Comparison of mid-term clinical experience with steroid-eluting active and passive fixation ventricular electrodes in children

Although active fixation ventricular leads seem to have advantages over passive fixation leads, this study compares the follow-up results of active and passive fixation leads in children. We evaluated the implantation and follow-up data of 41 children with active (Accufix II DEC, group 1) (n = 20) or passive (Membrane E, group 2) (n = 21) fixation, steroid-eluting ventricular leads. All but one of the patients in group 1 completed the 12-month follow-up. The mean follow-up period in group 2 was 10.4 +/- 2.9 months (range 3-12 months, median 12 months). In both groups the mean pacing threshold was measured as 0.51 +/- 0.09 V versus 0.48 +/- 0.15 V (P > 0.05) at 0.5-ms pulse width, mean R wave amplitude as 9.9 +/- 2.5 mV versus 9.4 +/- 3.2 mV (P > 0.05), and mean impedance as 557 +/- 92 omega versus 664 +/- 160 omega (P < 0.05), respectively, at implantation. After the first week of pacing, mean threshold values in group 1 were significantly lower than those of group 2 (P < 0.01 and P < 0.05, respectively). During the follow-up period, lead impedance measurements did not show a significant difference between the two groups. In one patient from group 1, the lead (by unscrewing) was removed easily because of pacemaker pocket infection. No lead dislodgement or helix deformation occurred in group 1. Nevertheless, in one patient from group 2, the lead was extracted at 4-month postimplantation because of lead displacement. We conclude that the steroid-eluting active fixation lead (Accufix II DEC) have advantages of easier implantation and lower acute and chronic stimulation thresholds compared to the passive fixation lead (Membrane E). Therefore, Accufix II DEC is superior to Membrane E, and it is a better first choice in children with an implanted single chamber ventricular pacemaker.

Evaluation by exercise testing of children with mild and moderate valvular aortic stenosis

BACKGROUND

The aim of the present paper was to determine the factors related to sudden death in aortic stenosis.

METHODS

The factors related to sudden death were investigated in 40 asymptomatic children with mild and moderate aortic stenosis by treadmill testing.

RESULTS

The QT interval of aortic stenosis cases were significantly longer than those of healthy children with increasing heart rates during exercise.

CONCLUSIONS

A longer QT interval of aortic stenosis cases compared to normal children during exercise is the first sign of myocardial ischemia and leads to fatal ventricular arrhythmias and sudden death. For this reason we recommend that exercise testing should be performed frequently in aortic stenosis patients and that close follow up is necessary for patients with long QT segments that can be a marker for severe arrhythmias.

Torsade de pointes associated with encephalitis

Torsade de pointes is a polymorphic ventricular tachycardia. Causes of torsade de pointes are well described. Although intracranial disease can produce dramatic electrocardiographic (ECG) changes, we are not aware of previous cases with torsade de pointes and encephalitis. We report a case with encephalitis who developed torsade de pointes, and was treated with temporary ventricular pacing and magnesium infusion.

Effectiveness and safety of intravenous amiodarone in drug-resistant tachyarrhythmias of children

BACKGROUND

Experience with pediatric use of intravenous amiodarone is limited. In this study, our experiences with intravenous amiodarone in children with acute life-threatening or chronic tachyarrhythmias are reviewed.

METHODS AND RESULTS

Twelve patients, with a mean age of 3.4 +/- 3.1 years, range 9 months-10 years (two with incessant ventricular tachycardia, one with ectopic atrial tachycardia, two with atrioventricular re-entrant tachycardia (three episodes), four with postoperative or congenital junctional ectopic tachycardia, two with bradycardia-tachycardia syndrome, one with atrial tachycardia) were treated with intravenous amiodarone during 13 tachycardia episodes. Left ventricular systolic functions were depressed in six patients. In 11 patients, a median of two drugs (range one-four), including adenosine infusion and in five cases direct current cardioversion were tried without success prior to intravenous amiodarone. The loading dose of amiodarone was 5 mg/kg in all episodes, infused over 1 h. Maintenance infusion was required in 12 episodes. In 10 episodes (77%), amiodarone was considered effective, in one (7.6%) partially effective (junctional ectopic tachycardia) and in two (15.4%) ineffective (sick sinus syndrome, atrial tachycardia). Therapeutic effect was obtained in a median period of 30 h (range 1-103 h). The mean effective maintenance dose was 10 +/- 4.7 micrograms/kg per min (range 5-15 micrograms/kg per min). In one patient, mild hypotension, and in three patients cellulitis occurred, but none of them necessitated termination of treatment.

CONCLUSIONS

Intravenous amiodarone is found to be an effective and safe antiarrhythmic agent for children with acute life-threatening and chronic tachyarrhythmias and depressed left ventricular systolic functions.

Replacement of aortic root with valved tubular prosthesis in a ten-year-old child with infective endocarditis--a case report

Aortic root abscess, aneurysm of sinus Valsalva, severe aortic valve insufficiency, and a fragile aortic wall caused by infective endocarditis were found in a 10-year-old child. Aortic valve replacement was intended as a preoperative strategy, but one of modifications of Cabrol had to be used urgently because of aortic root rupture between right atrial and aortic connection just after pericardiotomy.

Comparison of normal sinus rhythm and pacing rate in children with minute ventilation single chamber rate adaptive permanent pacemakers

Rate adaptive pacemakers are used to achieve a better cardiac performance during exercise by increasing the heart rate and cardiac output. The ideal rate adaptive sensor should be able to mimic sinus node modulation under various degrees of exercise and other metabolic needs. Minute ventilation sensing has proven to be one of the most accurate sensor systems. In this study, alterations in sinus rhythm and pacing rates during daily life conditions in 11 children (median age 11 years, range 6-14 years) with minute ventilation single chamber pacemakers were investigated. Correlation of sinus rhythm with pacing rates was assessed. ECG records were obtained from 24-hour Holter monitoring. Average rates of five consecutive P waves and pace waves were determined every half hour. The average of the two values was then used to determine hourly rates. Correlation coefficients between the sinus rhythm and pacing rates were calculated. In nine patients, pacing rates correlated well to sinus rhythm (range 0.6793-0.9558, P < 0.001 and P < 0.05), whereas in two cases correlation was not sufficient (P > 0.05). Most of the patients, in whom rate response factor (RRF) measurements during peak exercise by treadmill with chronotropic assessment exercise protocol were performed and pacemakers were programmed to these parameters, had more appropriate ventricular rates compared to spontaneous sinus rates. In these patients mean RRF value was 15.3 +/- 2.7 (range 12-20, median 15). This study shows that during daily activities minute ventilation rate adaptive pacemakers can achieve pacing rates well correlated to sinus rhythm that reflects the physiological heart rate in children.

Bruce treadmill test in healthy Turkish children: endurance time, heart rate, blood pressure and electrocardiographic changes

Heart rate, systolic and diastolic blood pressure and electrocardiographic changes were studied in 80 healthy children during treadmill exercise with Bruce protocol. Mean duration of exercise in boys increased from 10.01 +/- 1.61 minutes at age four to six years with a mean body surface area of 0.75 +/- 0.06 m2, to 17.86 +/- 2.66 minutes at age 13 to 15 years with a mean body surface area of 1.48 +/- 0.10 m2. Mean endurance time in girls increased from 11.06 +/- 1.92 minutes at age four to six years with a mean body surface area of 0.76 +/- 0.08 m2, to 15.69 +/- 2.23 minutes at age 13 to 15 years with a mean body surface area of 1.41 +/- 0.07 m2. Mean maximal heart rate was 193.38 +/- 10.89 beats/minute in boys and 196.78 +/- 10.99 beats/minute in girls. The maximum level of systolic blood pressure attained at peak exercise was lower in girls. Although data of healthy Turkish children including mean endurance time, heart rate and blood pressure responses to exercise were consistent with the results from several countries using the Bruce protocol, mean maximal heart rates for all groups were slightly higher than those obtained with the Balke protocol. The data obtained from this study offers age- and size-appropriate normal data in both sexes in healthy Turkish children and may be used as reference values during treadmill exercise.

Effect of carnitine supplementation on cardiac function in hemodialyzed children

Thirteen carnitine-deficient children (mean age, 16.1 +/- 2.56 years) on a three-times-weekly hemodialysis program for at least 1 year, and 11 healthy age matched children were involved in the study. All the patients had stable blood pressure and hemoglobin (Hb) levels with a maintenance dose of erythropoetin and none were digitalized. The total carnitine (TC) and free carnitine (FC) plasma levels were sampled prior to hemodialysis (HD) before and after 3 months of carnitine supplementation. A free carnitine (FC) to acylcarnitine (AC) ratio less than 4 was defined as carnitine deficiency. Intravenous L-carnitine was injected at a dose of 20-40 mg/kg three times weekly at the end of each dialysis session for a 3-month period. Echocardiographic examination was performed the day following HD, before and after carnitine treatment. Systolic and diastolic functions of the left ventricle, including the ejection fraction, were measured. Almost all the parameters were significantly different in controls and hemodialyzed patients. In carnitine-deficient hemodialyzed patients, 3 months of L-carnitine supplementation resulted in a significant increase in blood carnitine levels and the FC/AC ratio, but this was not associated with any significant improvement of cardiac function. Furthermore no significant changes were observed in plasma triglycerides, total cholesterol or other lipoprotein parameters before or after carnitine supplementation. Although there was a moderate increase in mean hematocrit (Hct) and Hb levels, these also did not reach statistically significant levels. These results suggest that the 3 months of carnitine supplementation is not sufficient to ameliorate cardiac function or increase Hb levels in children.

Balloon dilation of stenotic nonvalved conduits after Fontan operation

The Fontan operation is used to supply a ventriculo-arterial connection in patients with tricuspid atresia. An important complication is the obstruction of the conduit that may necessitate reoperation. In these patients balloon dilation of the conduit stenosis has been advocated as a method to relieve the obstruction and postpone surgical replacement. While there are several reports about the balloon dilation of stenotic valved conduits, we do not have enough information about the results of balloon dilation of nonvalved conduits. We performed successful balloon dilations in two patients with tricuspid atresia who underwent the Fontan operation and had stenotic nonvalved conduits. In the first patient, the stenosis was relieved but recurred. A second balloon dilation procedure was performed, and the patient has been symptom free for one year. In the second patient, the stenosis was relieved but recurred. Our preliminary results suggest that balloon dilation is an efficient method to relieve the obstruction in stenotic nonvalved conduits and can be repeated successfully if the stenosis recurs.

Vasovagal syncope: asystole provoked by head-up tilt testing under sertraline therapy

Syncope is defined as a sudden transient loss of consciousness. Vasovagally mediated hypotension and bradycardia are believed common, yet difficult to diagnose, causes of syncope in healthy children and adolescents. These episodes are often both sudden and sporadic in nature and, if recurrent and severe (malignant vasovagal syncope), can be a source of morbidity and possibly mortality. Head-up tilt testing has emerged as a useful investigation in patients who are thought to have recurrent vasovagal syncope with systemic hypotension, bradycardia, or both, and it has been suggested as a potential method to test for vasovagal episodes. Sertraline hydrochloride, a serotonin reuptake inhibitor, has been reported to be effective in preventing the vasovagal syncopal episodes in children and adults. Here, two cases of recurrent, unexplained syncope are presented. Both were under sertraline therapy and underwent provocative head-up tilt testing that resulted in asystole.

Role of adenosine in the diagnosis and treatment of tachyarrhythmias in pediatric patients

Tachyarrhythmias are common rhythm disturbances in infants and children. Despite the availability of diagnostic criteria arrhythmias are sometimes commonly misdiagnosed. Recent reports suggest that an endogenous purine nucleoside, adenosine, has a diagnostic effect in narrow QRS complex tachycardias, in addition to terminating supraventricular tachycardia involving the atrioventricular node. This report reviews the authors' experience with the use of adenosine for diagnosis of narrow and wide complex tachyarrhythmias in children. Adenosine was administered to 43 patients with several types of tachyarrhythmias (mean age, 8.3 +/- 5.24 years). Nineteen patients had structural or acquired heart disease. Of the 43 patients there were 28 (65%) several different types of narrow QRS complex tachycardia and 14 (33%) ventricular arrhythmias. One patient (2%) had long QT. Adenosine terminated supraventricular tachycardia, in 11 of 12 patients (92%), ventricular tachycardia in five of eight patients (63%), and transiently terminated premature ventricular contractions in two of six patients (33%). The diagnostic ability of adenosine was perfect in eight supraventricular tachycardia. In these eight cases the tachycardia mechanism was unclear before the administration of adenosine, which demonstrated three cases of sinus tachycardia, three of atrial flutter, one of atrial fibrillation and one of atrial fibrilloflutter. Confirmation of the primary diagnosis by adenosine was perfect in five tachyarrhythmias including three cases of atrial flutter, one of atrial fibrillation and one of ectopic atrial tachycardia. The average effective dose of adenosine was 212 micrograms/kg (range, 100-400 micrograms/kg). There were no serious side-effects except transient dyspnea, chest pain and flushing. These findings demonstrate adenosine to be helpful and safe in the diagnosis of tachyarrhythmias.

Incidence and severity of arrhythmias and conduction disturbance after repair of tetralogy of Fallot

Ventricular and supraventricular arrhythmias and conduction disturbances were evaluated by routine electrocardiography and 24-hour ambulatory monitoring in 31 patients who underwent correction of tetralogy of Fallot. The interval from operation to the study was 1 month to 14 years (mean 4.8 +/- 2.8). Complete right bundle branch block occurred in 22 (71%) patients and incomplete right bundle branch block in 9 (29%) patients. Bifascicular block with right bundle branch block and left axis deviation (LAD) occurred in one patient. Two patients had second degree type II atrioventricular block. Twenty-four-hour ambulatory electrocardiographic monitoring was performed in all patients and they were divided in two groups according to the frequency of ventricular arrhythmias (Lown classification). Group 1 included the 23 patients who had no arrhythmia or rare ventricular arrhythmias (Lown grade 0-1). Group 2 was comprised of eight patients (26%) with significant ventricular arrhythmias (Lown grade 2-5). Twelve patients (39%) had supraventricular arrhythmias, three patients rare supraventricular tachycardia attacks, and seven patients occasional supraventricular ectopies. One patient had bradycardia-tachycardia attacks and one patient had junctional tachycardia. There was no correlation between age at the time of surgery and ventricular arrhythmias. Of the patients who had ventricular and supraventricular arrhythmias of various degrees on ambulatory monitoring, two had significant arrhythmias on routine electrocardiogram. Symptoms were rare in these patients. In conclusion, both supraventricular and ventricular arrhythmias were found in considerable frequency in our patients. As ventricular arrhythmias may be the cause of sudden death and supraventricular arrhythmias are a main cause of morbidity, it is important to evaluate ventricular and supraventricular arrhythmias by ambulatory monitoring in patients who have undergone correction of tetralogy of Fallot.

The role of serotonin re-uptake inhibitors in preventing recurrent unexplained childhood syncope -- a preliminary report

To assess the efficacy of a serotonin re-uptake inhibitor, sertraline hydrochloride, in preventing recurrent neurocardiogenic syncope, we studied 15 patients (10 female; mean age 12.9 +/- 2 years) with positive head-upright tilt test and resistant to standard pharmacotherapy, atenolol or disopyramide. The patients were given 50 mg oral sertraline hydrochloride daily for 6 weeks. Intolerance to the drug was seen in 3 patients and 2 had syncopal episodes during the therapy. A head-upright tilt table test was then repeated in 10 patients. Six were tilt negative and asymptomatic over a mean follow up period of 7 +/- 3 months while four remained tilt positive: two experienced marked hypotension and bradycardia, characterized as mixed type syncope, and two had cardiac asystole, lasting > 10 s, during tilting, thereby exhibiting a cardio-inhibitory response.

CONCLUSION

Sertraline hydrochloride may be useful in preventing recurrent neurocardiogenic syncope resistant to standard pharmacotherapy but careful clinical studies are essential before such a treatment strategy can be recommended since serious asystole could develop.

Long-term clinical experience with a steroid-eluting active fixation ventricular electrode in children

In this study, the first study performed in pediatric patients, we assessed the safety and efficacy of a steroid-eluting active fixation ventricular electrode in 18 children. Our study shows that steroid-eluting active fixation leads are safe and effective in children, and suggests that these leads with their easy implantation and low chronic threshold values may be considered as the first choice in this age group.

Bicuspid aortic valve and coarctation of aorta

Bicuspid aortic valve (BAV) and coarctation of aorta (COA) are frequently seen together. It is believed that these malformations result from a single developmental diathesis. A case is presented of COA, aortic stenosis and aneurysm of the ascending aorta corrected by patch aortoplasty and commisurotomy. An aneurysm at the site of the coarctation repair can develop as late as 20 to 25 years after surgery. Almost all of the aneurysms described have occurred in patients undergoing patch aortoplasty. We do not recommend this technique except in special cases.

Comparison of sensitivity and specificity of tilt protocols with and without isoproterenol in children with unexplained syncope

Head-up tilt testing with or without isoproterenol is extensively used in the evaluation of patients with unexplained syncope. However, sensitivity and specificity of tilt protocols with and without isoproterenol have not been clarified in children, due to lack of age matched control subjects. This study was designed to assess and to compare the sensitivity and specificity of tilting alone and tilting in conjunction with isoproterenol. Thirty children with unexplained syncope (group I) and 15 age-matched control subjects (control group I) underwent successive 60 degrees head-up tilts for 10 minutes during infusions of 0.02, 0.04, and 0.06 microgram/kg/min of isoproterenol, after a baseline tilt to 60 degrees for 25 minutes. Also, 35 children (group II) with unexplained syncope and 15 healthy control subjects (control group II) were evaluated by head-up tilt to 60 degrees for 45 minutes without an infusion of isoproterenol. In response to tilt protocol with graded isoproterenol, 23 (76.6%) of the patients in group I and 2 of the 15 (13.3%) control subjects developed syncope. Accordingly, the sensitivity of tilt testing with isoproterenol was 76.6%, and its specificity was 86.7%. Tilt testing without isoproterenol was positive in 17 (48.5%) of the patients in group II but in only 1 of the 15 (6.6%) control subjects. Thus, sensitivity and specificity of tilt testing without isoproterenol were 48.5% and 93.4%, respectively. The mean heart rate and systolic blood pressure decreased significantly (P < 0.001) in all tilt positive patients during syncope. In conclusion, the head-up tilt test is a valuable diagnostic test in the evaluation of children with unexplained syncope, and isoproterenol is likely to increase the sensitivity of the test without decreasing its specificity.

Dual sensor pacemakers in children: what is the choice of sensor blending?

Dual sensor pacemakers were developed to obtain more appropriate responses to activity. We evaluated ten children with dual sensor pacemakers in different sensor blending circumstances using exercise testing to assess which ratio was optimal. Ten patients with several bradydysrhythmias (ages 6-16 years; mean 10.1 years) were included in the study. Eight patients had VVIR pacemakers (Vitatron Topaz), models and two patients had VDD pacemakers implanted via the transvenous route. All patients were in a paced rhythm (98.5% pacing). Accurate T wave sensing ranged from 81%-100%; mean 92%, median 95%. Voluntary exercise testing with a CAEP protocol was performed using a treadmill with the pacemaker in VVIR mode. Medium activity threshold with three sensor blending ratios (QT = ACT, QT > ACT, and QT < ACT) were done in all patients. The mean duration of exercise was not statistically different among the three sensor blending ratios. After 90 seconds of exercise, the mean pacing rate had increased by 12%, 3%, and 5%, respectively, in the three groups. At maximal exercise, the increases were 45%, 42%, and 54%. Mean HRs during exercise in each of the three ratios were not significantly different, although we found a statistically significant increase in HR during the first two stages of rest period in the QT = ACT sensor blending ratio compared to the QT > ACT ratio. No difference was observed after the second stage.

IN CONCLUSION

(1) there is no difference between the QT = ACT, QT < ACT, and QT > ACT sensor blending ratios; and (2) each child has to be evaluated by exercise testing to program a correct sensor blending ratio.

Short- and intermediate-term efficacy of amiodarone in infants and children with cardiac arrhythmia

The antiarrhythmic effect of amiodarone was examined in this retrospective study in a group of 20 patients with a mean age of 8.5 +/- 6.7 years (range 42 days to 20 years, median 9 years). Five patients with atrial flutter, one patient with atrial fibrillation, two patients with an intermediate rhythm between atrial flutter and atrial fibrillation, four patients with chaotic atrial tachycardia, three patients with atrioventricular reentry tachycardia, two patients with junctional ectopic tachycardia, and three patients with ventricular arrhythmias were treated with amiodarone. The mean duration of therapy was 9.1 +/- 12.3 months (range 1 month to 4 years). Before amiodarone treatment, 18 patients had been unresponsive to various antiarrhythmic drugs (range 1-8, median 2). Two patients received amiodarone as an initial therapy. It was administered orally at a dose of 10 mg/kg once per day for 10 days and then decreased to 5 mg/kg once per day. Amiodarone was effective in 16 patients (80%). Side effects occurred in three patients, including thyroid dysfunction, elevation of liver enzymes, and keratopathy. All side effects disappeared upon cessation of the therapy. We recommend amiodarone for the treatment of childhood arrhythmias, especially for the refractory types.

Transcatheter closure of patent arterial ducts using controlled-release coils

OBJECTIVE

To determine the efficacy of transcatheter closure of patent arterial ducts using controlled-release coils.

DESIGN

Transcatheter closure of patent arterial ducts was attempted in 52 patients using controlled-release coils.

SETTING

For the study, four tertiary paediatric cardiology units were used, two of which were in the U.K., one in Italy and one in Turkey.

PATIENTS

The 52 patients ranged in age between 3-5 months and 61 years (median 3-5 years), and weighted between 4.5 kg and 62 kg. The duct diameters were 1 mm to 6.5 mm.

RESULTS

In four patients the ducts were too large for safe release of the coils. In the remaining 48, one coil was inserted in 33 patients, two coils in nine, three coils in four and four coils in two patients. Immediately at the end of the procedure, the duct was completely occluded in 26/47 (55%) patients. Haemolysis occurred in one patient, in whom the coil was removed by a snare catheter and a large umbrella device was implanted with resolution of the haemolysis. Coil embolization to the pulmonary artery occurred in five (10%) patients. All were easily retrieved and replaced by larger coils. At the latest follow-up by colour Doppler echocardiography, the duct was completely occluded in 44/47 (94%) patients.

CONCLUSIONS

Transcatheter closure of patent arterial ducts by controlled-release coils is effective and safe. Even when more than one coil is inserted the technique is still less cumbersome and considerably cheaper than transcatheter umbrella closure.

Adenosine-sensitive right ventricular tachycardia in children

Right ventricular outflow tachycardia is a distinct subgroup of idiopathic ventricular tachycardia (VT) with characteristic clinical and electrophysiologic properties. This study was planned to evaluate the effects of adenosine on idiopathic right ventricular tachycardia in children, and to assess the long-term efficacy of verapamil treatment. Diagnostic tests including electrocardiogram, chest roentgenogram, echocardiogram, exercise stress test and 24-hour ambulatory electrocardiographic monitoring were performed in each patient. Adenosine was administered in increasing amounts until an effective dose or a maximal dose of 300 micrograms/kg was reached. In adenosine-sensitive patients verapamil was given orally (3-10 mg/kg/day) for long-term suppression of arrhythmia. Seven patients with a mean age of 10.2 +/- 4.7 years were enrolled in the study. There were five male and two female patients. Six patients had VT, and one patient had frequent ventricular ectopic bests. Arrhythmia originated from the right ventricle in all patients. Adenosine was effective in terminating the arrhythmia in all patients, with a mean effective dose of 183 +/- 75 micrograms/kg. Favorable long-term results (mean follow-up period 17 +/- 8 months) were obtained with verapamil treatment at an average dose of 6.3 +/- 2.2 mg/kg. In conclusion, adenosine can be used effectively for termination of VT originating from the right ventricular outflow tract in children. In these patients verapamil may be considered as the drug of choice for long-term therapy.

The angiocardiographic analysis of 73 patients with double-outlet right ventricle

The purpose of this study was to determine the cardiac anatomy of patients with double-outlet right ventricle by angiocardiography. A total of 73 patients between the ages of one day and 11 years were examined. The aorta was on the right side of the pulmonary artery in 23 cases (32%), right anterior in 20 (27%) and right posterior in 17 cases (23%). Pulmonary stenosis was found in 53 patients (73%) and subaortic stenosis in six cases. Ventricular septal defect (VSD) was subaortic in 39 cases (52%), remote type in 17 (23%), doubly committed in 10 (13%), and subpulmonic in 9 (12%). Double VSD was noted in two patients. Pulmonary hypertension was more frequent in subpulmonic ventricular septal defect (78%). The most common associated anomalies were atrial septal defect (34%), anomalous coronary arteries (12%) and endocardial cushion defect (10%). Aortic root angiography was not satisfactory in half of the cases with coronary arterial anomaly. In conclusion, double-outlet right ventricle is a complex anomaly, all of whose cardiac features can be successfully demonstrated in detail by echocardiography and angiocardiography. However, in order to determine the anatomy of the coronary arteries, selective coronary angiography may be necessary in some patients.

Transtelephonic ECG versus electrophysiologic study in children with recurrent palpitation attacks

Palpitation may be a terrifying event for children and pose diagnostic problems for pediatric cardiologists. Routine methods often fail to document episodic arrhythmia because the episodes may be brief or infrequent or both. The purpose of this study was to evaluate and compare values of non-invasive and invasive techniques. Twenty-three children (mean age 11.7 +/- 2 years, range 7-16 years) with recurrent palpitation attacks (> 2 times), who had normal physical examinations, ECG, echocardiography, 24 hour ambulatory ECG monitoring and treadmill exercise tests, were included in the study. Redline Model CG 4000 TTE recorders were given to patients for 10 or 20 days. We performed an intracardiac electrophysiologic study (EPS) on 14 patients. The mean number of palpitation attacks was 11.3 +/- 7.4 (median: 5), lasting 9.6 +/- 7 (median 3) minutes. The number of transmitting records was 2 +/- 1.4 (1-20). Of the 23 patients, only 15 (65%) transmitted during the palpitation attacks. Twenty-four-hour ambulatory ECG monitoring findings were normal in all patients. One patient had a wide QRS tachycardia attack in the TTE records. We stimulated ventricular tachycardia in the same patient in the EPS. Among the other patients who transmitted TTE records during palpitation attacks, we diagnosed two cases of concealed accessory pathway and eight cases of dual AV nodal pathway in the EPS. In conclusion, TTE is a sensitive and accurate method for diagnosis and follow-up of patients with cardiac arrhythmia. It can be used before invasive studies in children with recurrent palpitation attacks.

Isolated chylopericardium secondary to intrathymic lymphangiomatous malformation

A case of chylopericardium associated with lymphangiomatous malformation of the thymus is presented. The specific diagnosis of chylopericardium was made by pericardiocentesis and analysis of the fluid. Despite the pericardiocentesis and pericardial tube drainage, pericardial effusion recurred and the patient underwent pericardiectomy. At operation the thymus, which contained a tumor and showed diffuse hyperplasia, was excised and pericardiectomy was performed. The 2-year-old patient recovered uneventfully without reaccumulation of the chyle. The pathologic diagnosis of the mass was intrathymic ectatic lymphangiomatous malformation.

Transcatheter closure of patent ductus arteriosus using controlled-release coils

Controlled-release coils have become available recently for the closure of patent ductus arteriosus (PDA). Transcatheter closure of patent arterial ducts was attempted in 13 patients, ranging in age from 5 months to 15 years, mean 4.1 years. Implantation of controlled-release PDA coils was attempted via the femoral artery through 5 Fr catheters in all cases except one, in whom both the femoral arterial and venous routes were used. The procedure was successful in 10 of the 13 patients. In these, the pulmonary artery systolic pressure ranged between 25 and 42 mmHg and the duct diameter varied from 1.5 to 6 mm at its narrowest point. Six of the patients received a single coil. Two coils were inserted in three patients and three coils in one patient. In three patients the ducts were too large for safe release of the coils, despite attempted implantation of up to three coils simultaneously. These coils were easily withdrawn into the catheter. Immediately at the end of the procedure, the duct was completely occluded in nine of the 10 patients, and in one patient there was a small residual flow. The procedure time varied between 35 min and 2.5 h, mean 81 min and the fluoroscopy time varied from 5 to 78 min, mean 25 min. None of the patients experienced hemorrhage, diminished lower extremity pulse, hemolysis or infection. In one patient, a 5 mm coil embolized into the right pulmonary artery soon after release. It was retrieved with a snare, then 8 mm and a 5 mm coil were implanted satisfactorily in the arterial duct. At follow-up by color Doppler echocardiography, the duct was completely occluded in all patients. Transcatheter closure of patent arterial ducts by controlled-release PDA coils is effective and safe. Even when more than one coil is inserted, it is still cheaper than transcatheter umbrella closure. This method is therefore of great value, particularly in less affluent countries.

Radiofrequency catheter ablation of accessory pathways and modification of atrioventricular node in children and adolescents

Catheter ablation of an accessory pathway and atrioventricular node modification using 550 kHz radiofrequency was attempted in 23 children and adolescents between five and 19 years of age (mean = 15.7 years). Fifteen children had accessory-pathway-mediated tachycardia and eight had atrioventricular node reentrant tachycardia. Accessory pathways were present in ten children. Two patients had associated congenital heart disease. Symptoms included disabling palpitations and episodes of syncope. Ablation was attempted from the right and left sides of the heart. Single-catheter technique was used in seven patients. Eleven of the 15 patients with accessory pathways were treated completely. Two patients had recurrences, and one of them died after the arrhythmia surgery. There were two failures. Two patients with incomplete interruption of the accessory pathways were followed up clinically. There were three cases with temporary systemic embolization and one with severe pain related to radiofrequency energy application. Atrioventricular node modification was done by fast-pathway ablation in six, and by slow-pathway ablation in two patients. Two patients with fast-pathway ablation had recurrences of clinical arrhythmia, and one of them underwent a successful second session. There were no complications associated with the procedure in this group of patients. Radiofrequency catheter application was initially successful in 21 (84%) out of 25 procedures, and ultimately curative in 16 (69%) out of 23 patients. There were some serious complications which resolved in the immediate post-procedure period. Radiofrequency catheter ablation appears to be a safe and successful method for the management of supraventricular tachycardia secondary to accessory pathways or atrioventricular node reentrant tachycardia in children and adolescents.

Blade atrial septostomy: experience with 18 patients

Blade atrial septostomy was performed in 18 patients, including 14 with transposition of the great arteries, three with tricuspid atresia and one with severe mitral stenosis and ventricular septal defect. The patients' ages ranged from 25 to 210 days (mean: 108 +/- 64 days), and weights ranged from 3.0 to 6.0 kg. Following blade septostomy, partial arterial pressure of oxygen (PaO2) increased from an average of 22 +/- 3.3 mmHg to 38.9 +/- 7.6 mmHg (p < 0.001), and prompt clinical improvement was observed in the majority of patients. Significantly decreased atrial pressures (from 8.16 +/- 6.1 to 3.93 +/- 2.2 mmHg, p < 0.01) and significantly enlarged inter-atrial openings (from 1.6 +/- 0.9 to 7.5 +/- 1.8 mm, p < 0.001) were achieved with successful blade atrial septostomy. Blade atrial septostomy is an effective and life-saving procedure in patients who require nonrestrictive inter-atrial communication.

Initial experience with dual-sensor rate-responsive pacemakers in children

The efficacy of a new single-chamber, rate-responsive pacemaker that utilizes information from two sensors, activity and stimulus to T wave, was evaluated in 15 children during a mean follow-up period of 10.3 +/- 3.3 months (range 5-16 months). There were 10 males and five females, with a mean age of 5.9 +/- 3.8 years (range 9 months-16 years). The indication for pacing was high grade atrioventricular block in 10 (eight postoperative, two congenital), and sinus node dysfunction in five patients. In endocardial implants the mean T wave amplitude was 2.48 +/- 0.7 mV, and mean T wave sensing 91 +/- 6.3%, whereas in epicardial implants T wave amplitude and sensing were inadequate. Each patient underwent 24-h Holter monitoring and 10 performed a graded treadmill test in three sensor-blending modes (Stimulus-T = Activity, Stimulus-T > Activity, Stimulus-T < Activity), using the chronotropic assessment exercise protocol. Sensor cross-checking was analysed by continuous tapping over the pacemaker. Holter monitoring demonstrated that pacing rate variations were closely related to daily activity. At the initial phases of exercise testing, the mean percentage of increase in pacing rate was significantly lower in Stimulus-T > Activity mode, when compared to Stimulus-T = Activity (P < 0.01); however, the initial disparity among the three modes disappeared halfway through the exercise and similar heart rate changes were observed thereafter. Continuous tapping over the pacemaker in Stimulus-T = Activity mode caused an initial increase in pacing rate, and inappropriate responses were quickly corrected by sensor cross-checking. Rate modulation with a single-chamber, dual-sensor pacemaker is adequate and safe in children, and may offer significant advantages over single-sensor devices in endocardial implants.

Parameters of iron deficiency in children with cyanotic congenital heart disease

A group of 67 children with cyanotic congenital heart disease (CCHD) were studied, and 35 were given iron treatment according to a regimen that gives iron to patients with a hematocrit (Hct) below 60%. The patients were categorized as iron-deficient and iron-sufficient according to their transferrin saturation and ferritin values. The pretreatment hemoglobin (Hb) and Hct values of the groups were similar. The mean Hct was nearly three times as much as the mean Hb in the iron-sufficient group and more than three times as much as the Hb in the iron-deficient group. Excessive erythrocytosis in the iron-deficient group was impressive. Mean corpuscular volume (MCV) values were below 72.7 fl in all of the iron-deficient patients. After treatment the Hb, Hct, transferrin saturation, and ferritin increased significantly in both groups, with the increments greater in the iron-deficient group. Increments in the erythrocyte (RBC) count were significant in the iron-sufficient group but insignificant in the iron-deficient one. Increments of MCV in the iron-deficient group were significant but insignificant in the iron-sufficient group. Our study demonstrated that prediction of Hb, RBC count, and MCV, measurements of which are easy and inexpensive and require little blood, can suffice for the diagnosis of iron deficiency in patients with CCHD without altering systemic perfusion.

Pulmonary vascular sling responsible for esophageal and tracheal obstruction. A case report

The disease of pulmonary vascular sling is a rare congenital condition. When it does occur it is often in conjunction with tracheal compression. The authors report herein a newborn with this anomaly presenting with a tracheal and esophageal compression.

"Acquired" subvalvular aortic stenosis after repair of several congenital cardiac defects

Discrete subvalvular aortic stenosis is a progressive lesion. In this report we presented nine patients who had no significant left ventricular-aortic obstruction at initial cardiac catheterization or echocardiographic examination, but later developed significant subvalvular aortic stenosis. Associated lesions included ventricular septal defect in three, patent ductus arteriosus in two, aorticopulmonary window in one, tetralogy of Fallot in one, supramitral membrane in one, and ventricular septal defect and patent ductus arteriosus in one case. Nine patients were diagnosed with subvalvular aortic stenosis 18 months to eight years after surgical correction. Eight of the patients required surgery for subvalvular obstruction. In conclusion, discrete subaortic stenosis is a rare, late complication of the surgical repair of several congenital heart defects. It is a progressive lesion after surgery; therefore these patients require careful follow-up.

Head-up tilt test: a highly sensitive, specific test for children with unexplained syncope

Unexplained syncope may cause diagnostic and therapeutic problems in children. The head-up tilt test has been shown to be a useful tool for investigating unexplained syncope, especially for diagnosis of neurally mediated syncope. In this study 20 patients aged 9-18 years (12.0 +/- 2.5 years) with syncope of unknown origin and 10 healthy age-matched children were evaluated by head-up tilt to 60 degrees for 25 minutes. The test was considered positive if syncope or presyncope developed in association with hypotension, bradycardia, or both. If tilting alone did not induce symptoms (syncope or presyncope), isoproterenol infusion was administered with increasing doses (0.02-0.08 mu g/kg per minute). During the tilt test, symptoms were elicited in 15 (75%) of the patients with unexplained syncope but in only one (10%) of the control group (p < 0.001). The sensitivity of the test was 75% and its specificity 90%. Three patterns of response to upright tilt were observed in symptomatic patients: vasodepressor pattern with an abrupt fall in blood pressure in 67%; cardioinhibitory pattern with profound bradycardia in 6%; and mixed pattern in 27%. In patients with positive head-up tilt, there were sudden decreases in systolic blood pressure (from 130 +/- 15 to 61 +/- 33 mmHg) and in mean heart rate (from 147 +/- 26 to 90+/-38 beats per minute) (p < 0.001) during symptoms. Treatments with atenolol 25 mg/day has shown complete suppression of syncope in positive responders during a mean follow-up period of 18 +/- 6 months. The head-up tilt test is a noninvasive, sensitive, specific diagnostic tool for evaluating children with unexplained syncope.

Transcatheter embolization of a pulmonary collateral vessel in a child with tricuspid atresia: case report

When a significant systemic-pulmonary arterial collateral connection occurs in children with cyanotic congenital heart disease, they may present surgical difficulties making operative management undesirable. Transcatheter vessel occlusion can be a life-saving procedure or an important adjunct in reducing blood loss during surgery. This report describes the selective obliteration of a large systemic pulmonary arterial collateral vessel in a child with tricuspid atresia before Fontan operation. A transcatheter wire coil embolus technique was used, and no complications or errors in placement of the coils occurred.

Cardiac hydatid cyst in a child: diagnostic value of echocardiography and magnetic resonance imaging

Cardiac hydatid cyst is extremely rare in children. We report a case of a cardiac echinococcal cyst in an 11 year old boy, diagnosed by two-dimensional echocardiography and magnetic resonance imaging (MRI). The cyst was located in the posterior wall of the left ventricle and was excised surgically. Echocardiographic and MRI findings are discussed.

Double-chambered right ventricle: experience with 52 cases

The presence of anomalous muscle bundles may produce a pressure gradient between the inflow and outflow portions of the right ventricle, thus resulting in double-chambered right ventricle bearing troublesome clinically in its diagnosis. The aim of the present study was to review the diagnostic criteria. Fifty-two patients with a double-chambered right ventricle were seen during an 8-year period. They ranged in age at the catheterization from 4 months to 17 years (mean 7.5 +/- 4.4 years). Diagnosis was confirmed in 51 patients at cardiac catheterization and in other one on operation. The majority of the patients had associated cardiac anomalies: there were 33 ventricular septal defect (63%), 21 pulmonary valve stenosis (40%), nine atrial septal defect (17%), and four double-outlet right ventricle. The electrocardiograms revealed upright T waves alone in right precordial leads suggesting right ventricular hypertrophy in 33% of the patients. At cardiac catheterization, there was a pressure gradient of 20-160 mmHg between the right ventricular inflow and outflow portions. Forty patients have had surgery and four have undergone balloon pulmonary valvuloplasty. Surgical treatment was planned for two patients and other six had no indication for treatment.

Neonatal lupus syndrome: report of a case

Neonatal lupus syndrome (NLS) is characterized by the presence of cutaneous lupus, congenital heart block or both associated with maternal autoantibodies anti-Ro (SS-A) and anti-La (SS-B). NLS is responsible for more than 80 percent of cases with isolated congenital complete heart block. This report describes a neonate with third-degree atrioventricular block who was born to an anti-Ro (SS-A) positive mother. The dermatological and hematological manifestations of NLS were absent. The infant's clinical condition was good during the two months of follow-up with expectant management.

Adenosine induced torsades de pointes in a child with congenital long QT syndrome

Torsades de pointes is a rare arrhythmia characterized by its bradycardia dependence and increased adrenergic discharge, whether it occurs as a congenital anomaly or as an acquired problem resulting from drug intoxication or other conditions. There are no reliable tests to assess the propensity toward torsades de pointes or evaluate the efficacy of treatment in these patients. Adenosine can result in marked slowing of sinus and ventricular rate and leads to increased sympathetic discharge when given intravenously. We induced torsades de pointes in a child with congenital long QT syndrome (Jervell-Lange-Nielsen syndrome) using 200 micrograms/kg IV adenosine bolus. Higher dosage of adenosine (600 micrograms/kg) did not lead to torsades de pointes after beta blockade. Adenosine may induce torsades de pointes in patients with the long QT syndrome and may be used as a test to reproduce the clinical arrhythmia. Whether adenosine proves to be useful for assessing the efficacy of treatment will require extensive investigation in larger series of patients.

Cardiac depolarization and repolarization in Wolff-Parkinson-White syndrome

Delta wave and QRS complex polarities have been extensively studied in preexcitation syndromes. However, only limited data exist about ventricular depolarization and repolarization in the setting of maximal preexcitation in relation to the site of insertion of the accessory pathway. Therefore this study was designed to systematically analyze cardiac depolarization and repolarization in patients with maximal preexcitation. We analyzed the polarity of the QRS complex and T wave on the frontal plane on the conventional 12-lead electrocardiogram in 118 patients with maximal preexcitation. Fast atrial pacing was used to provoke maximal ventricular preexcitation. The 32 patients with a left lateral accessory pathway showed right-axis deviation of the QRS complex (110 +/- 20 degrees) with a left-axis deviation of the T-wave axis (-40 +/- 25 degrees). The 54 patients with a posteroseptal accessory pathway had a left axis of the QRS complex (-50 +/- 20 degrees) with a right-axis deviation of the T-wave axis (95 +/- 15 degrees). The 11 patients with a right lateral accessory pathway had a left axis of the QRS complex (-40 +/- 20 degrees) and a right axis of the T wave (110 +/- 10 degrees). In 7 patients with a left anterolateral accessory pathway and 14 patients with a right anteroseptal accessory pathway, the axis of the QRS complex was 50 +/- 25 degrees and 45 +/- 20 degrees, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Absent pulmonary valve syndrome with agenesis of the left pulmonary artery

Absent pulmonary valve syndrome is represented by rudimentary nodules without identifiable leaflets, and it is commonly associated with a ventricular septal defect and tetralogy of Fallot. Unilateral absence of a pulmonary artery is also a rare congenital anomaly. The following is a case report of a one-day-old newborn with cyanosis. The physical examination revealed a to-and-fro murmur and no expansion of the left hemithorax. Echocardiography revealed tetralogy of Fallot, absent pulmonary valve, and enlarged main and right pulmonary arteries. The catheterization and angiography confirmed the diagnosis and absence of the left pulmonary artery.

The signal-averaged electrocardiogram in diabetic children

A signal averaged ECG is a useful tool for detecting low-amplitude, high frequency electrical potentials in the terminal portion of QRS. There is a close association between abnormal signal averaged ECG and coronary heart disease. In this study we evaluated late potentials and total QRS duration determined by this technique in diabetic children with and without good glycemic control. The signal averaged ECG of 20 children with diabetes mellitus and nine healthy age-matched controls were compared. The total QRS duration was longer in diabetic children than in controls (104.6, and 97.9 ms vs. 82.7 ms, P < 0.0005). Late potentials were not observed in the patient and control groups. The RMS voltage of the QRS complex in the last 40 ms was significantly lower in the diabetic group compared to the control group. There was no significant difference in the signal averaged ECG indexes between the two diabetic groups determined by the glycemic control state. These findings suggested that the children with diabetes mellitus frequently have intraventricular conduction disturbance regardless of glycemic control condition.

Inappropriate sinus tachycardia following radiofrequency ablation of AV nodal tachycardia: incidence and clinical significance

The incidence and consequences of inappropriate sinus tachycardia following modification of the AV nodal area with radiofrequency energy were prospectively studied in a consecutive series of 118 patients. Twelve (10%) patients developed this complication, which persisted less than 1 week in all but three patients. Inappropriate sinus tachycardia was only observed after fast pathway ablation. Only four patients required temporary treatment with a beta blocker.

Heart rate variability in diabetic children: sensitivity of the time- and frequency-domain methods

Heart rate variability (HRV) is a noninvasive index of the neural activity of the heart. Although also influenced by the sympathetic activity of the heart, HRV is essentially determined by the vagal stimulation of the heart. Several HRV abnormalities have been described in adults with diabetes mellitus. However, there are few data on HRV in children with diabetes mellitus. In the present study, HRV was assessed in seven healthy children, 10 diabetic children with good glycemic control and 11 diabetic children with poor glycemic control. All had normal standard cardiac autonomic function tests, obtained from 24-h Holter tapes. HRV was measured by calculating six time-domain (mean R-R interval (RR), standard deviation of the R-R interval [SDRR], standard deviation of the mean of 288 R-R intervals [SDANN], the mean of the 288 standard deviations computed for each 5-min period [SD], percentage of differences of adjacent R-R intervals of > 50 msec for the entire 24 h [pNN50], and the root mean square of successive differences [rMSSD]) and four frequency-domain (low frequency [LF], high frequency [HF], total heart rate power spectra, and LF/HF ratio) indexes. SD, pNN50, rMSSD, LF, HF and total heart rate power spectra were markedly and significantly reduced in diabetic children with poor metabolic control. The 24-h variation of low- and high-frequency components of heart rate power spectra of the latter children had a different shape. Thus, diabetic children with poor metabolic control (elevated HbA1c and B2M levels) have a low HRV compared to those diabetic children with good control and healthy children.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory electrocardiographic monitoring in healthy newborn infants

Twenty-four hour ambulatory electrocardiographic monitoring is a useful method to document dysrhythmias and to assess treatment response. Various studies have been done in the pediatric age-group to determine normal heart rate values. In this study we determined the heart rate and rhythm patterns of 25 healthy newborn infants whose ages ranged between 3-10 days (mean 6.5 days). There were 15 males and 10 females. The maximum heart rate in these infants was 175-231 beats/min (207 +/- 14), minimum heart rate 60-121 beats/min (93 +/- 16) and the average heart rate was 130-161 beats/min (143 +/- 9). Five infants (20%) demonstrated marked sinus dysrhythmia, seven infants (28%) had ventricular premature contractions, two infants (8%) had supraventricular premature contractions, and five infants (20%) showed junctional rhythm disturbance. The sinus pause did not exceed 1.2 sec and there was no evidence of atrioventricular conduction disorders, or supraventricular-ventricular tachycardia attacks. Our results were consistent with previous studies carried out in newborn infants. Dysrhythmias were detected during 24-hour ambulatory electrocardiographic monitoring in our study group. Since they were generally benign, they need no treatment.

Causes of syncope in children: a prospective study

We prospectively evaluated 80 patients with syncope, between January 1991 and January 1992 to determine the causes of syncope in children. There were 35 male and 45 female patients, whose mean age was 10.5 years. A single syncopal attack had occurred in 30 patients and multiple attacks in 50. A cardiovascular cause was established in 22 (27.5%) patients and a noncardiovascular cause in 36 (45%). The cause remained unknown in 22 patients (27.5%). Vasovagal syncope was the leading cause of syncope in these patients with an incidence of 32.5%. These findings suggest that every patient who has even one syncopal attack should be promptly investigated since the underlying cause could be a life-threatening one.

Long-term results of patients with congenital complete atrioventricular block

Congenital complete atrioventricular block is an uncommon disorder with a prognosis which is usually favorable. The disorder is sometimes associated with syncope, sudden death or cardiac pacing. It is difficult to determine the patients at risk of sudden death. In this retrospective study, hospital records of children who had been admitted to the Hacettepe University Children's Hospital between 1970-1990 for evaluation of complete heart block were examined. The study population, consisting of 39 children, 27 males and 12 females, had electrocardiograms consistent with complete heart block. These patients, diagnosed as having congenital complete A-V block, had an otherwise normally structured heart, and were followed up for a period of from one month to 15 years. Age at diagnosis ranged from 27 days to 17 years (mean: 86.9 +/- 48 months). Of the 14 patients with symptoms (five with syncope, eight with exercise intolerance and one with presyncope), nine were paced electively and have done well. Clinical and laboratory features of the asymptomatic and symptomatic groups were compared to evaluate potential risk factors.

Familial sick sinus syndrome in two siblings

Two siblings with sinus node disease are presented. The patients were severely affected and required permanent pacing. A cardiac electrophysiologic study was conducted in Case 2, which revealed an atrioventricular conduction disturbance in addition to sinus node dysfunction. The parents and other siblings showed no evidence of sinus node disorder. The occurrence of this disease in these siblings suggests an autosomal dominant mode of inheritance with variable penetrance.