Shahab Noori

Targeted Neonatal Echocardiography in the Neonatal Intensive Care Unit: Practice Guidelines and Recommendations for Training Writing group of the American Society of Echocardiography (ASE) in collaboration with the European Association of Echocardiography (EAE) and the Association for European Pediatric Cardiologists (AEPC)

Luc Mertens, MD, PhD, FASE, FESC, Istvan Seri, MD, PhD, HonD, Jan Marek, MD, PhD, FESC, Romaine Arlettaz, MD, Piers Barker, MD, FASE, Patrick McNamara, MD, MB, FRCPC, Anita J. Moon-Grady, MD, Patrick D. Coon, RDCS, FASE, Shahab Noori, MD, RDCS, John Simpson, MD, FRCP, FESC, Wyman W. Lai, MD, MPH, FASE, Toronto, Ontario, Canada; Los Angeles and San Francisco, California; London, United Kingdom; Zurich, Switzerland; Durham, North Carolina; Philadelphia, Pennsylvania; New York, New York

Targeted Neonatal Echocardiography in the Neonatal Intensive Care Unit: Practice Guidelines and Recommendations for Training

AAP : American Academy of Pediatrics AEPC : Association for European Paediatric Cardiology ASE : American Society of Echocardiography CDH : Congenital diaphragmatic hernia CHD : Congenital heart disease EAE : European Association of Echocardiography ECMO : Extracorporeal membrane oxygenation EF : Ejection fraction LV : Left ventricular MPI : Myocardial performance index mVCFc : Mean velocity of circumferential fiber shortening NICU : Neonatal intensive care unit PA : Pulmonary artery PDA : Patent ductus arteriosus RA : Right atrial RV : Right ventricular RVSp : Right ventricular systolic pressure SF : Shortening fraction SVC : Superior vena cava TEE : Transesophageal echocardiography TNE : Targeted neonatal echocardiography TVI : Time-velocity integral 2D : Two-dimensional VLBW : Very low birth weight The role of echocardiography in the neonatal intensive care unit (NICU) has changed over the past few years. Previously, nearly all echocardiographic studies in the NICU were performed by pediatric cardiologists to diagnose or monitor congenital heart disease (CHD) and to screen for patent ductus arteriosus (PDA). More recently, neonatologists have become interested in the echocardiographic assessment of hemodynamic instability in infants. The terms functional echocardiography and point-of-care echocardiography have been introduced to describe the use of echocardiography as an adjunct in the clinical assessment of the hemodynamic status in neonates.1–4 The increasing availability of echocardiography, with miniaturization of the technology, has resulted in more widespread use of echocardiography in NICUs around the world.5 Perhaps the most significant challenge for the application of so-called functional studies is that newborns in the NICU with hemodynamic instability are at a much higher risk for having underlying CHD. In addition, newborns in the NICU are unique in that they are in the process of …

Cardiovascular Effects of Sildenafil in Neonates and Infants with Congenital Diaphragmatic Hernia and Pulmonary Hypertension

Background: Pulmonary hypertension is a common problem in patients with congenital diaphragmatic hernia (CDH). In a subset of these patients, pulmonary hypertension persists despite optimized ventilatory management and supportive care. Sildenafil, a phosphodiestrase V inhibitor, has been used in the treatment of pulmonary hypertension in adults and children. Cardiovascular effects of sildenafil in patients with CDH and pulmonary hypertension are not known. Objective: To describe the changes in cardiovascular and respiratory parameters in newborn infants with CDH and persistent pulmonary hypertension refractory to inhaled nitric oxide (iNO) during the first 2 weeks of sildenafil administration. Methods: Retrospective data analysis of seven patients with CDH (birth weight = 2,573 ± 1,019 g; gestational age = 35.6 ± 4.3 weeks) receiving oral sildenafil for pulmonary hypertension refractory to iNO. Findings of serial echocardiograms and data on cardiovascular and respiratory status were assessed. Results: Right cardiac output increased and left cardiac output tended to increase 1.5–4 h after initiation of sildenafil and the increase was sustained throughout the study. Echocardiographic indices of pulmonary hypertension showed an apparent reduction in abnormally high pulmonary vascular resistance. Systemic blood pressure tended to decrease. Shortening fraction did not change. Ventilatory index and the need for iNO tended to decrease in the five surviving infants. Conclusions: These preliminary findings suggest that sildenafil may improve cardiac output by reducing pulmonary hypertension refractory to iNO in patients with CDH.

Hemodynamic Changes After Low-Dosage Hydrocortisone Administration in Vasopressor-Treated Preterm and Term Neonates

OBJECTIVE. We sought to investigate whether the increase in blood pressure and decrease in vasopressor support after hydrocortisone administration are associated with changes in systemic hemodynamics in neonates who receive high-dosage dopamine to maintain blood pressure at the lowest acceptable levels. METHODS. In this prospective, observational study, preterm and term neonates who required dopamine ≥15 μg/kg per minute to maintain minimum acceptable blood pressure received intravenous hydrocortisone 2 mg/kg followed by up to 4 doses of 1 mg/kg every 12 hours. Fifteen preterm and 5 term neonates without a patent ductus arteriosus composed the study population. Echocardiograms and vascular Doppler studies were performed immediately before the first dose of hydrocortisone and at 1, 2, 6 to 12, 24, and 48 hours thereafter. RESULTS. In the 15 preterm infants, during the first 12 hours of hydrocortisone treatment, the 28% increase in blood pressure paralleled that in the systemic vascular resistance without changes in stroke volume or cardiac output, whereas dopamine dosage decreased. By 24 hours, the dosage of dopamine continued to decrease, whereas stroke volume increased without additional changes in systemic vascular resistance. By 48 hours, dopamine dosage decreased by 72%; blood pressure and stroke volume increased by 31% and 33%, respectively; and systemic vascular resistance and cardiac output tended to be higher (14% and 21%, respectively) compared with baseline. Contractility, global myocardial function, and Doppler indices of blood flow in the middle cerebral and renal artery remained normal and unchanged. The findings in the 5 term infants showed a similar pattern for changes in cardiac function, systemic hemodynamics, and organ blood flow after hydrocortisone administration. CONCLUSIONS. In preterm and term neonates who require high-dosage dopamine to maintain blood pressure at the lowest acceptable levels, hydrocortisone improves blood pressure without compromising cardiac function, systemic perfusion, or cerebral and renal blood flow.

Changes in Cardiac Function and Cerebral Blood Flow in Relation to Peri/Intraventricular Hemorrhage in Extremely Preterm Infants

OBJECTIVE To investigate whether changes in cardiac function and cerebral blood flow (CBF) precede the occurrence of peri/intraventricular hemorrhage (P/IVH) in extremely preterm infants. STUDY DESIGN In this prospective observational study, 22 preterm infants (gestational age 25.9 ± 1.2 weeks; range 23-27 weeks) were monitored between 4 and 76 hours after birth. Cardiac function and changes in CBF and P/IVH were assessed by ultrasound every 12 hours. Changes in CBF were also followed by continuous monitoring of cerebral regional oxygen saturation (rSO2) and by calculating cerebral fractional oxygen extraction. RESULTS Five patients developed P/IVH (1 patient grade II and 4 patients grade IV). Whereas measures of cardiac function and CBF remained unchanged in neonates without P/IVH, patients with P/IVH tended to have lower left ventricular output and had lower left ventricle stroke volume and cerebral rSO2 and higher cerebral fractional oxygen extraction during the first 12 hours of the study. By 28 hours, these variables were similar in the 2 groups and myocardial performance index was lower and middle cerebral artery mean flow velocity higher in the P/IVH group. P/IVH was detected after these changes occurred. CONCLUSIONS Cardiac function and CBF remain stable in very preterm neonates who do not develop P/IVH during the first 3 postnatal days. In very preterm neonates developing P/IVH during this period, lower systemic perfusion and CBF followed by an increase in these variables precede the development of P/IVH. Monitoring cardiac function and cerebral rSO2 may identify infants at higher risk for developing P/IVH before the bleeding occurs.

Systemic and cerebral hemodynamics during the transitional period after premature birth

Little is known about the effect on clinically relevant outcomes of the complex hemodynamic changes occurring during adaptation to extrauterine life in preterm neonates, particularly in very low birth weight neonates. As cardiovascular adaptation in this extremely vulnerable patient population is complicated by immaturity of all organ systems, especially that of the cardiorespiratory, central nervous, and endocrine systems, maladaptation has been suspected, but not necessarily proven, to contribute to mortality and long-term morbidities. This article describes recent advances in the understanding of hemodynamic changes in very low birth weight neonates during postnatal transition, and reviews the complex and developmentally regulated interaction between systemic and cerebral hemodynamics and the effect of this interaction on clinically relevant outcomes.

Continuous non-invasive cardiac output measurements in the neonate by electrical velocimetry: a comparison with echocardiography

Objective Electrical velocimetry (EV) is a non-invasive method of continuous left cardiac output monitoring based on measurement of thoracic electrical bioimpedance. The objective was to validate EV by investigating the agreement in cardiac output measurements performed by EV and echocardiography. Design In this prospective observational study, left ventricular output (LVO) was simultaneously measured by EV (LVOev) using Aesculon and by echocardiography (LVOecho) in healthy term neonates during the first 2 postnatal days. To determine the agreement between the two methods, we calculated the bias (mean difference) and precision (1.96×SD of the difference). As LVOecho has its own limitations, the authors also calculated the ‘true precision’ of EV adjusted for echocardiography as the reference method. Results The authors performed 115 paired measurements in 20 neonates. LVOev and LVOecho were similar (534±105 vs 538±105 ml/min, p=0.7). The bias and precision of EV were −4 and 234 ml/min, respectively. The authors found the true precision of EV to be similar to the precision of echocardiography (31.6% vs 30%, respectively). There was no difference in bias and precision between the measurements obtained in patients with or without a haemodynamically significant patent ductus arteriosus. Conclusions EV is as accurate in measuring LVO as echocardiography and the variation in the agreement between EV and echocardiography among the individual subjects reflects the limitations of both techniques.

Transitional Changes in Cardiac and Cerebral Hemodynamics in Term Neonates at Birth

OBJECTIVE To describe cardiac function, cerebral regional oxygen saturation (rSO(2)), and cerebral blood flow (CBF) that correspond to changes in arterial oxygen saturation (SaO(2)) in normal term neonates immediately after birth and after the transition. STUDY DESIGN In this prospective observational study, cardiac function and cerebral hemodynamics were assessed by echocardiography and Doppler ultrasonography 3 times during the first 20 minutes after vaginal delivery, then again at 24-48 hours after delivery. Cerebral rSO(2) (by near-infrared spectroscopy) and preductal SaO(2) (by pulse oximetry) were assessed continuously. RESULTS In 20 neonates, SaO(2) increased progressively from 65% at 1 minute after birth to 97% at 17 minutes after birth. Cerebral rSO(2) increased from 47% at 1 minute to 83% at 8 minutes, then decreased progressively to 73% at 20 minutes. Middle cerebral artery mean velocity decreased from 34 cm/s at 7 minutes to 25 cm/s at 14 minutes. The patent ductus arteriosus (PDA) shunt was balanced at 5 minutes but became increasingly left to right. Left ventricular stroke volume was increased. Middle cerebral artery mean velocity demonstrated an inverse relationship with the PDA shunt. Further hemodynamic changes were noted on the posttransitional assessment. CONCLUSION After birth, ductal shunting rapidly changes from balanced to left to right, with a responsive increase in left ventricular stroke volume. Cerebral rSO(2) increases as SaO(2) rises during the first 8 minutes, subsequently, it decreases due to a drop in CBF and despite a further increase in SaO(2). The reduction in CBF is likely due to an increase in arterial O(2) content, PDA shunting, or both.

Neonatal Blood Pressure Support: The Use of Inotropes, Lusitropes, and Other Vasopressor Agents

A solid understanding of the mechanisms of action of cardiovascular medications used in clinical practice along with efforts to develop comprehensive hemodynamic monitoring systems to improve the ability to accurately identify the underlying pathophysiology of cardiovascular compromise are essential in the management of neonates with shock. This article reviews the mechanisms of action of the most frequently used cardiovascular medications in neonates. Because of paucity of data from controlled clinical trials, evidence-based recommendations for the clinical use of these medications could not be made. Careful titration of the given medication with close monitoring of the cardiovascular response might improve the effectiveness and decrease the risks associated with administration of these medications.

Effects of low oxygen saturation limits on the ductus arteriosus in extremely low birth weight infants

Objective:Postnatal increase in oxygen promotes constriction of the patent ductus arteriosus (PDA). According to the findings of prospective observational studies, the clinical practice of targeting lower fractional oxygen saturation between 70 and 90% has been associated with a reduced incidence of severe retinopathy of prematurity (ROP) without affecting survival or neurodevelopmental disability at 1 year of age. Our objective was to investigate the impact of the use of a lower oxygen saturation target range on the incidence of early hemodynamically significant PDA (hsPDA) and the need for ductal ligation in extremely low birth weight (ELBW, <1000 g) infants.Study Design:In this retrospective study, we analyzed data from 263 ELBW infants managed 4 years before (episode I: target oxygen saturation 89 to 94%) and after (episode II: target oxygen saturation 83 to 89%) implementation of the use of lower oxygen saturation limits in two neonatal intensive care units. Infants with a birth weight of 1000 to 1500 g were managed with the same oxygen saturation target range (89 to 94%) during both episodes, and they served as controls. Parametric and nonparametric tests were used as appropriate and multivariate logistic regression models were used to correct for confounders.Results:There was an increase in the incidence of hsPDA (63.2 vs 74.8%, P=0.043), without an increase in the need for surgical ligation (24.2 vs 29.9%, P=0.3) after implementation of the lower oxygen saturation target range policy. After adjusting for confounders, there was an increase in the odds of having an hsPDA (odds ratio (OR) 1.77, 95% confidence interval (CI) (1.03 to 3.06), P=0.04) but the odds for ductal ligation did not change in episode II (OR 1.25, 95% CI (0.70 to 2.25), P=0.4). The incidence of ROP⩾stage III (50.7 vs 15.7%; P<0.0001) and the need for laser ablation (33.8% vs 8.7%; P<0.0001) were significantly reduced. There was no change in the incidence of hsPDA or ductal ligation in the control group.Conclusion:Targeting lower oxygen saturation limits to minimize periods of hyperoxemia in ELBW infants reduced the incidence of severe ROP and the need for laser ablation. The incidence of early hsPDA was increased; however, final closure rate and the incidence of surgical ligation of the ductus arteriosus were not affected.