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      Targeted Neonatal Echocardiography-Guided Therapy in Vein of Galen Aneurysmal Malformation: A Report of Two Cases with a Review of Physiology and Approach to Management

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          Abstract

          Vein of Galen malformation results in predictable changes in physiology which exist on a continuum. Severe pulmonary hypertension may present as hypoxemia; however, excessive reduction in pulmonary vascular resistance may precipitate progressive pulmonary overcirculation and impaired systemic blood flow. Right ventricular performance and the patency and direction of the ductus arteriosus may play a crucial role in postductal organ perfusion. Physiological stabilization may be complex and variable over time. The utilization of targeted neonatal echocardiography to guide treatment decisions may improve the ability to provide therapy tailored to the specific disease pathophysiology and monitor serially as conditions change. An enhanced approach to physiological stabilization may reduce the risk of unexpected decompensation and allow for thoughtful, controlled endovascular embolization in appropriate candidates.

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          Most cited references 16

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          The pharmacology of dobutamine.

          Dobutamine is a sympathomimetic amine that was designed as an inotropic agent for use in congestive heart failure. Clinically, dobutamine increases cardiac output by selectively augmenting stroke volume, and this is associated with a decrease in total peripheral vascular resistance that is mediated, in part, by reflex withdrawal of sympathetic tone to the vasculature. This hemodynamic profile of dobutamine makes the drug of value in the management of low output cardiac failure. The inotropic activity of dobutamine has previously been attributed to selective stimulation of myocardial beta 1-adrenoceptors. However, recent studies from a number of laboratories indicate that the mechanism of action of dobutamine is substantially more complex. Dobutamine has the capacity to stimulate beta 1-, beta 2-, and alpha 1-adrenoceptors in the cardiovascular system at doses that approximate those used clinically. It has recently been suggested that the inotropic activity of dobutamine results from combined beta 1- and alpha 1-adrenoceptor stimulation in the myocardium, and that this activity could explain, at least in part, the inotropic selectivity of the compound. Furthermore, in the vasculature, the beta 2-adrenoceptor-mediated vasodilatory effect of dobutamine is exactly offset by the alpha 1-adrenoceptor-mediated vasoconstrictor activity, such that net changes in blood pressure are minimal following the administration of dobutamine. It is concluded, therefore, that the hemodynamic profile of dobutamine in patients with congestive heart failure is derived from a unique and complex series of interactions with alpha- and beta-adrenoceptors in the cardiovascular system.
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            Clinical course and medical management of neonates with severe cardiac failure related to vein of Galen malformation.

            Neonatal presentation of vein of Galen aneurysmal malformations (VGAMs) with intractable cardiac failure is considered a poor prognostic sign. Interventional neuroradiology with embolisation has been shown to control cardiac failure, but there is a perception that neurological outcome in survivors is poor. To determine if aggressive intensive care and anaesthetic management of cardiac failure before urgent embolisation can influence morbidity and mortality. Nine newborns (four boys, five girls) were diagnosed with symptomatic vein of Galen malformations in the neonatal period during the period 1996-2001. Eight developed intractable high output cardiac failure requiring initial endovascular treatment in the first week of life. The immediate outcome after a series of endovascular procedures was control of cardiac failure and normal neurological function in six (66%) patients, one death from intractable cardiac failure in the neonatal period, and two late deaths with severe hypoxic-ischaemic neurological injury (33% mortality). Clinical review at 6 months to 4 years of age showed five infants with no evidence of neurological abnormality or cardiac failure and one child with mild developmental delay (11%). Aggressive medical treatment of cardiac failure and early neurointervention combined with modern neuroanaesthetic care results in good survival rates with low morbidity even in cases of high risk VGAM presenting in the immediate perinatal period with cardiac failure. Systemic arterial vasodilators improve outcome in neonates with cardiac failure secondary to VGAM. Excessive beta adrenergic stimulation induced by conventional inotropic agents may exacerbate systemic hypoperfusion.
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              A blind, randomized comparison of the circulatory effects of dopamine and epinephrine infusions in the newborn piglet during normoxia and hypoxia.

              To determine the hemodynamic responses to dopamine and epinephrine infusions in newborn piglets during normoxia and hypoxia. Prospective, randomized, blind cross-over study. Newborn piglets (n = 7). Animals were acutely instrumented for measurements of cardiac output, pulmonary and systemic pressures, carotid and coronary artery blood flow, and coronary artery oxygen consumption. Dopamine at infusion rates of 2 to 16 micrograms/kg/min and epinephrine 0.2 to 1.6 micrograms/kg/min were administered during normoxia. Six piglets were similarly prepared and were then made hypoxic to an arterial O2 saturation of 45% to 50%. Epinephrine at infusion rates of 0.2 to 3.2 micrograms/kg/min and dopamine at rates of 2 to 32 micrograms/kg/min were administered in random order during hypoxia. During normoxia, cardiac output increased similarly with both drugs and was significantly increased by > or = 0.2 micrograms/kg/min of epinephrine and significantly increased by 8 or 16 micrograms/kg/min of dopamine. Mean arterial blood pressure was not affected by dopamine but was significantly increased by epinephrine at a rate of 1.6 micrograms/kg/min. The relative effects of the drugs on pulmonary and systemic vascular resistance differed, the pulmonary/systemic vascular resistance ratio was reduced at the higher doses of epinephrine (i.e., 0.8 and 1.6 micrograms/kg/min) and was unaffected by dopamine. Coronary artery oxygen consumption and coronary blood flow increased significantly with both medications at rates > 0.4 and 4 micrograms/kg/min, respectively. Increases of both variables were greater with epinephrine than with dopamine. Myocardial extraction ratio was unaffected by dopamine and reduced at 0.2 and 1.6 micrograms/kg/min of epinephrine. Hypoxia caused significant increases in cardiac index, systemic blood pressure, pulmonary arterial pressure, carotid artery blood flow, coronary artery blood flow, coronary oxygen consumption, coronary oxygen extraction ratio, and the pulmonary/systemic vascular resistance ratio. Mean systemic arterial blood pressure increased significantly with 1.6 and 3.2 micrograms/kg/min of epinephrine, but was not significantly affected by dopamine at any infusion rate. Cardiac index was not affected significantly by either of the medications. Thus, there was a significant increase in the calculated systemic vascular resistance index with the highest dose of epinephrine, in contrast to the slight, statistically significant, decrease in calculated systemic vascular resistance index with the highest dose of dopamine. Epinephrine significantly reduced pulmonary arterial pressures at 0.2, 0.4, and 0.8 microgram/kg/min. Dopamine had no effect on this variable. The pulmonary/systemic vascular resistance ratio was significantly reduced by epinephrine at doses of 0.2 and 3.2 micrograms/kg/min, whereas the highest dose of dopamine caused a significant increase in the pulmonary/systemic vascular resistance ratio. Epinephrine infusion during normoxia increases systemic pressure more than pulmonary arterial pressure at doses > or = 8 micrograms/kg/min, and furthermore, produces a more appropriate hemodynamic profile in the presence of hypoxic pulmonary hypertension than dopamine infusion, in the acutely operated anesthetized piglet.
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                Author and article information

                Journal
                AJP Rep
                AJP Rep
                10.1055/s-00000169
                AJP Reports
                Thieme Medical Publishers (333 Seventh Avenue, New York, NY 10001, USA. )
                2157-6998
                2157-7005
                April 2019
                29 May 2019
                : 9
                : 2
                : e172-e176
                Affiliations
                [1 ]Division of Neonatology, The Hospital for Sick Children, Toronto, Canada
                [2 ]Departments of Paediatrics, University of Toronto, Toronto, Ontario, Canada
                [3 ]Division of Neonatology, Health Sciences Centre, Winnipeg, Manitoba, Canada
                [4 ]Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
                [5 ]Department of Physiology, University of Toronto, Toronto, Ontario, Canada
                Author notes
                Address for correspondence Patrick J. McNamara, MB, MSC Division of Neonatology, The Hospital for Sick Children 555 University Avenue, Toronto, ON M5G 1 × 8Canada patrick.mcnamara@ 123456sickkids.ca
                Article
                180068
                10.1055/s-0039-1688765
                6541491

                This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License, which permits unrestricted reproduction and distribution, for non-commercial purposes only; and use and reproduction, but not distribution, of adapted material for non-commercial purposes only, provided the original work is properly cited.

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