Grace S. Wolff

Cardiac Rhythm after the Mustard Operation for Complete Transposition of the Great Arteries

The Mustard operation corrects the effects of congenital transposition of the great arteries by creating an intraarterial baffle to direct pulmonary venous blood to the tricuspid orifice and systemic venous blood to the mitral orifice. To identify the long-term effects of this procedure, we followed 372 patients with complete transposition of the great arteries who survived the Mustard operation for at least three months. The mean follow-up period was 4.5 years (range, 0.4 to 15.9); the mean age at operation was 2.0 years. Mean resting heart rates were consistently lower than those for age-matched normal children. Seventy-six per cent of the patients had sinus rhythm during the year of operation--a figure that decreased to 57 per cent by the end of the eighth postoperative year. Twenty-five patients died during the follow-up period, nine suddenly. Life-table analysis revealed a cumulative survival rate of 91 per cent for 11 years and 71 per cent for 15 years after the operation. No strong risk factor for sudden unexpected death identified. This study demonstrates that extended survival among patients with transposition can be expected after the Mustard operation. However, over time there is a decreasing prevalence of normal sinus rhythm in survivors, as well as a small risk of sudden death.

Ventricular arrhythmias in postoperative tetralogy of Fallot.

Ventricular arrhythmias in patients after total surgical repair of tetralogy of Fallot have been associated with late sudden death. In this large multicenter retrospective study of 359 patients with postoperative tetralogy of Fallot, spontaneous ventricular premature complexes (VPCs) on 24-hour ambulatory electrocardiographic monitoring and laboratory-induced ventricular tachycardia (VT) by electrophysiologic stimulation were analyzed. The mean age at surgical repair was 5 years and the mean follow-up duration after repair was 7 years. Spontaneous VPCs on ambulatory monitoring were found in 48% and induced VT on electrophysiologic stimulation was found in 17% of patients. Both spontaneous VPCs and induced VT were significantly related to delayed age at repair, longer follow-up interval, symptoms of syncope or presyncope and right ventricular systolic hypertension (greater than 60 mm Hg) (p less than 0.05), but not to right ventricular diastolic pressure greater than 8 mm Hg. The VPCs on ambulatory monitoring were more complex with increasing age at repair and follow-up duration. Induction of VT on electrophysiologic stimulation correlated with spontaneous VPCs including VT on 24-hour ambulatory electrocardiographic monitoring. The electrophysiologic stimulation protocol varied and the induction of VT increased with a more aggressive stimulation protocol. While induced sustained monomorphic VT was related to all forms of spontaneous VPCs, induced nonsustained polymorphic VT was related to more complex forms of VPCs on ambulatory monitoring. VT was not induced in asymptomatic patients who had normal 24-hour ambulatory electrocardiographic monitoring and normal right ventricular systolic pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

NASPE expert consensus conference: Radiofrequency catheter ablation in children with and without congenital heart disease. Report of the writing committee

A Consensus Conference on Pediatric Radiofrequency Catheter Ablation took place at the 21 Annual Scientific Sessions of the North American Society of Pacing and Electrophysiology (NASPE). The participants included health professionals from the pediatric and adult electrophysiological communities, and involved physicians, nurses, and other allied professionals. This statement attempts to coalesce the information presented and is directed to all health professionals who are involved in the care of pediatric patients undergoing ablation. In an attempt to write such a document, the editors must try to represent what they believed was the general consensus of opinion amongst the participants. As generally understood in the medical world, “consensus” does not indicate complete harmony within a group but a substantial degree of agreement. It is hoped that the information presented falls within that definition and will serve as a foundation on which to build toward in the future. Even as this document was being prepared, new technologies were introduced that may expand the indications and possibly the type of personnel and training necessary to perform these procedures. It will be interesting to look back on this statement of the current state-of-the art over the next 5–10 years and see if some of the recommendations stand the test of time. As is true of many documents, only in retrospect can a judgement be made on the strength of what is stated in this statement. The goal of the Consensus Conference was to bring together pediatric and adult practitioners in electrophysiology for an all day discussion of catheter ablation in children and in patients with congenital heart disease (CHD). The organizers believed that, in choosing topics for discussion, the development of indications for catheter ablation should flow naturally from what is known concerning the natural history of the arrhythmias in question in the pediatric population and from the latest information available concerning outcomes from these procedures. Therefore, the initial part of this statement deals with the natural history issues of specific arrhythmias in children with and without CHD. Issues of radiation exposure and animal models of toxicity due to radiofrequency (RF) application are noted followed by outcomes and complications of RF ablation for various arrhythmias. Indications for ablation are then discussed. It is important to realize that these indications as presented are not necessarily “written in stone” and do not take the place of a “Policy Statement.” Rather, as mentioned above, this represents a general sense of agreement within the community of pediatric and adult electrophysiologists . The second half of the conference then dealt with the “nuts and bolts” of performing these proNASPE POSITION STATEMENT

Surgically Induced Right Bundle-Branch Block with Left Anterior Hemiblock An Ominous Sign in Postoperative Tetralogy of Fallot

A review of the electrocardiograms of 291 patients who survived more than 1 month after complete repair of tetralogy of Fallot disclosed that 24 (8.2%) developed a pattern of right bundle-branch block and left anterior hemiblock (RBBB-LAH) following surgery. When the course of these 24 patients was compared with a control group of 100 additional patients who did not develop this pattern following surgery, a significant increase in morbidity and mortality was noted.Complete heart block developed at some time in the follow-up period in 41.7% of the RBBB-LAH group and in 4% of the control group. The incidence of serious ventricular arrhythmias was 16.7% for the RBBB-LAH group and 1% for the control group. Sudden death occurred in 12.5% of the patients with RBBB-LAH and in 2% of the controls. At the time of this review (1-12 years following surgery) overall late mortality was 25% for the RBBB-LAH group and 2% for the control group.The study indicates that serious complications are much more frequent in tetralogy of Fallot patients who acquire the RBBB-LAH pattern during surgical repair. Prophylactic or therapeutic pacing may be indicated in many of these patients.

Recurrent Third-Trimester Fetal Loss and Maternal Mosaicism for Long-QT Syndrome

Background—The importance of germ-line mosaicism in genetic disease is probably underestimated, even though recent studies indicate that it may be involved in 10% to 20% of apparently de novo cases of several dominantly inherited genetic diseases. Methods and Results—We describe here a case of repeated germ-line transmission of a severe form of long-QT syndrome (LQTS) from an asymptomatic mother with mosaicism for a mutation in the cardiac sodium channel, SCN5A. A male infant was diagnosed with ventricular arrhythmias and cardiac decompensation in utero at 28 weeks and with LQTS after birth, ultimately requiring cardiac transplantation for control of ventricular tachycardia. The mother had no ECG abnormalities, but her only previous pregnancy had ended in stillbirth with evidence of cardiac decompensation at 7 months’ gestation. A third pregnancy also ended in stillbirth at 7 months, again with nonimmune fetal hydrops. The surviving infant was found to have a heterozygous mutation in SCN5A (R1623Q), previously reported as a de novo mutation causing neonatal ventricular arrhythmia and LQTS. Initial studies of the mother detected no genetic abnormality, but a sensitive restriction enzyme–based assay identified a small (8% to 10%) percentage of cells harboring the mutation in her blood, skin, and buccal mucosa. Cord blood from the third fetus also harbored the mutant allele, suggesting that all 3 cases of late-term fetal distress resulted from germ-line transfer of the LQTS-associated mutation. Conclusions—Recurrent late-term fetal loss or sudden infant death can result from unsuspected parental mosaicism for LQTS-associated mutations, with important implications for genetic counseling.

Usefulness of tissue Doppler echocardiography for evaluating ventricular function in children without heart disease.

Tissue Doppler echocardiographic imaging (TDI) is a novel method for accurately evaluating ventricular function. Currently, scant data are available on the distribution of tissue Doppler indexes in healthy children in the age range of 1 to 18 years. The aims of this study were to assess the distribution of tissue Doppler indexes of systolic and diastolic ventricular function in healthy children, to assess the influence of age on these indexes, and to compare them with conventional Doppler indexes. A total of 151 consecutive children aged 1 to 18 years were enrolled in the study. Nine different (7 diastolic and 2 systolic) TDI parameters were assessed. Peak velocities of systolic and diastolic excursions of the mitral and tricuspid annuli were obtained from the apical 4-chamber view. Mean velocities of early diastolic recoil of mitral and tricuspid annuli were measured from the apical 4-chamber view. The mean velocity of early diastolic relaxation of the left ventricular posterior wall was measured in the parasternal long-axis view. Results showed a statistically significant difference in some of the TDI indexes among the different pediatric age groups. Most of the TDI indexes showed a very weak correlation with age. There was no significant correlation (p >0.05) between peak velocities of the early diastolic mitral inflow Doppler pattern (E wave) and the corresponding TDI index. In contrast, there was a significant (p <0.001) correlation between the corresponding Doppler indexes in the tricuspid annulus. We conclude that TDI is a valuable tool for assessing ventricular function, particularly diastolic function. Establishment of normative data for TDI in the pediatric age group should broaden the clinical applicability of this useful modality for assessing ventricular function.

Dual atrioventricular nodal pathways: A benign finding in arrhythmia-free children with heart disease

The incidence and significance of dual atrioventricular (A-V) nodal pathways are described in 78 children with associated congenital or acquired heart disease. None of these patients had clinical or electrocardiographic evidence of arrhythmia. Dual A-V nodal pathways were observed in 35 percent of the preoperative group and in 33 percent of the postoperative group. Despite this substrate for A-V nodal reentry, supraventricular tachycardia was neither induced during electrophysiologic evaluation nor did it develop clinically over a follow-up period of 1 month to 15 years. It is concluded that dual A-V nodal pathways are common and may be a benign finding in arrhythmia-free children with heart disease.

Wolff-Parkinson-White syndrome in the neonate

Of 16 infants who presented with paroxysmal supraventricular tachycardia in the neonatal period, 50 percent had an electrocardiographic pattern consistent with Wolff-Parkinson-White conduction, type A. It is suggested that infants have bypass pathways similar to or identical with a Kent pathway as part of normal maturation. Infants with paroxysmal supraventricular tachycardia have electrically active bypass tracts but these are documented in only about one half of the patients because of the short duration of recordings or because of concealment (the bypass tract conducts only in retrograde fashion). The activity of these pathways is enhanced by the predominant cholinergic innervation of the neonatal heart. Resolution of the arrhythmias and the Wolff-Parkinson-White pattern in most patients occurs because of anatomic maturation of the conduction tissue, development of adrenergic innervation and a decrease in cholinergic dominance. In some children, maturation is incomplete and the bypass fibers remain quiescent or become active under certain circumstances such as those associated with increased autonomic discharge. Extended surveillance is recommended for all infants who present with paroxysmal supraventricular tachycardia and the Wolff-Parkinson-White pattern.

Cardiovascular malformations in oculoauriculovertebral dysplasia (Goldenhar syndrome)

Summary One of every seven infants with oculoauriculovertebral dysplasia (Goldenhar syndrome) has congenital heart disease. Fifty percent of the patients with cardiac anomalies have tetralogy of Fallot, which is usually severe and requires treatment during infancy.

Left isomerism and complete atrioventricular block: A report of six cases☆

Six children, aged 12 days to 13 years, with left isomerism and complete atrioventricular (A-V) block are presented. In all six patients the diagnosis of left isomerism was suggested by an interrupted inferior vena cava found during cardiac catheterization and angiocardiography; four patients had complex heart disease consisting of endocardial cushion defect, five had a common atrium, three had pulmonary stenosis, three had patient ductus arteriosus and two had dextrocardia. Further anatomic abnormalities included situs inversus of the viscera (four patients) as well as partial malrotation of the bowel. Of the six patients, four had congenital complete A-V block, whereas the remaining two had A-V conduction disturbances documented during early infancy that progressed to complete A-V block later in life. All six patients required pacemaker implantation and five of the six patients died. This report discusses the clinical presentation of complete AV block and left isomerism and reviews the literature.