Background: Performance of the functionally single right ventricle may deteriorate over time. Quantitative assessment of this chamber, however, is complicated by its asymmetric geometry. Automatic detection of borders, and the Doppler-derived index of myocardial performance, are echocardiographic techniques that allow for quantitative assessment regardless of ventricular shape. We sought to evaluate the mechanics of contraction and relaxation in the functionally single right ventricle using these parameters. Methods: We evaluated systemic ventricular function in 35 asymptomatic patients with functionally single right ventricle, having a mean age of 7.8 ± 3.1 years, who had undergone the Fontan procedure. We compared them with 32 age-matched normal controls using both automatic detection of borders and Doppler indexes. Results: When compared with the controls, the group with a functionally single right ventricle demonstrated diminished systolic function as evidenced by a lower fractional change in area (42.7 ± 10.1% vs. 54.6 ± 10.5%, p = 0.001), and diminished diastolic function, as demonstrated by a greater reliance on atrial contraction to achieve ventricular filling (32.0 ± 4.4% vs. 22.2 ± 4.1%, p = 0.001). The mean index of myocardial performance in those with functionally single right ventricles was also greater than in controls (0.41 ± 0.12 vs. 0.30 ± 0.05, p = 0.001), and the indexed ejection time was shorter (0.35 ± 0.05 vs. 0.39 ± 0.05, p = 0.01), suggesting less efficient ventricular mechanics. Conclusions: These data demonstrate that the systolic and diastolic properties of the functionally single right ventricle differ significantly from those of the normal systemic left ventricle. Use of the echocardiographic techniques provide insight into ventricular mechanics in patients with functionally single ventricles, and may be valuable tools for serial quantitative follow-up.

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.

We have investigated the relationship between oxygen free radicals and acute rheumatic fever with regard to diagnosis of the disease process. At the time of diagnosis, we measured the levels of reactive oxygen molecules in the plasma, this being a parameter for oxygen free radicals, and discovered the levels to be significantly higher when compared with those measured in a control group (P< 0.05). The levels measured in the plasma, however, were not statistically different among patients with and without carditis.

We found a progressive decrease in the levels measured in the plasma when patients with acute rheumatic fever were tested on the 15th, 30th and 90th days subsequent to diagnosis. By the 90th day, levels measured in the plasma were still higher, but no longer significantly elevated, when compared with the control group. The present study is preliminary, but raises the possibility that measurement of oxygen free radicals in the plasma could be used as a laboratory test for active state of acute rheumatic fever. Further investigations will be needed, nonetheless, to determine the clinical application of this technique.

It is well known that, subsequent to cardiopulmonary bypass, and particularly in children, an inflammatory response within the body can often result in a characteristic syndrome. Recently, it has been suggested that this phenomenon is due to a systemic inflammatory response, with significant involvement of cytokines. With this in mind, we investigated the behavior of tumour necrosis factor-α and interleukin–6 during the operative and in the immediate postoperative period in a group of children submitted to open heart surgery. We investigated any possible relation between the levels of these cytokines in the serum and the length of cardiopulmonary bypass, with the serum levels of lactate, and with the extent of use of inotropic drugs in postoperative period. The cytokines were measured in samples withdrawn after induction of anesthesia, after 10 minutes of cardiopulmonary bypass, after re-establishment of circulation, and then 2 and 24 hours after the end of cardiopulmonary bypass. The levels of tumour necrosis factor-α and interleukin–6 increased between the beginning and at two hours of the end of cardiopulmonary bypass. There was no correlation between the levels of these cytokines in the serum and the length of cardiopulmonary bypass, although there was a positive relation between levels of interleukin–6 and lactate in samples withdrawn at two hours of the end of bypass, and the measured levels of the cytokines correlated with the extent of inotropic drugs employed in the postoperative period.

Objective: To evaluate the origin of transient episodes of sinus bradycardia, atrial escape rhythm, and atrioventricular nodal escape rhythm in preterm infants. Material and methods: The study was observational, and was carried out in a third level neonatal intensive care unit. We studied 19 spontaneously breathing infants born healthy but prior to term, the examinations being carried out between the ages of 3 and 28 days. The mean gestational age was 29.2 ± 1.9 weeks, and the mean birth weight was 1154 ± 264 g. Transient episodes of bradycardia were defined as a decline in heart rate equal to or greater than 25% from baseline, lasting for at least 3 successive RR-intervals. To discriminate between different types of escape mechanisms, we used the P wave and the P axis of the electrocardiogram. Sinus bradycardia was diagnosed when the P axis was from +0 to +90 degrees; atrial escape rhythm when it was from +91 to +359 degrees, and atrioventricular nodal escape rhythm when the P wave was absent, hidden, or followed the QRS complex. Results: The mean P axis was +50 ± 11 degrees. We observed 60 transient episodes of bradycardia in 11 of the 19 infants. Of these, 34 (57%) were classified as sinus bradycardia, and 13 (22%) as atrial escapes. Atrioventricular nodal escapes developed during 6 episodes (10%), while 7 episodes (11%) could not be classified. Conclusions: Atrial excitation as evidenced by the P axis during sinus rhythm is similar in very preterm infants to that seen in children and adults. Escape rhythms with different origins occur during transient episodes of bradycardia in healthy preterm infants. In at least one third, the episodes are due to atrial or atrioventricul ar nodal escape.

Balloon dilation of coarctation of the aorta has been found to be an effective modality for treatment. Recently, in the older child and adult, implantation of endovascular stents has been considered a clinical alternative to dilation alone. Little is known, however, of the effect of implantation of stents on aortic compliance. To investigate this impact of implantation, we studied 18 piglets, divided into experimental and control groups. At median weight of 14 kg, 2 pairs of ultrasonic crystals were implanted on the aortic wall. After 1 week, all animals underwent catheterization. In the experimental group, a 3 cm long balloon expandable stent was implanted in the descending thoracic aorta between the pairs of crystals. Measurements of arterial pressure and dimensions were performed before implantation and immediately thereafter, and at follow-up catheterization. The index of stiffness, β, and the the elastic modulus of aortic pressure-strain, were calculated as indexes of arterial compliance. The change in compliance during the period of study was not different between groups. At follow-up, no difference was observed between groups in the velocity of the aortic pulse wave, the augmentation index, or the maximum velocity of flow of blood. The stents remained patent and did not affect aortic growth or medial wall thickness. There was no difference between groups in levels of plasma renin activity and serum aldosterone. In this animal model studied over the short term, therefore, implantation of stents does not affect aortic compliance. Further studies are required to elucidate the long term effects of stents on the hemodynamics affecting the aortic wall and local flow dynamics.

Most patients with the Mustard procedure are now adults. To date, however, there have been few reports on resting and exercise hemodynamics in a large population of adults with this circulation. The aim of this study is to describe such parameters in one of the largest and oldest populations of adults with the Mustard procedure. The database of the University of Toronto Congenital Cardiac Centre for Adults was examined to identify 84 adults with the Mustard procedure who have undergone cardiopulmonary exercise tests. Magnetic resonance imaging and echocardiography studies were obtained in order to assess right ventricular size, function and baseline hemodynamics. Patients achieved lower maximum uptake of oxygen, maximal heart rate, forced vital capacity, forced expiratory volume in 1 second, and oxygen saturations at maximal exercise compared to a healthy population. Magnetic resonance imaging showed significantly different right ventricular ejection fractions between patients and controls. There were no effects of operative variables or preoperative hemodynamics on current exercise capacity. Patients after the Mustard procedure have subnormal exercise capacities. Factors such as chronotropic incompetence, peripheral deconditioning, and impaired lung function may be responsible for these results.

Objective: Using a newly acquired archive of previously prepared material, we sought to re-examine the origin of the pulmonary vein in the human heart, aiming to determine whether it originates from the systemic venous sinus (“sinus venosus”), or appears as a new structure draining to the left atrium. In addition, we examined the temporal sequence of incorporation of the initially solitary pulmonary vein to the stage at which four venous orifices opened to the left atrium. Methods: We studied 26 normal human embryos, ranging from 3.8 mm to 112 mm crown-rump length, and representing the period from the 12th Carnegie stage to 15 weeks of gestation. Results: The pulmonary vein canalised as a solitary vessel within the mediastinal tissues so as to connect the intraparenchymal pulmonary venous networks to the heart, using the regressing dorsal mesocardium as its portal of cardiac entry. The vein was always distinct from the tributaries of the embryonic systemic venous sinus. The orifice of the solitary vein became committed to the left atrium by growth of the vestibular spine. During development, a marked disparity was seen between the temporal and morphological patterns of incorporation of the left-sided and right-sided veins into the left atrium. The pattern of the primary bifurcation was asymmetrical, a much longer tributary being formed on the left than on the right. Contact between the atrial wall and the venous tributary on the left initially produced a shelf, which became effaced with incorporation of the two left-sided veins into the atrium. Conclusions: The initial process of formation of the human pulmonary vein is very similar to that seen in animal models. The walls of the initially solitary vein in humans become incorporated by a morphologically asymmetric process so that four pulmonary veins eventually drain independently into the left atrium. Failure of incorporation on the left side may provide the substrate for congenital division of the left atrium.

Infants with coarctation of the aorta may have obstructions at other sites within the left heart which are not always apparent on the initial echocardiogram. The magnitude of the risk of having the additional obstructions is not well described, with few reliable quantitative criterions for identifying patients at the highest risk. We determined the frequency of additional, late appearing, stenotic lesions within the left heart, and the predictive morphologic features on the initial cross-sectional echocardiogram.

We identified all patients with coarctation of the aorta diagnosed by 3 months of age, excluding those with complex cardiac disease or definite additional stenotic lesions at presentation, leaving 101 patients for study. At follow-up, 31 stenotic lesions were diagnosed in 23 patients, 15 of whom had at least 1 intervention. Mitral stenosis was diagnosed in 11 patients, aortic stenosis in 10, subaortic stenosis in 8, and supravalvar aortic stenosis in 2. The probability for freedom from obstructive lesions was 81% at 1 year, 74% at 3 years, and 70% at 5 years. Echocardiographic predictors of mitral stenosis included smaller mitral valvar annuluses, presence of a mean transmitral gradient between 2.5 and 5.0 mmHg, and elongation of the area of intervalvar fibrous continuity. Predictors of aortic stenosis were smaller mitral valvar annuluses, an initial aortic valvar gradient between 15 and 20 mmHg, and obliteration of the commissure between the right and non-coronary leaflets of the aortic valve. Predictors of subaortic stenosis were smaller mitral valvar annuluses and elongation of the area of intervalvar fibrous continuity. Patients with Z-scores for the diameter of the mitral valve of less than −1 were at the highest risk for manifesting obstructive lesions at any level.

Associated stenoses in the left heart are common in the setting of aortic coarctation. When Doppler data is equivocal, features of the cross-sectional echocardiogram can identify the sub-group of infants at increased risk.

Atrioventricular nodal reentrant tachycardia was proven during electrophysiologic study in 41 children, aged from 3.7 to 16 years, who were referred for catheter ablation of symptomatic supraventricular tachycardia. Using an abbreviated combined anatomical and electrogram-guided approach for selective ablation of the slow pathway, a steerable ablation catheter was placed at the inferior region of the vestibule of the tricuspid valve close to the orifice of the coronary sinus, with the intention of recording a multicomponent local atrial electrogramm during sinus rhythm. If application of radiofrequency current of 500 kHz at 70°C at this site did not result in a slowly accelerated junctional rhythm, at a rate of less than 120 beats per minute, the catheter was stepwise advanced up to a position midway towards the apex of the triangle of Koch for additional applications of energy. Ablation was achieved in 35 of the patients. In 6 patients, the slow pathway was modulated such that the tachycardia could no longer be induced. The number of applications of energy ranged from 1 to 19, with a median of 6 applications. The mean period of fluoroscopy was reduced to 15.6 (4.3 to 39.8) minutes, while the overall duration of the catheterization procedures ranged from 88 to 280 (mean 173.2) minutes. In none of the patients did we observe permanent high grade atrioventricular block. During follow-up over a mean of 4.1 years, two patients had recurrence of tachycardia, corresponding to a 95% rate of success in the midterm. We conclude that selective radiofrequency ablation of the slow pathway using the abbreviated anatomical and electrophysiological approach is a safe and curative therapeutic approach in children with atrioventricular nodal reentrant tachycardia. Periods required for fluoroscopy can be significantly reduced, and mid-term results are excellent.

The occurrence of supradiaphragmatic decompressing venous collateral channels following construction of a bidirectional cavopulmonary connection or completion of the Fontan operation resulting in abnormal systemic hypoxemia has been infrequently described. In addition, the incidence and predictors of these channels have not been well delineated, especially in those patients without formation of such structures preoperatively. I evaluated, retrospectively, 40 patients who had undergone either construction of a bidirectional cavopulmonary shunt or completion of the Fontan operation, and who had complete pre and postoperative hemodynamic and angiographic data. Of the patients, 17 (43%) had developed a total of 21 decompressing venous collateral channels, of which 7 (18%) were considered to be hemodynamically significant requiring transcatheter coil occlusion. Of all variables examined, seven patients with significant decompressing collaterals had a greater transpulmonary gradient at follow-up catheterization (8 + /− 2 vs 5 + /− 2 mmHg, p= .01) and lower systemic saturations at routine clinical follow-up visits (82 + /− 5 vs 89 + /− 5 mmHg, p= .007) in comparison to the 33 others. When not evident preoperatively, decompressing venous collateral channels develop in a significant number of patients following conversion to Fontan physiology. If sufficiently large, they may produce lower than expected systemic saturations for the observed cardiac physiology. The larger decompressing channels are more likely to occur when a greater transpulmonary gradient exists postoperatively, which may require cardiac catheterization and transcatheter coil occlusion.

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.

Children with innocent murmurs are often referred to a paediatric cardiologist for diagnosis. The most common murmurs of early childhood are the so-called Still's murmurs, followed by ejection murmurs across the pulmonary or aortic vessels, and the venous hum. There also exists a high coincidence of murmurs with the presence of tendinous structures traversing the cavity of the left ventricle. In this report, we describe 6 patients who presented to our outpatient clinic with cardiac murmurs. None of them had abnormalities on the clinical examination, electrocardiographic, or echocardiographic investigation. They presented a similar murmur that was also audible over the back. On closer examination of the aorta with cross-sectional echocardiography, we discovered echogenic, tendinous structures crossing the lumen of the descending aorta or the aortic arch. Whilst we are not yet able to prove that the cords produced the innocent murmurs, the association is highly suggestive.

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.

Background: Non-invasive measurement of left ventricular output has been shown to be a repeatable technique. Little is known about the repeatability using echocardiography in determining pulmonary arterial diameters or right ventricular output. Aims: To find the most repeatable point at which to measure pulmonary arterial diameter, and to compare the repeatability of determining right ventricular output with left ventricular output. Methods: We assessed the Intra-observer and inter-observer repeatability for measuring the diameter of the pulmonary trunk in 24 term and 26 preterm infants, respectively. Interobserver repeatability was assessed for the diameters of the pulmonary trunk and aorta, for stroke distance, and for left and right ventricular output. Results: The coefficients of variation for intra-observer repeatability were 4%, 7.5% and 9% respectively for measurements of the pulmonary valve, the pulmonary trunk, and the right ventricular outflow tract. There were significant differences between observers for measurement of the pulmonary trunk (p< 0.001) and right ventricular outflow tract (p= 0.011) but not for the pulmonary valve measured in either its long (p= 0.22) or short axis (p= 0.22). Significant differences between observers were also found for the pulmonary stroke distance measured in the long axis (p= 0.004) and aortic diameter at end-diastole (p< 0.001). The other parameters did not differ significantly and were used to calculate right and left ventricular output, respectively. Mean left ventricular output was 241 mls/kg/min, with mean differences between observers of 0.6 mls/kg/min (95% confidence interval (CI): −39.2 to 40.3 mls/kg/min). Mean right ventricular output was 255 mls/kg/min, with mean differences of 0.3 mls/kg/min (95% CI: −24.1 to 23.4 mls/kg/min). Conclusion: Measuring the diameter of the pulmonary trunk at the base of the valvar hinge points was most repeatable. Repeatability of right ventricular output was similar to that of left, with absolute values similar to those published by other workers.

Obstruction of the reconstructed aortic arch, or the neoaortic arch, is now known to be an important factor increasing mortality after the Norwood operation for hypoplastic left heart syndrome. Transcatheter balloon angioplasty has been shown to provide effective relief of both native aortic coarctation and obstructions of the aortic arch occurring subsequent to therapeutic intervention. We sought to determine the outcomes of balloon angioplasty used as an initial treatment for obstruction of the neoaortic arch occurring after the Norwood operation. We gathered the characteristics of 58 patients with such obstruction from 8 institutions, noting procedural factors and outcomes of initial balloon dilation. Obstruction occurred at a median interval of 4 months, with a range from 1.5 months to 6.3 years, after a Norwood operation. Ventricular dysfunction was present before dilation in 13 patients. Mean peak to peak systolic pressure gradients were acutely reduced from 31±20 mm Hg to 6±9 mmHg (p<0.001), with outcome subjectively judged to be successful in 89%- Three patients with pre-existing ventricular dysfunction died within 48 hours of dilation. There were 10 additional deaths during the period of followup, with Kaplan Meier estimates of survival after intervention of 87% at 1 month, 77% at 12 months, and 72% after 15 months. In addition, 9 patients required re-intervention during the period of follow-up, with Kaplan Meier estimates of freedom from re-intervention after dilation of 87% at 6 months, 78% at 12 months and 74% after 18 months. Although transcatheter dilation of neoaortic arch obstructions after Norwood operation is successful, there is a high risk of re-intervention and ongoing mortality in this subgroup of patients. Close follow-up is recommended.

Objective: To investigate our surgical results of intraventricular rerouting in patients having double outlet right ventricle with doubly-committed ventricular septal defect. Methods: We undertook repair in 8 patients with this particular feature. Of these, 2 patients had pulmonary stenosis, and another had interruption of the aortic arch. The subarterial defect was unequivocally related to both the aortic and the pulmonary orifices in all, albeit slightly deviated towards the aortic orifice in one, and towards the pulmonary orifice in another. Intraventricular rerouting was carried out via incisions to the right atrium and the pulmonary trunk. To ensure reconstruction of an unobstructed pulmonary pathway, a limited right ventriculotomy was made in 5. Results: All patients survived the procedure, and are currently doing well, with follow-up of 25 to 194 months, with a mean of 117 ± 68 months. Catheterization carried out 16 ± 6 months after repair demonstrated excellent ventricular parameters. Mean pulmonary arterial pressure was 16 ± 7 mmHg, being higher than 20 mmHg in 2 patients. No significant obstruction was found between the right ventricle and the pulmonary arteries. A pressure gradient across the left ventricular outflow tract became significant in one patient in whom a small outlet septum was present, and a heart-shaped baffle had been used for intraventricular rerouting. Reoperation was eventually needed in this patient for treatment of the obstruction, which proved to be progressive. Conclusion: Precise recognition of the morphologic features is of paramount importance when choosing the optimal options for biventricular repair in patients with double outlet right ventricle and doubly-committed interventricular communication.

Objective: Thyroid hormone has important effects on cardiovascular performance. This study was performed to evaluate the changes in levels of triiodothyronine following the first stage of reconstruction for hypoplastic left heart syndrome. Methods: We enrolled 14 newborns with hypoplastic left heart syndrome scheduled for first stage reconstruction. Blood samples were obtained pre-, intra-, and post-operatively. Levels of free and total triiodothyronine were determined by radioimmunoassay. Statistical comparison was performed using Wilcoxon's signed rank test. Results: The levels of free triiodothyronine decreased from a baseline of 355 ± 31 pg/dl to 205 ± 21 pg/dl upon the institution of bypass, and declined to a level of 135 ± 9 pg/dl at 24 hours postoperatively. Similarly, levels of total triiodothyronine decreased from 101 ± 15 ng/dl to 65 ± 4 ng/dl upon the institution of bypass, and continued to decline during the first 24 hours postoperatively. Levels of free and total triiodothyronine had returned to baseline by the fifth postoperative day. Conclusions: The data demonstrate significant decreases in levels of free and total triiodothyronine during the early postoperative period. These changes in levels of thyroid hormone may have adverse effects on cardiac function during this phase of recovery.

Infection with varicella zoster virus, leading to chicken pox in susceptible hosts, is usually a benign self-limiting disease conferring immunity in those affected. Cardiac complications are rare, but when present may lead to severe morbidity or mortality.

We have recently encountered three children, all of whom developed significant cardiac complications secondary to infection with varicella. Myocarditis has long been associated with such infection. The pathological mechanism is presumed similar to other cardiotropic viruses, where both direct cytopathic and secondary auto-immune effects contribute to myocardial cellular destruction and ventricular dysfunction. Complications include arrhythmias and progression to dilated cardiomyopathy.

Pericarditis, and secondary pericardial effusion, related to infection with the virus is most commonly associated with secondary bacterial infiltration. Both cardiac tamponade and chronic pericardial constriction may result.

Endocarditis complicating varicella has only been described in the last fifteen years, and is associated with the emergence of virulent strains of both streptococcus and staphylococcus, the two organisms most commonly associated with endocarditis. The exact mechanism by which varicella causes secondary bacterial endocarditis remains unclear.

Whilst cardiac complications of infection with the varicella zoster virus are rare, the resulting complications are potentially life threatening. Evidence of varicella-induced carditis must be aggressively pursued in any child with signs of acute cardiac decompensation in whom chicken pox is confirmed or suspected.

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.