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The aim of this study was to compare, in vitro, the mechanical resistance to vertical displacement of the mandible after osteotomy for lateralization of the inferior alveolar nerve and installation of dental implants. One hundred eighty polyurethane mandibles were equally divided into 6 groups: G1-intact hemi-mandibles (control group), G2-hemi-mandibles after osteotomy for lateralization of the inferior alveolar nerve, G3-hemi-mandibles with installation of 3 bicortical dental implants (3.75 × 13 mm), G4-hemi-mandibles with installation of 3 dental implants that did not reach the basal cortical bone (3.75 × 11 mm), G5-hemi-mandibles after osteotomy for lateralization of the inferior alveolar nerve and installation of 3 bicortical dental implants (3.75 × 13 mm) and G6-hemi-mandibles after osteotomy for lateralization of the inferior alveolar nerve and installation of 3 dental implants that did not reach the basal cortical bone (3.75 × 11 mm). The specimens were subjected to linear loading tests. The highest mean value of maximum load was found in G1 (412.36N ± 11.99), followed by G2 (396.87N ± 23.94), G3 (319.63N ± 57.28), G4 (303.34N ± 18.25), G5 (231.75N ± 63.64) and G6 (228.13N ± 20.75). Based on this data, it can be concluded that the bicorticalization (or not) of the implants was not a statistically significant risk factor for the vertical displacement of polyurethane hemi-mandibles.

Edentulous patients with an atrophic maxilla associated with lip-palate fissures have unpredictable results after undergoing grafting procedures. In situations where the atrophic maxilla does not adequately allow reconstruction, the use of zygomatic implants has been indicated, and probably these implants can be indicated for the rehabilitation of patients with lip-palate fissures. This case report describes the oral rehabilitation treatment of a patient with a lip-palate cleft treated with zygomatic implants and implant-supported fixed prosthesis with two years of follow-up. A 65-year-old female patient had a lip-palate cleft and previously underwent surgery to close the cleft. The patient had a severely atrophic maxilla and had difficulty adapting to a removable total prosthesis. Due to the small amount of bone remaining and extensive fibrous tissue in the palate region, a rehabilitation with conventional implants associated with zygomatic implants was chosen. Two zygomatic implants and a conventional implant were placed on the right side, and a zygomatic implant and conventional implant were placed on the left side; these implants were later activated by a protocol-type prosthesis. The zygomatic implants provided an adequate aesthetic and functional outcome of the prosthesis in a patient with cleft palate.

Background: Focal atrial tachycardia (FAT) is an uncommon cause of supraventricular tachycardia in children. Incessant FAT can lead to tachycardia-induced cardiomyopathy. There is limited information regarding the clinical course and management of FAT. This study characterizes current management strategies for FAT in children including the prevalence of spontaneous resolution and the role of catheter ablation., Methods and Results: This is a retrospective chart review of pediatric patients with FAT managed between January 2000 and November 2010 at 10 pediatric centers. There were 249 patients with a median age at diagnosis of 7.2 (95% confidence interval, 5.8-10.4) years. Cardiomyopathy was observed in 28%. Resolution of FAT occurred in 89%, including spontaneous resolution without catheter ablation in 34%. Antiarrhythmic medications were used for initial therapy in 154 patients with control of FAT in 72%. Among first-line medications, β-blockers were the most common (53%) and effective (42%). Catheter ablation was successful in 80% of patients. FAT recurrence was less common with electroanatomic mapping compared with conventional mapping techniques (16% versus 35%; P=0.02). Patients were followed for a median of 2.1 (95% confidence interval, 1.8-2.6) years., Conclusions: FAT is managed successfully in most children. Current approaches are variable. Many patients have control of FAT with medications; however, catheter ablation is used for most patients. Spontaneous resolution is common for young children, emphasizing the role for delayed ablation in this group. Ablation is successful for all ages. Lower recurrence occurs when electroanatomic mapping techniques are used., (© 2014 American Heart Association, Inc.)

Introduction: The aim of this study was to evaluate the clinical presentation and outcomes of pediatric patients with ventricular tachycardia (VT) originating from left heart structures., Methods and Results: This international multicenter retrospective study including 152 patients (age 10.0 ± 5.1 years, 62% male), divided into those with fascicular VT (85%, 129/152) and nonfascicular LV VT (15%, 23/152). All patients had a normal heart structure or only a minor cardiac abnormality. Adenosine was largely ineffective in both groups (tachycardia termination in 4/74 of fascicular VT and 0/5 of nonfascicular LV VT). In fascicular VT, calcium channel blockers were effective in 80% (74/92); however, when administered orally, there was a 21% (13/62) recurrence rate. In nonfascicular LV VT, a variety of antiarrhythmic therapies were used with no one predominating. Ablation procedures were successful in 71% (72/102) of fascicular VT and 67% (12/18) of nonfascicular LV VT on an intention to treat analysis. Major complications occurred in 5 patients with fascicular VT and 1 patient with nonfascicular LV VT. After a follow-up period of 2 years (1 day to 15 years), 72% of all patients with fascicular VT were off medications with no tachycardia recurrence. One patient died of noncardiac causes. In nonfascicular LV VT, follow-up was 3.5 years (0.5-15 years), P = 0.38. A total of 65% of these patients were free from arrhythmias. Two patients died suddenly (P < 0.01)., Conclusion: The clinical course and outcomes of pediatric patients with fascicular VT and nonfascicular LV VT are varied. Catheter ablation procedures can be curative., (© 2013 Wiley Periodicals, Inc.)

Objectives: This study sought to determine institutional complication rates in a previously underreported patient population and discuss referral indications., Background: There has been a trend over the years for referral of younger and smaller patients for "elective" closure of atrial septal defects (ASD). In general, the risks associated with ASD device closure are believed and reported to be relatively low. Complication rates in this group of smaller patients are not well described in the literature for either percutaneous or surgical approaches., Methods: Retrospective review of all patients who underwent elective transcatheter closure of secundum ASD between March 2000 and April 2010. We excluded all children >15 kg, as well as those with complex congenital heart defects. Major and minor complications were predefined and indications for referral were evaluated., Results: We identified 128 patients meeting criteria with a median procedural age of 1.92 years (3 months to 4.92 years), and median weight of 10.8 kg (4.3 to 14.9 kb). There were 7 major (5.5%) and 12 minor (9.4%) complications. Nearly two-thirds of referrals were for right heart enlargement or poor growth. Rate of resolution of residual shunt was 99%. When compared with age, there was no difference in the rate of resolution of right heart enlargement. No clinically significant improvement in growth was observed., Conclusions: Transcatheter ASD closure in small children is highly successful, but with an increase in previously perceived complication rates. In small, asymptomatic patients, deferral of closure until the historically established timeline of around 4 to 5 years of age should be strongly considered., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Little data exist on the outcomes of cryoablation for the treatment of presumptive atrioventricular nodal reentrant tachycardia (AVNRT) in a pediatric population., Methods: We performed a retrospective chart review of patients undergoing cryoablation from January 2006 to October 2010 for presumed AVNRT at the Children's Hospital Colorado. Inclusion criteria were age ≤ 18, normal heart structure, no prior ablation procedures, documented narrow complex tachycardia, and no inducible tachycardia or other tachycardia mechanisms during electrophysiology study., Results: Thirteen patients underwent cryoablation for presumed AVNRT. Cryoablation catheter tip size varied from 4 to 8 mm with a median of eight cryoablation lesions. Isoproterenol was utilized preablation in 54% and none postablation. Procedural endpoints, per written report, were loss of sustained slow pathway, change in Wenckebach cycle length, and no specific endpoint. Procedural endpoints, per measured data, were a decrease in patients exhibiting sustained slow pathway conduction. Maximum atrial-His (AH) interval with atrial overdrive pacing was reduced from 266 ms preablation to 167 ms postablation, p = 0.006. The number of patients with an AH jump was reduced from 6 to 2. After follow-up of 13.8 ± 14.3 months, 23% (3/13) had documented tachycardia recurrence. No statistical significance was determined when comparing electrophysiology testing parameters pre- and postablation among the group with recurrence versus the group without recurrence., Conclusions: Cryoablation can be considered as a safe alternative to radiofrequency ablation for the treatment of presumed AVNRT among pediatric patients, albeit with a recurrence rate of 23%., (©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Background: Nonfunctional, dysfunctional, recalled, or additional endocardial leads in pediatric and congenital heart disease patients pose significant challenges for management. There are no set standards for lead extraction in this patient population., Methods: Physician members of the Pediatric and Adult Congenital Electrophysiology Society (PACES) were contacted via e-mail and invited to respond to a 33-question online Pediatric and Adult Congenital Endocardial Lead Extraction or Abandonment (PACELEAD) survey., Results: Responses were received from 75 of 138 (54%) physician members of PACES. Institutional volumes of device placement (<25 devices/year for 51% of responders), patients with abandoned leads (<25 patients for 71%), and lead extractions (<10 extractions/year for 51% and no extractions for 29%) were low for the majority of responders. Personal experience with lead extraction was also minimal with 49% not performing the procedure and 39% with less than 40 leads extracted as primary operator. Most responders (54, 72%) refer their lead extractions to another practitioner or facility with more experience. Responders were more likely to recommend lead extraction (>70%) for class IIa indications such as bacteremia, chronic pain that is not medically manageable, and functional leads with ipsilateral venous occlusion. Lead abandonment was favored (>70%) for one class IIb indication, a functional lead that is not currently being used., Conclusions: Optimal lead management is challenging in pediatric and congenital heart disease patients, and considerable variability of practice is reported in their care. Low institutional and personal volumes may account for this variability., (©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.)

In general, syncope in children and adolescents is a benign event. Syncope during exercise may identify patients with a potentially fatal condition. Catecholaminergic polymorphic ventricular tachycardia is characterized by life-threatening ventricular arrhythmias, usually polymorphic ventricular tachycardia or ventricular fibrillation, occurring under conditions of exercise or emotional stress. Catecholaminergic polymorphic ventricular tachycardia is a familial condition that presents with exercise-induced syncope or sudden death in children or young adults. Detailed evaluation should be considered for patients who have syncope during exercise, injure themselves during the fall (i.e., unprotected faint with no antecedent warning prodrome), or who have a family history of syncope, early sudden cardiac death, myocardial disease, or arrhythmias.

Background: Cryoablation for arrhythmia substrates in pediatrics has been available since 2003. The purpose of this study was to evaluate the current approach of pediatric electrophysiologists to the use of cryoablation in the current era., Methods: We sent an Internet link to an online survey to all members of the Pediatric and Congenital Electrophysiology Society. Individuals and not institutions were surveyed., Results: A total of 70 responses were received. Responding physicians were largely invasive pediatric electrophysiologists (94%) who practice at mid- to high-volume centers (>50 ablation procedures/year). Survey responders report that cryoablation was utilized for <50% of the ablation volume, and most utilize it for only 10%. With respect to specific arrhythmia substrates, 41% of responders use cryoablation as first-line therapy for atrioventricular nodal reentrant tachycardia. For accessory pathways, 94% report that cryoablation would only be utilized after mapping the accessory pathway to a "high-risk location." Other arrhythmia substrates considered for cryoablation would be accessory pathways mapped to high-risk areas, junctional ectopic tachycardia, a parahisian ectopic atrial tachycardia, or an atrial tachycardia near the phrenic nerve., Conclusion: For pediatric electrophysiologists who responded to the survey, radiofrequency energy remains the primary energy source for ablation. The current use of cryoablation technology is directed at arrhythmia substrates near the normal conduction system or other "high-risk" areas., (©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.)

Background: Dual atrioventricular (AV) nodal physiology is a substrate for the development of AV nodal reentrant tachycardia (AVNRT). However, the risk of developing AVNRT in patients with dual AV nodal physiology is not known. The purpose of this study is to identify the risk of developing AVNRT in children and adolescents with incidental findings of dual AV nodal physiology after accessory pathway ablation., Methods: This is a single center retrospective study of patients who underwent intracardiac electrophysiology study at The Children's Hospital, Denver, from March 1993 to August 2008, with findings of dual AV nodal physiology after successful ablation of an accessory pathway. Follow-up was obtained by chart review with the primary outcome of recurrent supraventricular tachycardia. Extended clinical follow-up was also achieved through phone contact with patients or parents of patients., Results: Mean age at initial electrophysiology study was 12.8 years (±3.7 years). Follow-up was obtained on all 66 patients for a mean duration of 3.1 years (±2.8 years). Mean age at follow-up was 15.8 years (±4.6 years). Recurrent supraventricular tachycardia occurred in nine of the 66 patients (13.6%). AVNRT was induced in two of the 66 patients (3.0%)., Conclusion: This study supports the hypothesis that incidental dual AV nodal physiology does not predict AVNRT in children and adolescents with after successful accessory pathway ablation., (©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.)

Background: A wearable automated external defibrillator has been shown to be efficacious in the prevention of sudden death in adults who had a history of cardiac arrest but who did not have a permanent internal cardioverter/defibrillator (ICD) placed. The use of a wearable defibrillator has not been established in the pediatric population., Methods: We retrospectively reviewed the clinical database for the wearable external defibrillator from ZOLL Lifecor Corporation (Pittsburgh, PA, USA). We compared the use of the wearable defibrillator in patients ≤18 years of age to those aged 19-21 years., Results: There were 81 patients ≤18 years of age (median age = 16.5 years [9-18] and 52% male). There were 103 patients aged 19-21 years (median age = 20 years [19-21] and 47% male). There was no difference between groups in average hours/day or in total number of days the patients wore the defibrillator. In patients ≤18 years of age, there was one inappropriate therapy and one withholding of therapy due to a device-device interaction. In patients aged 19-21 years, there were five appropriate discharges in two patients and one inappropriate discharge in a single patient., Conclusion: It is reasonable to consider the wearable automated external defibrillator as a therapy for pediatric patients who are at high risk of sudden cardiac arrest but who have contraindications to or would like to defer placement of a permanent ICD. As there were no appropriate shocks in our patients ≤18 years of age, this study cannot address efficacy of the therapy., (©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.)

A female infant presented with bradycardia and an electrocardiogram demonstrating 2:1 atrioventricular depolarization, a prolonged QT interval, and T wave alternans. After propranolol therapy was initiated, a lidocaine challenge was performed with progressive shortening of the QT interval. This positive lidocaine challenge prompted clinical suspicion of long QT syndrome type 3 (LQT3) and early initiation of mexiletine therapy. Subsequent genetic testing confirmed the infant's diagnosis of LQT3.

Surgical scars secondary to the placement of pacemakers or internal cardioverter/defibrillators in the infraclavicular area can be unsightly. This report describes a novel cosmetic approach for the placement of pacemakers or internal cardioverter/defibrillators. The approach involves a small infraclavicular incision for placement of the leads and then a larger incision hidden high up in the axilla. The theoretical advantages of this approach are improved cosmetic outcome, ease of subsequent surgeries for device generator changes, and potentially improved defibrillation thresholds.

We describe the case of a 3-year-old child with neonatal Marfan syndrome complicated by mitral valve prolapse with regurgitation, marked aortic root dilatation, and ventricular tachycardia. The patient had resolution of ventricular tachycardia following surgical intervention consisting of a valve-sparing aortic root replacement and mitral valve annuloplasty.

Study Objective: We assess accuracy of ECG interpretation and indications for obtaining ECGs and develop a clinical classification system of ECG abnormalities., Methods: Prospectively acquired ECG data on patients 0 to 21 years of age and presenting to our pediatric emergency department (ED) were obtained. Clinical indications were documented. The initial ECG interpretation (pediatric ED attending physician) was compared with the criterion standard (pediatric cardiologist). A blinded cardiology panel reviewed discrepancies, and a final concordance rate was determined. An ECG abnormality classification system was developed and used to categorize these abnormal ECGs., Results: One thousand six hundred fifty-three ECGs from 1,501 patients, aged 2 days to 21 years (median 10.0 years), were obtained during 3.5 years. Fifty-one percent were male patients. ECG indications included chest pain (21%), seizure or syncope (18%), arrhythmias (17%), apparent life-threatening event or respiratory symptoms (16%), ingestions (10%), cardiac abnormality (10%), and miscellaneous (8%). From 1,631 ECGs, 1,160 (71%) were normal (class 0), 259 (16%) were minimally abnormal (class I), 174 (11%) were moderately abnormal (class II), and 38 (2%) were severely abnormal (class III). Kendall's tau-b test showed concordance of 0.73 (95% confidence interval 0.70 to 0.77) between pediatric ED and cardiology interpretation. The sensitivity of pediatric ED interpretation was 75%, and the specificity was 98.5%. The positive predictive value of pediatric ED interpretation was 88.3%, and the negative predictive value was 96.3%., Conclusion: We conclude that, overall, a high rate of concordance exists between the pediatric emergency physician's and the cardiologist's ECG interpretation. The majority of discordant ECGs are not clinically significant. However, among the clinically significant ECGs, there is a higher rate of discordance. These data suggest that review of pediatric ECGs by pediatric cardiologists may significantly reduce underdetection of clinically important ECG findings in children.

Background: This multicenter study evaluated experience with implantable cardioverter defibrillators (ICD) as a bridge to orthotopic heart transplantation (OHT) in children., Methods: The application of ICD therapy continues to expand in pediatric populations, due in part to improved technology and new indications, including the prevention of sudden death while awaiting OHT., Methods: We performed a retrospective review of ICD databases at 9 pediatric transplant centers., Results: Twenty-eight patients (16 males) underwent implantation or had a preexisting ICD while awaiting OHT between 1990 and 2002. The median age at implant was 14.3 years (11 months to 21 years) with a median weight of 49 kg (11.7-88 kg). Diagnoses included cardiomyopathy (n=22), and congenital heart disease (n=6). Indications for ICD implantation included ventricular tachycardia/fibrillation (n=23), syncope (n=5), aborted sudden death with no documentation of rhythm disturbance (n=5), ventricular ectopy (n=1), and poor function (n=5). Of the 28 ICDs, 23 were implanted by a transvenous approach and 5 by epicardial route. There were 55 defibrillator discharges in 17 patients, 47 (85%) of which (in 13 patients) were appropriate. The 8 inappropriate discharges (in 6 patients) were triggered by sinus tachycardia, inappropriate sensing, and atrial flutter. The mean time from implantation to first appropriate shock was 6.9 months (1 day to 2.6 years). Twenty-one patients underwent transplantation during the study period, whereas 2 died while awaiting a donor. Morbidity included a lead fracture, 3 episodes of electromechanical dissociation, and 1 episode of electrical storm., Conclusions: ICD implantation represents an effective bridge to transplantation in pediatric patients. The complication rate is low, with inappropriate device discharge due primarily to sinus tachycardia or atrial flutter. There is a high incidence of appropriate ICD therapy for malignant ventricular arrhythmias in this highly selected group of patients.

Two neonates presented with sustained, monomorphic VT. Transesophageal electrophysiological studies demonstrated that the VTs were initiated with burst atrial pacing in one and noninducible in the other, and both terminated with burst atrial pacing and with adenosine. Oral verapamil suppressed the VTs in both. Following discontinuation of verapamil at 1 year of age, both children remain free of tachycardia recurrence at 3 and 4 years of age. These cases suggest that cAMP-mediated triggered activity may be responsible for some VTs in infancy.

Objective: This pharmacokinetic-pharmacodynamic study was designed to define the steady-state relationship between pharmacologic response and dose or concentration of sotalol in children with cardiac arrhythmias, with an emphasis on neonates and infants., Methods: The treatment consisted of an upward titration with unit doses of 10, 30, and 70 mg of sotalol per square meter of body surface area. The patients received 3 doses at each dose level. The dosing interval was 8 hours. The Class III and beta-blocking activities of sotalol were derived from the QT and R-R intervals, respectively, of the surface electrocardiogram, which was recorded at 6 scheduled times before and after the third, sixth, and ninth doses. During these three dose intervals, 4 scheduled blood samples were also collected. Drug concentrations were measured with a validated nonstereoselective liquid chromatographic tandem mass spectrometric detection assay. Pharmacokinetic and pharmacodynamic parameters were obtained with standard methods., Results: Twenty-one centers enrolled 25 patients in the study: 7 were neonates, 9 were infants, and 11 were children between the ages of 2 years and 12 years. The area under the drug concentration-time curve increased proportionately with dose. The apparent oral clearance of sotalol was linearly correlated with body surface area and creatinine clearance. The smallest children (body surface area <0.33 m2) displayed greater drug exposure than the larger children. The increase of QTc and R-R intervals was dose dependent. At the 70-mg/m(2) dose level, the mean (+/- standard deviation) maximum increase for the QTc interval was 14% +/- 7% and the average Class III effect during a dose interval was 7% +/- 5%. At the same dose level, the mean maximum increase of the R-R interval was 25% +/- 15% and the average beta-blocking effect during a dose interval was 12% +/- 13%. The effects tended to be larger in the smallest children. The Class III response and the plasma concentrations of sotalol were linearly related. The treatment was well tolerated., Conclusions: The steady-state pharmacokinetics of sotalol were dose proportionate. Pharmacologically important beta-blocking effects were observed at the 30-mg/m2 and 70-mg/m2 dose levels. Important Class III effects were seen at the 70-mg/m2 dose level. The Class III effect was linearly related to the drug concentration.

The pharmacokinetics (PK) of the antiarrhythmic sotalol, which elicits Class III and beta-blocking activity, has not been adequately defined in a pediatric population with tachyarrhythmias. The goal of this single-dose study with administration of sotalol HCl at a dose level of 30 mg/m2 body surface area (BSA) was to define the PK of the drug in the following four age groups: neonates (0-30 days), infants (1 month to 2 years), younger children (> 2 to < 7 years), and older children (7-12 years) with tachyarrhythmias of either supraventricular or ventricular origin. The drug was administered in an extemporaneously compounded syrup formulation prepared from the tablets containing sotalol HCl. For safety, vital signs and adverse events were recorded and the QTc interval and heart rate telemetrically monitored. Scheduled blood samples were taken over a 36-hour time interval following dose administration. The drug concentrations in plasma were measured by a sensitive and specific LC/MS/MS assay. Standard compartment model-independent methods were applied to compute the salient PK parameters of sotalol. Twenty-four clinical sites enrolled 34 patients. Thirty-three had analyzable data. Sotalol was rapidly absorbed, with mean peak concentrations occurring 2 to 3 hours after administration. The elimination of sotalol was characterized by an average half-life of between 7.4 and 9.2 hours in the four age groups. There existed statistically significant linear relationships between apparent total clearance (CL/f) or apparent volume of distribution (V lambda z/f) after oral administration and the covariates BSA, creatinine clearance (CLcr), body weight (BW), or age. The best predictors for CL/f were CLcr and BSA, whereas BW best predicted the V lambda z/f. The total area under the drug concentration-time curve in the smallest children with a BSA < 0.33 m2 was significantly greater than that in the larger children. This finding indicated that the BSA-based dose adjustment used in this study led to a larger exposure in the smallest children, whereas the exposure to the drug was similar in the larger children. The dose of 30 mg/m2 was tolerated well. No serious drug-related adverse events were reported. It can be concluded that the PK of sotalol in the pediatric patients depended only on body size, except for the neonates and smallest infants in whom the disposition of sotalol was determined by both body size and maturation of eliminatory processes.

Deaths have been reported following radiofrequency catheter ablation (RFCA), but the mortality rate in children has not been defined. This study sought to analyze the incidence and the factors associated with mortality related to RFCA. Ten of 4,651 cases (0.22%) reported to the Pediatric RFCA Registry resulting in death were reviewed and compared with a matched control group (n = 18). Death occurred in 5 of 4,092 children (0.12%, ages 0.1 to 13.3 years) with structurally normal hearts. Death was related to traumatic injury, myocardial perforation and hemopericardium, coronary or cerebral thromboembolism, and ventricular arrhythmia. All cases were left-sided (p = 0.019 vs right or septal) supraventricular arrhythmias with radiofrequency applications in the systemic atrium and/or ventricle, and all procedures were successful. Mortality occurred in 5 of 559 children (0.89%, p = 0.001 vs normals, ages 1.5 to 17.4 years) with structural heart disease. No new pathology except the mural radiofrequency lesions was seen at autopsy. Those with structurally normal hearts who died were smaller (32.7 vs 55.6 kg, p = 0.023) and had more radiofrequency applications (26.3 vs 8.7, p = 0.019) than those who survived. No differences were demonstrated for those with abnormal hearts. Operator experience was not different (deaths 103 +/- 106 vs controls 117 +/- 125, p = 0.41). Mortality associated with pediatric RFCA is rare, but is more frequent when there is underlying heart disease, lower patient weight, greater number of radiofrequency energy applications, and left-sided procedures. Operator experience does not appear to be a factor leading to mortality.

Desflurane has several properties making it a desirable agent for use in electrophysiological studies (EPS) for diagnosis and treatment of cardiac dysrhythmias. We studied 47 children, mean age 12.8+/-4.6 years, mean weight 52.9+/-24.0 kg, with clinical history of supra- ventricular tachycardia (SVT) during EPS using desflurane in a crossover comparison with fentanyl. The patients served as their own controls. All received oral premedication with lorazepam, and intravenous induction with thiopentone, rocuronium, and oxygen. Group 1 (n=24) were administered fentanyl 10 microg.kg-1 bolus i.v. with an infusion of 3 microg.kg-1.h-1 during initial EPS. Fentanyl was discontinued and desflurane, 6% endtidal, was administered and the EPS repeated. Group 2 (n=23) were initially administered 6% desflurane after induction, and following EPS the desflurane was discontinued and the patients administered fentanyl 3 microg.kg-1 bolus and EPS repeated (explanations of EPS abbreviations are provided). Desflurane reduced the mean arterial pressure (MAP) in all patients. In Group 1, desflurane shortened the sinus cycle length (SCL), i.e. increasing the heart rate, and atrial effective refractory period (AERP) while Group 2 demonstrated no such effect on AERP. There were no other significant differences between fentanyl or desflurane techniques in terms of EPS measurements. SVT was inducible with both agents in both groups. Desflurane seems an acceptable agent for use during EPS procedures.

Fetal atrioventricular dissociation is a dysrhythmia associated with significant antenatal and postnatal morbidity and mortality. We present a case of a 19-week-old fetus with atrioventricular dissociation, which spontaneously resolved. The mother had no signs of autoimmune disease. The fetus had an uneventful gestation and, after delivery, had a normal cardiac and transesophageal electrophysiological evaluation.

We sought to describe the morphologic characteristics of pulmonary arteries by intravascular ultrasound (IVUS) in children with and without pulmonary hypertension to compare these anatomic findings with those of pulmonary wedge angiography, and to determine the relation between these structural findings and functional reactivity to pulmonary vasodilators. Direct evaluation of pulmonary vascular structure in children with pulmonary hypertension with current imaging techniques has been limited and little is known about the relation between structural and functional characteristics of the pulmonary vasculature. In 23 children undergoing cardiac catheterization (15 with pulmonary hypertension and 8 controls) we performed IVUS and pulmonary wedge angiography of the distal pulmonary arteries in the same lobe. IVUS was performed in 44 pulmonary arteries measuring 2.5 to 5.0 mm internal diameter with a 3.5Fr 30-MHz IVUS catheter. We assessed vasoreactivity to inhaled nitric oxide (NO) and oxygen in 13 of 15 children with pulmonary hypertension. Baseline pulmonary vascular resistance (PVR) was greater in the 15 children with pulmonary hypertension than in the 8 controls (9.5+/-1.9 vs 1.5+/-0.3 U x m2, p <0.05). NO lowered PVR in patients with pulmonary hypertension (p <0.05). IVUS studies in patients with pulmonary hypertension showed a thicker middle layer, wall thickness ratio, and diminished pulsatility than did those in controls (p <0.05). The inner layer was not visualized by IVUS in any control patient, but was seen in 9 of 15 patients with pulmonary hypertension. Pulmonary artery wedge angiography correlated with baseline mean pulmonary artery pressure and PVR as well as with IVUS findings of wall thickness ratio and inner layer thickness. The inner layer was not visualized by IVUS in any patient with grade 1 wedge angiograms or in 86% of patients with grade 2 wedge angiograms. All patients with grade 4 and 80% of patients with grade 3 wedge angiograms had a visible inner layer. Vasoreactivity to NO and oxygen did not correlate with structural assessment of the pulmonary vasculature by IVUS. Structural changes in the pulmonary arteries in children with pulmonary hypertension can be directly visualized by IVUS, but are not predictive of NO-induced pulmonary vasodilation. IVUS examination of pulmonary arteries may complement current techniques utilized in the evaluation of children with pulmonary hypertension.

Background: Inadvertent atrioventricular block is a complication of radiofrequency ablation. The present study is an analysis of the incidence, significance, and factors associated with inadvertent atrioventricular block during radiofrequency catheter ablation in childhood and adolescence., Methods and Results: The records of the Pediatric Radiofrequency Ablation Registry were reviewed. Between January 1, 1991, and April 1, 1994, atrioventricular block occurred in 23 of 1964 radiofrequency ablations (1.2%): 14 as third-degree block (3 transient) and 9 as second-degree block (5 transient). Atrioventricular block occurred from 5 seconds to 2 months (mean, 4.1 days; median, 15 seconds) after the onset of the energy application. Eight transient cases lasted 1 hour to 1 month (mean, 9.4 days; median, 7 days). Inadvertent atrioventricular block was related to the ablation anatomic site: 3 of 111 (2.7%) anteroseptal, 11 of 106 (10.4%) midseptal, and 2 of 197 (1.0%) right posteroseptal sites (P = .0007) for anteroseptal, P = .0001 for midseptal, and P = .17 for right posteroseptal versus nonright septal sites). Five of 314 (1.6%) ablations for atrioventricular nodal reentrant tachycardia resulted in atrioventricular block (P = .004 versus nonright septal sites). Compared with a matched subgroup, radiofrequency ablation experience was the only significant risk factor (32.7 versus 106.6, P = .002) for the occurrence of atrioventricular block., Conclusions: Inadvertent atrioventricular block may occur during or late after radiofrequency catheter ablation. It is associated with ablations for (1) anterior and midseptal accessory pathways and atrioventricular nodal reentry and (2) relative institutional inexperience.

Overall, these results indicate that oral treatment of neurally mediated syncope is safe and efficacious. Further randomized trials in children will be required to determine the significance of a placebo effect, as well as potential differences in results related to the mechanism of syncope.

To determine whether circulating levels of endothelin-1 (ET-1), a potent vasoconstrictor peptide, are elevated in children with pulmonary hypertension and related to the degree of hypoxic pulmonary vasoconstriction, we measured arterial and mixed venous plasma concentrations of immunoreactive ET-1 (irET-1) in 13 children during cardiac catheterization. Clinical diagnoses in seven children with pulmonary hypertension (PH) included chronic lung disease (four children), congenital heart disease after surgical repair (two children), and primary ("reactive") pulmonary hypertension (one child). Blood samples were simultaneously obtained from pulmonary artery (venous) and systemic arterial sites during baseline conditions. Plasma irET-1 was elevated in children with PH (12.3 +/- 3.4 versus 3.6 +/- 0.7 pg/ml, PH versus non-PH; p < 0.01). Arterial/venous irET-1 ratios in the PH group (1.1 +/- 0.2) were not different from those in the non-PH group. During acute hypoxia, mean Ppa increased from 27 +/- 3 to 40 +/- 5 mm Hg. Basal irET-1 correlated strongly with the degree of elevation of mean Ppa during acute hypoxia (r = 0.69; p < 0.02). We conclude that irET-1 levels are often elevated in children with PH, and they are strongly correlated with pulmonary vasoreactivity during acute hypoxia. Whether elevated irET-1 levels contribute directly to or are markers of altered pulmonary vascular tone and reactivity in children with PH remains speculative.

Radiofrequency catheter ablation is fast becoming the procedure of choice for the nonpharmacological treatment of atrioventricular connections that are responsible for debilitating tachycardias. We, herein, present a case of reentrant supraventricular tachycardia secondary to an atrioventricular connection in a Fontan patient that was successfully treated with radiofrequency catheter ablation.

Ventriculoatrial (VA) intervals during narrow complex tachycardia were measured in a pediatric population. The VA intervals were similar to those in adults but were slightly shorter. In the pediatric subjects values less than 60 msec excluded the participation of an accessory pathway in the tachycardia circuit. Three out of 11 patients with atrioventricular nodal reentrant tachycardia (AVNRT) had VA values greater than or equal to 70 msec, while 5 of 28 patients with orthodromic reciprocating tachycardia (ORT) had values less than or equal to 70 msec. Using a cut-off value of 70 msec as the sole criteria to distinguish between ORT and AVNRT could lead to errors in classification of the underlying mechanism of the tachycardia.

Eleven hundred one healthy neonates in Charleston County, SC, were enrolled in a prospective, serial measurement sudden infant death syndrome/QT surveillance program. Automated computer-enhanced ECGs were recorded at 1 day of age in the hospital nursery and again at 1 week and 1, 2, and 3 months in the participant's home. At 1 year, the families were contacted by phone or mail and questioned as to the health of the child. Validation studies demonstrated the computer-enhanced ECGs to be 96% accurate, whereas traditional ECG recording and measurement was 94% accurate. No systematic differences in the QTc according to race and sex were observed. There were parallel longitudinal time courses for each race and sex group with a significant (P less than .001) shortening of the QTc at 1 week. There was no evidence of tracking of the QTc during the first 3 months of life. In conclusion, (1) automated, enhanced ECG QTc intervals are superior to traditional electrocardiography while retaining the advantages of automation; (2) there is a significant shortening of the QTc during the first month of life; and (3) a home follow-up sudden infant death syndrome surveillance program is feasible and produces accurate, reliable information.

Little data are available on the hemodynamic effects of premedications and anesthetic agents on infants and children. Ketamine is the most frequently used anesthetic agent for cardiac catheterization procedures in pediatric patients with congenital heart disease. Previous reports both suggest and deny ketamine's pulmonary vasoreactive effects. Since the advent of sophisticated noninvasive equipment, one of the few indications for cardiac catheterization is to obtain accurate pressure data. If ketamine alters pulmonary vascular resistance, it would negate the primary reason for the procedure. Because the patient population studied herein resides greater than or equal to 1,200 meters above sea level, concerns about pharmacologic effects on pulmonary vascular resistance are enhanced. Simultaneous pulmonary artery and aortic pressures, thermodilution cardiac outputs, and blood gases were measured in room air (16% oxygen) and with ketamine infusion in 14 patients at cardiac catheterization. Reaction to hypoxia identified 3 groups: normal, intermediate and hyperresponders. The normal responders had normal resistance ratios (0.11) in room air and had little resistance ratio response to hypoxia (+0.02), hyperoxia (-0.03) or ketamine (+0.01). The intermediate responders had a slightly higher but normal resistance ratio (0.20) in room air, and a moderate reaction to hypoxia (+0.13), hyperoxia (-0.08) and ketamine (+0.11). The hyperresponders had an elevated resistance ratio (0.42) in room air and a striking reaction to hypoxia (+0.65), hyperoxia (-0.17) and ketamine (+0.49). Hypoxia and ketamine have a greater effect on resistance ratio than hypoxia alone in patients with reactive pulmonary vascular beds. Ketamine should not be used in children undergoing procedures to establish operability based on pulmonary vascular resistance or pulmonary vascular reactivity.

The experience at the University of Colorado with the St. Jude Medical cardiac valve was reviewed to determine the feasibility of placing this prosthesis in children and the role of anticoagulation. A St. Jude Medical cardiac valve was placed in 33 patients ranging in age from 2.5 months to 17 years. Seven patients were less than 1 year of age. Nineteen valves were placed in the aortic position in patients aged 5 months to 17 years (mean 9.5 years). Five patients had valve replacement only, 13 had concomitant aortoventriculoplasty and 1 a Manouguian procedure. Indications for anulus enlarging procedures were recurrent subaortic stenosis or inability to place an adult-sized valve in the native aortic anulus, or both. There were no early or late deaths. Fourteen valves were placed in the mitral position. They were anular positioned in 6 patients aged 6 months to 16 years and supraanular positioned in 8 patients aged 2.5 months to 2 years. There were no deaths with the anular positioned replacements and seven deaths (two early and five late) with the supraanular positioned replacements. Four of the five late deaths were associated with marked pre- and postoperative left ventricular dysfunction. The follow-up time was 784 patient-months in 31 long-term survivors. Anticoagulation was achieved with warfarin, usually in combination with sulfinpyrazone, dipyridamole or aspirin. There were four episodes of thromboembolism, three occurring in patients with suboptimal anticoagulation, and one in a patient lost to follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

M-Mode echocardiography was performed in 22 normal children and 22 children with ventricular septal defects. Left ventricular and left atrial chamber dimensions and wall thicknesses were measured in all patients. Utilizing these data, indices of left ventricular function were derived: shortening fraction, velocity of fiber shortening, peak diastolic fiber lengthening, end-systolic wall stress, radius thickness ratio, and ventricular mass. The results showed that ventricular septal defect was associated with enlarged left ventricular and atrial dimensions and increased shortening fraction, but that velocity of shortening and early diastolic lengthening remained normal. Left ventricular mass was increased, thus maintaining normal wall stress and radius/thickness ratio. Cardiac failure complicating ventricular septal defect was associated with enlarged left ventricular and atrial dimensions (indexed for weight). Ventricular mass, wall stress and function, however, were similar in subjects with ventricular septal defect, with or without cardiac failure. Since left ventricular mass was adequate to maintain wall stress and function in subjects with heart failure, other factors were presumably responsible for heart failure complicating ventricular septal defect.

To determine the relative contribution of sudden death as a cause of late inpatient mortality in newborns after prolonged mechanical ventilation, we reviewed the charts of 348 patients who received ventilation assistance and who were admitted to the neonatal intensive care unit during a 26-month period. The overall mortality rate for these patients was 25%, with 88% (77/88) of these deaths occurring within 30 days of birth. Eleven infants died after more than 60 days of mechanical ventilation. Seven of these late deaths were sudden, unexpected in-hospital deaths. Sudden deaths occurred at a mean (uncorrected) age of 12 months (range, 4 to 27 months), during periods when infants appeared to be stable or clinically improving, were unrelated to recent respiratory exacerbations, and occurred despite prompt resuscitative efforts. Four infants still required mechanical ventilation, and 4 had tracheostomies at the time of death. All of the infants had chronic hypercarbia (greater than 50 mm Hg) and an elevated serum bicarbonate level (greater than 30 mmol/L), but not hyponatremia, hypochloremia (less than 80 mmol/L), or alkalemia. Left and right ventricular hypertrophy, multiple drug therapy, recurrent cyanotic episodes, and frequent unexplained fevers were common. In comparison with 17 bronchopulmonary dysplasia survivors who required longer than 60 days of ventilation therapy, the late deaths group more frequently had left ventricular hypertrophy and received prolonged combination theophylline anhydrous and beta-adrenergic agonist therapy. We report that sudden death can occur in infants with severe bronchopulmonary dysplasia despite in-hospital cardiopulmonary monitoring and the rapid institution of cardiopulmonary resuscitation, and is a significant cause of late mortality in infants who receive ventilation therapy for longer than 2 months.

With the recent advances in pediatric cardiology and cardiovascular surgery, assessment of ventricular function in single ventricle complexes is becoming increasingly important. The serial assessment of ventricular function helps our understanding of the natural and unnatural history in these patients. Equilibrium radionuclide ventriculography is safe, easy to perform, and well-suited to the serial assessment of ventricular function. Fifteen nuclear studies were performed in 15 children with single ventricle complex. Nuclear studies were imaged in both the anterior and left anterior oblique views in each patient. The ventricular ejection fraction calculated from the anterior view (the view with the best atrial-ventricular separation) closely approximated the cineangiographic ejection fraction (54.0 vs 59.1%). Equilibrium radionuclide ventriculography is a valid method to calculate ventricular ejection fraction in single ventricle. The anterior view should be used for region of interest selection and subsequent ejection fraction analyses.

Aortoventriculoplasty was performed in 16 children between July, 1980, and July, 1984. Indications for the procedure were 1) aortic stenosis or insufficiency, or both, necessitating replacement of an aortic valve whose anulus would not accept a 19 mm diameter valve, (2) replacement of a small valve prosthesis, or (3) recurrent tunnel subaortic stenosis. Patients were 5 months to 17 years old at operation, 14 had previous repairs, and four had prior aortic valve replacement. There were 13 long-term survivors followed up for 14 to 38 months; 12 are asymptomatic with normal exercise tolerance. Three had residual ventricular septal defects, two requiring repair. All patients were given warfarin with or without antiplatelet agents. There have been no thromboembolic episodes and no hemorrhagic complications. Aortoventriculoplasty is well tolerated in children and appears to be a viable surgical option in the management of young patients with a hypoplastic left ventricular outflow tract.

Pseudomonas aeruginosa elaborates a number of extracellular products which have been shown to play a role in the pathogenesis of disease caused by this organism. In this study, we showed that the host environment markedly affects the levels of exoproducts produced. We compared the phenotypes of a number of P. aeruginosa strains obtained from a variety of clinical sources, including burn wounds, skin wounds, urine, cystic fibrosis sputum, acute pneumonia sputum, and blood. The clinical isolates were examined quantitatively for levels of total protease, elastase, phospholipase C, exotoxin A, and exoenzyme S produced in vitro under defined conditions. The exoproduct levels varied significantly, depending on the site of isolation. Elevated levels of elastase were demonstrated in strains isolated from acute lung infections, phospholipase C levels were elevated in urinary tract and blood isolates, exotoxin A levels were elevated in blood isolates, and exoenzyme S levels were increased in acute pneumonia isolates. Isolates from cystic fibrosis sputum produced low amounts of virtually all of the tested exoproducts, particularly as compared with sputum isolates from acute P. aeruginosa lung infections.

Thirteen patients with hypertrophic cardiomyopathy (HCM) who presented by 2 years of age were evaluated. All had been referred because of a heart murmur. Four had positive family histories for HCM and 2 had congestive heart failure. Cardiothoracic ratios ranged from 0.43 to 0.70 (mean 0.56). In 12 cases, electrocardiograms showed abnormal Q waves, ventricular hypertrophy, or aberrant rhythms. Resting peak systolic pressure differences ranged from 0 to 92 mm Hg (mean 21.1) across the right ventricular outflow tract, and from 0 to 112 mm Hg (mean 36) across the left ventricular outflow tract (LVOT). Cardiac angiography showed evidence of asymmetric septal hypertrophy (ASH) in all patients, LVOT obstruction in 3, and aortic and mitral insufficiency in 1. Six patients received no therapy, 6 were treated with propranolol, and 3 were treated with left ventricular myomectomy. During follow-up (mean 6.1 years), no patient died and 10 became or remained asymptomatic. The apparently favorable clinical course observed in these patients during this period of follow-up may be related to early treatment, made possible by the early diagnosis.

An adolescent female with occult cystic medial necrosis died following spontaneous aortic rupture. A large saccular aortic aneurysm that had ruptured into the pericardial space was demonstrated by two-dimensional echocardiography and confirmed at surgery. Echocardiographic screening of the patient's family members revealed a 13-year-old brother with unsuspected aortic root dilatation. He is now being followed for possible progression of his disease. This case demonstrates the role of echocardiography in cystic medial necrosis. It can aid the acute management of patients with aortic dissection or aneurysm. It can also define patients with occult disease who require serial follow-up and genetic counseling.

Supine exercise equilibrium radionuclide right ventriculography was performed in 13 children (8-18 years) with hypercholesterolemia. Phase analysis was used to construct right ventricular regions of interest, and a peri-right ventricular region was used for background correction. Right ventricular ejection fraction at rest and exercise was 50.5 +/- 9.2% and 61.5 +/- 8.1%, respectively, with a mean increase of 11.0 +/- 7.5 percentage units (range 1-27 percentage units). During exercise, end-diastolic volume remained unchanged while end-systolic volume decreased by 19.4%, producing a 21.7% increase in stroke volume. Stroke volume ratios (left ventricular stroke volume counts/right ventricular stroke volume counts) approach unity (1.00 +/- 0.27). However, interobserver and intraobserver correlations are just fair, implying only a modest degree of accuracy and reliability of the procedure. This imprecision needs to be considered when evaluating the results of nuclear equilibrium right ventriculography.

Qualitative phase analysis of radionuclide angiocardiograms has been applied in pediatric nuclear cardiology. The technique involves the static and dynamic display of phase images. Qualitative phase analysis is valuable in two major images: (a) delineating borders of adjacent cardiac chambers such as the AV valve planes and the borders of the right ventricular outflow tract, for accurate selection of regions of interest, and (b) identifying and evaluating patterns of asynchronous contraction. Radionuclide angiography with phase analysis is a safe, noninvasive, and easily repeatable assessment of cardiac function well suited to patients with congenital heart disease.

A newborn with critical aortic stenosis and anular hypoplasia was treated with an aortic valvotomy using inflow occlusion. Five months later, important valvular insufficiency and residual stenosis necessitated aortic valve replacement. An aortoventriculoplasty using a 19 mm St. Jude Medical Valve was successfully performed with a good hemodynamic response.