The intrinsic physiologic properties of the developing heart

Friedman, William F.

doi:10.1016/0033-0620(72)90006-0

Cited by 533 publications

(252 citation statements)

References 30 publications

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“…The fact that atrial strips from young puppies respond to the inotropic effects of dopamine at an earlier age than ventricle is consistent with the concept that atrial sympathetic innervation occurs before ventricular sympathetic innervation (5,17). T o demonstrate that dopamine acts directly or indirectly upon the p-adrenergic receptor but not upon a "dopaminergic receptor" in the myocardium, the drug was evaluated after the addition of propranolol or haloperidol.…”

Section: Discussionsupporting

confidence: 84%

“…sympathetic nerve endings by about five days of age (5). Because of this relative lack of sympathetic innervation, ventricular myocardial levels of norepinephrine are reduced in the young animal (6).…”

Section: Discussionmentioning

confidence: 99%

“…Neonatal ventricular myocardium has fewer contractile elements per unit mass of myocardium than does adult ventricular myocardium (5,16). Furthermore, the sympathetic innervation of the ventricular myocardium is not complete at birth in many species and ventricular stores of norepinephrine are reduced (5-7, 9, 12, 17).…”

Section: Speculationmentioning

confidence: 99%

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Inotropic Response of the Neonatal Canine Myocardium to Dopamine

et al. 1978

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

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Inotropic Response of the Neonatal Canine Myocardium to Dopamine

et al. 1978

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“…Although it is well known that the premature neonatal heart is less compliant to volume overload, as induced by a systemic-pulmonary artery shunt [10], some congenital heart defects are not amenable to primary repair, due to anatomical features. Some authors demonstrated that performing a palliative operation in these low weight babies might not necessarily decrease the risk for mortality, especially in disorders where a single ventricle has to support the systemic and the pulmonary circulation [6].…”

Section: Commentmentioning

confidence: 99%

Outcome analysis of major cardiac operations in low weight neonates

Bové

François

Groote

et al. 2004

The Annals of Thoracic Surgery

101

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secutive neonates of less than 2,500 g underwent early surgery for congenital heart disease. A retrospective analysis was performed to evaluate the early to medium term outcome.Methods. Major cardiac surgery for congenital heart defects included a complete correction in 31 patients (group I) and a palliative procedure in 18 patients (group II). Mean age at operation was 15.2 days (1 day-90 days) and mean weight was 2,190 g (1,300 g-2,500 g). Twentyfour children (49%) were born prematurely. All neonates were critically ill and 47% were already ventilated preoperatively. Heart defects included mainly ventricular septal defect (10), tetralogy of Fallot complexes (8), aortic coarctation (8), transposition complexes (7), single ventricle anomalies (4), pulmonary atresia with intact septum (4), interrupted aortic arch (3), totally anomalous pulmonary venous return (3), and common atrioventricular septal defect (2).Results. Overall surgical mortality was 18%: 4 neonates died after definitive repair and 5 after palliation; repre-

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“…Several studies point to myocardial immaturity: incomplete development of sarcomeres (17)(18)(19)(20)(21), decreased functioning of {J-receptors (22,23), and myofibrillar disarray (24,25) have all been implicated. Although fetal myocardium is certainly immature relative to that of the adult, none of these factors have been shown to change immediately at birth.…”

mentioning

confidence: 99%

In Utero Ventilation Augments the Left Ventricular Response to Isoproterenol and Volume Loading in Fetal Sheep

et al. 1991

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The basis of this limitation in the ability of the fetal left ventricle to greatly increase output (systolic performance) is controversial. Several studies point to myocardial immaturity: incomplete development of sarcomeres (17-21), decreased functioning of {J-receptors (22, 23), and myofibrillar disarray (24,25) have all been implicated. Although fetal myocardium is certainly immature relative to that of the adult, none of these factors have been shown to change immediately at birth. In addition, many indices of systolic performance are increased in the newborn left ventricle relative to that of the adult (11,12), so that myocardial immaturity may not necessarily be associated with impaired ventricular function. It is remarkable that both the prematurely born animal (26-28) and human (29), which have not been exposed to prenatal hormone surges and labor to accelerate myocardial maturation, are capable of greatly increasing left ventricular output in response to a patent ductus arteriosus. In addition, recent studies of fetal sheep undergoing oxygen ventilation in utero have shown a doubling of left ventricular output (3,30), and other determinants of output such as septal compliance (31) have been shown to change in the perinatal period.Thus, left ventricular output may be limited in the fetus more because of its "circulatory environment" (the combination of a parallel circulation with central shunts, a dominant hypertrophied right ventricle that ejects more output and fills under similar pressures, a pulmonary vascular bed that is markedly constricted and that returns a very limited amount of blood to the left atrium and ventricle, and a highly compliant fetoplacental vascular bed that can absorb increases in volume that would otherwise increase left ventricular filling volume) than because of myocardial immaturity. For example, the fetal left ventricle has a very limited ability to increase output via the Frank-Starling mechanism (13), with a plateau occurring at 5-7 mm Hg. However, Hawkins et at.(32) have shown that some of this limitation is caused by a concomitant increase in afterload; if afterload is controlled, left ventricular output continues to rise at filling pressures of 10 mm Hg. In addition, high right ventricular filling and ejecting pressures may constrain left ventricular performance both in diastole and systole (33-36).We undertook the present study to determine whether the near-term (approximately 0.9 gestation) fetal left ventricle, functioning in a simulated "postnatal circulatory environment" (abolition of most central shunts with a small left to right shunt through the ductus arteriosus, a dominant left ventricle ejecting somewhat more blood than the right under higher filling pressures, a dilated pulmonary vascular bed returning a large amount of blood to the left atrium and ventricle, and a decrease in the fetoplacental vascular bed), is capable of increasing its output to levels similar to those seen in the newborn. We simulated the immediate postnatal circulatory environment in ute...

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The intrinsic physiologic properties of the developing heart

Cited by 533 publications

References 30 publications

Inotropic Response of the Neonatal Canine Myocardium to Dopamine

Inotropic Response of the Neonatal Canine Myocardium to Dopamine

Outcome analysis of major cardiac operations in low weight neonates

In Utero Ventilation Augments the Left Ventricular Response to Isoproterenol and Volume Loading in Fetal Sheep

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