Ventricular late potentials, and dispersion of the QT interval, are markers for risk of ventricular arrhythmias. Normal values for these parameters are well established in adults, but may not apply for children. This study has investigated the age dependency of signal averaged electrocardiographic parameters and QT dispersion in 111 normal children aged from 5 days to 16 years. The results indicate that parameters change with age: duration of filtered QRS and low amplitude (< 40 μV) terminal signal increase with age, especially in the younger patients. Filtered QRS is 88.9 ± 7.87 ms in infants, and increases to 108.7 ± 8.51 in teenagers (p<0.001). Low amplitude terminal signals are 17.0 ± 3.44 ms in infants, and 24.5 ± 5.64 ms in teenagers (p< 0.001). Root mean square of the last 40 ms decreases with age, but remains stable after the age of 10 years (122.4 ± 33.30 μV in infants, 60.9 ± 31.27 in teenagers,p<0.001). QT dispersion, on the other hand, does not change significantly with age. The mean value for the whole group is 36 ± 13.7 ms. A weak but significant correlation exists between QT dispersion and filtered QRS. Thus, age must be taken into consideration when interpreting signal-averaged electrocardiograms, but not when measuring QT dispersion.

The acute complications of therapeutic cardiac catheterization for congenital heart disease as performed currently in a small unit were reviewed. In recent years, there has been a significant increase in the number of lesions thought amenable to catheter therapy. Only a few reports, however, have addressed the overall incidence of acute complications of therapeutic cardiac catheterization, all representing the experience of centres performing moderate-to-large numbers of procedures. A retrospective review was performed of 425 therapeutic catheter procedures performed at our institution between May 1993 and November 1997. Acute complications were retrieved from the database. This included all adverse events that were clinically recognized at the time of or within 2 weeks after the procedure and which, to the best of the authors' clinical judgement, were related to the catheterization and not part of the natural history of the child's illness. All patients were observed overnight following the procedure, and stayed in hospital if a complication developed. There were 49 acute complications (11.5%), of which 43 (10.1%) were deemed minor and 6 (1.4%) were considered major. The rate was low in patients with valvar pulmonary stenosis, including three neonates (3/45, 6.7%), for those undergoing angioplasty of native co-arctation (1/15, 6.7%) and pulmonary arteries (2/21, 7.4%); and for coil embolization of systemic to pulmonary collateral arteries (1/16, 6.3%). The rate was high in patients with valvar aortic stenosis, including 12 neonates (9/37, 24.3%), and for angioplasty of re-coarctation (4/23, 21.7%). There were more overall complications in neonates (25.6%) than in older patients (10.1%) (p < 0.01). Two patients died (0.5%), but no patient required emergency surgical intervention. In spite of the introduction of many new therapeutic modalities with greater intrinsic risk, and the fact that patients with more complex lesions and who are more acutely ill are being treated, the overall rate of complications remains relatively low. This probably reflects improvements in pericatheterization medical management, in selection of patients, in procedural techniques, and in the experience of operators.

Fifteen patients requiring palliation for tetralogy of Fallot were treated by balloon dilation because of hypercyanotic spells. The mean age at dilation was 1.9 ± 0.7 years (range 0.5 – 3), and the mean weight 9.8 ± 2.1kg (range 6.0 –13.5). Dilation of the outflow tract was combined with dilation of the left and/or right pulmonary arteries in 5 patients. Successful dilation was achieved in 12 patients (80%), but failed in 3 patients with hypoplastic pulmonary arteries. In one patient, the stenosis of the right pulmonary artery could not be dilated because of a very sharp angle at the site of the stenosis. Two of the 3 patients in whom the procedure failed died of severe cyanotic spells within 24 hours of the unsuccessful procedure. No major complications occurred during or after the procedure in the cases undergoing successful dilation. The arterial oxygen saturation increased significantly, from 71 ± 5.7% to 89 ± 3.9%, immediately after the procedure (p < 0.005). During a period of follow up of 6 ± 3.7 months (range 1 – 13), the procedure was repeated on 3 occasions, and successfully accomplished in 2 of these. In conclusion, balloon dilation is a satisfactory palliative procedure for tetralogy of Fallot in those units in which total correction is not performed under 2 to 3 years of age.

The aim was to determine whether the clinical features of tachycardias originating from the right ventricular outflow tract in children with an apparently normal heart could predict the presence and the severity of the histopathological substrate. Thirteen children (median age 6 years; range 6 months–12 years) with tachycardia originating from the right ventricular outflow tract of apparently normal hearts, were assessed by echocardiography, heart catheterization with angiography, endomyocardial biopsy (13 patients) and magnetic resonance imaging (MRJ) (nine patients). Tachycardia was symptomatic in six and sustained in nine. Endomyocardial biopsy and MRI revealed acute myocarditis in five patients (38%), fatty infiltration of the right ventricle in two (15%), and minor histologic abnormalities in three (23%). Myocarditis was diagnosed in three of nine patients with sustained ventricular tachycardia, as opposed to two of four with non-sustained tachycardia (p = NS); in three of six symptomatic versus two of seven asymptomatic patients (p = NS); and in two of eight patients in whom ventricular tachycardia was induced during exercise testing as opposed to one of three in which it was not inducible (p = NS). A histopathological substrate was found in six of nine patients with sustained ventricular tachycardia, and in all four with non-sustained tachycardia (p = NS); in five of six patients with symptoms versus five of seven asymptomatic patients (p = NS); and in five of eight with inducible ventricular tachycardia during exercise testing versus all three in whom it was not inducible (p = NS). The mean rate of tachycardia was 184 ± 39 beats min−1 in patients with myocarditis, as opposed to 171 ± 48 in patients without myocarditis (p = NS); and 163 ± 33 in patients with a histopathological substrate compared with 210 ± 65 in patients without a histopathological substrate (p = NS). It is concluded that a histopathological substrate is present in the greater majority of children affected by the so-called right ventricular outflow tract tachycardia, but that the clinical features of the tachycardia do not predict the presence and the severity of this histopathological substrate.

Balloon valvoplasty was undertaken in 27 patients with tetralogy of Fallot for first-stage palli-ation. Indications were arterial saturation of oxygen <80%, hypoxic spells and duct-dependant pulmonary perfusion. The dilation was performed following diagnostic heart catheterization. Saturations improved from 75% ± 8.5 before valvoplasty to 85% ± 8.4 after the procedure, and worsened little to 83% ± 9.6 at follow-up after 3.4 months. The pulmonary valvar orifice was hypoplastic in most patients (Z = — 3.3 ± 1.2), and did not change after the procedure. The cross-sectional area of the pulmonary arteries was diminished initially, reflected by a Nakata index of 186 ± 95 mm2/rn2. After valvoplasty, we found widening of the vessels (Nakata index 225 ± 100 mm2/m2). At follow-up no further growth of the arteries was observed (Nakata index 209 ±109 mm2/m2). The procedure was complicated by hypoxic spells in three patients which were controlled by intravenous propranolol, and deep venous thrombosis in four patients. Our data demonstrate that balloon valvoplasty is feasible for initial palliation in patients with tetralogy of Fallot. It does not, however, produce growth of the pulmonary arteries or of the pulmonary valve.

To judge whether an Amplatzer™ Septal Occluder can be used as standard therapy instead of surgery for closure of atrial septal defects we report our experiences in 200 patients. Of these patients, 127 had an atrial septal defect with haemodynamically significant left-to-right shunt, 68 patients a persistent oval foramen after presumed paradoxical embolism, and 5 had a fenestration after Fontan-repair. Mean age was 29.8 years (0.8 to 77.7 years). Body weight ranged from 6.9 to 120.0 kg (mean 51.5 kg). After diagnostic cardiac catheterization, and balloon-sizing of the defect, we implanted Amplatzer™ Septal Occluders with stents of 4 to 28 mm diameter. Follow-up studies were obtained after 48hours, and one, six, and twelve months. Transcatheter closure of the atrial septal defect proved successful in all without any relevant residual shunts. In particular, complete closure was achieved in all patients after presumed paradoxical embolism. The mean period of follow-up is 9–5 months, with a range from 0.4 to 23.5 months, giving a total of 1898 patient months. The occlusion rate after three month was 98.1°. A trivial haemodynamically insignificant residual shunt remained in 1.9° of the patients. Fluoroscopy times ranged from 0 to 43.5 minutes, with a median of 8.7 minutes. The excellent results in the short and medium term in children and adults have resulted in using this device routinely at the present time for closure of central atrial septal defects up to a diameter of 28 mm. Final judgement, however, is only possible after long-term follow-up.

We postulated previously that variables related to pulmonary flow are independent predictors of levels of atrial natriuretic peptide in children with congenital heart disease. The aim of this study was to test this hypothesis in relation to other hemodynamic and clinical variables.

During catheterization we measured the levels of plasma N-terminal atrial natriuretic peptide prohormone in the plasma of 68 children with congenital heart disease. All had undergone complete clinical, echocardiographic and invasive hemodynamic investigations. The influence on the prohormone was analyzed for 10 different variables in a multiple linear regression model. The variability could be explained in large parts (adjusted R2 = 77.2%) by variations in atrial pressures or sizes, together with the degree of excessive pulmonary blood flow and signs of heart failure.

A value for atrial natriuretic peptide prohormone above 800 pmol/1 predicted hemodynamic imbalance (defined as elevated pressures in left or right atrium or the pulmonary arteries, and/or Qp/Qs > 1.5) with a specificity of 94%, a sensitivity of 73%, a positive likelihood ratio of 12.2, and a negative likelihood ratio of 0.29.

In conclusion, variables related to pulmonary blood flow are influential determinants of the levels of atrial natriureic peptide in children with congenital heart disease. Atrial pressures, and symptoms of heart failure are also of major importance.

The objective was to describe the epidemiologic, clinical, bacteriologic and therapeutic features of seven infants who developed sternal wound and mediastinal infections following palliation and/or repair procedures for congenital heart disease. A retrospective chart review was used. All infants with sternal wound and mediastinal infections were < 30 days of age at the initial operative procedure. Six of the infants had hypoplastic left heart syndrome, and one had complete transposition. Two infants required delayed closure of their chest wound. Three infants had superficial sternal infections and presented at a mean of 12 days postoperatively. Four infants had infection of the deep mediastinal structures: they were all asymptomatic and had purulent collections in their mediastinum at their second palliative operation, which was performed at a mean of 120 days after the initial surgery. Staphylococcus aureus, or coagulase-negative Staphylococcus, was isolated from the wound and/or blood of six infants. All infants with mediastinal infections were managed with operative debridement. Infants with superficial infections underwent local debridement. All infants received long-term intravenous antibiotics. Mediastinal infections in infants undergoing palliative staged procedures for congenital heart lesions may be chronic and indolent, resulting in delayed repair of congenital heart lesions.

Balloon dilation of the pulmonary valve was performed in 54 patients with tetralogy of Fallot with severe cyanosis, high haematocrit and severe valvar pulmonary stenosis. Clinical, echocardiographic, angiographic, and haemodynamic data were analyzed before and after the procedure. After balloon dilation, the systemic oxygen saturation increased from a mean value of 66% to 85<%. The mean value of the haematocrit before dilation was 55 + 13, and decreased to 47 after dilation (p < 0.002) in 2 months follow-up. Balloon dilation increased the size of the pulmonary valvar orifice from a mean value of 9 + 5mm to 11.5 + 2mm (p < 0.005). The mean Z score of the pulmonary valves, which was -3 + 1.3 before dilation, increased to -1.1 + 1.1 immediately after the procedure (p < 0.05).

The size of the right and left pulmonary arteries increased after dilation from 9mm to 10 mm, and from 8.7 + 2.4mm to 9.8 + 2.3mm, respectively (p <0.05). The comparable mean Z scores increased from -2.8 + 1.9 SD to -1.8 + 1.4 SD, and from -2.4 + 1.9 SD to -1.5 + 1.6 SD for the right and left branches, respectively (p < 0.05).

In patients with stenosis at the bifurcation of the pulmonary trunk and hypoplasia of the left artery, successful dilation of the pulmonary valve lead to an increase of flow and improvement in size of the hypoplas-tic segment.

In conclusion, initial balloon dilation of the pulmonary valve in tetralogy of Fallot resulted in increase of the Z score for the pulmonary valve and improved antegrade pulmonary blood flow, inducing growth of the pulmonary arteries and ameliorating the anatomic and physiologic preoperative condition.

Examined was the effect of surgical technique, particularly the insertion of a transannular patch, on right ventricular diastolic function, and the relationship of forward flow in the pulmonary arteries during late diastole to right ventricular diastolic function in patients with tetralogy of Fallot. Transtricuspid, superior caval venous and pulmonary arterial Doppler spectrals were obtained and compared between 44 patients who had been repaired with a transannular patch; 14 patients who had been repaired with muscular resection and/or pulmonary valvotomy; six who had been repaired with an infundubular patch; and 32 normal children. The velocities of forward flow during late diastole in the pulmonary arteries of normal children ranged from 19.8 to 29.4 cm s−1 (mean 24.9 ± 2.8 cm s−1) throughout the respiratory cycle. Restrictive right ventricular physiology, defined on the basis of increased forward flow in the pulmonary arteries during late diastole (> 30 cm s−1) was present in 25 (57°) of 44 patients with tetralogy of Fallot repaired using a transannular patch. Right ventricular volume was 50.1 ± 23.7 cm3 in patients with a restrictive right ventricle and 64.9 ± 21.4 cm3 in patients in whom the ventricle was non-restrictive (p < 0.03). QRS duration was 140 ± 18 and 156 ± 24 ms in patients with restrictive and non-restrictive right ventricular physiology respectively (p < 0.003). Restrictive physiology was not encountered in patients with tetralogy in whom the pulmonary valve had been preserved. It is concluded that right ventricular restriction is present in many patients with tetralogy of Fallot at mid-term follow-up subsequent to repair using a ‘transannular’ patch. Restriction is associated with smaller right ventricular size and less prolongation of the QRS complex.