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We report a case of a lymphocutaneous fistula in a 19-month-old boy who had been a premature neonate, born in the 23rd week of gestation. The fistula, an apparent complication of central venous line placement during the patient's first 5 months of life, was composed of a distinct lymphatic vessel bundle in the right supraclavicular region, with its exit point at the posterior aspect of the right shoulder. The drainage ceased immediately after resection and repair of a 1-cm obstruction in the superior vena cava.

Purpose: To examine the effects of temperature on auditory brainstem responses (ABRs) in infants during hypothermic cardiopulmonary bypass for total circulatory arrest (TCA). The relationship between ABRs (as a surrogate measure of core-brain temperature) and body temperature as measured at several temperature monitoring sites was determined., Methods: In a prospective, observational study, ABRs were recorded non-invasively at normothermia and at every 1 or 2 degrees C change in ear-canal temperature during cooling and rewarming in 15 infants (ages: 2 days to 14 months) that required TCA. The ABR latencies and amplitudes and the lowest temperatures at which an ABR was identified (the threshold) were measured during both cooling and rewarming. Temperatures from four standard temperature monitoring sites were simultaneously recorded., Results: The latencies of ABRs increased and amplitudes decreased with cooling (P < 0.01), but rewarming reversed these effects. The ABR threshold temperature as related to each monitoring site (ear-canal, nasopharynx, esophagus and bladder) was respectively determined as 23 +/- 2.2 degrees C, 20.8 +/- 1.7 degrees C, 14.6 +/- 3.4 degrees C, and 21.5 +/- 3.8 degrees C during cooling and 21.8 +/- 1.6 degrees C, 22.4 +/- 2.0 degrees C, 27.6 +/- 3.6 degrees C, and 23.0 +/- 2.4 degrees C during rewarming. The rewarming latencies were shorter and Q10 latencies smaller than the corresponding cooling values (P < 0.01). Esophageal and bladder sites were more susceptible to temperature variations as compared with the ear-canal and nasopharynx., Conclusion: No temperature site reliably predicted an electrophysiological threshold. A faster latency recovery during rewarming suggests that body temperature monitoring underestimates the effects of rewarming in the core-brain. ABRs may be helpful to monitor the effects of cooling and rewarming on the core-brain during pediatric cardiopulmonary bypass.

Thoracotomy patch leads used for implantable cardioverter defibrillators (ICDs) are generally safe and effective. We describe two patients in whom a late complication of patch lead migration occurred years after the original implants, causing a bronchopleural fistula in one and lingular lobe collapse in the other patient. We conclude that patch migration is a late but possible complication of extrapericardial ICD leads, and should be suspected in patients who present with hemoptysis, atypical pneumonia, or lung collapse after the initial ICD surgery.

Staged reconstruction has become the preferred approach to hypoplastic left heart syndrome at many centers in the United States. The overall results of this strategy are most adversely affected by a high mortality at the initial stage, the Norwood procedure. The hemodynamic instability of a single ventricle providing blood flow in parallel to the systemic and pulmonary circulations combined with the stresses of cardiopulmonary bypass and circulatory arrest result in a precarious postoperative condition. Diligent perioperative management at this stage is essential to survival. To help simplify the complexity of single-ventricle physiology, this article describes a mathematical model that identifies the key elements that affect systemic oxygen delivery. The importance of balancing the circulation is underscored. The value of monitoring both systemic arterial and venous oxygen saturations to assess systemic-to-pulmonary blood flow ratio is derived from this mathematical model and confirmed experimentally and clinically. Recent research using animal models of single-ventricle physiology is also described. Using these concepts and information, techniques for achieving adequate systemic oxygen delivery are discussed. Copyright 1998 by W.B. Saunders Company

Background: Right ventricular failure can lead to circulatory collapse while on left ventricular assist device support. By shunting blood from the femoral vein to the left ventricular assist device, cardiac output can be increased, but arterial oxygen saturation will decrease., Methods: To determine the effects on O2 delivery, a model was developed on the basis of O2 uptake in the lungs and whole body O2 consumption. An equation was derived that related cardiac output, pulmonary venous O2 saturation, O2 consumption, and the ratio of shunt-to-systemic blood flow to systemic O2 delivery., Results: When total cardiac output increases, the shunt will increase systemic O2 delivery while decreasing arterial O2 saturation and leaving systemic venous O2 saturation unaltered. When total output does not increase, the shunt will decrease systemic O2 delivery, arterial O2 saturation, and systemic venous O2 saturation., Conclusions: The analysis suggests that measuring systemic venous oxygen saturation may be a useful way to monitor patient safety. A decrease in systemic venous O2 saturation when creating the shunt implies an inadequate increase in cardiac output.

Background: Pediatric patients undergoing repair of congenital cardiac abnormalities have a significant risk of an adverse neurologic event. Therefore this retrospective cohort study examined the potential benefit of interventions based on intraoperative neurophysiologic monitoring in decreasing both postoperative neurologic sequelae and length of hospital stay as a cost proxy., Methods: With informed parental consent approved by the institutional review board, electroencephalography, transcranial Doppler ultrasonic measurement of middle cerebral artery blood flow velocity, and transcranial near-infrared cerebral oximetry were monitored in 250 patients. An interventional algorithm was used to detect and correct specific deficiencies in cerebral perfusion or oxygenation or to increase cerebral tolerance to ischemia or hypoxia., Results: Noteworthy changes in brain perfusion or metabolism were observed in 176 of 250 (70%) patients. Intervention that altered patient management was initially deemed appropriate in 130 of 176 (74%) patients with neurophysiologic changes. Obvious neurologic sequelae (i.e., seizure, movement, vision or speech disorder) occurred in five of 74 (7%) patients without noteworthy change, seven of 130 (6%) patients with intervention, and 12 of 46 (26%) patients without intervention (p = 0.001). Survivors' median length of stay was 6 days in the no-change and intervention groups but 9 days in the no-intervention group. In addition, the percentage of patients in the no-intervention group discharged from the hospital within 1 week (32%) was significantly less than that in either the intervention (51%, p = 0.05) or no-change (58%, p = 0.01) groups. On the basis of an estimated hospital neurologic complication cost of $1500 per day, break-even analysis justified a hospital expenditure for neurophysiologic monitoring of $2142 per case., Conclusions: Interventions based on neurophysiologic monitoring appear to decrease the incidence of postoperative neurologic sequelae and reduce the length of stay. Inasmuch as the break-even cost for neurophysiologic monitoring is more than four times the actual average charge, both patients and hospital may profit from this service. Because this study was not a truly randomized clinical trial, unintentional statistical bias may have occurred and caution is urged in interpreting the magnitude of apparent intergroup outcome differences.

The aim of this study is to document our experience with the use of extracorporeal life support (ECLS) in the neonatal cardiac patient, to detect differences in the morbidity and mortality between patients who required ECLS preoperatively and those who required ECLS postoperatively, and to determine the long-term effects of these morbidities. A chart review was undertaken of all neonatal cardiac patients who required ECLS between May 1985 and July 1994 at Kosair Children's Hospital, Louisville, Kentucky. Twenty-three neonatal cardiac patients had received preoperative or postoperative ECLS with an overall survival rate of 35%. Our preoperative and postoperative patients had similar demographics, diagnoses, decannulation rates and survival rates. However, patients receiving postoperative ECLS more frequently required more than two inotropes (p < 0.001), had an increased incidence of renal failure (p < 0.02), had more central nervous system abnormalities on brain imaging studies (p < 0.004), and had a longer hospital stay (p < 0.05). Follow-up testing of survivors yielded normal Bayley Scale of Infant Development (BSID) scores in half of the patients. Survival in the two groups was similar, but a significant difference in morbidity was found. Except for severe intracranial abnormalities, the morbidity was shown to be reversible on follow-up examination. We recommend the continued use of ECLS for neonatal cardiac patients who require preoperative or postoperative support even when severe renal failure ensues or minor abnormalities are detected on brain imaging studies.

Although progress has been made in treating hypoplastic left heart syndrome, improvements in perioperative care may further decrease mortality. We present a case in which continuous monitoring of systemic venous oxygen saturation allowed stabilization and successful management of a critically ill infant. Systemic venous oxygen saturation may provide a more accurate representation of a child's clinical status, allowing more rapid intervention and better outcomes.

During routine laboratory dissections an unusually long ligamentum arteriosum, measuring 40 mm, was observed. Apparently, such a length for an otherwise normal ligamentum has not been reported previously. Forty-three other ligamenta in adults and three in newborn or stillborn infants were also measured having a range of 8 mm to 24 mm (mean 15.47 mm) and 7.5 mm to 11 mm (mean 9.5 mm) respectively. Since short and long ligaments have been reported previously, both in the newborn as well as in the adult, the variability in length of this structure appears normal and without any functional significance.

Objective: Respiratory manipulations are a mainstay of therapy for infants with a univentricular heart, but until recently little experimental information has been available to guide their use. We used an animal model of a univentricular heart to characterize the physiologic effects of a number of commonly used ventilatory treatments, including altering inspired oxygen tension, adding positive end-expiratory pressure, and adding supplemental carbon dioxide to the ventilator circuit., Results: Lowering inspired oxygen tension decreased the ratio of pulmonary to systemic flow. This ratio was 1.29 +/- 0.08 at an inspired oxygen tension of 100%, 0.61 +/- 0.09 at an inspired oxygen tension of 21%, and 0.42 +/- 0.09 at an inspired oxygen tension of 15% (p < 0.05 compared with an inspired oxygen tension of 100% and a positive end-expiratory pressure of 0 cm H2O). High-concentration supplemental carbon dioxide (carbon dioxide tension of 80 to 90 mm Hg) added to the ventilator circuit decreased inspired oxygen tension from 1.29 +/- 0.11 to 0.42 +/- 0.12 (p < 0.05 compared with baseline). A mixture of 95% oxygen and 5% carbon dioxide (carbon dioxide tension of 50 to 60 mm Hg) did not decrease the pulmonary/systemic flow ratio significantly. All three types of interventions influenced systemic oxygen delivery, which was a function of the pulmonary/systemic flow ratio. As the pulmonary/systemic flow ratio decreased from initially high levels (greater than 1), oxygen delivery first increased and reached an optimum at a flow ratio slightly less than 1. As the pulmonary/systemic flow ratio decreased further, below 0.7, oxygen delivery decreased. The ability of systemic arterial and venous oxygen saturations to predict the pulmonary/systemic flow ratio was examined. Venous oxygen saturation correlated well with both pulmonary/systemic flow ratio and systemic oxygen delivery, whereas arterial oxygen saturation did not accurately predict either pulmonary/systemic flow ratio or oxygen delivery., Conclusion: This model demonstrated the value of estimating the pulmonary/systemic flow ratio before initiating therapy. When the initial ratio was greater than about 0.7, interventions that decreased the ratio increased oxygen delivery and were beneficial. When the initial pulmonary/systemic flow ratio was below 0.7, interventions that decreased the ratio decreased oxygen delivery and were detrimental. We conclude by presenting a framework to guide therapy based on the combination of arterial and venous oxygen saturations and the estimate of the pulmonary/systemic flow ratio that they provide.

The univentricular heart complexes are a fairly common and potentially lethal set of congenital cardiac anomalies. Progress in developing new therapeutics has been hampered by a lack of suitable animal models. The authors developed a stable, closed heart preparation to systematically examine potential interventions. Using neonatal piglets (3.5-6.0 kg), a 6-mm PTFE graft was anastomosed end to end to the innominate artery and end to side to the pulmonary artery. An atrial septostomy was made, using a Rashkind septostomy catheter passed transvenously. With the same catheter, the tricuspid valve was rendered incompetent. Occlusion of the right ventricular outflow tract completed a univentricular circuit. All cardiac output exited from the left ventricle, and pulmonary blood flow was maintained via the innominate artery-to-pulmonary artery shunt. Pressure transducers measured central venous (mid inferior vena cava), aortic, and pulmonary arterial pressures. Oximetric probes recorded systemic venous and arterial oxygen saturations. Transit-time flow probes measured total cardiac output and pulmonary flows. Systemic flow was calculated by subtracting pulmonary flow from total cardiac output. This model has been completed in 30 animals. Minimal pressure drops have been recorded across the innominate-to-pulmonary artery graft. Pulmonary flows up to 700 +/- 52 mL/min were seen. Total cardiac outputs are as high as 1370 +/- 88 mL/min. Mean ratios of pulmonary to systemic flow (Qp/Qs ratio) range from 1.29 +/- 0.08 to 0.41 +/- 0.09. The model allows for full continuous monitoring of systemic and pulmonary pressures and flows and for accurate characterization of the physiological effects of respiratory and pharmacological interventions. In addition, mechanical constriction of the graft may allow direct alteration of the Qp/Qs ratio, with determination of an optimum value for this ratio.

Background: Despite substantial changes in the surgical treatment of children born with the hypoplastic left heart syndrome, overall mortality remains high. Although further improvements in outcomes appear to depend on more effective perioperative care, few experimental data exist to guide appropriate pharmacologic therapy in these infants. Because different inotropic agents may have different effects on the ratio of pulmonary to systemic flow (Qp/Qs), we hypothesize that they may not be equally effective at increasing oxygen delivery., Methods: In neonatal piglets (n = 6; 3.5 to 6.5 kg), we placed an innominate artery-to-pulmonary artery shunt, created an atrial septal defect, and then occluded right ventricular outflow. We examined the effects of a number of commonly used inotropic agents, administering high and low concentrations of dopamine (5 and 15 micrograms.kg-1 .min-1), dobutamine (5 and 15 micrograms.kg-1.min-1), and epinephrine (0.05 and 0.1 microgram /min)., Results: Dobutamine at 15 micrograms.kg-1.min-1 increased the Qp/Qs ratio from 1.03 +/- 0.6 at baseline to 2.52 +/- 0.55 (p < 0.05) and decreased oxygen delivery from 50 +/- 4.3 to 36 +/- 1.7 mL/min (p < 0.1). The arterial-venous oxygen difference increased as oxygen delivery went down, going from 44% +/- 1% to 48% +/- 2% (p < 0.1). Epinephrine at 0.1 microgram.kg-1.min-1 decreased the Qp/Qs ratio from 1.23 +/- 0.21 to 0.82 +/- 0.08 (p < 0.05) and increased oxygen delivery from 40 +/- 9.7 to 56 +/- 1.7 mL/min (p < 0.05). Systemic venous oxygen saturation increased from 36% +/- 4.8% to 50% +/- 8.6% (p < 0.05). Although dopamine decreased the Qp/Qs ratio and increased oxygen delivery, these changes were not statistically significant., Conclusions: Dopamine, dobutamine, and epinephrine all increased cardiac output but had substantially different effects on the Qp/Qs ratio and on oxygen delivery, possibly due to differential effects on systemic and pulmonary vascular resistances. This suggests that inotropic agents may not be equally beneficial in the clinical setting. Systemic venous oxygen saturation and the arteriovenous oxygen difference may help determine if a given inotrope improves oxygen delivery.

This review describes the techniques currently used for quantitative neurophysiologic measurement during cardiac surgery and their potential impact on clinical outcome. Electroencephalography (EEG) characterizes cerebrocortical neuronal electrical activity and was part of some of the earliest cardiopulmonary bypass procedures, yet today it is not widespread use. Each of the common misunderstandings regarding a supposed limitation of this technology is explained. Its major genuine shortcoming, a lack of selectivity, may now be overcome with the combined use of additional monitoring modalities. The influence of intracranial hemodynamics on observed EEG changes may be determined continuously and noninvasively with transcranial Doppler (TCD) ultrasound. TCD provides an indication of sudden change in either blood flow or vascular resistance as well as the detection of emboli. In addition, the metabolic status of cortical neurons can be monitored by regional cerebral venous oxygen saturation (rCVOS) using noninvasive transcranial near-infrared spectroscopy. The % rCVOS tends to remain remarkably stable over a wide range of temperatures, perfusion pressures, and anesthetic states. Marked change in either direction signifies a serious imbalance between oxygen delivery and consumption. Measurement of rCVOS does not require blood flow, pulsatile or otherwise, so that it offers the only means of monitoring during circulatory arrest. By characterizing the dynamic interplay among cerebral hemodynamics, metabolism, and electrogenesis, these technologies permit the rapid detection and correction of potentially hazardous conditions.

Cerebral perfusion is reduced after prolonged periods of total circulatory arrest in infants. Methods of rewarming after arrest may modify the flow pattern of recovery, and a single report has suggested that using cold reperfusion to delay rewarming could mitigate abnormalities in cerebral blood flow. Cerebral perfusion was evaluated by transcranial Doppler sonography in 16 infants who required periods of total circulatory arrest of 35 minutes or more. In group A (n = 9) rewarming was begun immediately on reperfusion, whereas in group B (n = 7) a 10-minute period of cold reperfusion was instituted before rewarming was begun. The mean and end-diastolic flow velocities were measured before incision (baseline) and at 20, 45, and 90 minutes after conclusion of cardiopulmonary bypass. Mean arterial pressure, hematocrit value, and arterial carbon dioxide tension were controlled, with no significant differences between the two groups (p > 0.05). In group A, the mean cerebral blood flow velocity was below the baseline level at all three postbypass measurements (p < 0.001). In group B, however, mean velocity did not differ significantly from the baseline value (p > 0.05). Twenty minutes after bypass, 89% of the patients in group A had no diastolic Doppler signal, indicating absence of perfusion during diastole, compared with only 28% in group B (p = 0.02). These preliminary results suggest that a delay in rewarming on reperfusion may be beneficial in infants after circulatory arrest.

Variations in core temperature and cerebral blood flow during open heart surgery may affect auditory brainstem responses (ABRs) and middle latency responses (MLRs) in both adults and children. We documented the changes in ABRs of two infants (ages 3 and 11 weeks, respectively) with variations in core temperature during hypothermic cardiopulmonary bypass and total circulatory arrest and compared them with those of a 19-year-old adult. Changes in MLRs that occurred in association with reductions in cerebral blood flow as monitored by transcranial Doppler are also reported in a 6-year-old child. With the reductions in temperature in both infants and the young adult, ABR latencies increased and amplitudes decreased. Effects of hypothermia on ABR latencies were completely reversed by rewarming. MLR amplitudes were transiently reduced during periods of normothermic hypoperfusion. Hypothermia partially prevented these changes, and normoperfusion after rewarming recovered MLRs. Monitoring ABRs and MLRs may be a useful technique for assessment of brain function during hypothermic cardiopulmonary bypass in children and infants.

Pulmonary arteriovenous malformation (AVM) is a congenital condition, but because the symptoms usually do not occur until middle age, the diagnosis is often delayed. The authors report on a neonate, diagnosed at 2 weeks of age, who was treated by lobectomy at 35 months of age. This prompted a review of the diagnosis, pathophysiology, and treatment of pulmonary AVM. In the literature there are approximately 500 cases of pulmonary AVM. Special attention is given to the reports involving children. Eight cases have been reported in which the diagnosis was made in the first year of life. In two series, a chest roentgenogram showed abnormalities in all affected patients. Because of the strong association of pulmonary AVM with hereditary telangiectasia (Rendu-Osler-Weber syndrome), it is recommended that family members of affected patients be screened by chest roentgenograms for pulmonary AVM.

Until recently, a mechanical prosthesis has been the substitute valve of choice for children and young adults who require aortic valve replacement. The preference for using mechanical valves in this group resulted from the discovery that porcine valves experienced accelerated structural degeneration in the young. Unfortunately, mechanical valves impose a constant risk of thromboembolism, resulting in a lifelong requirement for anticoagulant therapy. Thus, young patients with the potential for longer survival face a higher likelihood of having a thromboembolic or hemorrhagic event. To provide young patients with a durable replacement aortic valve that is not thrombogenic and does not require anticoagulation, some cardiac surgeons are transferring the patient's own pulmonary valve to the aortic position and replacing the pulmonary valve with a cryopreserved valve (a homograft) from a cadaveric donor. Long-term follow-up of the experience of Mr Donald Ross of London, England, who introduced this operation in 1967, indicates that the pulmonary autograft has the best event-free survival of any form of aortic valve replacement. The technical demands of this operation are greater than those for routine aortic valve replacement with a mechanical prosthesis; however, the pulmonary autograft can be performed at an acceptably low risk. As more experience is acquired with this technique, it may become the preferred procedure for aortic valve replacement in the young.

Cerebrospinal fluid (CSF) hypertension during aortic surgery is a poorly understood, multifactorial event that may increase the risk of spinal cord injury. To assess the factors that may contribute to changes in CSF pressure during aortic surgery, measurements of ascending arterial and CSF pressures were made in 17 anesthetized mongrel dogs. Changes in CSF patterns were monitored under several conditions tested in random sequence. These included systemic hypertension produced by an infusion of phenylephrine, cross-clamping of the descending thoracic aorta, and manual, superior displacement of the transverse aortic arch (arch elevation), either alone or in conjunction with the cross-clamp. Hypertension, cross-clamping, and cross-clamping combined with arch elevation all produced significant increases in ascending mean arterial pressure (204 +/- 20, 170 +/- 8, and 158 +/- 11 mm Hg, respectively, vs. 117 +/- 8 mm Hg [control]; (p less than 0.01). Small, nonsignificant increases in CSF pressure were detected in the cross-clamp group, but none were detected with hypertension alone, despite significant increases in ascending arterial blood pressure in both groups. Thus, neither arterial hypertension nor cross-clamping alone could be demonstrated directly to cause significant CSF hypertension. However, when aortic elevation (displacement) was combined with cross-clamping, the rise in CSF pressure increased to significant levels, even though the ascending arterial hypertension was least severe in this group. In contrast, arch elevation alone did not produce any significant increase in ascending arterial pressure but did produce an approximately 114% increase in CSF pressure (15.2 +/- mm Hg vs. 7.7 +/- 1 mm Hg [control]; p less than 0.01.(ABSTRACT TRUNCATED AT 250 WORDS)

These experiments were designed to determine whether the limited cardiac output during open cardiac massage could be preferentially directed to the coronary and cerebral vessels by balloon occlusion of the descending thoracic aorta. Sixteen dogs were instrumented to monitor cardiac output and left atrial, right atrial, right ventricular, left ventricular, and arterial blood pressures. Measurements of myocardial and cerebral blood flow distribution during massage were made using the radioactive microsphere technique. Each animal underwent two episodes of fibrillation and resuscitation. In one episode the arrest was managed by open massage alone, and in the other, open massage was accompanied by balloon occlusion, with the order randomized. When compared to control, open cardiac massage was associated with a significant decrease in mean arterial pressure; however, the addition of balloon occlusion produced a 130% increase in the mean arterial pressure that was obtained during open CPR (control, 93 +/- 5 mm Hg; massage alone, 35 +/- 2 mm Hg; massage + balloon, 76 +/- 2 mm Hg, P less than 0.01). In a similar fashion, although the absolute blood flow was reduced by 50% when compared to control, the blood flow (ml/min/g) to the brain and heart during massage was 100% better when balloon occlusion was employed (brain: control, 0.41 +/- 0.03; massage only, 0.05 +/- 0.01; massage + balloon, 0.25 +/- 0.02, P less than 0.01; heart: control, 1.46 +/- 0.11; massage alone, 0.35 +/- 0.05; massage + balloon, 0.71 +/- 0.05, P less than 0.01). These results suggest that aortic occlusion significantly increased myocardial and cerebral perfusion patterns during ventricular fibrillation and open cardiac massage.(ABSTRACT TRUNCATED AT 250 WORDS)