Fetal magnetocardiography: the clinician's viewpoint

The fetal magnetocardiogram (FMCG) can be reliably recorded from approximately the 15th week of gestation onwards. The MCG has the ability to accurately record cardiac time intervals, and to provide a real-time recording that reflects cardiac electrical activity. Standardisation of the recording, signal processing, and measurement techniques can result in data that is reproducible, and when combined with the establishment of normal values for different gestational ages can be of clinical application universally, particularly in selected groups of patients at risk of potentially lethal arrhythmias.

The brugada syndrome

The diagnostic and therapeutic aspects of Brugada syndrome, one of the important genetic arrhythmias which causes sudden cardiac death in young people, and the relevance of this diagnostic entity to the paediatric population are briefly summarised. The role of diagnostic testing (genetic, pharmacologic and invasive electrophysiologic) for establishing the diagnosis and for risk stratification are discussed. Finally, while the implantable defibrillator is the only therapy of proven effectiveness in preventing sudden cardiac death, alternative therapies which are being considered (pharmacologic, hormonal and catheter ablation) are overviewed. The aim of this manuscript is to raise the awareness among doctors caring for young patients to the possibility of Brugada syndrome in patients presenting with potentially life-threatening symptoms of syncope or near-miss sudden death, and in index patients with a similar family history.

Combined transhepatic and transjugular approach for radiofrequency ablation of an accessory pathway in a child with complex congenital heart disease

We report on a boy with recurrent drug resistant atrioventricular reentrant tachycardia. The patient had complex structural heart disease consisting of right atrial isomerism, systemic venous anomaly (mirror image orientation of the intrathoracic veins, hemiazygos continuation to the left-sided superior vena cava, with separate drainage of the hepatic veins into the left-sided atrium, congenitally corrected transposition (ccTGA), pulmonary atresia (PA), ventricular and atrial septal defects (VSD and ASD). At the age of 22 months RF ablation was performed. Access to the heart was obtained by percutaneous puncture of a hepatic vein, the left internal jugular vein, and femoral artery. Earliest retrograde atrial conduction during tachycardia was localized to the free wall of the left-sided AV groove, and ablation in this area was successful. There were no procedure-related complications. RF ablation of accessory pathway is feasible in young children with complex structural heart disease and abnormal systemic venous return. In such patients access to the heart must be planned with the knowledge of the anatomy and judicious use of the hepatic venous approach, which should be done only by experienced investigators.

Transhepatic approach for catheter ablation of accessory pathway in a child with complex congenital heart disease

We report on a 22-month-old boy with drug-resistant atrioventricular reentrant tachycardia and complex structural heart disease consisting of right atrial isomerism, mirror image orientation of the intrathoracic veins, hemi-azygos continuation to the left superior vena cava, separate drainage of the hepatic veins into the left-sided atrium, congenitally corrected transposition, pulmonary atresia, and atrial and ventricular septal defects. Access to the heart for radiofrequency (RF) ablation was obtained by percutaneous puncture of a hepatic vein, the left internal jugular vein, and femoral artery. The accessory pathway was localised to the free wall of the left-sided AV groove and successfully ablated. There were no procedure-related complications. RF ablation of an accessory pathway is feasible in young children with complex structural heart disease and abnormal systemic venous return. In such patients access to the heart must be planned with knowledge of the anatomy and judicious use of the hepatic venous approach.

[Closure of a ventricular septum defect in a 4-year-old boy during percutaneous heart catheterisation]

A 4-year-old boy in whom a muscular ventricular septal defect (VSD) had been diagnosed at birth presented with limited exercise tolerance and mild cardiomegaly. The moderately large defect was closed with an umbrella device via percutaneous heart catheterisation. Thereafter, his symptoms disappeared and the dimensions of the left heart returned to normal. A VSD occurs in 1.5-3.5 per 1,000 live births. In symptomatic patients with a medium or large-sized VSD, surgical closure is indicated to prevent the development of a fixed pulmonary resistance hypertension, ventricular dysfunction and the risk of endocarditis. Depending on the size and localisation of the defect, closure with an umbrella device may be chosen. The initial results have been promising in children. The safety and efficacy in the long term are still unknown.

Immediate and intermediate results of stent therapy for aortic coarctation

OBJECTIVES

The aim of the study was to assess the immediate and intermediate outcomes of stent therapy for coarctation or recoarctation of the aorta.

SETTING

Tertiary referral centres.

METHODS

A case review of all patients who have undergone stent implantation for coarctation of aorta in the Netherlands and Belgium.

RESULTS

Stents were implanted in 33 patients (mean age 21±16 years) and successful outcome occurred acutely in 32 of these 33 patients. Peak systolic blood pressure decreased from 149±37 to 124±24 mmHg. The pressure gradient decreased from 37±16 to 7±7 mmHg. The diameter of the coarctation segment increased from 7.3±3.8 to 13.3±3.9 mm. Three patients had major complications and three had minor complications. During a mean follow-up of 21±17 months recoarctation was found in ten patients, seven of whom have undergone further procedures. There were no deaths at follow-up.

CONCLUSIONS

Stent implantation is a good alternative to balloon dilation in selected patients with coarctation of the aorta. However, follow-up evaluation reveals a varying incidence of recoarctation and the long-term outcomes need to be determined.

The double-switch procedure for atrioventricular and ventriculoarterial discordance

BACKGROUND

Late ventricular failure remains a major concern in patients with congenitally corrected transposition of the great arteries (ccTGA). A new treatment for this condition is the double-switch procedure.

METHODS

Three consecutive children with atrioventricular and ventriculoarterial discordance (congenitally corrected transposition of the great arteries) and associated ventricular septal defect underwent pulmonary artery banding in infancy, followed by a double-switch procedure and closure of the ventricular septal defect at a median age of 5.8 years (range 4.5 to 6 years).

RESULTS

There were no major procedure-related complications and the median duration of hospital stay was 13 days. One patient required stent implantation in the superior vena cava five months after surgery to relieve a persistent caval stenosis associated with recurrent pleural and pericardial effusions. Apart from this, no other complications have occurred over a median follow-up of five months.

CONCLUSION

The double-switch procedure offers the potential advantage of restoring the morphological left ventricle to systemic ventricle. Longer-term follow-up of this procedure is warranted.

Persistent junctional reciprocating tachycardia in the fetus

BACKGROUND

Persistent junctional reciprocating tachycardia (PJRT) tends to be a persistent arrhythmia and requires aggressive therapeutic management. Diagnosis and management of this infrequently occurring tachycardia in the fetus at an early stage is of importance for the prevention of congestive heart failure (CHF).

METHODS

A retrospective study of four fetuses with supraventricular tachycardia (SVT) of the PJRT type was performed.

RESULTS

All had sustained SVT (mean of 228 beats/min) at a mean gestational age of 34 + 5 weeks, with CHF present in two. Three fetuses had prenatal characteristics of PJRT on M-mode echocardiography with a ventriculoatrial (VA)/atrioventricular ratio of > 1 on M-mode echocardiography suggesting a slow conducting accessory pathway. All four fetuses had postnatal confirmation of the diagnosis. Transplacental treatment with flecainide was effective in one patient; sotalol as a single drug or in combination with digoxin was partially effective in the remaining three. Two developed sinus rhythm, with short intermittent periods of tachycardia and decreasing signs of CHF; one case showed a minimal decrease in heart rate. Oral propranolol therapy converted two patients postnatally; in the remaining two patients radiofrequency ablation was performed at the age of 5 months and 6 years.

CONCLUSIONS

The characteristics of our prenatal PJRT cases included a sustained heart rate not exceeding 240 beats/min with a long VA interval, the presence of CHF and therapy resistance. Transplacental treatment should be initiated, possibly with a combination of sotalol and digoxin in non-hydropic cases, or flecainide, especially in case of fetal hydrops. Pharmacological therapy is to be preferred postnatally, but radiofrequency ablation seems to be indicated in therapy-resistant cases with CHF, even in the first months of life.

Catheter ablation of sinoatrial re-entry tachycardia in a 2 month old infant

Successful catheter ablation of sinoatrial re-entry tachycardia in an infant has not been previously reported. This procedure is described in a 2 month old boy with tachycardia induced cardiomyopathy.

Implantable diagnostic and therapeutic devices in children

Many advances have been made in the use of implantable diagnostic and therapeutic devices in adults. In children the indications for and diagnostic and therapeutic value of these devices still have to be determined. Our aim is to provide an overview of the clinical use of diagnostic and therapeutic devices in children. The role of implantable loop recorders (ILR), the feasibility and safety of transvenous pacing in neonates, the value of permanent pacing in children with recurrent syncope or reflex anoxic seizures and the role of implantable cardioverter defibrillator devices are highlighted with relevant case histories.

Implantable loop records in paediatric pratice

BACKGROUND

Symptoms of syncope and palpitations are not uncommon in children with and without heart disease. They present a diagnostic dilemma when conventional cardiovascular testing is inconclusive. The implantable loop recorder (ILR) has been shown to play an important role in diagnosing recurrent syncope in adult patients. In paediatric practice its role still has to be defined.

AIM

The aim of this article is to assess the diagnostic yield of the ILR in children and young adults.

METHODS

Seven patients, four male and three female, were included in the study. The mean age at implantation was 12.8 years, with a range from 0.8 to 25.9 years.

RESULTS

The symptoms leading to ILR implantation were recurrent syncope or near-syncope (n=3), syncope in combination with palpitations (n=2), and syncope with an acute life-threatening event (ALTE) (n=2). Previous testing included 12-lead ECG (n=7), echo (n=7), 24-hour Holter (n=7), four-week ambulatory Holter (n=3), exercise test (n=4) and invasive electrophysiological study (n=3). Over a mean follow-up period of 7.5 months (range 3 to 16 months), four (57%) patients continued to have symptoms.

CONCLUSIONS

The ILR enabled the correct diagnosis to be established in all four patients with persistent symptoms allowing appropriate therapy to be given.

Endocardial and epicardial steroid lead pacing in the neonatal and paediatric age group

AIM

To compare the performance of steroid eluting epicardial and endocardial leads in infants and children requiring permanent pacing.

METHODS

Evaluation of pacing and sensing characteristics, impedances, and longevity of 159 steroid eluting leads implanted in 95 children. Group A consisted of 24 children weighing less than 15 kg with 15 endocardial leads (five atrial, 10 ventricular) and 19 epicardial leads (five atrial, 14 ventricular). Group B consisted of 71 children weighing more than 15 kg with 106 endocardial leads (56 atrial, 58 ventricular) and 19 epicardial leads (nine atrial, 10 ventricular).

RESULTS

Group A: Stimulation thresholds were lower for ventricular endocardial leads at implant (mean (SD) 0.84 (0.54) v 1.59 (0.64) V, p < 0.014) and at two year follow up (ventricular 0.64 (0.24) v 1.65 (0.69) V, p < 0.003). Impedance and sensing thresholds did not differ significantly at implant and follow up. Group B: Stimulation thresholds were lower for ventricular endocardial leads at implant (0.72 (0.48) v 1.48 (0.58) V, p < 0.001) and at follow up (0.88 (0.46) v 1.55 (0.96) V, p < 0.009). Impedance did not differ. Sensing thresholds were also better for ventricular endocardial leads at follow up (9.1 (5.2) v 14.2 (6.4) mV, p < 0.02). Complications requiring intervention occurred in both groups (n = 7 for endocardial v n = 18 for epicardial leads).

CONCLUSIONS

Endocardial and epicardial steroid eluting leads have comparable performance in the paediatric population.

Technique of pulmonary vein isolation by catheter ablation

In selected patients with atrial fibrillation, the fibrillation episodes may be initiated by single or short bursts of ectopy often originating from one or more pulmonary veins (PVs). Therefore, electrical isolation of these veins by catheter ablation is currently being explored as a treatment modality for patients with paroxysmal and even more permanent types of atrial fibrillation. At present, two different techniques are used: 1) selective ablation of electrical connections between left atrium and myocardial sleeves inside the PVs; and 2) contiguous encircling lesions around and outside the PV ostia. With both techniques, moderate to high success rates have been reported with a limited follow-up duration. Both types of procedure are very complex and require a highly skilful team. With the variable anatomy of the PVs, non-invasively acquired angiographic images may serve as a roadmap for catheter manipulation. Modern three-dimensional catheter navigation techniques can be applied to facilitate accurate catheter positioning with limited fluoroscopic exposure. Experimental and clinical research is needed to define patient selection criteria.

Catheter ablation of incisional atrial tachycardia using a novel mapping system: LocaLisa

Incisional atrial tachycardia occurs due to reentry around surgical scars. Pharmacological therapy is often ineffective. This study assessed the efficacy of a novel mapping system (LocaLisa) in facilitating catheter ablation of incisional atrial tachycardia circuits. Eight consecutive patients (four men, four women) with incisional atrial tachycardia (median age 23.5 years, range 9-44) following previous repair of congenital heart defects underwent transcatheter mapping and ablation of the arrhythmogenic substrate using a mapping system (LocaLisa) that allows localization of endocardial electrodes in a three-dimensional space. Critical isthmuses for the tachycardia circuits were identified by demonstrating concealed entrainment using standard pacing and mapping techniques. Scars and natural anatomic barriers were marked on the LocaLisa image. Lines of block were created by radiofrequency current application between scars and natural anatomic barriers, or between two scars, to close isthmuses demonstrated to be critical for the reentrant circuit. All lines of block were verified in both directions. All reentrant circuits around incisions were successfully ablated. Seven additional tachycardia mechanisms were identified in four patients (common atrial flutter [n = 4], atrioventricular nodal [AVN] reentry [n = 2], ectopic atrial tachycardia [n = 1]) and were also ablated in a single session. The mean fluoroscopy time was 28.4 +/- 13.8 minutes. All patients are arrhythmia-free at a median follow-up of 20 (6-22) months. The LocaLisa mapping system is effective for identification of scars and ablation targets, for confirming lines of block, and facilitating ablation of complex reentrant circuits.

Aneurysmal pericardial patch producing right ventricular inflow obstruction

A 2-month-old infant presented with acute onset of heart failure, having previously undergone anatomical repair of transposition of the great arteries and ventricular septal defect (VSD). Echocardiography demonstrated aneurysmal dilation of the native pericardial patch used for VSD closure, resulting in right ventricular inflow obstruction. The pericardial patch was excised, and the VSD closed using a GoreTex patch.

Congenital heart block: development of late-onset cardiomyopathy, a previously underappreciated sequela

OBJECTIVE

We report 16 infants with complete congenital heart block (CHB) who developed late-onset dilated cardiomyopathy despite early institution of cardiac pacing.

BACKGROUND

Isolated CHB has an excellent prognosis following pacemaker implantation. Most early deaths result from delayed initiation of pacing therapy or hemodynamic abnormalities associated with congenital heart defects.

METHODS

A multi-institutional study was performed to identify common clinical features and possible risk factors associated with late-onset dilated cardiomyopathy in patients born with congenital CHB.

RESULTS

Congenital heart block was diagnosed in utero in 12 patients and at birth in four patients. Ten of 16 patients had serologic findings consistent with neonatal lupus syndrome (NLS). A pericardial effusion was evident on fetal ultrasound in six patients. In utero determination of left ventricular (LV) function was normal in all. Following birth, one infant exhibited a rash consistent with NLS and two had elevated hepatic transaminases and transient thrombocytopenia. In the early postnatal period, LV function was normal in 15 patients (shortening fraction [SF] = 34 +/- 7%) and was decreased in one (SF = 20%). A cardiac pacemaker was implanted during the first two weeks of life in 15 patients and at seven months in one patient. Left ventricular function significantly decreased during follow-up (14 days to 9.3 years, SF = 9% +/- 5%). Twelve of 16 patients developed congestive heart failure before age 24 months. Myocardial biopsy revealed hypertrophy in 11 patients, interstitial fibrosis in 11 patients, and myocyte degeneration in two patients. Clinical status during follow-up was guarded: four patients died from congestive heart failure; seven required cardiac transplantation; one was awaiting cardiac transplantation; and four exhibited recovery of SF (31 +/- 2%).

CONCLUSIONS

Despite early institution of cardiac pacing, some infants with CHB develop LV cardiomyopathy. Patients with CHB require close follow-up not only of their cardiac rate and rhythm, but also ventricular function.

[Balloon angioplasty as the primary treatment for coarctation of the aorta in 30 children; immediate results and follow-up]

OBJECTIVE

Evaluation of the results of balloon dilatation in coarctation of the aorta in children.

DESIGN

Retrospective.

METHOD

In the years 1990-1999 30 patients with a congenital coarctation of the aorta were treated with balloon angioplasty in the Children's Heart Centre of Utrecht University Medical Centre, the Netherlands. The group comprised 5 girls and 25 boys, with a mean age of 4.8 years (range 1 month-16 years) without severe associated congenital heart defects or a long segment coarctation. Follow-up included Doppler echocardiography and MRI within the first 6 years after the procedure. The fall of the pressure gradient was assessed with Student's t-test for paired observations and the reintervention period was calculated by the Kaplan-Meier method.

RESULTS

No children died. Of 30 procedures performed, 28 (93%) were considered successful. Mean pressure gradient was reduced from 36.2 mmHg (SD: 12.7) to 13.1 mmHg (SD: 9.3) (p < 0.001). Mean follow-up was 4.1 years; the follow-up of 11 patients was longer than 5 years. Four patients (13%) developed a recoarctation. No aneurysm formation was encountered (n = 14).

CONCLUSION

Balloon angioplasty for the treatment of native coarctation of the aorta in children may be an efficient and not very damaging solution for this selected group of patients.

Neurophysiological effects of pediatric balloon dilatation procedures

Balloon dilatation of valvar and vascular stenoses has become routine therapy in pediatric cardiology. Repeated balloon inflations cause many episodes of low cerebral oxygen delivery. This study is a prospective study to assess the effects of balloon dilatation on cerebral perfusion and oxygenation. The study included 11 patients scheduled for elective catheterization and balloon dilatation at a university pediatric hospital. Blood flow velocity in the middle cerebral artery (Vmca) and regional cerebral oxygen saturation (rSO2) were monitored by means of transcranial Doppler sonography and near infrared spectroscopy, respectively. In group 1, consisting of 6 patients without an intracardiac shunt, inflation of the balloon resulted in a decrease in Vmca followed by a minor decrease in rSO2. In group 2, consisting of 5 patients with an interatrial communication, inflation resulted in an increase in right-to-left shunt fraction, arterial desaturation. and a major decrease in rSO2 with minor changes in Vmca. Balloon dilatation causes an important decrease in cerebral oxygen delivery by different mechanisms. This may lead to serious morbidity and even mortality. Neuromonitoring is a useful tool in assessing the cerebral effects of balloon dilatation and brain recovery.