Cardiac Function In Preterm Infants Research Articles

Analysis of the value of echocardiographic parameters in the early diagnosis of preterm infants with bronchopulmonary dysplasia.

The objective of this study was to investigate the role of echocardiographic parameters in diagnosing bronchopulmonary dysplasia (BPD) in preterm infants. Ninety preterm infants with a gestational age of less than 32 weeks and a weight less than 1.5 kg, admitted to the neonatal intensive care unit of the hospital between January 2020 and January 2021, were selected for the study. The study subjects were divided into two groups: a BPD group (54 cases, observation group) and a non-BPD group (36 cases, control group). The correlation between tricuspid regurgitation (TR) velocity and BPD was investigated by detecting the cardiac function of preterm infants in both groups using a color Doppler ultrasound diagnostic instrument and analyzing the cardiac ultrasound results. The early prediction efficiency of TR velocity (m/s) for BPD was evaluated using the receiver operator characteristic (ROC) curve. The incidence of patent ductus arteriosus (PDA) and pulmonary hypertension (PH) in the observation group was significantly higher than that in the control group. The levels of left ventricular ejection fraction (LVEF) and left ventricular shorting fraction (LVFS) were significantly lower than those in the control group (p < 0.05). The incidence of patent foramen ovale (PFO), atrial septal defect (ASD), and ventricular septal defect (VSD) in the observation group were not significantly different from the control group (p > 0.05). The proportion of tricuspid regurgitation in the observation group was significantly higher than that in the control group, and the TR velocity was significantly higher than that in the control group. The Spearman correlation analysis showed that TR velocity (m/s) was positively correlated to BPD severity (r = 0.379, p < 0.05). The area under the curve (AUC) for predicting BPD with TR velocity was 0.735. The sensitivity and specificity were 88.0% and 62.6%, respectively, when the TR velocity was 1.45 m/s. Echocardiography is useful for understanding the degree of impaired cardiac function in preterm infants and for early detection of PH, which may reduce the mortality rate to a certain extent. The risk of BPD is significantly increased when TR velocity is higher than 1.45 m/s.

Preterm growth restriction and bronchopulmonary dysplasia: the vascular hypothesis and related physiology.

Approximately 5-10% pregnancies are affected by fetal growth restriction. Preterm infants affected by fetal growth restriction have a higher incidence of bronchopulmonary dysplasia. The present study is the first to measure pulmonary artery thickness and stiffness. The findings show that impaired vasculogenesis may be a contributory factor in the higher incidence of bronchopulmonary dysplasia in preterm growth restricted infants. The study addresses the mechanistic link between fetal programming and vascular architecture and mechanics. Bronchopulmonary dysplasia is the most common respiratory sequelae of prematurity and histopathologically features fewer, dysmorphic pulmonary arteries. The present study aimed to characterize pulmonary artery mechanics and cardiac function in preterm infants with fetal growth restriction (FGR) compared to those appropriate for gestational age (AGA) in the early neonatal period. This prospective study reviewed 40 preterm infants between 28 to 32weeks gestational age (GA). Twenty infants had a birthweight <10th centile and were compared with 20 preterm AGA infants. A single high resolution echocardiogram was performed to measure right pulmonary arterial and right ventricular (RV) indices. The GA and birthweight of FGR and AGA infants were 29.8±1.3vs. 30±0.9weeks (P=0.78) and 923.4g±168vs. 1403g±237 (P<0.001), respectively. Assessments were made at 10.5±1.3 days after birth. The FGR infants had significantly thicker right pulmonary artery inferior wall (843.5±68vs. 761±40μm, P<0.001) with reduced pulsatility (51.6±7.6μm vs. 59.7±7.5μm, P=0.001). The RV contractility [fractional area change (28.7±3.8%vs 32.5±3.1%, P=0.001), tricuspid annular peak systolic excursion (TAPSE) (5.2±0.3%vs. 5.9±0.7%, P=0.0002) and myocardial performance index (0.35±0.03vs. 0.28±0.02, P<0.001)] was significantly impaired in FGR infants. Significant correlation between RV longitudinal contractility (TAPSE) and time to peak velocity/RV ejection time (measure of RV afterload) was noted (r2 = 0.5, P<0.001). Altered pulmonary vascular mechanics and cardiac performance reflect maladaptive changes in response to utero-placental insufficiency. Whether managing pulmonary vascular disease will alter clinical outcomes remains to be studied prospectively.

Echocardiographic assessment of left ventricular outflow tract diameter in preterm infants.

Introduction: Left ventricular output (LVO) measurement is an important part of the echocardiographic assessment of cardiac function in preterm infants. The accurate measurement of left ventricular outflow tract diameter (LVOD) is key to the calculation of LVO. Given the lack of an appropriate gold standard, we used right ventricular output (RVO) as the comparator and sought to identify the most accurate method of determining LVO in preterm infants. Methods: We studied stable preterm infants without significant cardiac shunts. LVOD was measured at the aortic valve, the aortic sinus and at the sinotubular junction. LVOs were calculated and the precision and accuracy of each was determined relative to the RVO using the Bland‐Altman method. Results: 52 infants were included in this analysis. The mean difference between RVO and LVO was largest when LVOD was measured at the aortic valve and aortic sinus, +106 and −115 ml/kg/min, respectively, and smallest when measured at the sinotubular junction, 9 ml/kg/min. Limits of agreement between RVO and LVO were narrowest when LVOD was measured at the STJ. Conclusion: LVOD measurement at the sinotubular junction provides more precise and accurate measurement of LVO, in comparison to RVO, than measurement at the aortic valve or the aortic sinus.

O-079 Nasal Continuous Positive Airway Pressure And Cardiac Function In Preterm Infants With Lung Disease

<h3>Introduction</h3> Previous studies of infants on ventilatory support suggest that right ventricular output (RVO) decreases with increasing mean airway pressure. This may be due to increased pressure in the thoracic cavity. We investigated changes in cardiac output (CO) at different levels of nasal continuous positive airway pressure (nCPAP) in preterm infants with evolving chronic lung disease. <h3>Methods</h3> We studied infants between 28 and 34 weeks corrected gestational age, a minimum of two weeks old, treated with nCPAP of 5 to 7 cm H₂O, with an O₂ requirement of 25–40%, in whom written parental consent was obtained. Infants with significant cardiac shunts were excluded. Infants were randomly assigned to nCPAP levels of 4, 6, and 8 cm H₂O for 15 min each. Right and left ventricular output, left pulmonary artery flow, superior vena cava flow, heart rate and blood pressure were measured after each change with a Vivid-I ultrasound machine by a single examiner (FB) blinded to nCPAP levels. <h3>Results</h3> Thirty infants with a median (IQR) gestational age of 25.9 (25.6–26.8) weeks and a birth weight of 0.78 (0.66–0.94) kg were studied at a median age of 43 (24–53) days. There were no significant differences in any cardiovascular parameters at different levels of nCPAP. <h3>Discussion</h3> We conclude that nCPAP levels between 4 and 8 cm H₂O did not have an effect on CO in our study population of stable preterm infants with evolving chronic lung disease.

Tissue Doppler–Derived Strain and Strain Rate during the First 28 Days of Life in Very Low Birth Weight Infants

Preterm infants may have cardiac stress related to patent ductus arteriosus (PDA) or bronchopulmonary dysplasia (BPD). In this study, we examined the development of cardiac function in preterm infants by measuring tissue Doppler-derived peak systolic strain (PSS) and strain rate (PSSR) in the first 28 days of life. Peak systolic strain and strain rate were measured in series in the free wall of the right (RV) and left (LV) ventricles on days 1, 7, 14, and 28 of life in 119 preterm infants <1500 g birth weight along with weight, heart rate, and presence of hemodynamically significant (hs) PDA or BPD. Both were assigned retrospectively. HsPDA was defined as a PDA requiring intervention whereas BPD was determined based on an infant's need for supplemental oxygen at 36 weeks of gestational age. Peak systolic strain and strain rate of the RV rose significantly during the first 28 days of life (P < 0.01). Infants who developed BPD had significantly lower RV free wall PSS on days 14 and 28 (P < 0.01 and <0.05). HsPDA resulted in a significantly lower PSS in the LV free wall as of day 14 (P < 0.01). After PDA intervention (day 28), LV PSS remained significantly lower (P < 0.05), but showed a tendency to increase (P = 0.18). Peak systolic strain determined in preterm infants appears to reflect increased afterload (decreased RV PSS in BPD infants) and increased preload (decreased LV PSS in hsPDA infants). The merits of such measurements as a basis for making clinical decisions still need to be explored.

PH and the heart in preterms

Cardiac function in preterm infants has been minimally evaluated. From the clinicians' perspective, if the blood pressure is normal—and normal is difficult to define—the heart function will be normal. Conversely, if blood pressure is low, then cardiac function likely is abnormal. In contrast to older children or adults, drugs are selected for blood pressure and myocardial support of preterm infants without evaluations of myocardial function. But the preterm heart differs even from the term heart and has unique challenges during transition after birth. Cardiac function deteriorates as pH falls in the mature heart, but, in this issue of The Journal, Noori et al report that the preterm heart is insensitive to changes in pH for about 2 weeks after birth. Subsequently, contractility degrades as acidosis increases, as with the mature heart. Vascular responses to acidosis change toward a mature pattern relatively rapidly after birth. The treatment of a low pH with bicarbonate has been discouraged in preterm newborns in recent years; a pH-insensitive myocardium is another reason not to treat acidosis with bicarbonate.Article page 958▶ Cardiac function in preterm infants has been minimally evaluated. From the clinicians' perspective, if the blood pressure is normal—and normal is difficult to define—the heart function will be normal. Conversely, if blood pressure is low, then cardiac function likely is abnormal. In contrast to older children or adults, drugs are selected for blood pressure and myocardial support of preterm infants without evaluations of myocardial function. But the preterm heart differs even from the term heart and has unique challenges during transition after birth. Cardiac function deteriorates as pH falls in the mature heart, but, in this issue of The Journal, Noori et al report that the preterm heart is insensitive to changes in pH for about 2 weeks after birth. Subsequently, contractility degrades as acidosis increases, as with the mature heart. Vascular responses to acidosis change toward a mature pattern relatively rapidly after birth. The treatment of a low pH with bicarbonate has been discouraged in preterm newborns in recent years; a pH-insensitive myocardium is another reason not to treat acidosis with bicarbonate. Article page 958▶ pH Effects on Cardiac Function and Systemic Vascular Resistance in Preterm InfantsThe Journal of PediatricsVol. 162Issue 5PreviewTo investigate the effect of pH on cardiac function and systemic vascular resistance (SVR) in preterm infants. Full-Text PDF

Three-Tesla Cardiac Magnetic Resonance Imaging for Preterm Infants

We aimed to establish the feasibility of acquiring 3.0-T cardiac MRIs without sedation, anesthesia, or breath-holding for preterm infants and to obtain preliminary quantitative data on left ventricular function in this population. Twelve preterm infants underwent 3.0-T cardiac MRI without sedation or breath-holding. The median gestational age was 29 weeks (range: 26-33 weeks), the median birth weight was 1240 g (range: 808-2200 g), and the median postconceptional age at the time of cardiac MRI was 33 weeks (range: 31-40 weeks). Anatomic images were acquired with T2-weighted spin-echo sequences, and ventricular function was assessed with balanced steady-state free precession cine sequences. We assessed left ventricular function by using the area-length ejection fraction method on horizontal long-axis images and the volumetric Sergeant's discs method of analysis on short-axis images. Imaging was successful for 10 of 12 infants. For those 10, the area-length ejection fraction method in the horizontal long-axis plane estimated median stroke volume at 2.9 mL, cardiac output at 0.4 L/minute, end-diastolic volume at 3.8 mL, end-systolic volume at 0.3 mL, and ejection fraction at 74.6%. Short-axis volumetric estimations were made for 4 infants. With this approach, the median stroke volume was 2.4 mL, cardiac output 0.35 L/minute, end-diastolic volume 4.3 mL, end-systolic volume 2.1 mL, and ejection fraction 56%. Three-tesla cardiac MRI is feasible for preterm infants without sedation, anesthesia, or breath-holding and has the potential to provide a wide range of precise quantitative data that may be of great value for the investigation of cardiac function in preterm infants.

126 Cardiac Mri At 3.0 Tesla in Preterm Infants

Background: Cardiac function is often impaired in preterm infants undergoing intensive care but poorly understood. Cardiac magnetic resonance imaging (CMRI) is the method of choice for assessment of cardiac function in adults, but has not been used previously in the preterm population. CMRI in adults is usally done at 1.5 T, however we hypothesised that in preterm infants it would be possible to take advantage of higher field strengths. Aims: To assess the feasibility of undertaking CMRI in preterm infants and to develop novel approaches to acquire images at 3.0 T. Methods: Five preterm babies underwent cardiac MRI. Gestational age was median 33 weeks [range 30 - 35 weeks]. Median birthweight was 1860g [1480 - 2750g]. The median corrected gestational age at time of MRI was 35 weeks [33 - 37 weeks]. Each scan took approximately 45 minutes. Babies were monitored throughout the scan by a trained neonatologist. Results: Imaging was successful in 3/5 infants, and these images were sufficient to allow detailed assessment of cardiac function. 2 dimensional real time CMRI movies provide precise visualisation of cardiac function. Conclusion: This preliminary study demonstrates that CMRI can provide detailed assessment of cardiac function in preterm infants, and this can be achieved at 3.0 T.

Acute Effects of Inhaled Nitric Oxide on Pulmonary and Cardiac Function in Preterm Infants with Evolving Bronchopulmonary Dysplasia

Inhaled nitric oxide (iNO) reduces pulmonary vascular resistance by preferential vasodilation in ventilated lung units. In experimental animals, iNO also reduces airway resistance by smooth muscle relaxation. Hence, there may be a therapeutic role for iNO in evolving bronchopulmonary dysplasia (BPD). To evaluate the acute effects of low-dose iNO on lung mechanics, ventilation distribution, oxygenation, and cardiac function in preterm infants with evolving BPD. Measurements of lung compliance (C(L)), airway resistance (R(L)), ventilation-distribution (N(2) clearance in multiple-breath washout), oxygenation (SpO(2)), left ventricular ejection fraction (LVEF) and right ventricular shortening fraction were obtained before and during 2 hours of iNO (10 ppm) in a group of ventilated preterm infants with evolving BPD. A total of 13 preterm infants with (mean+/-SD) BW: 663.8+/-116 g, GA: 24.9+/-1.2 weeks, age: 32+/-14 days, mean airway pressure: 6.7+/-0.9 cmH(2)O and fraction of inspired oxygen: 0.35+/-0.06 were studied. iNO did not affect C(L), R(L) or N(2) clearance. There was a small increase in LVEF. Mean SpO(2) remained unchanged, but the duration of spontaneous hypoxemic episodes increased during iNO. Low-dose iNO had no acute effects on lung function, cardiac function and oxygenation in evolving BPD.