Norman Gootman

Effects of angiography on renal function and histology in infants and piglets

Histologic examination of the kidneys of 34 infants who died following cardiac catheterization revealed medullary necrosis in 3 and proximal tubular epithelial vacuolization in another 4. In piglets, intra-aortie administration of either sodium iothalamate or meglumine dlatrizoate caused a prompt and sustained decrease in renal blood flow. Histologlc examination of the kidneys revealed changes in tubular epithelium similar to those observed in the infants. In a prospective study of children undergoing cardiac catheterization, 8 infants developed hematuria after administration of contrast material, 3 to 5 ml. per kilogram of body weight. Hematurla did not occur when the dose did n,ot exceed 3 ml. per kilogram. These studies indicate that contrast material utilized in cardiac catheterization can influence renal function and may produce irreversible renal damage.

Hemodynamic basis for clinical manifestations of patent ductus arteriosus

Abstract A prosthesis made of silicone rubber has been developed for insertion between the aorta and pulmonary artery of dogs. The size of the communication can be controlled in the closed-chest, unanesthetized animal. The hemodynamic effects of complete acute opening and closing of the shunt have been studied in 35 dogs. The basic hemodynamic changes are related to a decrease in systemic vascular resistance, an increase in pulmonary blood flow, and direct transmission of aortic pressure to the pulmonary artery. When the shunt is opened, there is an immediate decrease in aortic and left ventricular systolic pressure, a rise in pulmonary arterial, left atrial, and left ventricular end-diastolic pressure, an increased stroke volume, and an increased heart rate. A systolic gradient between the left ventricle and the aorta frequently develops when the shunt is opened, and is probably related to the high stroke volume which occurs. The pulmonary arterial pressure tracing shows a triphasic contour when the shunt is open; left ventricular ejection is slightly prolonged, but the right ventricular ejection period is markedly reduced. This explains the paradoxical splitting of the second sound, which is also observed in some patients with patent ductus arteriosus. Systemic blood flow is moderately reduced, but pulmonary blood flow is increased about twofold. Pulmonary diastolic blood flow is markedly increased, so that peripheral pulmonary blood flow becomes much more continuous. During diastole, blood flows perferentially into the low-resistance shunt and pulmonary vascular system, and a marked backflow during diastole occurs in the descending aorta distal to the shunt. The animals varied in their ability to tolerate the shunt. After the initial responses, some dogs showed a gradual increase in aortic stroke volume and left ventricular systolic pressure, and tolerated the shunt well. Others developed a “failure response” that was characterized by a continuing fall in aortic stroke volume and left ventricular systolic pressure, with a rise in left ventricular end-diastolic, left atrial, and pulmonary arterial pressures.

Cardiac effects of esophageal stimulation: possible relationship between gastroesophageal reflux (GER) and sudden infant death syndrome (SIDS)

Twenty-six artificially ventilated newborn pigs were subjected to simulated gastroesophageal reflux; saline (10 cc) of varying pH was flushed through the esophagus from below. At a given pH threshold, reflex bradycardia, which could be blocked by atropine, was elicited. Transecting of the superior laryngeal nerves, the recurrent laryngeal nerves, and the pharyngeal plexus nerves did not block the reflex bradycardia. However, bypassing the regions superior to the esophagus with a shunt prevented the bradycardia. These results indicate that bradycardia caused by gastroesophageal reflux is independent of changes in ventilation and may be an important cause of sudden infant death.

Cardiac responses elicited by stimulation of loci within stellate ganglia of developing swine

Stimulation with bipolar electrodes of specific loci in stellate ganglia elicited in anesthetized piglets, 1-4 weeks of age, alterations in cardiac function and aortic pressure. Responses were also elicited by chemical stimulation in specific loci of these ganglia. The probability of eliciting a cardiovascular response by stimulating loci in a stellate ganglion increased with increasing postnatal age. For instance, no responses were elicited when loci in the left stellate ganglia of 1-week-old piglets were stimulated. Significant heart rate responses were obtained only when loci in right stellate ganglia were stimulated. The number of ganglionic loci from which cardiovascular responses were obtained increased with increasing postnatal age. It is concluded that the capacity of stellate ganglion neurons to modulate the cardiovascular system matures during the first four weeks of life, heart rate being modulated primarily by neurons in the right stellate ganglion and inotropism by neurons in both stellate ganglia.

Chest pain in adolescents

Adolescents with chest pain were compared with healthy adolescents to determine if they were more likely to believe they had cardiac disease and were less healthy than their peers. Perceptions were examined with a questionnaire and results analyzed by chi 2 analysis. Twenty-two percent of adolescents with chest pain were diagnosed with cardiac problems, a prevalence rate higher than previous reports. While knowledge of possible etiologies of chest pain was similar for both patient and control groups, 68% of those with the symptom associated their own pain with heart disease and 44% altered their behavior because of it. Health professionals should avoid inadvertent reinforcement of the patients fear of heart disease, particularly because subsequent unnecessary self-restrictions can result in an age group in which the symptom most often represents a noncardiac etiology.

Anomalous left coronary artery arising from the pulmonary artery with large left-to-right shunt in infancy

Anomalous origin of the left coronary artery from the pulmonary artery has been separated into the “infantile” type with poor collateral circulation and early death due to myocardial infarction and the “adult” type in which there is well-developed collateral circulation and long survival. That this classification cannot be held too rigidly is demonstrated by the patient described, who developed a myocardial infarct in spite of the presence of a large collateral circulation.

Age-Related Effects of Single Injections of Dopamine on Cardiovascular Function in Developing Swine

The cardiovascular effects of single intravenous injections of dopamine (DPA; 2, 5, 10 and 25 micrograms/kg) were evaluated in swine, less than or equal to 1 day to 2 months of age, anesthetized with halothane in 50% N2O-O2. Mean aortic pressure increased following all doses of DPA in swine less than or equal to 1 month of age. Renal vasoconstriction was obtained with 5-25 micrograms/kg in the younger animals and with 25 micrograms/kg in the oldest. After 2 micrograms/kg, renal vasodilation occurred in 2-month-old swine. Femoral and carotid vasoconstriction was elicited in day-old swine after 5-25 micrograms/kg DPA, but carotid vasodilation occurred in the oldest swine. Responses to 25 micrograms/kg DPA after combined alpha and beta adrenergic receptor blockade were generally vasodilator. Thus, dopaminergic receptors were unmasked and a postnatal maturation of these receptors was revealed.

Effects of elevated plasma magnesium concentration on cerebrospinal fluid levels of magnesium in neonatal swine.

Abstract To determine whether magnesium (Mg) can cross the blood brain barrier in developing swine, simultaneous measurements of [Mg] in plasma and cerebrospinal fluid (CSF) were made during experimental elevation of plasma [Mg] in 12 swine of differing postnatal age. All were anesthetized with Saffan and maintained at normal arterial blood gas composition. Aortic pressure and heart rate were monitored. Plasma and CSF samples, drawn at the beginning and end of a 60-min intravenous infusion of MgCl2 in all animals and every 10 min during the infusion in three, were analyzed for [Mg] and osmolality. CSF [Mg] increased in all animals as plasma [Mg] increased. There were no changes in CSF osmolality. The differences between plasma and CSF [Mg] was smallest in the youngest animals. These results indicate that Mg crosses the blood brain barrier in neonatal swine and suggest that the blood brain barrier is still maturing within the first postnatal month.

Maturation-related differences in regional circulatory effects of dopamine infusion in swine.

The cardiovascular effects of dopamine (DPA) infusions were evaluated in developing swine, less than or equal to 1 day, 2 weeks, and 2 months of age, anesthetized with halothane in 50% N2O and O2. DPA was given by intravenous infusion in randomized doses of 2, 5, 10 and 20 micrograms/kg/min for 10 min. Depressor responses and bradycardia were observed during 2 micrograms/kg/min in 2-week-olds and during 2, 5 and 10 micrograms/kg/min in 2-month-olds. During infusion of 20 micrograms/kg/min, DPA pressor responses were observed in animals less than or equal to 2 weeks of age; in addition, tachycardia occurred in 1-day-old swine. Renal resistance decreased during infusion of 2 micrograms/kg/min in all swine. It increased during 10 and 20 micrograms/kg/min in the 1-day and 2-week groups, but not in the 2-month group. Mesenteric resistance decreased during infusion of 2, 5 and 10 micrograms/kg/min in less than or equal to 2-week-olds and at all doses in 2-month-olds. Following combined alpha- and beta-adrenergic receptor blockade, infusion of 20 micrograms/kg/min DPA inhibited renal vasoconstriction in most animals and elicited mesenteric vasodilation in all. The results indicate that dopaminergic responses undergo a postnatal maturation which has a different time course for different regional circulations.

Autonomic Nervous System Regulation of Heart Rate in the Perinatal Period

In all vertebrates more advanced than elasmobranch, cardiac muscle is innervated by the autonomic nervous system [15]. There are two major divisions of the autonomic nervous system: the parasympathetic originating in the third, seventh, ninth, and tenth cranial nerves, and the sacral spinal cord region; and the sympathetic system, originating in the thoracolumbar regions of the spinal cord. For both subdivisions of the autonomic nervous system, the cells of origin within the central nervous system project to ganglia located peripherally. The cells of these ganglia send their axons to the various effector organs throughout the body. The transmitter for all preganglionic neurons is acetylcoholine (ACh), while the post ganglionic neurons of the parasympathetic nervous system are also cholinergic. With few exceptions, post-ganglionic neurons of the sympathetic nervous system are adrenergic, utilizing norepinephrine (NE) as their neurotransmitter. In all vertebrates the heart is innervated by a parasympathetic inhibitory system, and a sympathetic excitatory system.