The child with recurrent syncope: autonomic function testing and beta-adrenergic hypersensitivity.

Recurrent syncope in the child with a normal heart poses both diagnostic and therapeutic problems. To assess autonomic contributions to syncope, formal autonomic function testing was performed in 22 children (aged 7 to 18 years) with recurrent syncope and a normal heart. Autonomic testing consisted of eight to nine separate tests; 14 of the 22 patients had reproduction of syncope or symptoms during testing. Patients with a positive test had a lower norepinephrine level while supine (334 +/- 86 versus 547 +/- 169 pg/ml, p less than 0.01) and lower norepinephrine level in the upright position (628 +/- 219 versus 891 +/- 270 pg/ml, p less than 0.05) than did patients with a negative test. The slope of heart rate response versus log isoproterenol dose was greater in patients with a positive test than in those with a negative test (1.70 +/- 0.70 versus 0.89 +/- 0.19, p less than 0.01). All five patients with a positive test who were given intravenous propranolol had elimination of syncope with repeat testing. Eight of 10 patients with a positive test were successfully treated with atenolol, including 2 patients without prior resolution of symptoms after pacemaker implantation for symptoms attributed to bradycardia. Beta-adrenergic hypersensitivity may cause recurrent syncope in young patients. Inappropriate heart rate response to standing may elicit the Bezold-Jarisch reflex, resulting in bradycardia or hypotension, or both, in some patients. Beta-adrenergic blockade is of benefit in many of these patients.

Sudden death in a pediatric cardiology population, 1958 to 1983: relation to prior arrhythmias.

This review of sudden death in patients previously seen in a pediatric cardiology clinic attempts to identify factors that may have been predictive of sudden death. The denominator for these factors is unknown. For example, the number of patients with these possible risk factors who have well tolerated arrhythmias is not known. Further studies are planned to document the incidence of these factors in patients with similar lesions whom we continue to follow up. The following conclusions can be drawn from the study: More than three-quarters of the patients who died suddenly had severe limitation of activity, cardiac enlargement on chest radiograph or poor hemodynamic status at cardiac catheterization. The majority of patients who died suddenly had an arrhythmia in the 12 month period before death. A significant number of these arrhythmias developed for the first time in the year before death. The presence of arrhythmias was generally related to poor hemodynamic status in patients who died suddenly. Most sudden deaths occurred with the patient at rest and only approximately one-quarter occurred during participation in sports. Each cardiac diagnosis had its own specific profile of types of arrhythmias Conspicuously absent from the list of diagnoses were children with a normal heart and children with mitral valve prolapse.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

Supraventricular tachycardia due to Wolff-Parkinson-White syndrome in children: early disappearance and late recurrence.

UNLABELLED: The clinical course of 140 patients with Wolff-Parkinson-White syndrome who had their initial episode of supraventricular tachycardia before 18 years of age was reviewed. Among those whose tachycardia began at age 0 to 2 months, it disappeared in 93% and persisted in 7%. In 31%, it disappeared and reappeared at an average age of 8 years. Among patients whose tachycardia was present after age 5 years, it was persistent in 78% at a mean follow-up period of 7 years. Accessory connection location was mapped by electrophysiologic study in 87 patients and estimated by electrocardiography in 53 patients. There were no differences in tachycardia onset or recurrence based on accessory connection location. Congenital heart defects were present in 37% of all patients, 23% of whom had Ebstein's anomaly. Among all patients who underwent cardiac catheterization, 63% of those with a congenital heart defect had a rightsided accessory connection, whereas 61% of patients with a normal heart had a left-sided connection (p less than 0.01). Multiple accessory connections were found in 12% of patients with a congenital heart defect compared with 6% of those without such a defect. IN CONCLUSION: 1) supraventricular tachycardia due to Wolff-Parkinson-White syndrome that begins in infancy may disappear, but it frequently recurs in later childhood; 2) if tachycardia is present after age 5 years, it persists in greater than 75% of patients; and 3) the location of the accessory connection does not affect the clinical course of tachycardia in children with Wolff-Parkinson-White syndrome.

Clinical course of idiopathic dilated cardiomyopathy in children.

Previous studies in adults with dilated cardiomyopathy suggest that the presence of arrhythmia, especially ventricular tachycardia, correlates with increased mortality. We performed a retrospective analysis of 63 children with idiopathic dilated cardiomyopathy to determine the prognostic significance of arrhythmias and other findings with respect to mortality. The mean age at diagnosis of the cardiomyopathy was 4.96 +/- 5.3 years. The overall mortality rate was 16% over a 10 year follow-up period. Persistent congestive heart failure and ST-T wave changes correlated with increased mortality (p less than 0.05). No other variables affected outcome. Arrhythmias were found in 46% of the patients; of the arrhythmias, 48% were atrial arrhythmias. Ventricular tachycardia was present in six patients. Death occurred in 4 (14%) of 29 patients with known arrhythmia; 1 of the 5 died suddenly. The remaining 6 deaths in the series occurred in the 34 patients without a documented arrhythmia. It is concluded that 1) arrhythmias are frequently seen in children with dilated cardiomyopathy but are not predictive of outcome; 2) sudden death in children with this disease is rare; and 3) persistent congestive heart failure portends a poor prognosis.

Mexiletine: an effective antiarrhythmic drug for treatment of ventricular arrhythmias in congenital heart disease.

The use of antiarrhythmic drugs to suppress ventricular arrhythmias in pediatric patients with a structurally or hemodynamically abnormal heart appears to improve long-term prognosis. The previously successful use of phenytoin to treat serious ventricular arrhythmias led to the investigation for an alternative antiarrhythmic agent, in the same antiarrhythmic drug class, for those patients who develop side effects or become intolerant to phenytoin's antiarrhythmic effect. Forty-two children and young adults (age range 5 months to 34 years, mean 15.5 years) were treated with mexiletine. Arrhythmias treated were ventricular tachycardia (25), ventricular couplets (8), multiform ventricular premature beats (4) and frequent uniform ventricular premature beats (5). Anatomic diagnoses included congenital heart disease (postoperative in 26, unoperated in 2), cardiomyopathy (7), no heart disease (4) and other (3). Thirty-three patients had been previously treated with 1 to 5 (mean 1.6) antiarrhythmic drugs. In the short term, ventricular arrhythmias were effectively suppressed in 30 (71%) of all 42 patients treated. During follow-up (ranging to 42 months, median 10.6), 18 (60%) of the 30 acute responders continued to have excellent control. Early suppression of ventricular arrhythmias was more effective in patients with congenital heart disease (89%) than in those with cardiomyopathy (29%) or no heart disease (43%) (p less than 0.01). Initial complexity of ventricular ectopic activity had no effect on treatment results. Of 25 patients previously treated with phenytoin, in whom alternative antiarrhythmic therapy was required, 40% had long-term arrhythmia control when treated with mexiletine. Mexiletine therapy was terminated for side effects in only five patients (12%). Mexiletine is recommended for young patients with congenital heart disease and serious ventricular arrhythmias.

Wolff-Parkinson-White syndrome and supraventricular tachycardia during infancy: management and follow-up.

The records of 90 patients with Wolff-Parkinson-White syndrome who presented with supraventricular tachycardia in the first 4 months of life were reviewed. Among these, 63% were male. Structural heart disease was present in 20%, most commonly Ebstein's anomaly. All patients presented with a regular narrow QRS tachycardia, and pre-excitation became evident only when normal sinus rhythm was established. Only one infant had atrial flutter and none had atrial fibrillation. Type A Wolff-Parkinson-White syndrome was most common (49%), with heart disease occurring in only 5% of these patients. In contrast, heart disease was identified in 45% of those with type B syndrome. Initially, normal sinus rhythm was achieved in 88% of the 66 infants treated with digoxin with no deaths. Normal sinus rhythm resumed after electrical countershock in 87% of the 15 infants so treated. Maintenance digoxin therapy was used in 85 patients. The Wolff-Parkinson-White pattern disappeared in 36% of the patients. Four infants died of cardiac causes during the mean follow-up period of 6.5 years. Two of these four infants had congenital heart disease; the third, with a normal heart initially, developed ventricular fibrillation and died from a cardiomyopathy considered related to resuscitation. The remaining infant, with a normal heart, died suddenly at 1 month of age. All were receiving digoxin. A wide QRS tachycardia later appeared in three patients, all with heart disease, one of whom died.(ABSTRACT TRUNCATED AT 250 WORDS)

Transvenous catheter ablation of a right atrial automatic ectopic tachycardia.

A 10 year old patient with right atrial automatic ectopic tachycardia underwent successful transvenous catheter ablation after endocardial mapping. Tachycardia had been present for 7 years before ablation and associated with development of dilated cardiomyopathy. A single 50 J discharge at the point of earliest atrial activation was followed by the establishment of sinus rhythm that remains at 10 months' follow-up. This case represents the first reported successful catheter ablation of an atrial automatic ectopic tachycardia. Specific anatomic factors favoring successful ablation and improvement in technique are discussed.

Rapid ventricular pacing in dogs with right ventricular outflow tract obstruction: insights into a mechanism of sudden death in postoperative tetralogy of Fallot.

OBJECTIVES: We explored the hypothesis that residual outflow tract obstruction and ventricular hypertrophy associated with rapid ventricular rhythm contribute to sudden death, in part because they result in humoral or hemodynamic changes that predispose to ventricular fibrillation, such as increased catecholamine release or decreased coronary flow, or both. BACKGROUND: Ventricular arrhythmia after surgical repair of tetralogy of Fallot has been associated with sudden death, particularly in patients with residual right ventricular hypertension. However, the mechanisms by which sudden death occurs remain unclear. METHODS: Seven awake, unanesthetized mature beagles with chronically elevated right ventricular pressure (high pressure group: right ventricular/left ventricular systolic pressure ratio > 0.5) were compared with six beagles with low right ventricular pressure at rest and at the end of 5 min of ventricular pacing at 240 beats/min (low pressure group). RESULTS: In the high pressure group, cardiac output decreased during ventricular pacing (compared with sinus rhythm) from 304 +/- 21 to 218 +/- 21 ml/min per kg (p < 0.01) and plasma norepinephrine increased substantially from 673 +/- 64 to 1,047 +/- 92 pg/ml (p < 0.01). Comparable changes were not observed in the low pressure group. Plasma epinephrine levels were similar in both groups at rest and did not change with pacing. Postpacing norepinephrine levels from both groups correlated positively with both right ventricular systolic and diastolic pressure at rest and correlated negatively with the change in cardiac output from rest to pacing. Regional right ventricular myocardial blood flow increased with pacing in the low pressure group, whereas in the high pressure group it was increased at rest and did not increase further with pacing. CONCLUSION: During ventricular pacing, dogs with right ventricular outflow tract obstruction and high right ventricular pressure had a decrease in cardiac output and an increase in plasma norepinephrine, coupled with a loss of right ventricular myocardial blood flow reserve. Similar changes may occur in postoperative patients with similar hemodynamics and tachyarrhythmia and could contribute to the occurrence of ventricular fibrillation and sudden death.

Induction of ventricular tachycardia during electrophysiologic study after repair of tetralogy of Fallot.

An association among premature ventricular complexes on routine electrocardiogram, elevated right ventricular systolic pressure and sudden death after repair of tetralogy of Fallot was previously reported. To examine this relation further, noninvasive, hemodynamic and invasive electrophysiologic data were studied in 27 patients who had undergone repair of tetralogy of Fallot 7 months to 21 years (mean 1.75 years) previously. Syncope, which had occurred in four patients, was not significantly related to ventricular arrhythmia on rest electrocardiogram, 24 hour electrocardiogram or treadmill test. All four patients with syncope had either nonsustained (two patients) or sustained (two patients) ventricular tachycardia induced at electrophysiologic study. His bundle to ventricle conduction interval was prolonged in two patients and Q to right ventricular apex interval was prolonged in three of the four patients. All four had abnormal anatomic or hemodynamic findings: two had a right ventricular systolic pressure of 70 mm Hg or more, one had right ventricular dysfunction with tricuspid insufficiency and one a septal aneurysm. The 9 patients with induced nonsustained or sustained ventricular tachycardia were then compared with the 15 patients without induced ventricular arrhythmias. Those with ventricular tachycardia had a greater prevalence of: more complex ventricular arrhythmia on 24 hour electrocardiogram (63 versus 0%, p less than 0.001), long His bundle to ventricle interval (44 versus 0%, p less than 0.001), right ventricular systolic pressure of 70 mm Hg or more (56 versus 0%, p less than 0.01) and reduced right ventricular ejection fraction (33 versus 7%, p less than 0.025). It is concluded that: 1) induction of nonsustained or sustained ventricular tachycardia was associated with a history of syncope; 2) all patients at risk for syncope could not be identified by routine electrocardiogram 24 hour electrocardiogram or treadmill test; 3) hemodynamic alterations may interact with intraventricular conduction abnormalities and predispose to ventricular tachycardia.

Transcatheter ablative techniques for treatment of the permanent form of junctional reciprocating tachycardia in young patients.

Five patients with medically refractory incessant supraventricular tachycardia due to a posterior septal, slowly conducting accessory connection underwent transcatheter closed chest ablative treatment. The tachycardia characteristics were consistent with the permanent form of junctional reciprocating tachycardia. In each patient the ablative attempts resulted in independent interruption of either the anterograde limb (atrioventricular node-His bundle conduction) or the retrograde limb (accessory connection) of the tachycardia circuit. Permanent retrograde pathway ablation was achieved in only one patient and followed separate permanent transcatheter His bundle ablation. In three of the other four patients the ablation attempt caused temporary interruption of retrograde conduction. Each patient had improved control of tachycardia related to the ablation attempt. Of the five patients, four required pacemaker implantation. With further refinements, selective ablation of the retrograde limb of the tachycardia circuit may be possible. This experience confirms the anatomic independence of the anterograde and retrograde limbs of the tachycardia circuit.

Surgical management of refractory supraventricular tachycardia in infants and children.

Sixty-seven children underwent attempted surgical correction of refractory supraventricular arrhythmias using a combination of intraoperative electrophysiologic mapping followed by surgical division or cryoablation of an aberrant conduction pathway or atrial ectopic focus. The patients ranged in age from 4 months to 18 years (mean 11.4 years). Fifty-five patients (82%) had an abnormal conduction pathway crossing the atrioventricular junction (Kent bundle). Thirty-six (65%) of these 55 patients had classic Wolff-Parkinson-White syndrome with a delta wave of pre-excitation on the surface electrocardiogram. Nineteen (35%), however, demonstrated only retrograde conduction across the Kent bundle and had a normal surface electrocardiogram when tachycardia was not present. Kent bundles were isolated to the following locations: right anterior or lateral in 19 (34.5%), left posterior or lateral in 22 (40%), posteroseptal in 10 (18%), anteroseptal in 2 (4%) and both right and left in 2 (4%). Follow-up evaluation of as long as 8 years (mean 34.9 months) has shown seven immediate failures and one late recurrence of arrhythmia (14.5%). Recent refinements in technique and the use of cryoablation for septal aberrant pathways have improved these results. There have been two failures (8%) in the last 25 attempts. Twelve patients underwent surgery for an atrial ectopic focus by the following techniques: cryoablation in seven patients, excision in one patient and both excision and cryoablation in four patients. At a mean follow-up of 16.6 months, there was one late recurrence in the group with an atrial ectopic focus.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular arrhythmias and sudden death in children.

In children, sudden death related to ventricular arrhythmias occurs virtually always in a patient with an abnormal heart. Therefore, children with ventricular tachycardia should be thoroughly investigated by anatomic cardiac catheterization and possibly electrophysiologic study. Sudden death may occur in a patient who had been relatively asymptomatic. This especially occurs in patients after repair of congenital heart disease. The patient may also never have had documented ventricular tachycardia, although most have had at least premature ventricular complexes on a Holter monitor recording. Finally, sudden death related to ventricular arrhythmias can often be prevented with vigorous medical and surgical therapy.

Flecainide acetate for resistant arrhythmias in the young: efficacy and pharmacokinetics.

Drug efficacy and pharmacokinetics were assessed in 63 patients, aged 5 days to 30 years (mean 8 years), who received flecainide acetate for control of resistant arrhythmias. Doses of flecainide ranged from 59 to 225 mg/m2 body surface area per day (mean 141) in divided doses every 8 to 12 h and serum trough levels ranged from 0.10 to 0.99 micrograms/ml (mean 0.36). Flecainide controlled or partially controlled arrhythmia in 53 (84%) of the 63 patients: 7 of 7 patients who had the permanent form of junctional reciprocating tachycardia, 12 of 13 who had an atrial ectopic tachycardia, 10 of 10 who had ventricular tachycardia and 18 of 25 patients who had reentrant supraventricular tachycardia. Five of seven patients who had the latter arrhythmia were unsuccessfully treated with flecainide. They had Wolff-Parkinson-White syndrome and developed asymptomatic, incessant, slower orthodromic reciprocating tachycardia while receiving the drug. Transient blurred vision was reported in three patients and two patients had transient hyperactivity. No significant hemodynamic side effects were seen in any patient. Twenty-five patients underwent oral pharmacokinetic investigation. Young infants (less than 1 year of age) had a mean plasma elimination half-life (t 1/2) approximating that (11 to 12 h) found in older children and healthy adults; children aged 1 to 12 years had a shorter mean t 1/2 of 8 h. Dosing schedules based on milligrams per square meter body surface area correlated better with plasma flecainide levels than did dosing based on milligrams per kilogram body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ouabain on the anterograde effective refractory period of accessory atrioventricular connections in children.

The anterograde effective refractory period of the accessory connection was determined before and after the administration of ouabain (0.015 mg/kg intravenously) during electrophysiologic studies in 21 patients with Wolff-Parkinson-White syndrome. The mean age (+/- standard deviation) was 10 +/- 2 years (range 1 month to 31 years). Each patient had stopped taking all cardiac drugs for more than 36 hours. Determination of the anterograde effective refractory period of the accessory connection was made using the atrial extrastimulus technique. A change in the anterograde refractory period of the accessory connection was defined as an increase or decrease of greater than 10 ms from the value before ouabain administration. The post-ouabain anterograde effective refractory period of the accessory connection increased in 2 (9%) of the 21 patients, decreased in 9 (43%) and was unchanged in 10 (48%). This study demonstrated a decrease in the anterograde effective refractory period of the accessory connection of 43% of patients with Wolff-Parkinson-White syndrome after the administration of ouabain.

Treatment of atrial automatic tachycardia by ablation procedures.

Sixteen cases of atrial focus tachycardia are described clinically, electrophysiologically and hemodynamically. In each case multiple attempts at drug treatment (average 2.5 drugs) had failed. After delineation of the electrophysiologic mechanism, the patients were treated by surgical removal or cryoablation or catheter electroablation of the focus. In two of four patients catheter ablation was successful and without complication. Surgical treatment was successful in 13 of 14 patients. Left ventricular function, which had been abnormal in 10 patients, normalized in all but 1 patient whose echocardiographic shortening fraction improved from 10 to 27%. There have been no recurrences in a follow-up period of 6 months to 5 years (mean 2.2 years). It is recommended that any atrial automatic focus tachycardia that produces hemodynamic compromise undergo definitive treatment. Patients with chronic tachycardia rates of more than 140 beats/min should be followed up closely.

Fetal ventricular pacing for hydrops secondary to complete atrioventricular block.

The advent of ultrasound recording has expanded the capabilities for treatment of the fetus in utero. The diagnosis of specific disease processes has allowed for prenatal intervention by new techniques designed to improve fetal survival. The application of ventricular pacing in a hydropic fetus with complete atrioventricular (AV) block is reported. Complete AV block resulted from maternal collagen vascular disease. The application of ventricular pacing was to allow for further in utero development and for reversal of hydrops fetalis after improvement in cardiac output. Despite fetal death 4 hours after placement of the ventricular pacing lead, this procedure when applied earlier in the development of hydrops may allow for fetal survival. Ventricular pacing was accomplished without apparent trauma to mother or fetus and no evidence of fetal injury was seen at necropsy. Therefore, in the fetus who would otherwise die in utero before the point of viability ex utero, fetal ventricular pacing may be a rational alternative to current observation.

Doppler echocardiography in the diagnosis and management of persistent fetal arrhythmias.

Thirteen fetuses with persistent arrhythmias underwent combined noninvasive echocardiographic evaluation utilizing M-mode, two-dimensional and pulsed Doppler echocardiography. This group (Group A) was compared with 14 fetuses in which only two-dimensional and M-mode echocardiographic evaluations were performed (Group B). In both groups correct prenatal interpretation of the arrhythmia was confirmed by postnatal electrocardiograms in all surviving fetuses. Although Doppler echocardiography was not more sensitive than M-mode echocardiography in the interpretations of the arrhythmia, Doppler tracings of sufficient quality to analyze rate and rhythm were easier to obtain in all cases and provided additional information about valvular incompetence and the functional state of the fetal heart. Cardiac malformations and hydrops fetalis were commonly associated with persistent arrhythmias. Congenital heart disease occurred frequently (6 of 11) with complete atrioventricular (AV) block. Pulsed Doppler echocardiography defined the AV contraction sequence, atrial and ventricular rates and AV valve insufficiency, allowing rapid interpretation of fetal arrhythmias.

Computer-guided surgery for tachyarrhythmias in children: current results and expectations.

OBJECTIVES: The purpose of this report is to summarize our entire surgical experience in the treatment of tachyarrhythmias in children. We emphasize our application of a newer computerized mapping system for use in both the electrophysiology laboratory and the operating room to localize points of activation of the tachyarrhythmias. BACKGROUND: A retrospective review was undertaken to examine the results of operative procedures in 290 children undergoing surgical treatment for tachyarrhythmias from 1977 to the present. METHODS: Operative procedures were performed in 290 children and consisted of the following: surgical ablation of accessory pathways of the Kent bundle type (210 children); surgery with cryoablation for atrial ectopic tachycardia (35 children); surgical excision or cryoablation, or both, for ventricular tachycardia (26 children); cryoablation for the permanent form of junctional reciprocating tachycardia (15 children) and atrioventricular (AV) node reentrant tachycardia (4 children). RESULTS: The surgical cure rate for accessory pathway tachycardia in the era before computerized mapping was 80% (41 patients) in the period from 1977 to 1982 and 95% (86 patients) in the period from 1982 to 1988. This rate improved to 100% (83 patients) after the advent of the computerized mapping technique. These improved results are probably due to a combination of factors, including increasing experience in electrophysiologic mapping and surgery, and cannot be attributed to the computerized mapping system alone. Surgical cure or major improvement in symptoms was documented in 33 (94%) of 35 patients with atrial ectopic tachycardia. Surgical cure was accomplished in 25 (96%) of 26 patients with the complex form of ventricular tachycardia. In 19 patients with the permanent form of junctional reciprocating tachycardia and the more typical AV node reentrant tachycardia, the surgical cure rate was 100%. CONCLUSIONS: In all forms of supraventricular reentrant tachycardia that occur in children, preoperative computerized mapping techniques combined with intraoperative computerized mapping and surgical ablation can eliminate tachycardia at a success rate of close to 100%. Computerized mapping techniques are less accurate in patients with atrial ectopic tachycardia because of multiple foci and a broader surface area to be mapped. This experience demonstrates that excellent results can be achieved in the surgical treatment of tachyarrhythmias in children.

Prevention of sudden death after repair of tetralogy of Fallot: treatment of ventricular arrhythmias.

The majority of sudden deaths after repair of tetralogy of Fallot have been presumed to be due to ventricular arrhythmia; however, it remains to be demonstrated that antiarrhythmic medication reduces the incidence of sudden death. Since 1978, ventricular arrhythmias have been treated aggressively; these include any ventricular arrhythmia on routine electrocardiogram and more than 10 uniform premature ventricular complexes per hour on 24 hour electrocardiogram. A review was undertaken of 488 patients followed up for more than 1 month after repair of tetralogy of Fallot (mean follow-up time 6.1 years); 13.5% had ventricular arrhythmia on routine electrocardiogram. Ventricular arrhythmia appeared from 2 months to 21 years postoperatively (mean 7.3 years). Ventricular arrhythmias were significantly (p less than 0.01) related to: longer follow-up duration, older age at follow-up, older age at operation and higher postoperative right ventricular systolic and end-diastolic pressures. Ventricular arrhythmia on routine electrocardiogram occurred in 100% of those who later died suddenly compared with 12% of those who did not die (p less than 0.01). Treatment for ventricular arrhythmia was given to 46 patients and considered "successful" if there were fewer than 10 uniform premature ventricular complexes per hour on 24 hour electrocardiogram. A successful drug was found in 44 of the 46: 30 of 34 given phenytoin, 6 of 9 given propranolol, 1 of 7 given quinidine, 1 of 2 given disopyramide, 8 of 9 given mexiletine and 4 of 5 given amiodarone.(ABSTRACT TRUNCATED AT 250 WORDS)