Margreet Th.E. Bink-Boelkens

Dysrhythmias after atrial surgery in children

A retrospective study was done in 50 patients after Mustards operation (group A) and in 204 patients after closure of a secundum atrial septal defect (group B) to analyze the postoperative dysrhythmias and to relate them to surgical factors. Forty-two percent of the patients in group A had dysrhythmias at the end of the follow-up, compared to 23% of group B patients. There was a high late mortality in group A (16%) significantly related to AF and AVJ. In group A a significant correlation was found between dysrhythmias and age at operation, use of cardioplegia, perfusion time, and the type of cannulation. In group B there was a significant relation between the location of the defect and the presence of abnormal pulmonary venous drainage. After ASD closure using hypothermia instead of cardiopulmonary bypass, the incidence of dysrhythmias was significant lower. Damage to the sinus node by cannulation and by suturing in the sinus node area is the main cause of the high incidence of dysrhythmias after atrial surgery. This high incidence should be a factor in the consideration of new types of operations.

Comparison of longevity, pacing, and sensing characteristics of steroid-eluting epicardial versus conventional endocardial pacing leads in children

OBJECTIVE Because of either cardiac anatomy or small size, pacing in children often occurs by means of epicardial leads. The disadvantage of epicardial leads is the shorter longevity of these leads compared with endocardial leads. During short-term follow-up, improved stimulation thresholds were found for the newer steroid-eluting epicardial leads. The longevity of these leads may be better than that of conventional epicardial leads. An improved longevity of epicardial leads may influence the choice to either epicardial or endocardial pacing in children. METHODS We studied the longevity and the pacing and sensing characteristics of 33 steroid-eluting epicardial pacing leads (group I, 15 atrial, 18 ventricular) implanted between November 1991 and October 1996 in 20 children with a mean age of 7.6 +/- 6.5 years (mean +/- SD), and 29 endocardial pacing leads (group II, 15 atrial, 14 ventricular) implanted during the same period in 21 children with a mean age of 11.7 +/- 4.7 years. RESULTS The mean follow-up in group I was 2.9 +/- 1.6 years and in group II 3.1 +/- 1.7 years (P =.61). The 2-year survival of the leads in group I was 91% +/- 5% and in group II 86% +/- 7% (P =.97). Lead failure occurred in both groups in 4 leads (P =.85). Chronic stimulation and sensing thresholds were similar. CONCLUSIONS Steroid-eluting epicardial leads have the same longevity as the conventional endocardial leads. Pacing and sensing thresholds were similar and did not change during follow-up. Therefore steroid-eluting epicardial pacing leads are a good alternative for endocardial leads in small children and in children with congenital heart disease.

ARRHYTHMIAS AFTER REPAIR OF SECUNDUM ATRIAL SEPTAL-DEFECT - THE INFLUENCE OF SURGICAL MODIFICATION

A retrospective study performed in our institution showed a significant correlation between venous cannulation and the incidence of arrhythmias after atrial septal defect (ASD) repair. We now report the results of a prospective study in 50 children operated on for ASD with selective cannulation of the superior vena cava. ECGs and Holter recordings were made before and after surgery, with a mean follow-up of 2.6 years. We found a significant decrease in postoperative arrhythmias (p less than 0.05) after changing the cannulation technique. Severe arrhythmias, present in 10% of the children in the retrospective group, were not found in the prospective study. Six children had asymptomatic arrhythmias on the Holter recording 1 year after surgery. Three of them, however, already had arrhythmias before the operation. We conclude that the incidence and severity of arrhythmias after ASD repair can be reduced significantly by surgical modifications, at least for the follow-up period of this study. The long-term significance has to be awaited.

Permanent cardiac pacing in children: Morbidity and efficacy of follow-up

The data from 50 permanently paced children [mean standard deviation follow-up 5.3 +/- 3.7 years] were reviewed, with special attention being paid to the cause of complications and the efficacy of follow-up. The 5-year survival (SD) of the patients was 78 +/- 6%; mortality was mainly due to the underlying cardiac disease. The 5-year survival (SD) of the pacing systems was 48 +/- 8%. Surgical interventions were necessary every 4.9 patient years. Of these interventions, 58% were caused by lead-related problems. Epicardial leads showed significantly more exit blocks and high thresholds than endocardial leads. Endocardial leads, therefore, should be used at a younger age than is now the current practice, from 5 years of age onwards, for example. If epicardial leads are used, the pacemaker must have a high output facility. Since exit block occurred only within the first 3 months after implantation, we suggest frequent transtelephonic monitoring during the first 3 months. Holter monitoring appeared to be the most effective and sensitive method of detecting malsensing and should be performed regularly.

Systolic and diastolic dysfunction in long-term adult survivors of childhood cancer.

AIM To assess systolic and diastolic function in adult childhood-cancer survivors (CCS) after treatment entailing potential cardiovascular toxicity. METHODS The study cohort consisted of 277 adult CCS (median age 28 [range 18-48]years), who had been treated with anthracyclines, platinum, and/or radiotherapy between 1976 and 1999, along with 130 healthy sibling controls. The assessments included echocardiography, baroreflex sensitivity measurement, and plasma N-terminal pro-brain natriuretic peptide (NT-proBNP). Echocardiography measurements were shortening fraction (SF) (abnormal<29%) for systolic function and tissue velocity imaging of early diastole (TVI Et) (abnormal<8.00)cm/sec for diastolic function; systolic function was also assessed by the wall motion score index (WMSI). RESULTS At 18 (5-31)years post-treatment, the prevalence of both impaired SF and abnormal WMSI was increased in CCS compared to controls (p=0.003 and p<0.001, respectively). CCS also had an increased prevalence of diastolic dysfunction compared to the controls (12% versus 1%, p<0.001). Abnormal SF and/or abnormal diastolic function were found in 43% of CCS. NT-proBNP was higher in CCS and was associated to increased WMSI. Baroreflex sensitivity was lower in CCS and was associated with diastolic dysfunction. Systolic as well as diastolic dysfunction was associated with cumulative dose of anthracyclines and mediastinal irradiation. CONCLUSION After treatment with potential cardiovascular toxic therapies, the risk of systolic and diastolic dysfunction in CCS is considerable. Since these abnormalities, in particular diastolic dysfunction, are age related, the observed effects might be considered a sign of precocious cardiac ageing.

Sotalol for atrial tachycardias after surgery for congenital heart disease

Atrial tachycardias, in particular atrial flutter after surgery for congenital heart disease, is associated with a high mortality. Treatment with various antiarrhythmic drugs and/or antitachycardia pacemakers is not very successful. Sotalol, a Class III drug, has shown to be a promising drug in adults with atrial tachycardias. However, the experience with sotalol in children after surgery for congenital heart disease is limited. Therefore, we describe our results here. Between December 1990 and February 1997, 26 children with atrial tachycardias, most of them with atrial flutter or fibrillation (n = 20), after surgery for congenital heart disease were treated with sotalol orally. The age of the children at the start of treatment was 7.5 ± 5.8 years (mean ± SD). The time interval between surgery and the start of atrial tachycardia ranged from 1 day to 14.3 years (3.8 ± 3.8 years). Conversion to sinus rhythm was achieved in 16 out of 22 hemodynamically stable children with a dosage of 4.0 ±1.6 mg/kg per day. The six children without sinus rhythm on sotalol and four hemodynamically unstable patients were treated prophylactically with sotalol after DC cardioversion for their tachycardias. Two children complained of mild transient fatigue. Heart rate decreased during therapy (95 ± 33 vs 81 ± 21 beats/min; P = 0.01). QTc‐intervals did not change. Proarrhythmias such as torsades de pointes were not encountered. Two children with a preexis‐tent sick sinus syndrome showed aggravation of bradycardia and needed pacemaker implantation. The percentage of children with a recurrence‐free interval of 1 and 2 years was 96% and 81 %, respectively, for all atrial tachycardias, and 92% and 66% for atrial flutter. The recurrences of atrial tachycardias during the follow‐up period, which ranged from 0.1‐6.1 years (2.5 ± 1.8 years) could be treated with only an increase of the dosage of sotalol in all but one patient. We conclude that sotalol is an effective drug for the treatment and prevention of atrial tachycardia in children afler surgery for congenital heart disease.

FUNCTIONAL ABNORMALITIES OF THE CONDUCTION SYSTEM IN CHILDREN WITH AN ATRIAL SEPTAL-DEFECT

We performed an electrophysiologic study in 40 children with an atrial septal defect and analyzed their pre- and postoperative electrocardiograms and 24-hour Holter recordings. The electrophysiologic study showed a prolonged corrected sinus node recovery time in 83% and an abnormal sinuatrial conduction time in 25% of the children. An early Wenckebach response to atrial pacing was seen in 18%. Sixteen percent had a prolonged atrial conduction time. The atrial functional refractory period was abnormal in 35%. Two children developed nonsustained supraventricular tachycardia during the electrophysiologic study. The preoperative electrocardiogram showed first-degree atrioventricular block in 15% of the children; prolonged periods of accelerated atrial rhythm were found in 35% of the preoperative 24-hour Holter recordings. The incidence of first-degree atrioventricular block and accelerated atrial rhythm decreased postoperatively. We could not find a significant correlation between age or shunt size and the presence of electrophysiologic abnormalities or arrhythmias. These results indicate that the sinus node, atrioventricular node and atrial myocardium show some degree of dysfunction in patients with an atrial septal defect. An early operation may prevent further progression of electrophysiologic abnormalities and the development of symptomatic arrhythmias.

Effectiveness of Sotalol for Atrial Flutter in Children After Surgery for Congenital Heart Disease

This study describes the efficacy of oral sotalol in the treatment and prevention of atrial flutter in children after surgery for congenital heart disease. In 11 of 13 children (85%), conversion to sinus rhythm was achieved, and in 8 of 11 within 24 hours.

The asymptomatic child a long time after the mustard operation for transposition of the great arteries

We studied 36 asymptomatic children 7.7 +/- 2.5 years after a Mustard operation. Fifteen children had sinus rhythm on all electrocardiograms made during follow-up. Only 2 had normal 24-hour Holter recordings throughout follow-up, 6 had periods of supraventricular tachycardia, and 3 had periods of atrial flutter. The electrophysiological evaluation of sinus node function was normal in 5 of the 31 children who were studied. The behavior of the atrial myocardium was electrophysiologically abnormal in most of the children. Atrioventricular node function, on the contrary, was normal in nearly all of the children. Eleven children had normal hemodynamics. Four had severe or complete obstruction of the superior vena cava, 1 had a severe pulmonary venous obstruction, 3 had a severe left ventricular outflow tract obstruction, and 2 had a large left-to-right shunt. Only 3 children had normal hemodynamic and electrophysiological studies. We conclude that the absence of symptoms and a normal routine examination of children a long time after a Mustard operation does not exclude hemodynamic and electrophysiological abnormalities, which can sometimes be severe. In view of these disappointing results, we decided to replace the Mustard operation with the arterial switch operation in children with transposition of the great arteries.

Oral propafenone as treatment for incessant supraventricular and ventricular tachycardia in children

Abstract Incessant tachycardia, which can result in tachycardiainduced cardiomyopathy, is difficult to treat with conventional drugs. Better results are obtained with class Ic antiarrhythmic agents, but they may elicit proarrhythmias. 1,2 Propafenone appears to be less proarrhythmic. 3 In children with a normal heart, as well as with structural heart disease, oral propafenone has been used in different types of tachyarrhythmias including ventricular ectopy and paroxysmal tachycardia. 4–9 In incessant tachycardia, however, the experience with oral propafenone is limited. Therefore, we studied the efficacy and side effects of oral propafenone in children with incessant supraventricular and ventricular tachycardia.