Biomedical subjects
Publications and source records attributed to J B Norton.
Formalin infiltration of the ductus arteriosus, a recent palliative procedure in neonates with certain congenital cardiac defects, has been shown to result in delayed left recurrent laryngeal nerve paralysis. Implication for the airway and later management are discussed.
Continuous positive airway pressure (CPAP) is used routinely to improve oxygenation in newborns who have intrapulmonary shunts and hypoxemia tha tis refractory to usual oxygen therapy. Although the cardiovascular and pulmonary effects of CPAP on newborns are well known, little information is available concerning the effect of CPAP on renal function. Therefore, we determined the effect of CPAP (7.5 cm H2O) on urine flow, sodium excretion, and glomerular filtration rate in six newborn goats that were lightly anesthetized with methoxyflurane. CPAP decreased urine flow, sodium excretion, and glomerular filtration rate. CPAP also decreased pulse pressure but did not change mean systemic arterial pressure or heart rate. We conclude that CPAP can impair renal function in newborns without significantly altering renal perfusion pressure.
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23 premature infants were placed on a randomized double-blind study to evaluate the effectiveness of indomethacin in closing a patent ductus arteriosus. Infants received 0.2 mg/kg indomethacin or placebo by gavage. In the treatment group, 7 patients responded out of a total of 12, while in the placebo group, 2 responded out of a total of 11. Indomethacin plasma levels were obtained in 6 patients in the treatment group. Plasma levels showed marked variability in peak level (60-3,100 ng/ml), time to peak level (0.5-6 h) and t1/2 (1 to greater than 24 h).
This study was undertaken to determine if the production of pulsatile flow by the intra-aortic balloon pump during cardiopulmonary bypass has any beneficial effect on coronary flow, regional myocardial flow, myocardial metabolism, and left ventricular function. Thirty-six conditioned dogs were subjected to one hour of total normothermic cardiopulmonary bypass. They were divided into the following five groups: (1) controls, beating heart and femoral inflow; (2) balloon, beating heart, and femoral inflow; (3) balloon, beating heart, and aortic inflow; (4) control, fibrillating heart and femoral inflow; and (5) balloon, fibrillating heart, and femoral inflow. Total coronary flow, left ventricular flow, coronary sinus flow, and the endocardial-to-epicardial flow ratio increased in group 3. This increase in flow may have been in part due to increased resistance to flow in the descending aorta by the balloon. No differences in flow were noted in the other groups, all of which were perfused via the femoral artery. No significant differences in myocardial metabolism or left ventricular contractility could be demonstrated between balloon-treated and control groups in these normal hearts.
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Thirty consecutive infants undergoing hypothermia and circulatory arrest for repair of ventricular septal defect, transposition of the great vessels, or atrioventricular canal defects were alternately selected for conventional high flow nonpulsatile perfusion or pulsatile perfusion during core cooling and rewarming. All received morphine anesthesia, 30 mg/kg of Solu-Medrol, and 10 to 15 mcg/kg of phentolamine. Those receiving nonpulsatile flow were perfused at a rate of 160 to 180 cc/kg/min with a roller pump and oxygenator with arterial pressure of 50 to 55 mm Hg. In the pulsatile flow group, a roller pump and oxygenator were used, and an especially constructed Datascope PAD (pulsatile assist device) was interposed in the arterial line to provide pulsatile perfusion with 75/40 mm Hg pressure at slightly reduced flow (150 cc/kg/min). The average rectal, esophageal, and tympanic membrane temperatures were reduced to approximately 16 degrees C prior to circulatory arrest. Following repair, perfusion was resumed until these temperatures returned to 37 degrees C. Cooling and rewarming were enhanced by pulsatile perfusion, with over 30% reduction in total pump time. Additionally, the larger patients in the pulsatile group cooled almost as rapidly as the smaller. The rates of decline and subsequent rise of rectal, esophageal, and tympanic membrane temperatures were equal in the pulsatile group, but the rectal temperature lagged far behind in the nonpulsatile group. Urine production during bypass was 100% greater in the pulsatile group. The plasma free hemoglobin was similar in both groups. The average postrewarming pH was 7.31 in the nonpulsatile group and 7.42 in the pulsatile group. Infants receiving pulsatile flow awakened more quickly, were more alert, and required less postoperative mechanical ventilation. We suggest that pulsatile perfusion for core cooling and rewarming of infants is safe and is more rapid and physiological than conventional high-flow nonpulsatile perfusion.
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Ventricular fibrillation is frequently induced during cardiac surgery to quiet the operative field. The reported effects of fibrillation on the myocardium vary considerably. In an attempt to better define these effects, we subjected 28 dogs to one hour of total normothermic bypass. Myocardial blood flow, lactate, adenosine triphosphate (ATP), oxygen consumption, and left ventricular fibrillation was induced in 5 dogs and continuous electrical fibrillation in 7 dogs. These groups were compared to two respective control groups with beating hearts of 8 animals each. Coronary sinus flow, total coronary blood flow, left ventricular flow, myocardial oxygen consumption, and myocardial tissue lactate increased significantly in the fibrillating hearts. Left ventricular dp/dt decreased with fibrillation, but not significantly. It is concluded that the metabolic demands of ventricular fibrillation exceed the increase in coronary blood flow, when compared to demands of the beating heart, and that decreased left ventricular performance may result.
A small infant with severe congenital aortic stenosis presents a difficult therapeutic problem. Both operative and nonoperative treatment are hazardous--especially when other cardiovascular anomalies are present. This report describes a simple, effective technique for dilating the stenotic aortic valve and simultaneously repairing certain associated defects. The procedure has been used successfully in 3 infants with a postoperative follow-up of 6 months to 4 years. There were no deaths, and the functional results have been excellent. This technique is presented as an alternative to the more hazardous approach to open valvotomy and/or stage correction of associated anomalies.
The eighteenth survivor of correction of an anomalous left pulmonary artery arising from the right pulmonary artery is reported. This is the first case in which postoperative angiography demonstrated patency of the left pulmonary artery. The onset of symptoms in infancy, predominance of expiratory rather than inspiratory stridor, anterior indentation of the esophagus, and lethal progression of symptoms during the first year of life are peculiar to this anomaly. Operation through a left thoracotomy is advocated, with division of the proximal left pulmonary artery and implantation into the main pulmonary artery posterior to the phrenic nerve. Previously reported cases are collectively reviewed.
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We compare the data of three studies of hospitalized infants with cardiac disease performed between 1967 and 1987. The studies were from the New England Regional Infant Cardiac Program (1967-1974), the Brompton Hospital (1973-1982), and the Northern Great Plains Regional Cardiac Program (1982-1987). Considering differences in classification among the studies, the distribution of cardiac anomalies during the first year of life is similar among the three studies. Although about 30% of infants are admitted during the first week of life and nearly 40% between 3 and 6 months, the proportion of infants admitted between 6 and 12 months was larger (25%) in the latest than in the earliest study (10%). There were also differences in the distribution of the diagnoses at various ages, reflecting changes in the patterns of care during the three eras.