Background: Acute renal failure is an occasional complication after cardiopulmonary bypass in infants. Whereas it is well known that postoperative hemodynamics inflict acute renal failure, the influence of extra-corporeal circulation on the kidney is less clear. Moreover, changes in blood viscosity occur during and after surgery, which may influence renal dysfunction. For this reason, we investigated the impact of blood viscosity on renal function during cardiopulmonary bypass. Methods: In 34 patients weighting less than 10 kg, we performed repeated analysis of urine, blood, and plasma viscosity. Results: Polyuria and proteinuria that appeared during cardiopulmonary bypass indicated an elevated transglomerular filtration gradient, which recovered within 24 hours. The appearance of N-acetyl-β-D-glucosaminidase in the urine, and elevated excretion of sodium, were additionally indicative of mild tubular damage. Elevation of blood viscosity during hypothermic perfusion showed a statistical correlation with proteinuria and N-acetyl-β-D-glucosaminidaseuria. With hypothermia, the relation of blood viscosity to plasma viscosity became stronger, while the relation to the hematocrit decreased compared to normothermia. Conclusions: During cardiopulmonary bypass perfusion, the kidney can be stressed by proteinuria and mild tubular damage. Our data provide evidence that the kidneys can be protected by improved blood viscosity during cardioplegia, but this needs confirmation in a prospective interventional study.

Background: The clinical symptoms of heart failure in infants with left-to-right shunts are thought to be explained by well-known hemodynamic disturbances such as pulmonary hypertension and overcirculation, but previous studies have not, thus far, found the expected correlations with hemodynamic and clinical parameters. Based on the neurohormonal model of heart failure, we hypothesised that the clinical symptoms of infants with left-to-right shunts are also related to neurohormonal disorders. Methods: We compared various neurohormonal and hemodynamic parameters measured invasively in 70 infants with left-to-right shunts to the respiratory rate and gain in weight over a corresponding period of time. Heart rate correlated significantly with respiratory rate (r = 0.62***, p < 0.001) and gain in weight (r =−0.31*, p = 0.015), but more conventional measures of severity, such as the ratio of pulmonary to systemic flows, failed to show comparable correlations with clinical symptoms. Respiratory rate was related to levels of norepinephrine (r = 0.47***, p < 0.001) and plasma renin activity (r = 0.65***, p < 0.001). The important impact of autonomic imbalance on respiratory rate was underlined by an analysis of variability of heart rate in 26 infants that showed significantly reduced values for the domains of time and frequency. We were not able to find a conclusive multiple regression model with which to explain the symptom "failure to thrive". Conclusions: A increased heart rate, reduced variability in heart rate, and elevated levels of norepinephrine and renin are significant predictors of clinical symptoms such as tachypnea in infants with congenital cardiac malformations. The neurohormonal hypothesis, in which heart failure is interpreted not only as a hemodynamic derangement but also as a neurohormonal disorder, may be valid for infants with congenital cardiac malformations.

The development of pulmonary arteriovenous malformations is a well-known complication after Fontan operations, and may result in significant morbidity due to increasing arterial desaturation. We compared the use of bubble contrast echocardiography and pulmonary angiography in detecting such malformations. We also examined which anatomical and haemodynamic variables were associated with their development. Our study includes 20 patients who had undergone modified Fontan procedures, 10 with atriopulmonary and 10 with total cavopulmonary connections, in Gothenburg between 1980 and 1991. All patients underwent cardiac catheterisation and pulmonary angiography. Bubble contrast echocardiography was performed at the same time, with injection of agitated polygelin colloid solution (Haemaccel, Hoechst) into the right and left pulmonary arteries, respectively. Transoesophageal echocardiography was used to detect the appearance of bubble contrast in the pulmonary venous atrium. The aim was also to evaluate the role of hepatic venous blood. Of the 20 patients, 9 (45%) had a positive contrast echocardiography study, compared with only 2 (10%) detected by pulmonary angiography. Patients with positive contrast echocardiography had a significantly lower arterial oxygen saturation than those with negative studies, both at rest (88% vs 95%, p < 0.01) and during exercise testing (78% vs 89%, p = 0.01). Bubble contrast echocardiography is much more sensitive in detecting pulmonary arteriovenous malformations than pulmonary angiography. By injecting echo contrast into the right and left pulmonary arteries, the method can be made highly selective. Pulmonary arteriovenous malformations develop much more frequently in patients with the Fontan circulation than previously reported.

Objective: As the morpholgic severity of coarctation of the aorta is difficult to assess, especially after previous repair, the value of the technique of multiplanar reconstruction of magnetic resonance imaging data to achieve a 3-dimensional reconstruction of the aortic arch was evaluated and compared to hemodynamic measurements. Methods and Results: We performed 30 examinations in 27 patients aged from 6 to 54 years, with a mean of 21 years, by magnetic resonance imaging using a 1.5 Tesla scanner with a standard body coil. Measurements of flow across the coarctation were performed using phase! shift velocity mapping, and peak velocity was calculated at the site of stenosis. Aortic cross-sectional area before, at, and beyond the stenosis was reconstructed 3-dimensionally to calculate a percentage degree of stenosis. Morphologic severity of stenosis was correlated to invasively assessed hemodynamic gradients and morphologic data from biplane angiography in 23 patients. Among the 30 examinations, 24 patients had been previously treated by either surgery, in 17 patients, or balloon dilation, while 6 had native coarctation. 3-dimensional reconstruction was possible in all and better delineated the anatomy concerning the hemodynamic relevance of stenoses even as compared with biplane angiography. The correlation between severity of narrowing assessed by diameter measurements in the biplane angiography and 2-dimensional magnetic resonance imaging was r = 0.94, and multiplanar reformation with 2-dimensional magnetic resonance imaging was r = 0.87 with a tendency of higher grading with the 3-dimensional technique (p = 0.0001). The correlation of 2-dimensional magnetic resonance imaging with invasively measured hemodynamic gradients was r = 0.67 versus r = 0.74 for the areas assessed by multiplanar reformation, indicating that the hemodynamic relevance of a morphological approach to evaluate the degree of a stenosis should better be assessed 3-dimensionally. Conclusions: The 3-dimensional reconstruction of the morphologic severity of coarctation offers additonal information over conventional imaging especially in patients with kinking, complex geometry, or collaterals,in whom hemodynamic measurements can become unreliable.

Since June 1998, we have used an Amplatzer device whenever considered appropriate in patients with isolated defects within the oval fossa. The aim of this study was to define the total cohort of patients with isolated defects in the oval fossa seen at this hospital, so as to assess the impact of this policy on contemporary management. In the two-year period commencing 1st June 1998, 116 patients older than 6 months were seen with an isolated septal defect within the oval fossa. Mean age at closure or last review was 5.8 years, with a range from 0.5 to 20 years. In total, 42 (36%) patients were assigned to surgical closure, 25 (22%) to closure using an Amplatzer device, and 49 (42%) remained under clinical follow up. Direct referral for surgical closure occurred in 24 (21%) patients, in whom transcatheter closure was considered not appropriate after transthoracic echocardiography. Transoesophageal echocardiography was performed in 45 (39%) patients to assess suitability for closure using the Amplatzer device. Of these, 20 (44% of the group undergoing transoesophageal echocardiography) were considered unsuitable for closure in this fashion. Of these, 8 were referred for surgery and 2 with small defects were considered not to require closure. Patients undergoing closure with the device were older than the group referred for surgical closure, having a median age of 7.8 versus 3.6 years, and stayed for a shorter period in hospital. Those closed using the device stayed for 2 days, as opposed to a median of 5 days, with a range from 4 to 10 days for those undergoing surgical closure. Closure was complete as assessed by echocardiography after follow up of 1–3 months in both groups. There were no recognised complications related to insertion of the device, whereas transient postoperative morbidity occurred in 38% of those closed surgically. Insertion of an Amplatzer device was considered to be appropriate in 37% of patients older than 6 months requiring closure of an atrial septal defect in the oval fossa.

A trial of 11 video-conferenced teaching sessions for residents in pediatric cardiology was performed by the 7 training programs in Canada in order to share expertise in specialized areas, to expose trainees to educational telemedicine, and to acquaint residents with other programs and personnel. Topics included cardiac pathology, arrhythmias, magnetic resonance imaging, fetal physiology, pulmonary hypertension, and cardiomyopathy. The sessions were evaluated by 93 residents by questionnaire for content and technology. Session content was highly rated. Videoconference picture quality was highly rated, but sound quality and visual aids were rated as neutral or unsatisfactory by a significant minority,related to problems with several early sessions, subsequently corrected. 60% of respondents rated the videoconferences as good as live presentations. Presenters were generally satisfied although they required some adjustments to videoconferencing. The average cost per session was $700 Canadian. Videoconferencing of resident educational sessions was generally well accepted by most presenters and residents, and the trial has formed the basis for a national network. Adequate organizational time, and careful attention to audiovisual needs, are most important. Videoconference guidelines are suggested for presenters based on this experience.

The direct visualization of systemic microcirculation using intravitalmicroscopy permits the classification of proinflammatory and ischemic microvascular alterations during normothermic and hypothermic cardiopulmonary bypass in neonates. We used seven newborn piglets, on average aged 9 days, and weighing 3200 g, as a control group. In addition, we studied nine piglets subjected to 60 minutes of constant non-pulsatile flow using hypothermic extracorporeal circulation at 28°C, and five piglets using normothermic conditions at 37°C. The microvascular network of the greater omentum and the subcutaneous tissue was directly visualized using intravitalmicroscopy. We analysed interactions between leukocytes and endothelial cells, microvascular morphology, and microrheological conditions, focussing on signs of ischemic and proinflammatory alterations. During normothermic cardiopulmonary bypass, the numbers of activated leukocytes were elevated compared to hypothermic cardiopulmonary bypass (p > 0.05). Arteriolar diameter decreased during hypothermia. Capillaries were markedly dilated during normothermia. Patterns of microvascular perfusion, for both types of cardiopulmonary bypass, showed signs of ischemic damage, revealed by a reduced functional capillary density. Perfusion dependent levels of lactate were higher during normothermic cardiopulmonary bypass (p > 0.05). This new experimental approach revealed that non-pulsatile cardiopulmonary bypass, independent of temperature, induces a proinflammatory and ischemic response compared to an unaltered control group. The markedly elevated numbers of activated adherent leukocytes, the reduced capillary density, and the high lactate levels in those undergoing bypass in normothermic conditions indicate a more pronounced inflammatory stimulus and tissue hypoperfusion compared to the possible protective effect of hypothermia for children undergoing cardiopulmonary bypass.

Primary tumors of the cardiac valves are rare. One of the most common reasons that left-sided cardiac tumors come to clinical attention is embolization to the systemic circulation. We present two children who suffered left coronary arterial occlusion due to embolization of a sarcoma of the mitral valve. A 6-year-old female who had been admitted to the hospital after cerebrovascular embolization of a fragment of sarcoma of the mitral valve experienced sudden cardiovascular collapse due to occlusion of the left coronary artery. She was placed on extracorporeal membrane oxygenation, and underwent coronary embolectomy and resection of the tumor from the mitral valve and its tendinous cords. Left ventricular function did not improve, and she underwent orthotopic heart transplantation. On follow-up 32 months after transplant, the patient is well, with no evidence of recurrence of or metastasis from the tumor. The tumor arose from the leaflets and tendinous cords of the mitral valve, and was composed grossly of multiple white nodules. Histopathologic evaluation disclosed fragments composed predominantly of peripheral spindle cells in an extensive fibromyxoid stroma. The mildly pleomorphic cells of the tumor gradually blended with adjacent pieces of the mitral valvar leaflet and tendinous cords. Immunohistochemical studies revealed strong staining for vimentin, smooth muscle actin, muscle specific actin, and myoglobin, suggesting myogenic differentiation. The other patient was a 2½-year-old female who died suddenly at home. Grossly and histologically, the tumor was essentially identical to the first case, and there was a 3 cm string-like extension passing into the orifice of the left coronary artery. To put the cases in context, we compare them with other descriptions of this rare type of tumor.

Numerous investigations have addressed the most appropriate anatomical structures to be used for the identification of segmental arrangement (“situs”). Variations from normal have been termed “heterotaxy syndromes”. The assumption is frequently made that, in such instances, all the organs in a given individual case follow the same rules for segmental morphology. This leads to confusion. The starting point for cardiac analysis is the structure of the atriums. On this basis, we can define viscero-atrial discordance when, in usual arrangement, mirror imagery, and heterotaxy, the atriums and their appendages are no longer concordant with the remaining thoracic and abdominal organs. With this in mind, we examined a large number of autopsied specimens to identify all possible variations of thoracic structures and abdominal organs relative to atrial arrangement. We analyzed 1100 malformed hearts. Of these, 1046 had usual arrangement with normally situated heart (95%); 10 cases had usual arrangement with right-sided heart (0.90%); 25 showed mirror imagery (2.27%), and 19 were found with heterotaxy (1.72%). There was a total of 54 hearts of usual arrangement with right-sided heart, mirror imagery and heterotaxy, (4.90%) and, amongst them, 17 showed viscero-atrial discordances (31.48%). In those having usual arrangement with right-sided heart, there were 2 cases (20%); 8 in those with mirror imagery (32%); and 7 in heterotaxy (36.8%). In the 1046 cases of usual arrangement with normally situated heart, there were 12 examples of viscero-atrial discordances (1.14%). In all, we found a total of 29 cases of viscero-atrial discordances. Taken together, the discordances are best dealt with by describing separately, in every case of normal or abnormal atrial arrangement, the thoracic structures, the atrial appendages, and the abdominal organs. In the final analysis, the diagnosis of the cardiac arrangement rests on the location and morphology of the atriums and their appendages.

A 6-year-old boy presented with endocarditis of the tricuspid valve caused by penicillin resistant pneumococcus. He had no history of congenital cardiac disease. The likely portal of entry for the organism was the middle ear.

Pseudoachondroplasia is an autosomal dominant variant of osteochondroplasia that results in mild to severe short-limb dwarfism and early-onset of osteoarthrosis. It has been linked to results from mutations in the gene for cartilage oligomeric matrix protein. We describe a 4-year-old boy with pseudoachondroplasia who also had prolapse of the mitral valve. To the best of our knowledge, this association has not previously been reported.

Tissue harmonic imaging improves the quality of images in adults with poor acoustic windows, but its utility in children has yet to be evaluated. The use of fundamental and harmonic imaging were compared in 70 children with poor echocardiographic windows. Scores were higher for harmonic in comparison to fundamental imaging for all views. Harmonic imaging improves the visualization of cardiac structures over fundamental imaging in children with poor echocardiographic windows.

Rheumatic carditis is a major manifestation of acute rheumatic fever. Conventional therapy includes the use of salicylates and steroids. To date, however, such therapy has not been proven to have a clear benefit in reducing valvar heart disease. We report the use of high-dose intravenous immunoglobulin in two chidlren with acute rheumatic carditis in whom we have been able to document the beneficial effect.

Anomalous origin of the left coronary artery from the pulmonary arteries is a rare and life-threatening defect, usually needing prompt surgical correction during infancy. We describe the case of a young asymptomatic patient with this defect who underwent surgical reimplantation despite the absence of signs of myocardial ischemia, due to the presence of proximal stenosis of the anomalous coronary artery.

We report a 17 year old boy with a large fistula from the right coronary artery to the right ventricle. The fistula consisted of two major branches. The smaller branch could be embolised with three detachable platinum microcoils without problems. The high flow of blood in the larger branch, however, prevented conventional occlusion using coils. Interventional occlusion of this branch was achieved in a second attempt. Following creation of an arterio-venous wire-loop, we advanced a balloon catheter into the distal end of the fistula. Under temporary occlusion of the fistula, complete closure was achieved by delivery of 7 detachable platinum microcoils. Thus, even large coronary arterial fistulas can be closed safely with these new platinum detachable microcoils. The procedure, however, requires temporary control of the flow of blood by balloon occlusion.

We report the successful use of a cutting-balloon catheter in dilating stenoses in major systemic-to-pulmonary collateral arteries which had been resistant to high pressure balloons. After dilation using the cutting balloon, we implanted stents to produce a marked improvement in both pulmonary blood flow and arterial saturation. The technique provides useful palliation for patients having such stenotic collateral arteries.