Among patients with surgically repaired atrial septal defects, those operated on before the age of 25 have an excellent prognosis, but older patients require careful, regular supervision.

In general, syncope in children and adolescents is a benign event. Syncope occurring during exercise may identify patients with a potentially fatal condition. Detailed evaluation should be considered for patients who have syncope during exercise or who have a family history of syncope, sudden death, myocardial disease or arrhythmias. It may be prudent to obtain an electrocardiogram for all patients who seek medical attention for syncope.

Background: The human cardiac SCN5A gene encodes for the a subunit of the human cardiac voltage-dependent sodium channel hNav1.5 [Neuron 28 (2) (2000) 365] and carries inward Na current (I Na ). Mutations in SCN5A cause arrhythmia syndromes including Brugada syndrome (BrS) and congenital long QT syndrome subtype 3 (LQT3). Here, we report a trafficking defective BrS-causing SCN5A mutation that was drug-rescued. Methods and Results: A 14-year-old Caucasian male was diagnosed with BrS with typical ECG pattern for BrS and ventricular fibrillation was easily induced. He also had significant HV interval delay ( f 65 ms) and high (31 J) defibrillation thresholds (DFTs). Genomic analysis revealed the SCN5A mutation (G1743R). We engineered G1743R into the cardiac Na channel and transfected HEK-293 cells for functional studies. The mutant channel yielded nearly undetectable sodium channel currents. Coexpression with the h 1 subunit, or incubation at low temperature did not increase current density. However, mexiletine, a sodium channel blocker, increased current density 93-fold in G1743R, but only twofold in WT. Conclusions: This study identifies an expression-defective BrS mutation in SCN5A with pharmacological rescue. The profoundly decreased sodium current associated with the G1743R suggests a molecular basis for the delayed His-Purkinje conduction and elevated DFTs observed in the proband. Whether the mutant channel may be rescued in vivo by mexiletine and normalize the patient's electrophysiologic parameters remains to be tested.

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As children with cardiac disease grow older, atrial flutter becomes more prevalent. A collaborative study was performed in 19 institutions to determine the clinical characteristics of these children and the factors affecting prognosis. There were 380 patients with one or more electrocardiographically documented episodes of atrial flutter that first occurred between ages 1 and 25 years (mean age at onset 10.3). Episodes of flutter continued to occur for a mean of 2.5 years after the onset. Of the 380 patients, 60% had repaired congenital heart disease, 13% palliated congenital heart disease, 8% unoperated congenital heart disease, 8% an otherwise normal heart, 6% cardiomyopathy, 4% rheumatic heart disease and 2% other lesions. Overall, drugs were effective in eliminating atrial flutter in 58% of patients; specifically, amiodarone and digoxin plus quinidine were effective in 53%, digoxin alone in 44% and propranolol in 21%. Amiodarone was effective in seven (78%) of nine patients. Corrective surgery was performed after the onset of atrial flutter in 66 patients; in 52% the atrial flutter was easier to control or it resolved and in only 4% it was worse. At follow-up (mean 6.5 years), 83% of the patients were alive (49% without atrial flutter and 34% with atrial flutter) and 17% died (10% suddenly, 6% of nonsudden cardiac cause and 1% of noncardiac cause). Cardiac death occurred in 20% of those for whom an effective drug could not be found to eliminate atrial flutter compared with 5% of those who were treated with an effective drug (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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Many factors may have contributed to decreased early mortality after Fontan. Improved patient selection, younger age at time of operation, refinements in surgical techniques and postoperative management may all have had important roles. Proposed technical modifications of the Fontan operation must be evaluated in light of these improved results.