Experience with an ambulatory 12-lead Holter recording system for evaluation of pediatric dysrhythmias.

BACKGROUND: The 12-lead electrocardiogram demonstrates noninvasively many details concerning cardiac arrhythmias and their mechanism, but only for a limited period. A Holter system can record heart rhythm for a longer period, but shows 2 or 3 leads only. An ambulatory 12-lead Holter recording system combines the advantages of both. We report on our experience with the 12-lead Holter system in children. STUDY POPULATION: Twenty-four patients (age range, 3-22 years) underwent one or more 12-lead Holter recordings. Twelve patients had suspected or documented tachyarrhythmia, and 12 patients had suspected or proven long QT syndrome (LQTS). RESULTS: In the tachyarrhythmia group, 4 patients had supraventricular tachycardia and 7 ventricular tachycardia (VT). In the supraventricular tachycardia, group 1 patient had intra-atrial reentrant tachycardia with a single reentrant circuit, whereas another had multiple P-wave morphologies, suggesting multiple circuits. Two others had evidence for concealed atrioventricular accessory pathways. One patient had isolated supraventricular ectopy. In the VT group, 4 patients had uniform VT, and 3 patients had polymorphic VT. One patient with LQTS had macroscopic T-wave alternans. Two others showed intermittent extreme QT prolongation and T-wave notching during 12-lead Holter recording. THERAPEUTIC IMPLICATIONS: Patients with uniform VT underwent catheter ablation, guided in 2 instances by intracardiac pace mapping and comparison with the 12-lead Holter QRS morphology. All reentrant supraventricular arrhythmias with single P-wave morphology were ablated. One patient with intra-atrial reentrant tachycardia and multiple circuits received an antitachycardia pacemaker. In the LQTS group, the neonate with T-wave alternans received mexiletine in addition to beta-blocker therapy. CONCLUSION: In individual patients, the 12-lead Holter system provides important additional information about the arrhythmia and helps to plan appropriate therapy. Intermittent T-wave morphology changes can be diagnosed using 12-lead Holter recordings in patients with LQTS, allowing dynamic T-wave changes to be monitored. In specific cases, this may help identify patients with LQTS and also influence pharmacological therapy.

Paradoxical increase of pulmonary vascular resistance during testing of inhaled iloprost.

The case of a 14 month old girl with primary pulmonary hypertension treated with domiciliary oxygen is described. After invasive evaluation and testing of nitric oxide with very good response, the testing was repeated to study the effect of inhaled iloprost on pulmonary vascular resistance (PVR). An unexpected and severe increase of PVR was observed, rising from 392 dynes x s x cm(-5) with oxygen to a maximum of 1192 dynes x s x cm(-5) with oxygen and iloprost. Underlying ventilatory and technical problems were excluded. While inhaled iloprost has been described to be highly effective in the treatment of primary pulmonary hypertension, the possibility of contrary "paradoxical" reactions in isolated patients is emphasised, with a dramatic increase of PVR and a possible adverse outcome.

Myocardial protection by pressure- and volume-controlled continuous hypothermic coronary perfusion in combination with Esmolol and nitroglycerine for correction of congenital heart defects in pediatric risk patients.

OBJECTIVE: This study assesses the technical applicability and the clinical value of the continuous coronary perfusion with oxygenated blood as a method for myocardial protection used for congenital heart surgery in pediatric risk patients. METHODS: Thirty non-consecutive pediatric risk patients aged from 1 month to 16 years (mean 3.9 years; 11/30 patients aged <6 months) underwent open heart procedures on the beating heart for simple and complex cardiac malformations using a self designed perfusion system with pressure- and volume-controlled continuous hypothermic coronary perfusion (PVC-CONTHY-CAP) in combination with ultra-short beta1-receptor blockade (Esmolol) and nitroglycerine for myocardial protection. The following procedures were done: VSD patch closure (n = 6), repair of total a-v canal with 'double patch' (n = 4), total repair of tetralogy of Fallot (n = 7), correction of truncus arteriosus communis type IV (n = 1), mitral valve reconstruction (n = 4), total cavo-pulmonary connection (n = 4), and Rastelli procedure (n = 4). RESULTS: The mean cardio-pulmonary bypass time was 131.5 min (range: 44-245 min), the mean coronary perfusion time: 90.1 min (range: 13-202 min). The weaning off extracorporeal circulation was uneventful in all patients, in 21 patients with low-dose and in nine patients with moderate catecholamine support: the mean weaning time was 25 min (range: 7 58 min). The post-operative mean peak creatine kinase (CK-MB) value was 58 U/l, (range: 14-202 U/l). The mean ICU stay in the cardiac surgery unit was 2.9 days, (range: 1-10 days). The mean post-operative mechanical ventilatory support was 2 days (range: 6 h-9 days). Six patients developed thrombocytopenia with values <40 tsd/microl, four patients renal dysfunction, two patients ascites, five patients heart rhythm disturbances, one patient neurological deficits. In three patients (VSD closure: n = 2; age: 1 and 2 months; total a-v-canal: n = 1; age: 3 months) re-do procedures for significant intraventricular shunt had to be done, in one patient implantation of a permanent pacemaker system was necessary. One patient died due to multiple organ failure after uneventful surgery (total cavo-pulmonary connection for single ventricle). CONCLUSIONS: PVC-CONTHY-CAP can be successfully used for repair of simple and complex congenital cardiac malformations. However, in children less than 3 months of age, the transatrial repair of intraventricular defects is technically much more demanding and challenging than under conventional cardioplegic arrest and is possibly accompanied by an increased incidence of residual or recurring intraventricular shunts.

Pulmonary artery growth after systemic-to-pulmonary shunt in children with a univentricular heart and a hypoplastic pulmonary artery bed. Implications for Fontan surgery.

The aim of the study was to investigate the developmental pattern of hypoplastic pulmonary artery (p.a.) bed augmented by systemic-to-pulmonary shunt in children with univentricular heart scheduled for Fontan surgery. For the study, a highly selected patient cohort was chosen (12 patients aged between 5 and 19 years; mean 9.5 years) with comparable initial morphological conditions of univentricular heart and hypoplastic p.a. bed, who after mandatory systemic-to-pulmonary shunt underwent Fontan procedure at time of normalization of pulmonary artery size. Further selection criteria were: normal pulmonary vascular resistance at time of Fontan procedure, competent a-v valve(s), and globally unimpaired ventricular function. All patients were grouped according to the preoperative pulmonary flow index (Qpi; L/min/m2 b.s.a.) measured immediately before Fontan operation: Group A: 1.5-2.5; B: 3.0-4.0; C: 4.0-5.0; D: > 6.0, and their cardio-pulmonary hemodynamic situation (Hb, SAsat%, Qp/Qs, PAP, Rp/Rs, EDVP, FS%, ventricular diastolic compliance (VC = EDVP/Qpi + Qsi) as well as the pulmonary artery size and area using standard (Nakata-index, McGoon-ratio) and a self designed computer assisted planimetric area calculation (PPAAI; cm2/m2 b.s.a.) analysed. Each patient underwent 1-3 shunt procedures, the mean shunt patency period for groups A, B, C and D was 12, 8.6, 5.3, and 4.5 years, respectively. The mean Nakata-index (283, 297, 324, 405 in groups A-D) and the McGoon-ratio (2.0, 2.2, 2.8, 3.3 in groups A-D) correlated with the Qp index, reflecting flow dependent development of pulmonary artery bed. No correlation was found between Qpi and PPAAI (47, 40, 41 and 47 in group A-D). The VC/Qp relation showed an inversely proportional pattern with values 2.3, 1.0, 0.8, 0.7 for corresponding groups A-D, the lowest VC in group A correlated with polyglobulic status (Hb- values; g/dl): 21.3 in A vs 19.8, 18.0 and 16.5 in B-D) and mean arterial SAsat-values (77% in A vs 83%, 84% and 89% in B-D). In conclusion, in our highly selected patient cohort, the development of p.a. size was strongly flow-dependent, and patients with restrictive pulmonary flow needed an approximately threefold longer time period to normalize their p.a. size compared to those with excessive flow. In patients with restrictive pulmonary flow, the Nakata-index underestimated the degree of development of the pulmonary artery system, probably due to the distortion of the proximal p.a. segment. In consequence, in these patients the normalization of the p.a. bed and thus suitability for the Fontan procedure probably occurred much earlier. Based on our observations and those of others, in patients with excessive flow the normalization of p.a. bed, provided it occurs within 3-4 years, seems not necessarily to be associated with a deterioration of ventricular function.

Open heart interventions in premature low- and very-low-birth-weight neonates: risk profile and ethical considerations.

In premature, very-low-birth-weight (VLBW) neonates, complex cardiac malformations can be successfully repaired under conditions of cardiopulmonary bypass. However, due to the immaturity of organ systems, these patients are exposed to a specific risk resulting from noxious effects of extracorporeal circulation, especially on the central nervous system. Two premature neonates with low and very low birth weight of 1160 g and 1650 g, were operated on using cardiopulmonary bypass for severe pulmonary artery stenosis and truncus arteriosus communis type II, respectively. The neonate with pulmonary valve stenosis survived, but at 2-year-follow-up examination motoricity retardation as a result of cerebral immaturity-related changes was evident. The other neonate died suddenly on the fifth postoperative day of a massive intracranial haemorrhage. Due to the fact that the natural history of VLBW children is a priori characterized by a high incidence of major neurological handicaps, open heart surgery may by improving survival chances contribute to an increased incidence of mentally handicapped children.

Left-side pulmonary vein obstruction after arterial switch operation in infants with D-transposition of the great arteries.

We describe two cases of left-side pulmonary vein obstruction observed after the arterial switch operation (Jatene) for D-transposition of the great arteries. This appears to be related to left-sided pulmonary vein obstruction occurring coincidently with D-transposition of the great arteries, rather than a consequence of arterial switch operation.

Spiral CT angiography in an infant with severe hypoplasia of a long segment of the descending aorta.

CT angiography, or the spiral CT technique, is a promising minimally invasive method of visualising the arterial vascular system and can be applied in children in whom ultrasound, MRI and/or angiography or cardiac catheterisation cannot be performed, or where an exact diagnosis cannot be made. CT angiography should be considered in special cases as a diagnostic alternative to MRI, ultrasound and angiography. As an example of the possibilities of CT angiography, a case is described in which hypoplasia of the descending aorta was diagnosed and a postoperatively encountered perigraft reaction was demonstrated. Perforation of the blood vessel could be excluded by CT angiography.

Down syndrome as a factor influencing hemodynamic response to pulmonary artery banding.

The hemodynamic response to pulmonary artery banding (PAB) in relation to the preoperative pulmonary/systemic vascular resistance (Rp/Rs) ratio and to the timing of surgery, with special regard to Down syndrome, was investigated in 56 nonconsecutive pediatric patients aged 3 days to 6 months (mean 2.5 months) with simple and complex congenital shunt-related cardiac malformations. Among the non-Down patient group (39 patients; mean age 6.9 weeks) there was a good hemodynamic response in all but three cases, irrespective of the preoperative Rp/Rs ratio; these three poor responders had preoperatively normal or nearly normal Rp/Rs ratios (Rp/Rs < 0.3) and were affected postoperatively by lung complications. In the Down patient group (17 patients; mean age 8.2 weeks) the mean preoperative as well as the mean postoperative Rp/Rs ratio was higher than in the non-Down patient group (preoperative Rp/Rs 0.49 versus 0.32; postoperative Rp/Rs 0.31 versus 0.18). There was a good hemodynamic response in all five patients with Down syndrome who had preoperative normal or nearly normal pulmonary vascular resistance ratios (Rp/Rs < 0.3). Among 12 patients with Down syndrome and preoperative increased resistance ratios (Rp/Rs > 0.3) PAB did not cause a reduction in pulmonary vascular resistance (PVR) in five patients (postoperative Rp/Rs 0.49-1.00), all operated on at more than 6 weeks of age. PAB resulted in effective reduction of postoperative Rp/Rs ratios (range 0.10-0.27) in seven patients, six of them younger and one older than 6 weeks at the time of the banding procedure. In conclusion, patients with Down syndrome and shunt-related cardiac malformations (predominantly total atrioventricular canal cases) in general have higher pre- and postoperative Rp/Rs ratios than non-Down children and also have a higher potential for developing pulmonary vascular obstructive disease despite hemodynamically effective PAB. Especially in children with Down syndrome and pathologically high resistance ratios, PAB, if indicated, should be performed as early as possible.

Efficacy of pulmonary artery banding in the prevention of pulmonary vascular obstructive disease.

In 57 nonconsecutive pediatric patients (mean age: 2.6 months) with shunt-related pulmonary hypertension, the efficacy of pulmonary artery banding (PAB) was analysed retrospectively with special reference to the development of pulmonary vascular obstructive disease (PVOD). The patients were grouped in accordance to morphology, hemodynamics and incidence of PVOD. Efficacy of PAB was assessed by pulmonary to systemic pressure, flow and resistance ratios obtained by heart catheterization performed pre- and postoperatively. PAB was very effective in 49 out of 57 patients (= 85.9%), in 8 cases a progression or possible progression of PVOD must be suggested. Only Down syndrome can be considered as a predisposing factor for the development of PVOD. Based on our results we conclude that PAB is a high effective procedure in the prevention of PVOD; however, despite the surgical effectiveness of PAB, PVOD can occur. Strict post-PAB examination of pulmonary flow and resistance parameters is recommended and the definite surgical repair should be performed as early as possible.

[Silent persistent ductus arteriosus]. / Der stumme persistierende Ductus arteriosus.

We report on 14 observations undertaken by ourselves of silent persistent ductus arteriosus (SPDA). During a three year period with the routine use of color doppler flow evaluation we found cases of SPDA in 14 children. A very little ductus arteriosus is already known to us through earlier heart catheter examinations which were undertaken because of other isolated heart defects (16 cases in 345 isolated heart defects over 10 years). We also consider the fact that SPDA is not an infrequent result after the occlusion of a patent ductus arteriosus with the Rashkind-Occluder-System and after operative ligatures of patent ductus arteriosus. Finally, we compare our results concerning the frequency of SPDA with current literature and discuss consequential therapies.

[Magnetic resonance tomography in pediatric cardiology]. / Die magnetische Resonanztomographie in der pädiatrischen Kardiologie.

Magnetic resonance imaging (MR) is a relatively new non-invasive imaging method that has not been used as a routine procedure in pediatric cardiology. To evaluate MR in pediatric cardiology we performed 110 examinations in 91 children during the period from December, 1984, to November, 1987. The children were divided into the following groups: 1) Diseases of the great vessels (54 examinations in 39 children); 2) Cardiac diseases (42 examinations in 39 children); 3) Diseases of the pericardium (four examinations in three children); 4) Ten children without cardiovascular diseases (imaging of the heart in conjunction with examination of other organs). The ages of the children ranged from five weeks to 19 years in the following distribution: 13% infants, 20% children 2-5 years, 30% children 6-14 years, 37% adolescents from 15 to 19 years. On the basis of our experiences we conclude that MR can be used as an additional diagnostic tool in pediatric cardiology, especially for imaging of areas that are not well visualized by echocardiography, i.e., the great vessels and their branches and in addition, the right ventricle, in older children.

[Noninvasive determination of oxygen saturation using pulse oximetry in pediatric cardiology]. / Die nicht-invasive Bestimmung der Sauerstoffsättigung mittels Pulsoxymetrie in der pädiatrischen Kardiologie.

Pulse oximetry is a relatively new noninvasive method to measure arterial oxygen saturation (SO2). We evaluated the reliability of a pulse oximeter (N-100, Nellcor/Drger, Lübeck) in single and continuous measurements of SO2. During cardiac catheterisation we compared pulse oximeter (puls.SO2) measurements to those in simultaneously taken arterial samples (art.SO2), and obtained 203 pair measurements in 85 patients, mostly newborns and infants; in 20 of them before and during the breathing of oxygen through a mask. We also have 67 pair measurements of capillary blood samples (kap.SO2) and puls.SO2. Continuous measurements with the pulse oximeter were carried out in 17 patients for up to 116 h. Our main results are: 1. In the puls.SO2 range of 66% to 100% the measurements with the pulse oximeter were accurate (r = 0.97, Syx = 2.1). Below 66% the puls.SO2 values were on average much higher than the art.SO2 values, with an increased variance. Intraindividual oxygenation changes before and during the breathing of oxygen were accurately measured. 2. Pulse oximetry is much more informative than kap.SO2 measurements, because its information about the SO2 before blood sampling (= resting value) and following SO2 changes during the painful procedure (= stress values). 3. Continuous measurements with the pulse oximeter are very simple and very reliable and are not associated with skin injury. Because the pulse oximeters responses rapid to oxygenation changes and does not need calibration it is very valuable in the assessment of therapeutic procedures in patients with cyanotic heart disease. We conclude that the pulse oximeter is a very important new diagnostic tool in pediatric cardiology.

[Diagnosis and treatment of cardiac rhabdomyomas]. / Diagnostik und Behandlung der kardialen Rhabdomyome.

A diagnosis of primary cardiac tumors was achieved by two-dimensional echocardiography in 3 patients. Two of them were female neonates, born of the 29th and 40th gestational week who had shown intrauterine arrhythmias. Subsequently, we were able to diagnose tuberous sclerosis in both. The third child, a 121/2 year old boy, with already diagnosed tuberous sclerosis, presented an electrocardiographical preexcitation syndrome. Because of the multiplicity of the tumors and the association with tuberous sclerosis we presumed that the tumors were rhabdomyomas. As it is known that rhabdomyomas show no, or only a minimal postnatal growth, we decided neither to perform a heart catheterization nor to treat them surgically unless the children show hemodynamical deterioration, although the tumors were huge in both neonates. The subsequent 14 months showed a clear regression in the size of the tumors. One of the neonates was successfully treated with amiodarone because of ventricular tachycardia. The second neonate didn't require any treatment. We conclude that: Surgical management is only necessary in patients presenting with cardiac insufficiency and/or arrhythmias that are resistant to conventional medical treatment. Primary cardiac tumors should be looked for in patients presenting with arrhythmias, even when occurring already during intrauterine life. Diagnostic measures in order to diagnose tuberous sclerosis in patients with cardiac tumors are necessary and vice versa.

[Diastolic micropotentials in high-resolution surface ECG in QT syndrome]. / Diastolische Mikropotentiale im hochverstärkten Oberflächen-EKG bei QT-Syndrom.

Patients suffering from long QT syndrome are threatened by torsade de pointes tachycardias and sudden arrhythmic cardiac death. An inhomogenic sympathetic innervation of the heart with dominance of the left cervicothoracic sympathetic nerves has been considered to be a major cause of life threatening cardiac arrhythmias. This study presents the electrocardiographic and electrophysiologic results of 7 patients with long QT syndrome. In agreement with data published earlier our results of Holter monitoring, exercise testing and programmed electrical right ventricular stimulation were of no diagnostic or prognostic significance in predicting syncopal attacks or sudden arrhythmic cardiac death. Thus, the high resolution ECG methods played an important role in this study. During noninvasive recordings of signal averaged ECGs and high resolution surface ECGs with beat to beat registration, diastolic microvolt potentials could be detected in 6/7 patients within the ST segment and in 5/7 patients after the T wave. Our results evidently show that the signal averaged ECG and the high resolution surface ECG could be of diagnostic significance in patients with long QT syndrome.

[Cortical hyperostoses after long-term prostaglandin E2 therapy]. / Kortikale Hyperostosen unter längerfristiger Prostaglandin E2-Therapie.

Cortical hyperostoses are found to be side effects after therapy in early infancy with prostaglandin E1 and E2. Correlation seems to exist between dosage and duration of therapy. Radiologically the lesions cannot be differentiated from Caffey's disease. Pathogenetic relationship of the two diseases is discussed; 62 cases of newborn children with ductal related vitium cordis, who were treated for a short time or for longer with prostaglandin E2 are demonstrated.

Nutritive and non-nutritive blood flow in canine skeletal muscle after partial microembolization.

Partial microembolization of the previously dilated gastrocnemius muscle of the dog was performed by intra-arterial injection of latex microspheres (max. diameter 50 mum). No particles larger than 10 mum were recovered from the venous blood. Blood to tissue clearance of 4-amino-antipyrine was found to decrease after microembolization, and capillary transport coefficients were disproportionately lowered in comparison with the observed decrease of total blood flow. Venous oxygen saturation increased despite decreasing total blood flow in the working muscle after microembolization. The data indicate a shift of blood flow from nutritive to functionally non-nutritive channels.

Method for simultaneous determination of red cell and plasma flow velocity in vitro and in vivo.

A method is described which can be used to simultaneously determine the flow velocity of plasma and of red blood cells in small glass tubes in vitro or in living microvessels of the microcirculation. The principle of dual slit photometry is applied to the measurement of plasma flow by determining the passage time of a dye bolus across two photodetectors separated by a variable distance. Measurements performed both in vitro and in vivo indicate a significant difference (up to 85%) between cellular and plasmatic flow velocity.