Porter, Co-burn J.

Objective. To determine whether accelerated idioventricular rhythm (AIVR) is benign in pediatric patients. Methods. The records were reviewed of all patients younger than age 15 years who had been diagnosed with a ventricular arrhythmia between 1976 and 1991. Results. AIVR was diagnosed in 12 patients, ages 1 day to 15 years (mean, 8.9 years). In 3 patients the arrhythmia was discovered on ambulatory electrocardiographic monitoring after presentation with syncope or presyncopal symptoms. One patient had palpitations. The remaining diagnoses were made during routine examinations or at postoperative follow-ups for congenital heart disease. The AIVR rate ranged from 90 to 150 beats per minute. The rate was within 10 beats per minute of the preceding sinus rate in 11 patients. Echocardiograms were normal in 8 patients. Two patients had double-outlet right ventricles; 1 had repair of the tetralogy of Fallot; and 1 had abnormal ventricular septal motion. Seven patients were taking antiarrhythmia medication without control of the AIVR at presentation. Patients were followed for a mean of 68.4 months (range, 31 to 191 months). All patients were alive and asymptomatic, with normal activity at the last follow-ups. Conclusions. Complete resolution of AIVR may not occur. However, AIVR seems to be a benign arrhythmia. Treatment was not effective in controlling the arrhythmia and is likely unnecessary.

Objective. Tilt-table testing is useful for investigating unexplained syncope in pediatric patients. No data are available on the use of intravenous metoprolol during testing to identify children who might respond to subsequent oral β-adrenergic blockade or on the efficacy and safety of such oral therapy. Design. To provide these data, we obtained follow-up information on 27 consecutive pediatric patients who had tilt-table testing for unexplained syncope. Results. Nineteen patients (70%) had positive test results with or without isoproterenol infusion. All these patients had negative test results after intravenous infusion of metoprolol and subsequently were treated with oral metoprolol. Taking oral metoprolol therapy alone, 9 (47%) of the 19 patients were asymptomatic, 8 (42%) reported a decreased frequency of syncopal episodes, and 2 (11%) had unchanged or more frequent episodes. The mean dosage of metoprolol required to prevent symptoms was 1.5 mg/kg per day. Mild side effects were reported by 6 (32%) of the 19 patients. Six patients (32%) required additional medications. Conclusions. We conclude that metoprolol is safe and effective for the treatment of most cases of neurocardiogenic syncope in children and that this response cannot be predicted accurately by the use of intravenous metoprolol during testing.

Background: Although multiple macroreentrant atrial flutters are seen in postoperative patients with congenital heart disease, cavotricuspid isthmus (CVTI) dependent flutter remains a fairly common arrhythmia in this group. When a Fontan or atrial switch (Mustard/Senning) type of procedure is performed, a portion of the CVTI is excluded from catheter access obtainable via a systemic venous route. We evaluated different techniques to access this excluded portion and completely ablate CVTI dependent flutter. Methods/Results: Between 1990 and 2007, 140 patients with surgically corrected congenital heart disease underwent an ablation procedure at our institution. Their records were reviewed to identify those with prior Fontan or atrial switch procedure who had documented CVTI dependent flutter requiring ablation. Data collected included methods of catheter access, circuits observed or induced, the location and number of ablation lines, immediate and long-term success, and complications. Results: Sixteen patients were identified (14, Fontan; 2, Mustard). In 12/16 (75%) patients bidirectional block of CVTI dependent flutter could not be achieved by right atrial (venous approach) ablation alone. In 7 of those, the excluded portion of the CVTI was targeted for ablation. This was accomplished by a retrograde transaortic approach via an interventricular communication then through the right atrioventricular valve (5 patients). Another retrograde transaortic approach was used with the catheter crossing the left atrioventricular valve then an atrial septal communication (one patient). A third approach involved an antegrade transconduit puncture (one patient). In all 7 patients, successful ablation of CVTI dependent flutter with bidirectional block was achieved. Post-procedure, one patient had temporary AV block requiring pacemaker placement. Follow-up was available on 4/7 patients (3 to 22 months, mean 10 months) with no documented recurrence of their CVTI dependent flutter. Conclusion: Even when surgical procedures exclude a portion of the CVTI, complete ablation for typical atrial flutter with resulting bidirectional block can be achieved via “non-traditional” approaches targeting the surgically excluded arrhythmogenic tissue.

Significant functional impairment and psychological distress have been observed in adolescent patients with postural orthostatic tachycardia syndrome (POTS). Interdisciplinary rehabilitation programs have been shown to be beneficial in the treatment of chronic pain in adults and adolescents. Only preliminary data have examined interdisciplinary rehabilitation efforts in patients with POTS. This study evaluated the impact of an interdisciplinary rehabilitation program on the functional impairment and psychological distress in 33 adolescents diagnosed with POTS. Patients included in the study were adolescents ages 11 to 18 diagnosed with POTS. Measures completed at admission and discharge from the program included the Functional Disability Index, Center for Epidemiological Studies–Depression–Child scale, and the Pain Catastrophizing Scale for Children. After participation in the 3-week program, adolescents with POTS demonstrated a significant increase in overall functional ability and significant reductions in depression and catastrophizing.

Background —The objectives of our study were to determine the frequency of supraventricular tachyarrhythmias (SVTAs) among modifications of the Fontan operation and identify risk factors for developing SVTA. Methods and Results —The population consisted of all patients who had any modification of the Fontan operation at the Mayo Clinic between 1985 and 1993. Clinically significant SVTAs were those requiring initiation or change of antiarrhythmic treatment, and they were divided into early SVTAs (<30 days after the operation) and late SVTAs (≥30 days after the operation). Clinical histories were reviewed, and health status questionnaires were sent. Four hundred ninety-nine patients had various modifications of the Fontan operation. Frequency of early SVTA was 15%. Risk factors identified by multivariate analysis for early SVTA were AV valve regurgitation, abnormal AV valve, and preoperative SVTA. Frequency of late SVTA was 6% by 1 year, 12% by 3 years, and 17% by 5 years. Risk factors for late SVTA were age at operation (<3 or ≥10 years) and systemic AV valve replacement. By univariate and multivariate analysis, the type of Fontan operation was not a significant risk factor for late SVTA when all 6 modifications were considered. However, when we analyzed the frequency of late SVTA for the 2 recently used modifications, we found a lower frequency of late SVTA in patients with atriopulmonary connection with lateral tunnel compared with those with total cavopulmonary connection. Conclusions —Postoperative SVTA continues to be a significant problem. Risk factors for SVTA are AV valve regurgitation, abnormal AV valve, preoperative SVTA, and age at operation. Frequency of SVTA does not appear to be related to type of Fontan procedure except for slightly lower frequency in patients with atriopulmonary connection with lateral tunnel compared with those with total cavopulmonary connection.

The outlook for patients with double-outlet right ventricle has improved since the development of corrective operations. Late arrhythmic deaths after successful procedures have been reported; however, the magnitude remains unknown. This study was undertaken to identify the magnitude of late sudden death and the significant factors associated with it. From 1965 through 1985, 118 patients underwent corrective operation for double-outlet right ventricle; of these, 23 died in the hospital and six were lost to follow-up. The 89 remaining patients (52 male and 37 female) made up the study population. Their mean age (+/- SD) was 10.3 +/- 7.8 years at the time of repair. The mean duration of follow-up was 82 months. Of the 22 late deaths, 16 (73%) were sudden. Eight (50%) of the sudden deaths occurred within 1 year of operation. Cox proportional hazards multivariate analysis revealed the following significant risk factors for late sudden death: older age at the time of operation, perioperative or postoperative ventricular tachyarrhythmias, and third-degree atrioventricular block. Factors not associated with late sudden death included year of operation, sex, type and number of associated cardiac anomalies, preoperative functional class, previous palliative procedures, surgical technique, perioperative or postoperative single premature ventricular contractions, and postoperative left or right bundle branch block with or without fascicular block. We conclude that the incidence of late sudden death after successful surgical repair of double-outlet right ventricle is very high. Complete corrective operation at an early age and aggressive diagnosis and treatment of arrhythmias and conduction defects after operation are warranted.

In a group of 191 consecutive patients who underwent operation at the Mayo Clinic for isolated pulmonary valve stenosis between 1956 and 1967, late results were excellent. In patients surviving operation before the age of 21 years, long-term survival was similar to that in an age- and sex-matched control population. In the other patients, late survival and functional status were good, but survival was poorer than in the control population. This late attrition, most likely due to the sequelae of long-standing right ventricular hypertrophy, suggests the need for continued surveillance. Late sudden death occurred in only three patients, between 10 and 21 years postoperatively. The finding of normal life expectancy for such patients who survive operation before age 21 is important for actuarial purposes and for the patients' career and employment plans.

Background— Right ventricular pacing increases the risk of heart failure in adults with structural heart disease. The impact of prolonged right ventricular pacing in adults without structural heart disease is not fully characterized and may depend on interactions of pacing with abnormal substrate predisposing to ventricular dysfunction. Methods and Results— We assessed the effect of right ventricular pacing in patients who underwent pacemaker implantation for isolated congenital atrioventricular block between 1964 and 2005. To assess for immunologic contribution to cardiac dysfunction, outcomes were compared between patients with (Ab + ) and without (Ab − ) antinuclear antibody during adulthood and an age- and sex-matched Olmsted County, Minnesota, population. Of 103 patients (mean±SD age, 32±19 years), 18 were Ab + . Long-term survival free of new heart failure after pacemaker implantation in isolated congenital atrioventricular block patients was worse than in the matched population ( P <0.001). This difference was attributable to the development of heart failure in 12 Ab + patients (67%; P <0.001), without differences between Ab − patients (2%) and the matched population (2%; P =0.7). Compared with baseline, at last follow-up, left ventricular ejection fraction did not decline in Ab − (53±9% to 57±12%) but decreased in Ab + (52±10% to 38±12%; P =0.03) patients. Survival was similar in Ab − patients and the Minnesota population (98%; P =0.7) but worse in Ab + patients (79%; P <0.01). Conclusions— The natural history of patients with isolated congenital atrioventricular block who require pacing depends upon their antibody status. Antinuclear antibody status was a predictor for the development of heart failure and death. Long-term right ventricular pacing alone does not appear to be associated with development of heart failure, deterioration in ventricular function, or reduced survival in Ab − isolated congenital atrioventricular block patients.

This descriptive population study of 307 public high school students, ages 15 to 17 years, was performed to establish reference ranges for orthostatic changes in heart rate and blood pressure in adolescents, and to identify influential variables. Noninvasive measurements of blood pressure and heart rate were obtained. Reference ranges for orthostatic heart rate change in this population at 2 minutes were –2 to +41 beats per minute and at 5 minutes were –1 to +48 beats per minute. Orthostatic blood pressure changes were within the adult range for 98% of adolescents tested. One-third of participants experienced orthostatic symptoms during testing. In conclusion, this study shows that orthostatic symptoms and large orthostatic heart rate changes occur in adolescents. This suggests that the current orthostatic heart rate criterion aiding the diagnosis of adult orthostatic intolerance syndromes is likely not appropriate for adolescents and should be reevaluated.

Objective. To determine whether children with pallid breath-holding spells associated with bradycardia can be treated safely and successfully with permanent pacemaker implantation. Methods. The records of pediatric patients who had apparent breath-holding spells and associated bradycardia and were treated with permanent pacemaker implantation were reviewed. Results. Ten pediatric patients with apparent breath-holding spells associated with bradycardia were treated with a permanent ventricular demand pacemaker at the Mayo Clinic between 1985 and 1995. Patients had onset of symptoms between ages 6 days and 12 months and presented for evaluation between ages 12 months and 5 years. Duration of spells was 15 seconds to 10 minutes. Medications to prevent spells were unsuccessful. Electrocardiograms documented asystolic pauses of 1.7 to 24 seconds (mean: 11.9 seconds). Permanent ventricular demand pacemakers were implanted at 10 months to 5 years of age (median: 14.5 months): 9 endocardial and 1 epicardial. Three patients required pacemaker revision. At follow-up of 38 to 170 months (median: 65.5), 5 patients had complete resolution of spells, 2 had only mild color change without loss of consciousness or seizure activity, and 3 continued to have minor brief spells. Conclusions. Permanent pacemaker therapy for children with pallid breath-holding spells associated with severe bradycardia is safe, efficacious, and warranted.