic and diastolic function of the fetal single left ventricle

BACKGROUND

The functionally single fetal right ventricle demonstrates reduced longitudinal relative to circumferential contraction velocities and deformation, a pattern similar to the normal fetal left ventricle. Altered diastolic properties are also present, with greater reliance on atrial contraction for right ventricular filling. It is unknown whether the functionally single left ventricle (SLV) demonstrates similar altered deformation patterns and diastolic properties.

METHODS

Echocardiograms from 29 fetuses with SLVs were retrospectively compared with those from 48 controls with appropriately grown left ventricles. Ventricular function was assessed using Velocity Vector Imaging velocity, tissue deformation, two-dimensional, and Doppler flow parameters.

RESULTS

Fetuses with functionally SLVs showed no difference in peak global left ventricular longitudinal velocity or displacement or strain, while global radial displacement was increased (P < .001). The ratio of longitudinal to circumferential deformation was also no different from that in controls. The SLVs showed increased diameters (P < .001) with normal lengths. Mitral inflow peak E-wave (P < .05) and A-wave (P < .0001) velocities were increased, with a reduced E/A ratio (P < .001). A-wave inflow fraction was also increased (P < .05), with no change in A duration. Although ejection time was no different, inflow duration was increased (P < .01) and there was a trend toward reduction of the Tei index (P = .07).

CONCLUSIONS

The functionally single fetal left ventricle shows comparable changes to the single right ventricle, with a more spherical morphology and greater reliance on atrial contraction for ventricular filling than in controls. However, in contrast to the single right ventricle, the SLV had a normal longitudinal to circumferential deformation ratio with enhanced early diastolic filling.

Assessment of myocardial function in preterm infants with patent ductus arteriosus using tissue Doppler imaging

OBJECTIVE

To assess myocardial function in preterm infants with different degrees of ductal patency in the first week of life using tissue Doppler imaging.

STUDY DESIGN

Infants <30 weeks of gestation underwent echocardiography on day 3. A total of 72 infants were recruited into the study and categorised into three groups (i) haemodyamically significant ductus arteriosus, (ii) patent ductus arteriosus and (iii) no patent ductus arteriosus. Those with haemodynamically significant ductus arteriosus were treated with indometacin and echocardiography was repeated after 48-72 hours following treatment. Peak systolic and diastolic myocardial velocities were obtained using tissue Doppler imaging, and myocardial performance index was calculated.

RESULTS

Initial myocardial velocities were significantly lower and myocardial performance index significantly higher in the haemodynamically significant ductus arteriosus group compared with other groups. For the haemodynamically significant ductus arteriosus group, post-treatment myocardial velocities were higher and myocardial performance index lower than pre-treatment.

CONCLUSION

Preterm infants with haemodynamically significant ductus arteriosus had lower myocardial velocities and higher myocardial performance index, suggesting relative systolic and diastolic myocardial dysfunction. Babies whose patent ductus arteriosus remained open despite indometacin had lower pre-treatment myocardial velocities and higher myocardial performance index than those babies whose patent ductus arteriosus closed, suggesting worse myocardial function in this group. Measurement of myocardial function using tissue Doppler imaging in preterm infants is feasible and may prove to be helpful in the management of babies with patent ductus arteriosus.

Diastolic ventricular function improves during the first 48-hours-of-life in infants weighting <1250 g

AIM

Few studies have focused on cardiac ventricular diastolic function in preterm neonates in the immediate post-natal period. This study evaluated Doppler-derived parameters of diastolic ventricular function in infants with birth weights of <1250 g during the transitional period.

METHODS

This was a prospective observational study conducted in the Coombe Women and Infants University Hospital in Dublin, Ireland. Flow patterns on the mitral and tricuspid valve, isovolumic relaxation time (IVRT), left and right ventricular output and superior vena cava flow were measured in 22 infants with a birth weight of below 1250 g at six, 12, 24 and 48 h of age.

RESULTS

Early filling peak velocity of the left and right ventricle increased significantly from 30.3 to 39.5 cm/sec and 26.6 to 32.1 cm/sec, respectively. IVRT of the right ventricle decreased from 70 to 57 ms, and there was a nonsignificant decrease in IVRT of the left ventricle from 61.6 to 54 ms over the first 48 h.

CONCLUSION

We have demonstrated that parameters of diastolic ventricular function change significantly over the first 48 h of life in preterm infants <1250 g and that these changes may represent early diastolic dysfunction during the transitional period.

Cardiovascular magnetic resonance of cardiac function and myocardial mass in preterm infants: a preliminary study of the impact of patent ductus arteriosus

BACKGROUND

Many pathologies seen in the preterm population are associated with abnormal blood supply, yet robust evaluation of preterm cardiac function is scarce and consequently normative ranges in this population are limited. The aim of this study was to quantify and validate left ventricular dimension and function in preterm infants using cardiovascular magnetic resonance (CMR). An initial investigation of the impact of the common congenital defect patent ductus arteriosus (PDA) was then carried out.

METHODS

Steady State Free Procession short axis stacks were acquired. Normative ranges of left ventricular end diastolic volume (EDV), stroke volume (SV), left ventricular output (LVO), ejection fraction (EF), left ventricular (LV) mass, wall thickness and fractional thickening were determined in "healthy" (control) neonates. Left ventricular parameters were then investigated in PDA infants. Unpaired student t-tests compared the 2 groups. Multiple linear regression analysis assessed impact of shunt volume in PDA infants, p-value ≤ 0.05 being significant.

RESULTS

29 control infants median (range) corrected gestational age at scan 34+6(31+1-39+3) weeks were scanned. EDV, SV, LVO, LV mass normalized by weight and EF were shown to decrease with increasing corrected gestational age (cGA) in controls. In 16 PDA infants (cGA 30+3(27+3-36+1) weeks) left ventricular dimension and output were significantly increased, yet there was no significant difference in ejection fraction and fractional thickening between the two groups. A significant association between shunt volume and increased left ventricular mass correcting for postnatal age and corrected gestational age existed.

CONCLUSION

CMR assessment of left ventricular function has been validated in neonates, providing more robust normative ranges of left ventricular dimension and function in this population. Initial investigation of PDA infants would suggest that function is relatively maintained.

Hemodynamic changes in preterm neonates with septic shock: a prospective observational study*

OBJECTIVE

We evaluated hemodynamic changes in preterm neonates with septic shock using functional echocardiography and studied the effects of vasoactive drugs on hemodynamic variables.

DESIGN

Prospective observational study.

SETTING

Level III neonatal ICU.

SUBJECTS AND PATIENTS

We enrolled 52 preterm neonates with septic shock (shock group) and an equal number of gestation and postnatal age-matched healthy neonates (control group).

INTERVENTIONS

We measured functional hemodynamic variables (left and right ventricular output, ejection fraction, isovolumetric relaxation time, and early passive to late active peak velocity ratio) by echocardiography in the shock group during initial fluid resuscitation, before initiation of vasoactive drugs, and again 30-40 minutes after initiation of vasoactive drug infusion. Control group underwent a single assessment after enrollment. We compared various hemodynamic variables between shock group and control group using paired t test or Wilcoxon signed-rank test.

MEASUREMENTS AND MAIN RESULTS

The baseline left ventricular output was significantly higher in neonates with septic shock as compared with controls (median [interquartile range], 305 mL/kg/min [204, 393] vs 233 mL/kg/min [204, 302]; p < 0.001), but ejection fraction was similar between the two groups (55% ± 12% vs 55% ± 5%, p = 0.54). Other hemodynamic variables were comparable between the two groups. After vasoactive drug infusion, there was a significant increase in heart rate (152 ± 18 to 161 ± 18 beats/min, p ≤ 0.001) and right ventricular output (median [interquartile range], 376 [286, 468] to 407 [323, 538] mL/kg/min; p = 0.018) compared with the baseline, but left ventricular output and ejection fraction did not change significantly.

CONCLUSIONS

We found an elevated left ventricular output but normal ejection fraction in preterm neonates with septic shock. This suggests that septic shock in preterm neonates is predominantly due to vasoregulatory failure. Vasoactive drugs significantly increased right ventricular output, which was predominantly due to increase in heart rate.

NT-proBNP Levels Improve the Ability of Predicting a Hemodynamically Significant Patent Ductus Arteriosus in Very Low-Birth-Weight Infants

Purpose:

A hemodynamically significant Patent ductus arteriosus (HsPDA) in premature infants is known to be associated with significant morbidity. Recently brain natriuretic peptides and superior mesenteric artery (SMA)-resistive indices have been used to effectively diagnose HsPDA.

Objective:

To assess the sensitivity and specificity of N-terminal proBNP (NT-proBNP) in predicting an HsPDA diagnosed by clinical and echocardiographic criteria including pulsatility index (PI) of SMA.

Materials and Methods:

All preterm neonates <1500 g were evaluated with echocardiograms and NT-proBNP levels on the 3^rd to 5^th day of life and then every week until the echo showed either a closed PDA or non-HsPDA.

Results:

Sixty-nine babies with mean gestational age of 27 weeks were included in the study. NT-proBNP levels were significantly higher in the HsPDA group (n=22) with a mean±SEM of 24420±3190 compared to 3072±332 in the non-HsPDA group (n=47) (P<0.001). NT-pro BNP level of 5900 pg/ml had 96% sensitivity and 90% specificity of predicting HsPDA.

Conclusions:

With frequently changing hemodynamics in low-birth weight infants, including NT-proBNP and PI of SMA improve the ability of assessing the effects of a HsPDA and will help timing of intervention.

Interparametric correlation between echocardiographic markers in preterm infants with patent ductus arteriosus

Various echocardiographic parameters are determined in the assessment and evaluation of a patent ductus arteriosus. In isolation, many of these parameters have a low sensitivity and specificity for ductal hemodynamic significance compared with ductal size. This study aimed to correlate various echocardiographic parameters with ductal size (transductal diameter) in infants with a symptomatic patent ductus arteriosus and to ascertain the accuracy of various parameters in predicting a duct 3 mm in size or larger. In this retrospective study, preterm infants younger than 32 weeks gestation who were evaluated for the presence of a patent ductus arteriosus during the period June 2010-2012 were assessed. The following echocardiographic parameters were measured: transductal diameter (TDD), ductal velocity, end-diastolic left pulmonary artery flow, ductal diameter-to-left pulmonary artery ratio (TDD:LPA), left atrial-to-aortic root ratio (LA:Ao), left ventricular output-to-superior vena cava flow ratio (LVO:SVC), transmitral E:A ratio, and isovolumic relaxation time (IVRT). The study enrolled 52 infants with a mean gestation age of 26 ± 2 weeks and a mean birth weight of 837 ± 240 g. The mean transductal diameter was 2.8 ± 0.5 mm. Transductal diameter correlated significantly with ductal velocity, end-diastolic LPA flow, TDD:LPA ratio, LA:Ao ratio, and LVO:SVC ratio but not with transmitral indices. The LVO:SVC ratio had the highest specificity (0.83) and sensitivity (0.95) for detecting a duct 3 mm in size or larger, the area under the curve being 0.95 (95 % confidence interval [CI], 0.85-0.99). Significant correlations between ductal size and surrogate markers of pulmonary overcirculation were noted.

Neonatologist-performed functional echocardiography in the neonatal intensive care unit

The use of point-of-care functional ultrasound to assess cardiovascular function is gaining interest in the neonatal intensive care unit (NICU). The modality has been in use in adult intensive care units for some time and has often guided management. Clinical signs such as heart rate, blood pressure, and capillary refill time, which physicians traditionally have relied upon, provide limited insight into the adequacy of systemic blood flow and organ perfusion. Enhanced cardiovascular imaging and hemodynamic evaluation offers novel insights regarding the contribution of the ductus arteriosus, myocardial performance and pulmonary hemodynamics to ongoing clinical instability. In addition, it allows more accurate delineation of the nature of the underlying disease process and facilitates the evaluation of response to therapeutic intervention. This review examines the potential clinical role of ultrasound methods in the NICU; specifically, its applications in different disease states, and how the technology may be introduced safely in the NICU.

Echocardiography predicts closure of patent ductus arteriosus in response to ibuprofen in infants less than 28 week gestational age

BACKGROUND

Patent ductus arteriosus (PDA) is a frequent problem in preterm infants, and its incidence is inversely correlated with gestational age. The efficacy of medical treatment decreases with decreasing gestational age (GA), and failure rates as well as ductus ligation rates of 40% have been reported in <28 week GA newborns. The aim of this study was to determine whether echocardiographic parameters can predict response to ibuprofen treatment of PDA.

STUDY DESIGN

In a longitudinal study, 29 infants born <28 week GA were screened for a significant PDA (left atrial to aortic root ratio>1.4, anterior cerebral artery resistance index>0.8, and oxygen requirement>35%) at 24-72 h of life and, if a PDA was found, treated with 10-5-5mg/kg ibuprofen intravenously every 24h. Ductal parameters were monitored by serial echocardiography. Infant neurodevelopmental outcomes were assessed at 24 month corrected age.

RESULTS

All 15 infants with significant PDA responded to the ibuprofen loading dose indicated by reduced PDA diameters or increased PDA maximum flow velocities (PDA V(max)), and 7 patients showed an ongoing response resulting in a closed PDA after the 1st cycle (47%). Of the 8 non-responders, 7 received a 2nd cycle with 2 further responders (29%). All non-responders to the 2nd course had a PDA V(max)<or=180 cm/s and increasing ductal diameters after the 3rd ibuprofen dose of the 1st course.

CONCLUSION

Maximum flow velocity and diameter of the PDA at the end of the 1st cycle discriminate between responders and non-responders to further ibuprofen treatment.

Does echocardiography facilitate determination of hemodynamic significance attributable to the ductus arteriosus?

INTRODUCTION

The assignment of hemodynamic significance to a patent ductus remains a challenge for neonatal intensivists. The impact is medical uncertainty and ongoing debate as to when treatment should be provided if ever.

DISCUSSION

Patent ductus arteriosus is associated with significant neonatal morbidities including necrotizing enterocolitis and brain injury; causality has not been proven. In addition, there are limited data suggesting a beneficial effect of therapeutic intervention. The inability to accurately differentiate the pathological ductus arteriosus from the innocent ductus arteriosus may contribute, in part, to the lack of scientific evidence of benefit or causality. Our group has previously proposed the need for a staging system to characterize the clinical and echocardiography impact of the ductus arteriosus. This approach requires comprehensive echocardiography evaluation to assess ductal size and the degree of pulmonary overcirculation/systemic hypoperfusion related to the transductal shunt.

CONCLUSION

In this review, we will highlight the evidence for echocardiography markers of hemodynamic significance and speculate as to how they may facilitate improved decision making in the neonatal intensive care unit.

Transient dynamic subaortic stenosis in premature neonates after patent ductus arteriosus ligation

We describe 2 premature infants with PDA that did not respond to medical therapy and required surgical ligation. Both infants developed transient dynamic subaortic obstruction that resolved without specific therapy. This may have occurred due to sudden changes in the left ventricular volume.

Changes in myocardial function and hemodynamics after ligation of the ductus arteriosus in preterm infants

OBJECTIVE

To characterize the changes in systemic hemodynamics and systolic, diastolic, and global myocardial performance after patent ductus arteriosus (PDA) ligation in very-low-birth-weight infants.

STUDY DESIGN

Echocardiograms were performed on 23 neonates (mean gestational age, 26.2 +/- 2.2 weeks) at 2.3 +/- 2.0 hours before PDA ligation (n = 23) and at 2.0 +/- 1.4 hours (n = 23) and 23.5 +/- 2.5 hours after (n = 11) PDA ligation.

RESULTS

Mean blood pressure, heart rate, load-independent contractility, shortening fraction, left ventricular (LV) afterload, and diastolic function did not change. Preload (early and atrial mitral inflow velocities) decreased immediately after ligation but remained unchanged thereafter. LV output decreased and systemic vascular resistance increased after surgery. The LV myocardial performance index (MPI), a measure of global myocardial performance, deteriorated acutely after ligation but improved by 23.5 hours after surgery. Changes in LV MPI were most closely correlated with changes in LV output.

CONCLUSIONS

After PDA ligation, LV output and MPI decrease, due primarily to a decrease in LV preload, although LV contractility and diastolic function do not change. However, the changes in LV MPI after ligation also reflect an acute deterioration followed by an improvement in global cardiac function, because LV loading conditions remained unchanged after surgery and thus cannot explain the improvement in MPI by 24 hours after ligation.

Echocardiographic measures of diastolic function in pediatric heart disease

PURPOSE OF REVIEW

The past year has seen a continued evolution in the echocardiographic assessment of diastolic function in children. This paper reviews published studies from the past year that have helped characterize diastolic function using echocardiography in children.

RECENT FINDINGS

Characterization of diastolic function using Doppler and Doppler tissue imaging in the normal infant and child was a primary focus of pediatric echocardiographic investigation. These technologies appear to hold significant promise as tools to improve understanding of diastolic function in the normal child as the heart matures. Diastolic function in children with congenital heart disease has also been better characterized using these tools, specifically in patients with atrial septal defects, tetralogy of Fallot, single ventricle physiology, and following cardiac transplantation. Finally, diastolic function in acquired heart disease or with systemic disease in the child has been evaluated using echocardiography, with recent reports describing findings in children with dilated cardiomyopathy, chronic renal disease, obesity, type I diabetes, juvenile rheumatoid arthritis, obstructive sleep apnea, and after anthracycline exposure for childhood cancer.

SUMMARY

Pediatric echocardiography has clearly become the primary tool for describing and characterizing diastolic function in infants and children both with and without heart disease. It is becoming an important noninvasive diastolic monitoring tool that allows serial assessment of pathologic diastolic disease in both primary myocardial and systemic disease states.

Utility of a Doppler-derived index combining systolic and diastolic performance (Tei index) for detecting hypoxic cardiac damage in newborns

The purpose of this study was to assess cardiac function of newborns with mild asphyxia by a Doppler-derived index combining systolic and diastolic performance (Tei index). We studied 20 preterm infants with mild asphyxia. A control group consisted of 20 gestational age-matched preterm infants without asphyxia. Echocardiograms were performed during the fourth and seventh days after birth. Peak velocities of an early filling wave (E) and an atrial contraction wave (A) were measured from the mitral inflow velocity profile and the ratio of peak E to A was calculated. Ejection time was measured from the left ventricular outflow Doppler signal. The sum of isovolumetric times was obtained by subtracting the ejection time from the interval between cessation and onset of mitral inflow. The index was the sum of isovolumetric times divided by ejection time. Ejection fraction was also calculated. The ratio of peak E to A and ejection fraction were the same in both groups. The myocardial performance index in patients with asphyxia was higher than that in patients without asphyxia. We concluded that patients with mild asphyxia have a mild cardiac dysfunction and this change can be detected by a myocardial performance index.