Successful management of junctional tachycardia by hypothermia after cardiac operations in infants

BACKGROUND

Junctional ectopic tachycardia is an early postoperative complication after intracardiac repair of congenital heart disease, especially in infants. Because of the high ventricular rate and the usually poor response to antiarrhythmic drugs, this condition is associated with a high morbidity and mortality. The purpose of this study was to assess the safety and efficacy of moderate body surface hypothermia in the treatment of postoperative junctional ectopic tachycardia in infants.

METHODS

Six consecutive infants with postoperative junctional ectopic tachycardia (mean age at operation, 14 weeks) were treated with surface cooling. The decision to start treatment was based on the definition of a critical heart rate (180 to 200 beats/min) in the presence of junctional ectopic tachycardia diagnosed according to established criteria. Moderate hypothermia (rectal temperature between 32 degrees and 34 degrees C) was achieved by placing ice bags on the child's body surface. The patients were sedated, mechanically ventilated, and paralyzed.

RESULTS

Mean interval between diagnosis of tachycardia and initiation of hypothermia was 4 hours. Rectal temperature was rapidly (within 1 hour) lowered to 32 degrees to 34 degrees C in all 6 patients. This significantly lowered the tachycardia rate from 219 +/- 27 beats/min to 165 +/- 25 beats/min (mean +/- standard deviation; p < 0.001). Three patients with signs of low cardiac output had restoration of stable hemodynamics once the tachycardia rate had been decreased by hypothermia. Cooling was maintained for a period of 24 to 88 hours (mean, 59 hours). No serious side effects were observed.

CONCLUSIONS

Early institution of moderate hypothermia by body surface cooling was a safe and efficient measure to control ventricular rate in infants with postoperative junctional ectopic tachycardia.

Recurrent ventricular tachycardia in asymptomatic young children with an apparently normal heart

Ventricular tachycardia without underlying heart disease is rare in infancy and childhood. Four young children (median age 8 months at initial presentation) with frequently recurrent episodes of asymptomatic and self-limiting ventricular tachycardia are reported. By noninvasive investigation no apparent heart disease has been found in all patients. Initially three of the four children had been treated with an anti-arrhythmic drug. Treatment was soon stopped in two patients for lack of symptoms and for lack of efficacy of therapy; one patient remained on beta-blocker therapy. One child did not receive anti-arrhythmic therapy. After a mean follow up of 32 months all patients continued to be asymptomatic despite frequently recurrent episodes of self-limiting ventricular tachycardia.

CONCLUSION

Ventricular tachycardia in asymptomatic children with an otherwise normal heart carries a good prognosis. Invasive investigation (cardiac catheterization with electrophysiological study and right ventricular biopsy) can be withhold, as long as there are no symptoms. For lack of efficiency of antiarrhythmic drugs in suppressing ventricular tachycardia in asymptomatic children with apparently normal hearts, these patients may be left without therapy but have to be followed closely.

The incidence of end-stage renal disease in two regions of kingdom of saudi arabia

Maintaining patients with end-stage renal disease (ESRD) on renal replacement therapy is expensive and it is important to increase efforts towards reducing the incidence of ESRD. For this, a sound knowledge of the magnitude of the problem is necessary. This study was undertaken to estimate the incidence of ESRD in two regions of Saudi Arabia namely: Gizan, situated in the Southern area with a population of 654,685; and Al-Madinah, situated in the North Western area with a population of 828,477. All general hospitals and primary care centers under the Ministry of Health in the two regions were included in the study. Those patients in whom two consecutive serum creatinine values above 265 micromol/L were recorded were recruited into the study. There were no non governmental centers offering care for patients with renal failure in the study regions at the time of the study. A total of 108 patients in Al-Madinah region and 187 patients in Gizan fulfilled the criteria of the study. Sex distribution was similar in both regions, 61% male and 39% female. There were 71.3% Saudi and 28.7% Non-Saudi patients in Al-Madinah and 65.2% Saudis and 34.7% Non-Saudi patients in Gizan. Analysis of age distribution showed that the highest prevalence occurred among patients between 41 and 60 years of age in Al-Madinah whereas in Gizan it was between 21 to 50 years. The annual incidence of ESRD in Al-Madinah was 65.2 per million population (PMP) and in Gizan 189 PMP. The higher incidence in Gizan may be due to ethnic, socio-economic and environmental factors. A large scale study covering all parts of the Kingdom is needed to throw more light on such variations in the incidence of ESRD in the Kingdom.

[Therapeutic efficacy and diagnostic potential of adenosine in infants and children]

In an open study a total of 53 episodes of supraventricular reentrant tachycardia in 31 infants and children were treated with intravenous adenosine at two centers. Adenosine was given as a rapid intravenous bolus injection beginning with a dose of 0.1 mg/kg. If there was persistence of the dysrhythmia dosage was increased in 0.05 mg/kg-steps up to a maximum dose of 0.3 mg/kg if necessary. The median dose required for successful termination of the tachycardias was 0.15 mg/kg. In 26 patients with 48 episodes of regular narrow-QRS-complex tachycardia adenosine was used as the therapeutic agent of first choice. In all patients a shortlasting atrioventricular block occurred within seconds after the administration of adenosine. In 42 of 48 episodes of tachycardia (87%) the dysrhythmias were converted to a stable sinus rhythm. In six episodes (13%) recurrence of the tachycardia was observed immediately. In five children adenosine was used for diagnostic purpose: in three children with wide-QRS-complex tachycardia successful termination with adenosine proved the supraventricular origin of the dysrhythmia. In two children with suspected atrial flutter adenosine-induced atrioventricular block allowed identification of flutter waves in one patient while in the other patient no effect of adenosine was seen. Side-effects such as flush, chest-pain or abdominal pain were frequent but mild and only of a few seconds' duration. No influence of adenosine on blood pressure was noted. Only in one child with previously unknown sinus node dysfunction was a relevant electrophysiologic side effect seen: a prolonged sinus arrest with asystole of 12 seconds' duration occurred after adenosine administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcatheter ablation of incessant ectopic left atrial tachycardia using radiofrequency current

Catheter ablation of ectopic atrial tachycardia has been previously reported in a small number of patients in whom the ectopic focus was predominantly located in the right atrium. We report on a 51-year-old patient with atrial automatic tachycardia originating in the left atrium, in whom successful radiofrequency catheter ablation was performed via a transseptal puncture. The patient had suffered incessant atrial tachycardia for several years, refractory to antiarrhythmic drug treatment and DC-cardioversion. Radiofrequency ablation terminated left ectopic atrial tachycardia and, therefore, should have been attempted before resorting to open heart surgical ablation.

Role of late potentials in identifying patients at risk for ventricular tachycardia after surgical correction of congenital heart disease

This study evaluates the role of late potentials in identifying patients with sustained ventricular tachycardia (VT) after surgery for congenital heart defects using right ventriculotomy. Nine patients with early (1 to 12 months) or late VT (spontaneous in 7 [induced during electrophysiologic study in 6 of the 7] and induced in 2) and 104 patients without VT were studied. All patients had complete right bundle branch block. Late potentials were quantified by 3 time-domain parameters of the signal-averaged electrocardiogram: total filtered QRS duration, root-mean-square voltage in the last 40 ms, and low-amplitude signal duration of the terminal filtered QRS complex. Root-mean-square voltage filtered at 80 to 250 Hz was lower in patients with than without VT (9 +/- 6 vs 16 +/- 8 microV, p < 0.01). By multivariate analysis, more complex surgery (i.e., insertion of extracardiac conduits, Kawashima operation, etc.), lower root-mean-square voltage, and higher Lown grade (2 to 5) of ventricular arrhythmias on routine postoperative Holter recordings were the only independent predictors of VT (p < 0.001, < 0.05, and < 0.05, respectively). A combination of more complex surgery, root-mean-square voltage < 14 microV, and Lown grade 2 to 5 ventricular arrhythmias was highly predictive of VT (positive predictive value 75%). Conversely, patients without complex surgery and with root-mean-square voltage of > 13 microV were not likely to develop VT (negative predictive value 100%). Late potentials are an independent predictor of VT and may improve the identification of patients at low and high risk of VT after surgery for congenital heart defects using right ventriculotomy.

[Nitric oxide in therapy of pulmonary hypertension after correction of congenital single atrium]

We report on a 19-month-old boy with congenital single atrium. Cardiac catheterization preceding the surgical repair revealed an elevated pulmonary artery pressure of 60/15 mmHg (mean pressure 40 mmHg). Pulmonary flow was 8.4 l/min.m2 and systemic flow was 5.5 l/min.m2. Pulmonary arteriolar resistance was elevated to 4.2 U.m2 with 64% left-right shunt and 25% right-left shunt. Arterial O2-saturation varied around 90%. After surgical repair (insertion of a Goretex patch), the patient required mechanical ventilation with 100% oxygen for adequate oxygenation. Cardiac catheterization was repeated on the first postoperative day. No residual shunts were found. The pulmonary artery pressure was 66/40 mmHg (mean pressure 50 mmHg), systemic arterial pressure was 85/62 mmHg (mean pressure 68 mmHg). Cardiac index was 2.8 l/min.m2, pulmonary vascular resistance was 12 U.m2. After administration of prostacyclin a significant decrease of pulmonary artery pressure was observed, but without changing the ratio between pulmonary and systemic pressure. The AaDO2 varied between 400 and 580 mmHg and the oxygenation-index (PaO2/FiO2) was less than 1.0. In this situation, an attempt with inhaled nitric oxide (NO) was performed. After adding 20 ppm NO to the inspired gas, the AaDO2 decreased significantly from 580 to 270 mmHg and the oxygenation-index (OI) rose from 0.9 to 1.5. The inspired fraction of oxygen could be reduced quickly to 60%. During the next days, the concentration of NO was reduced stepwise to 1 ppm. Finally, the AaDO2 was within the normal range (25-65 mmHg) and the OI rose to a level about 4.0. The FiO2 could be reduced to 30% and nitric oxide therapy could be stopped and the child could be extubated.

[Results of oral sotalol therapy in children with supraventricular and ventricular arrhythmias]

Experience with oral sotalol, a beta-blocker with class III-antiarrhythmic properties, is limited in the pediatric population. Sotalol was administered to 32 patients with a mean age of 8.7 years (range 1 day-19.9 years). Mean dosage was 4.6 (1.5-9.4) mg/kg or 122.1 (52-306) mg/m2, respectively. In 27/32 patients, at least 1 antiarrhythmic agent had failed to control the dysrhythmia before sotalol was started. Cardiac diagnoses included normal heart (n = 16), status after correction of congenital heart disease (n = 13), and cardiomyopathy (n = 3). Success (based on symptoms and 24-h electrocardiogram) was achieved in 16/18 patients with reentry supraventricular tachycardia, in 7/8 patients with atrial flutter, and in 4/6 patients with ventricular tachycardia. During a mean follow-up of 15.6 (2-78) months, proarrhythmia occurred in five (16%) patients (symptomatic bradycardia n = 2, QT-prolongation and ventricular extrasystoles n = 1, ventricular extrasystoles n = 1, 2 degrees av-block n = 1), requiring dosage reduction (n = 3), cessation of treatment (n = 1) and pacemaker implantation in one patient, respectively. Symptomatic hypotension was noted in two patients, in whom therapy had to be stopped. Sotalol was a very effective agent for the treatment of various pediatric cardiac dysrhythmias. However, incidence of proarrhythmic effects warrants close electrocardiographic monitoring.

Atrial baffle procedures for complete transposition of the great arteries: natural course of sinus node dysfunction and risk factors for dysrhythmias and sudden death

359 patients after the Mustard (275) or Senning (84) operations for transposition of the great arteries were followed-up for a mean of 103.7 (range 0.4 to 204) months. 259 patients had postoperative 24-h Holter recordings. In 129 Mustard children serial (mean 4.4) postoperative Holter recordings were available for evaluation. Criteria based on Holter and scalar electrocardiograms at normal sinus node functions were used for rhythm analysis. Postoperative dysrhythmias appeared in 70% of the patients: sinus node dysfunction in 62.8%, second or third degree atrioventricular block in 3.2%, sustained atrial tachycardia or atrial flutter in 4.5%, and significant ventricular arrhythmia (Lown 2-5) in 21.4%. The prevalence of sinus node dysfunction increased slightly from 50.8% during the first 2 postoperative years to 64.4% in patients more than 10 years postoperatively. Fifteen patients (4.2%) died suddenly during follow-up. By multivariate analysis severe tricuspid regurgitation and/or right ventricular dysfunction and uncontrolled supraventricular tachydysrhythmias were identified as the two significant risk factors for sudden death.

[Ablation of permanent left atrial ectopic tachycardia by high-frequency energy]

Catheter ablation of ectopic atrial tachycardia has been previously reported in a small number of patients in whom the ectopic focus was predominantly located in the right atrium. We report on a 53-year-old patient with atrial automatic tachycardia originating in the left atrium, in whom successful radiofrequency catheter ablation was performed via a transseptal puncture. The patient presented a permanent atrial tachycardia for several years, refractory to antiarrhythmic drug treatment and DC-cardioversion. Radiofrequency ablation terminated left ectopic atrial tachycardia and, therefore, should be attempted before resorting to open-heart surgical ablation.

New antiarrhythmic drugs in pediatric use: propafenone

Propafenone hydrochloride, a class 1C antiarrhythmic agent, combines sodium channel-blocking effects with beta-blocking capacities and a weak calcium antagonism. The drug exerts marked electrophysiologic effects on accessory atrioventricular pathways. In patients with atrioventricular nodal reentry tachycardia, propafenone is able to block conduction in the fast conducting pathway. In addition, propafenone is very effective in young patients with supraventricular tachycardia based on enhanced abnormal automaticity. In pediatric patients, left ventricular performance remains unimpaired. Proarrhythmic events have been noted in children only occasionally. In accordance with the electrophysiologic profile, intravenous and oral propafenone is an effective agent for treatment of supraventricular tachycardia based on a reentry mechanism and due to abnormal automaticity (i.e., supraventricular tachycardia based on an accessory atrioventricular pathway, atrioventricular nodal reentry tachycardia, junctional ectopic tachycardia, and atrial ectopic tachycardia). In children with ventricular dysrhythmias, efficacy seems to be related to the underlying cardiac diagnosis. Propafenone is well tolerated in the majority of young patients. Incidence of proarrhythmic events seems to be lower with propafenone than with other class 1C agents. However, the risk of these serious adverse events should be taken into account when therapy with propafenone is considered, particularly in patients with structural heart disease.

[Malignant hyperthermia in swine during isoflurane anesthesia]

A case of porcine malignant hyperthermia (MH) is reported, which occurred during a cardiological animal experiment under general anaesthesia using isoflurane as inhalational anaesthetic. Initially, tachycardia (238 bpm) and a sudden increase of end-exspiratory pCO2 were noticed. Discontinuation of isoflurane followed by administration of dantrolene (7 mg/kg body weight) led to a rapid recovery. Two days later, no difference in clinical state was apparent in comparison with the remaining swine. After regular euthanasia, acute muscle necrosis was seen macroscopically in back and glutaeal muscles, which was confirmed by histological examination. The rise of end-tidal pCO2 was the striking symptom thus allowing the detection of the incipient malignant hyperthermia. Early onset of dantrolene therapy is shown to be sufficient in termination of this hyperacute complication, and may prevent its deleterious outcome. Therefore, the administration of dantrolene should be taken into account in case of porcine MH, especially in time-consuming and costly series of animal experiments.

New antiarrhythmic drugs in pediatric use: amiodarone

Amiodarone, a class III antiarrhythmic agent, prolongs action potential duration and refractoriness of all cardiac structures. The drug is more rapidly metabolized in pediatric patients than in adults, but its kinetics are still unique compared with other drugs. Due to the unusual pharmacokinetic characteristics of amiodarone, treatment has to be started by administering loading doses, and there is a significant delay both in the achievement of the full anti-arrhythmic effect and in the development of side effects. Amiodarone is a highly effective agent in pediatric patients with automatic and reentrant supraventricular tachycardia as well as in refractory atrial flutter. Efficacy in ventricular tachycardia has been shown to be variable depending on the underlying anatomical substrate. The incidence of side effects is lower than that observed in adult studies with similar duration of therapy but their incidence is still significant. Amiodarone treatment is associated with a significant risk of proarrhythmic effects, requiring hospitalization of the patient during the loading period.

Development of a questionnaire for assessing the school environment

This article describes the development of a school environment questionnaire to assess students' perception of their school environment. The dimensions and internal consistency reliability were examined utilizing various statistical methods-factor analysis and alpha coefficient. The sample consisted of 705 students from two high schools with ages ranging from ten to nineteen years. Results showed that the students perceived their school as having various aspects, rather than a global point of view. Factor analysis identified seven dimensions in the school environment: external characteristics of the environment, aesthetic and functional elements of the classroom, students' bathroom, the canteen and staffroom, the aesthetic and functional elements of the school as a whole and sanitation. Overall the internal reliability of the factors was high. Implications for school health programs are addressed.

[Familial idiopathic atrial fibrillation with bradyarrhythmia]

Based upon a report of a 10-year-old boy, familial occurrence of idiopathic atrial fibrillation with bradyarrhythmia is presented. An autosomal dominant trait seems possible.

[The automatic implantable cardioverter-defibrillator for prevention of sudden heart death in children and adolescents]

Little experience exists with the automatic implantable cardioverter-defibrillator in the pediatric population. Since 1990, an automatic implantable cardioverter defibrillator was implanted in four young patients (mean age 15.8 years, mean body weight 53.3 kg) with life-threatening ventricular tachyarrhythmias at our institution. In three patients, a cardiac anomaly was evident (dilated cardiomyopathy, status post Rastelli operation for complex transposition of the great arteries, status post atrial switch for transposition of the great arteries), the last patient had a normal cardiac anatomy. Indications for implantation were resuscitation from documented hypotensive ventricular tachycardia in one patient and recurrent syncope of suspected cardiac origin in the remaining three patients. At preimplantation electrophysiological study, all four patients had inducible ventricular tachycardia and/or ventricular fibrillation. At implantation of the cardioverter defibrillator in the operating theatre, the ventricular tachyarrhythmias were again induced and terminated reliably by the device. After a mean follow-up of 13 months, three of the four patients had appropriate discharges without syncope or resuscitation. The automatic implantable cardioverter-defibrillator appears to be a feasible and effective therapy also in pediatric patients for prevention of sudden cardiac death due to ventricular tachyarrhythmias.

[Emergency 12-hour transesophageal stimulation in a 21-month-old infant]

In a 21-month-old child with complex cyanotic congenital heart disease an aortopulmonary shunt was created as preparation for a modified Fontan operation. During the early postoperative period low cardiac output with right atrial pressures of 20 mm Hg developed due to a slow ventricular tachycardia (ventricular rate 135 bpm). Pharmacological interventions (isoprenaline 0.01 mg/kg hourly and lidocaine 1 mg/kg hourly were without any effect. As epicardial pacing leads had not been implanted during surgery, atrial pacing was performed via the transoesophageal route using a 9.5-F bipolar electrode catheter with an interelectrode distance of 15 mm. Atrial capture could be established with an impulse width of 9.9 ms and 10 mA output at a rate of 150 bpm. With restoration of atrioventricular synchronicity, right atrial pressure finally decreased to 10 mm Hg with consecutive stabilization of the cardiovascular status. After 12.5 h transoesophageal pacing could be stopped without any problems due to spontaneous cessation of ventricular tachycardia. No clinical signs of oesophageal injury were noted. It is concluded that transoesophageal pacing is a practical, safe and effective method for emergency cardiac pacing.

Usefulness of propafenone for supraventricular arrhythmias in infants and children

The relation between propafenone dose, serum level, electrocardiographic parameters, antiarrhythmic drug efficacy and adverse effects was studied in 47 children with symptomatic supraventricular arrhythmias aged 1 day to 10.3 years (median 2.2 months) with a mean follow-up of 14.3 months. Propafenone trough serum levels were measured using gas chromatography. Oral propafenone (mean dose 353 mg/m2/day) was effective in 41 of the 47 patients (87.2%). Serum levels did not differ between patients responding and not responding to propafenone (0.45 +/- 0.40 vs 0.36 +/- 0.41 mg/liter). PR interval and QRS complex duration increased more significantly with propafenone dose increments (p < 0.001), than with propafenone serum levels (p < 0.05). At successful treatment PR interval and QRS complex were prolonged by a mean of 19.2 and 20.5% compared with pretreatment status. Five patients exhibited unexpected marked QRS complex prolongation (50 to 200%) despite low propafenone dosage (< 300 mg/m2/day) and level ranging from 0.05 to 1.33 mg/liter. Three patients (6.1%) were suspected of being "poor" metabolizers of propafenone. Mild chronic elevation of serum liver enzymes was observed in 5 patients treated with a larger dose (mean 448 mg/m2/day, p < 0.001). No proarrhythmia was noted on serial Holter monitors. One patient with Wolff-Parkinson-White syndrome and a normal heart had cardiac arrest after aspiration. Serial monitoring of PR interval and QRS complex duration was more useful for proper dosage adjustment than propafenone serum levels. Serum liver enzymes should be closely monitored when using higher propafenone doses. Malignant proarrhythmia could not be excluded in the 1 patient with cardiac arrest.

[Definitive therapy of supraventricular tachycardia using high frequency current catheter ablation]

BACKGROUND

Catheter ablation using radiofrequency current has been proven to be an effective and save tool for the treatment of adult patients with accessory atrioventricular pathways and with atrioventricular nodal reentry tachycardia. This study was designed to analyse the efficacy of this method in children and adolescents.

PATIENTS AND METHODS

Using radiofrequency current, catheter ablation of an accessory pathway or of AV nodal reentry tachycardia was performed in 13 patients (mean age 12.7 years) with drug-refractory supraventricular tachycardia. Radiofrequency current was applied through a 6 French steerable catheter positioned against the mitral or tricuspid anulus. Criteria for radiofrequency current application (at 70 degrees C or with 30 W) were the recording of an accessory pathway potential or a local atrioventricular interval < 40 ms. In the patient with atrioventricular nodal reentry tachycardia, a potential of the slow pathway was recorded.

RESULTS

In 6 of 7 patients with left-sided accessory pathways and in 4 of 5 patients with right-sided connections, conduction over these pathways was permanently interrupted. In the patient with atrioventricular nodal reentry tachycardia, radiofrequency current eliminated the tachycardia without affecting normal atrioventricular nodal conduction. In a patient with an anteroseptal pathway, induction of atrioventricular block was inevitable. No other complications were noted.

CONCLUSION

Catheter ablation using radiofrequency current is a highly effective method for definite treatment of supraventricular tachycardia in children and adolescents.

[Atrial arrhythmias after modified Fontane operation: effect of preoperative hemodynamics and the kind of operation (atriopulmonary vs. total cavopulmonary anastomosis)]

Between October 1986 and March 1992, occurrence of supraventricular tachycardia and sinus node dysfunction was investigated pre- and postoperatively by serial ECG and Holter monitors in 63 consecutive patients with univentricular circulation after modified Fontan operation (total cavopulmonary connection 39 patients, atriopulmonary connection 24 patients). Mean age at operation was 7.2 (0.1-20.3) years. Of the 63 patients, 14 (22%) had early (< 14 d) supraventricular tachycardia or sinus node dysfunction, which was not related to the type of operation. None of nine patients with a preoperative mean right atrial pressure < or = 2.5 mm Hg had early supraventricular tachycardia or sinus node dysfunction, in contrast to 16/54 patients (30%) with a preoperative mean right atrial pressure > or = 2.5 mm Hg. 6/63 patients died during the early (< 14 d) postoperative period. In only one child death was related to a dysrhythmia (junctional ectopic tachycardia). During a mean follow-up of 2.5 years, 12 patients (21%) had late supraventricular tachycardia or sinus node dysfunction. Early supraventricular tachycardia/sinus node dysfunction was a predictor of late atrial dysrhythmias, as it occurred in eight of the surviving 14 patients with early dysrhythmias, in contrast to four children without early atrial dysrhythmias (p < 0.001). After creation of an atriopulmonary connection, 10/22 patients (45%) had late supraventricular tachycardia/sinus node dysfunction, but only 2/35 patients (6%) with a total cavopulmonary connection had late atrial dysrhythmias (p < 0.001).

CONCLUSIONS

Early atrial dysrhythmias after the Fontan operation were related to preoperative hemodynamics. Early supraventricular tachycardia/sinus node dysfunction and the atriopulmonary type of Fontan connection were significant risk factors for late atrial dysrhythmias.

[Therapy of postoperative ectopic junctional tachycardia by surface hypothermia]

Postoperative junctional ectopic tachycardia is associated with a poor prognosis in patients after open-heart surgery. This dysrhythmia has been shown to be resistant to medical treatment as well as to epicardial pacing and external cardioversion. Successful therapy with surface hypothermia in an infant with junctional ectopic tachycardia (ventricular rate 210-230 bpm) after repair of tetralogy of Fallot is presented. Hypothermia (rectal temperature 32-34 degrees C) was effective in decreasing the ventricular rate of the dysrhythmia (< 170 bpm). After spontaneous cessation of the tachycardia, sinus rhythm resumed, resulting in stable hemodynamics.

Molecular genetic study of the frequency of monosomy 22q11 in DiGeorge syndrome

It is well established that DiGeorge syndrome (DGS) may be associated with monosomy of 22q11-pter. More recently, DNA probes have been used to detect hemizygosity for this region in patients with no visible karyotypic abnormality. However, DGS has also been described in cases where the cytogenetic abnormality does not involve 22q11; for instance, four cases of 10p- have been reported. In this study we have prospectively analyzed patients, by using DNA markers from 22q11, to assess the frequency of 22q11 rearrangements in DGS. Twenty-one of 22 cases had demonstrable hemizygosity for 22q11. Cytogenetic analysis had identified interstitial deletion in 6 of 16 cases tested; in 6 other cases no karyotype was available. When these results are combined with those from our previous studies, 33 of 35 DGS patients had chromosome 22q11 deletions detectable by DNA probes.

Histological and immunopathological analysis of recovered encapsulated allogeneic islets from transplanted diabetic BB/W rats

Allogeneic islets encapsulated in an alginate/poly-L-lysine membrane and transplanted into diabetic BB/W rats resulted in graft failure within 2 weeks of transplantation. Graft failure was associated with a dense pericapsular infiltrate (PCI) that resulted in necrosis of the encapsulated islets. The PCI could be inhibited by immunosuppressive agents, including cyclosporine and dexamethasone, and this resulted in a significant increase in graft survival. Immunopathological characterization of the PCI indicated that there was a predominance of macrophages. T helper cells also appeared to be present in this PCI. Empty capsules were also found to induce a similar PCI that was identical in composition to that found around encapsulated islets. Thus alginate/poly-L-lysine capsules do not appear to be biocompatible and may account for the variable results in islet graft survival found with these capsules.

Efficacy and safety of propafenone in congenital junctional ectopic tachycardia

OBJECTIVES

Class IC antiarrhythmic drugs have recently been shown to be effective in some patients with atrial ectopic tachycardia. We therefore studied the efficacy of these drugs in patients with congenital junctional ectopic tachycardia.

BACKGROUND

Follow-up data on patients with junctional ectopic tachycardia suggest that this potentially lethal arrhythmia may cease spontaneously in a significant proportion of affected children. Therefore, temporary antiarrhythmic treatment appears to be the therapy of choice.

METHODS

The efficacy of propafenone was prospectively assessed in four infants with junctional ectopic tachycardia (ventricular rate 180, 185, 210 and 320 beats/min, respectively). The diagnosis of junctional ectopic tachycardia was established before the age of 2 months in all four infants. Propafenone was given orally in a mean dose of 350 (300 to 500) mg/m2 body surface area per day. Success of therapy was determined by serial electrocardiograms (ECGs) and Holter ambulatory ECG monitoring.

RESULTS

In two patients, junctional ectopic tachycardia was completely suppressed. In the remaining two patients, the tachycardia rate decreased to less than 150 beats/min. Serum propafenone levels did not correlate with efficacy of treatment. The mean duration of therapy was 18 months (range 3 to 36). No chemical or clinical side effects were noted.

CONCLUSIONS

Because of its effectiveness, safety and lack of side effects, propafenone appears to be a valuable drug in the treatment of junctional ectopic tachycardia in newborns and infants.

[Experiences with triple antibiotic combination in neonatal infection]

BACKGROUND

In-vitro and clinical efficacy of a combination therapy consisting of 3 antibiotic agents was to be assessed in neonatal septicemia.

METHODS

From 1980 to 1987, 152 newborns with septicemia as proven by blood culture were treated with an initial antibiotic regimen consisting of azlocillin (150 mg/kg bw), cefotaxime (100 mg/kg bw), and tobramycin (5 mg/kg bw).

RESULTS

According to the microbiologic testing, antimicrobic therapy was effective in each of the 152 organisms: 101/152 bacteria were susceptible to all 3 agents; resistance to 1 or 2 of the antibiotics was evident in 33/152 and in 18/152 organisms, respectively. Mortality due to septicemia was 7.2%.

CONCLUSION

As no difference was observed in the frequency in which one of the three antibiotic substances was the only effective drug, each of the 3 agents seemed to be necessary for clinical effectiveness of this antibiotic combination.

[Effectiveness of propafenone in congenital ectopic junctional tachycardia--a case report]

Junctional ectopic tachycardia is associated with a poor prognosis when it occurs in newborns and young infants. Like other automatic tachyarrhythmias, junctional ectopic tachycardia has been shown to be very resistant to medical treatment. Successful therapy with propafenone in a newborn with congenital junctional ectopic tachycardia is presented. Due to its high effectiveness, safety, and lack of side-effects, propafenone appears to be a valuable drug in the treatment of young patients with congenital junctional ectopic tachycardia.

Efficacy and safety of intravenous and oral propafenone in pediatric cardiac dysrhythmias

Propafenone was administered to 58 patients with a mean age of 3.2 years (range 0.1 to 16). Mean intravenous dose was 1.2 mg/kg body weight (range 0.3 to 1.5 mg). The final mean oral maintenance dose was 308 mg/m2 body surface area (range 200 to 600 mg/m2, 16.8 mg/kg body weight). After intravenous application, propafenone was effective in 21 of 36 patients; atrial flutter was converted in 1 of 5 patients, and reentry supraventricular tachycardia was controlled in 15 of 25 patients. Propafenone was partially or completely effective in 3 of 4 patients with chaotic atrial tachycardia. Junctional ectopic tachycardia was suppressed in 2 infants. Thirty-seven patients had oral treatment with a mean follow-up of 2.2 years. Propafenone was effective in 33 of 37 patients (89%); atrial flutter was controlled in 2 patients, ventricular ectopy was suppressed in 1 of 2 patients. In reentry supraventricular tachycardia, propafenone was effective in 25 of 28 patients. Chaotic atrial tachycardia (n = 3) and junctional ectopic tachycardia (n = 2) were controlled after successful intravenous therapy. Systemic side effects were rare. Two patients developed a proarrhythmic effect, and 1 patient with ventricular ectopy after repair of tetralogy of Fallot died suddenly during propafenone maintenance therapy.

[Complex cyanotic heart defect in a newborn infant with cat eye syndrome]

In a cyanotic newborn with characteristic features of Cat-Eye-Syndrome, cytogenetic examination disclosed a supernumerary small bisatellited chromosome. Angiography showed Tetralogy of Fallot with pulmonary atresia and a narrow patent ductus arteriosus with additional stenosis of the bifurcation of the pulmonary artery. At an age of 14 weeks, the patient died after the attempt of corrective cardiac surgery. Congenital cardiac malformation is present in more than one third of patients with cat-eye-syndrome and is usually the lifelimiting malformation in this syndrome.

Long-term follow-up of amiodarone therapy in the young: continued efficacy, unimpaired growth, moderate side effects

Long-term follow-up data on young patients receiving amiodarone is lacking, especially in relation to growth and late side effects. The records of 95 young patients (mean age 12.4 years; range 3 weeks to 31.5 years) who received amiodarone were reviewed. Minimal follow-up time for those continuing to take amiodarone was 1.5 years; the mean duration of therapy was 2.3 years (maximal 6.5). The mean maintenance dosage was 7.7 (1.5 to 25) mg/kg body weight per day. Initial success (based on symptoms and 24 h electrocardiogram) was achieved in 23 of 34 patients with ventricular tachycardia, in 32 of 33 with atrial flutter and in 21 of 28 patients with supraventricular tachycardia. However, in 7 of 33 patients with atrial flutter, the arrhythmia returned after 6 months. Patient growth continued in the same percentiles achieved before amiodarone in all but eight patients, improving in six and worsening in two with severe underlying disease. Proarrhythmia occurred in three patients: one had torsade de pointes that disappeared when amiodarone administration was stopped; two with severe anatomic heart disease died suddenly during the loading period (one with atrial flutter and one with ventricular tachycardia). Side effects occurred in 28 (29%) of the 95 patients: keratopathy (in 11), abnormal thyroid function test (in 6), chemical hepatitis (in 3), rash (in 3), peripheral neuropathy (in 2), hypertension (in 1) and vomiting (in 1). All side effects disappeared when amiodarone was discontinued or the dose was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular couplets in the young: prognosis related to underlying substrate

Ventricular couplets may be a risk factor for sudden death in adults, but their prognosis in children is unknown. From 1981 to 1987 104 patients, mean age 13.2 years (0.2 to 37 years), had ventricular couplets on a 24-hour electrocardiogram (ECG) (Holter monitor) and on follow-up with a second Holter (mean, 2.5 years). Of the 104 patients, 22 had a normal heart and 82 had an abnormal heart. Patients with a normal or an abnormal heart did not differ in incidence or severity of symptoms (patients with a normal heart had 17 instances of palpitations and none of syncope; patients with an abnormal heart had 49 instances of palpitations, six of dizziness, and none of syncope). Number of ventricular couplets was higher in patients with a normal heart (33 +/- 50/day: mean +/- 1 SD) than in those with an abnormal heart (17 +/- 15/day; p less than 0.05). Of the 22 patients with a normal heart, 11 underwent an electrophysiologic study (EPS); none had inducible ventricular tachycardia. After mean follow-up of 29.7 months, all 22 patients with a normal heart were alive without ventricular tachycardia; 6 of 22 were treated for palpitations, with complete suppression of couplets in two. In 11 of 16 untreated patients with a normal heart, ventricular couplets disappeared spontaneously. Of the 82 patients with an abnormal heart, 32 had an EPS: nine (28%) had sustained ventricular tachycardia, 16 (50%) had nonsustained ventricular tachycardia, and seven (22%) had no inducible ventricular tachycardia. ECG criteria and hemodynamic status were of limited value in predicting inducibility of ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Epicardial mapping: how to measure local activation?

Epicardial ventricular mapping was performed in 5 dogs during sinus rhythm with a sock array containing 41 electrodes. Maps were generated with a computer-assisted mapping system using four different definitions of local epicardial activation: (1) maximal negative slope (intrinsic deflection) of the unipolar electrogram, (2) maximal slope of the bipolar electrogram, (3) maximal amplitude of the bipolar electrogram, and (4) first onset by 45 degrees from the baseline of the bipolar electrogram. The site of earliest and latest epicardial activation was identical with maximal negative slope in the unipolar electrogram and maximal slope and maximal amplitude of the bipolar electrogram in all five animals. Times of earliest and latest epicardial activation calculated with maximal amplitude of the bipolar electrogram were most similar to those evaluated with maximal negative slope of the unipolar electrogram. Using onset of the bipolar electrogram, activation times were measured 10 to 12 msec earlier than with each of the other three definitions of local activation, and in two of the five animals, first epicardial breakthrough was mapped to a different site than with the three other methods.

CONCLUSIONS

(1) Maximal amplitude of the bipolar electrogram coincided with maximal negative slope of the unipolar electrogram; (2) Using onset of the bipolar electrogram, timing and location of earliest epicardial activation may be misinterpreted.

Relation of syncope in young patients with Wolff-Parkinson-White syndrome to rapid ventricular response during atrial fibrillation

Syncope in patients due to Wolff-Parkinson-White (WPW) syndrome may be related either to a rapid rate of supraventricular tachycardia or to rapid ventricular response over the accessory pathway during atrial fibrillation (AF). From 1982 to 1987, 74 patients less than or equal to 25 years old (mean age 12.6 years) with WPW syndrome on electrocardiogram underwent electrophysiologic study. Of the 74 patients, 14 (19%) had a history of syncope. During electrophysiologic study 9 of 14 patients with syncope had sustained (greater than 5 minutes or requiring termination due to hypotension) AF. Of the remaining 5 patients, 3 had inducible nonsustained AF and 2 had no AF. None of the 60 patients without syncope developed sustained AF; 34 had nonsustained and 26 had no AF. Occurrence of sustained AF had a sensitivity of 64% and specificity of 100% for history of syncope. All patients with syncope and AF (12) had a short RR interval between 2 consecutive preexcited QRS complexes during AF at less than or equal to 220 ms, in contrast to 9 of 34 patients without syncope (p less than 0.001, sensitivity 100%, specificity 74%). No patient with a short RR interval between 2 consecutive preexcited QRS complexes during AF of greater than 220 ms had a history of syncope. Thus, in these young patients with WPW syndrome, occurrence of AF with a rapid ventricular response during electrophysiologic study correlated well with a history of syncope and may be the cause of syncope in most patients. Electrophysiologic study may be helpful in identification of young patients with WPW at risk for syncope.

Epicardial mapping: ventricular epicardial activation is unaffected by heart position

Epicardial ventricular mapping was performed in five dogs during sinus rhythm with a sock array containing 41 bipolar electrodes. Maps were generated with a computer-assisted mapping system when the heart was in situ and when the heart was lifted by 44 degrees out of the chest. Times of earliest and latest epicardial activation in these two states did not differ. Despite a different frontal plane QRS axis, location of earliest activation was not affected by lifting the heart. In two of the five animals, the site of latest epicardial activation was minimally different from the heart in situ, but the general pattern of epicardial activation was unchanged. Therefore, the change in frontal plane QRS axis with lifting the heart was due to a change in heart position rather than a general change of heart activation.

[Echocardiography diagnosis of total anomalous pulmonary venous drainage in the neonatal period]

A 20-days-old female newborn was referred to our hospital because of persistent respiratory distress and a mild central cyanosis. On echocardiography from the suprasternal notch all 4 pulmonary veins could be visualized entering a common chamber posterior to the left atrium. This chamber communicated with a left vertical vein which drained through a large innominate vein into the right superior vena cava. The diagnosis of supracardiac type of TAPVD was confirmed the following day by angiography. The child was successfully operated and the postoperative course was uneventful. Cardiac catheterization carries an increased risk in patients with TAPVD in case of pulmonary hypertension due to pulmonary-venous obstruction. In experienced centers echocardiography has become the definite diagnostic method with a high level of sensitivity and specificity in patients with atrial sitlus solitus, unifocal pulmonary venous connection, and no evidence of other major congenital cardiac defects. With continuously improving knowledge an increasing number of newborns will benefit from improved ability to perform surgical repair without prior cardiac catheterization.

Relationship marketing for health care providers

A relatively new concept termed "relationship marketing" is examined in terms of its usefulness for providers targeting employers as direct purchasers of health care services. The discussion includes (1) a consideration of why employers' rhetoric about health care purchasing practices has so far exceeded the reality of change and (2) ways in which relationship marketing can be adopted by providers to influence the health care purchasing practices of organizational buyers.

[Percutaneous intraluminal balloon dilatation of valvular pulmonary stenoses in infancy and childhood. Presentation of results with special reference to balloon size]

34 percutaneous balloon valvuloplasties (BVP), including four repeat procedures, were performed in 30 patients (aged 3 months to 19.4 years, mean 5.8 years) with congenital pulmonary valve stenosis. Out of six failures four were due to dysplastic thickened valves; in two children a significant part of obstruction was on the subvalvular level. After first BVP a significant reduction of the right ventricular outflow tract (RVOT) gradient (mean 58.8 +/- 13.2%) was achieved in 24 of 30 cases. The mean pre-BVP RVOT gradient of 67 +/- 24.4 mm Hg was reduced to 27.2 +/- 10.2 mm Hg. Of 24 patients, 14 had a residual RVOT gradient of 25 mm Hg or less. Of the 24 patients, nine were recatheterized 12 to 24 months later, and a further RVOT gradient reduction (33.4 +/- 9.9 mm Hg to 24.2 +/- 14.5 mm Hg) was observed. In four patients additional RVOT gradient reduction (37.3 +/- 11.6 mm Hg to 18.5 +/- 10.5 mm Hg) was achieved by repeat BVP. Balloon size exceeded valve annulus diameter by up to 58% (mean 22%). No definite correlation between balloon size related to pulmonary valve annulus diameter and magnitude of right ventricular systolic pressure reduction was observed. Even using a maximal balloon size of 158%, no significant complications were noted, not even pulmonary valve insufficiency.

Sleep apnea and sleep-related periodic leg movements in community resident seniors

The elderly have a high incidence of sleep complaints. A high incidence of sleep apnea (SA) and sleep-related periodic leg movements (PLMs) is also suspected. The relationship between the incidence and severity of SA and PLMs and sleep complaints has not, however, been determined in terms of symptomatology and physiologic abnormality. In a group of 46 community resident seniors (60 to 95 years old), the incidence of SA and PLMs was correlated with subjective sleep-wake complaints. Sixty-one percent of subjects had SA and/or PLMs. Apneas/hypopneas were associated with an average oxygen desaturation of less than 5% and an average change in heart rate of less than 10 beats per minute. While subjects with SA or PLMs had clear evidence of objective sleep disturbance, only one quarter of them admitted to any subjective sleep complaints or daytime sleepiness. Furthermore, severity of SA or PLMs failed to predict sleep-wake complaints, and vice versa. This study confirms that typically mild SA and PLMs are widespread in the elderly but tend not to be manifested in sleep-wake complaints and probably go untreated as a result. Further research is needed to determine any long-term medical significance.

[Acute epiglottitis: therapeutic consequences of change in the resistance of Haemophilus influenzae serotype B]

From July 1977 to May 1987, 27 children with acute epiglottitis were treated in our intensive care unit. Haemophilus influenzae type b was identified by positive blood culture in 14 of 27 cases. Until 1983 the first 11 children were treated with ampicillin (100 mg/kg) for a mean duration of 10 days according to the standard therapeutic regimen and/or proven sensitivity from blood cultures (5 of 11 cases). The first finding of an ampicillin resistant Haemophilus influenza type b strain dates from January 1984. From this date on initial antibiotic therapy consisted of cefotaxime (100 mg/kg). Blood cultures proved good sensitivity to cefotaxime (100%) but an increasing rate of resistance to ampicillin (3 of 9 identified strains). Haemophilus influenzae septicemia in acute epiglottitis is verified by the isolation of Haemophilus influenzae type b from blood cultures (14/27) and the additional pneumonias (14/27). Additional meningitis as seen is a very rare complication. Facing these potentially life-threatening secondary foci of this invasive infection, an effective antibiotic therapy is mandatory. Our experiences confirm recommendations from US, UK, Australia, and Spain, where ampicillin was replaced by third generation cephalosporins as initial antibiotic therapy due to the increasing rate of resistance of Haemophilus influenzae type b.

The effect of small increases in dietary iodine on thyroid function in euthyroid subjects

Dietary iodine intake in the United States is greater than that considered necessary for the maintenance of normal thyroid function. The administration of pharmacologic quantities of iodine (10 to 1,000 mg daily) to euthyroid subjects results in small decreases in the serum T4 and T3 concentrations and a compensatory increase in the basal and TRH-stimulated serum TSH concentrations. Studies were carried out to determine whether a far smaller increase in iodine intake would also affect thyroid function. Normal volunteers received 1,500, 500, or 250 micrograms supplemental iodine daily for 14 days. Following the administration of 1500 micrograms iodine daily, there were small but significant decreases in the serum T4 and T3 concentrations and a small compensatory increase in the serum TSH concentration and the serum TSH response to TRH. In contrast, no changes in pituitary-thyroid function occurred during the administration of 500 or 250 micrograms iodine daily. These findings indicate that a small increase in dietary iodine can induce subtle changes (all values remaining within the normal range) in pituitary-thyroid function, probably by inhibiting thyroid hormone release. The smaller iodine supplements of 500 and 250 micrograms daily, quantities that may easily be achieved under normal conditions, did not, however, affect thyroid function.

Industrial marketing perspectives for health care providers

Hospitals and other providers have begun to market services directly to employers and other organizations. This paper describes employers' purchasing process for health care services, explains why changes have been limited so far, and suggests how the perspective of industrial marketing can be applied by providers to serve their own needs and those of employers more effectively.

Effect of iodine intake and methimazole on lymphocytic thyroiditis in the BB/W rat

Spontaneous LT and elevated serum anti-Tg occur in the diabetes prone BB/W rat, but thyroid function is essentially normal in the rats with LT. Prolonged low dose MMI decreases the incidence of LT in BB/W rats. The administration of excess iodine beginning at 30 days of age markedly accelerates the occurrence of LT and anti-Tg at 90 days of age. Low iodine intake decreases the incidence of LT. Excess iodine intake did not induce LT in W-line, Wistar-Furth, and Sprague-Dawley rats. This suggests that iodine induced LT occurs only in genetically susceptible rats. Despite the increased incidence of LT during iodine administration, thyroid function remains essentially normal. This is in contrast to the frequent induction of hypothyroidism following iodine administration to euthyroid patients with Hashimoto's thyroiditis. In order to decrease thyroid reserve, rats were hemi-TX at 30 days of age. The administration of iodine markedly increased the incidence of LT and serum anti-Tg, increased the weight of the remaining lobe, and induced hypothyroidism as determined by significantly lower serum T4 and T3 concentrations and elevated serum TSH concentrations. Excess iodine administration to hemi-TX W-line rats (genetically equivalent, non-diabetes, non-LT prone BB/W rats) did not induce LT but did induce hypothyroidism, suggesting that BB/W and W-line rats are susceptible to iodine induced hypothyroidism, perhaps unrelated to the induction of LT. Excess iodine did not induce LT or affect thyroid function in hemi-TX Wistar-Furth and Sprague-Dawley rats.