Comparability of different Z-score equations for aortic root dimensions in children with Marfan syndrome.

BACKGROUND: Aortic root dilation is a major complication of Marfan syndrome and is one of the most important criteria in establishing the diagnosis. Currently, different echocardiographic nomograms are used to calculate aortic root Z-scores. The aim of the present study was to assess the potential differences in aortic root measurements when aortic root Z-scores were obtained in a cohort of paediatric Marfan patients using several published nomograms. METHODS: In a cohort of 100 children with Marfan syndrome, Z-scores for aortic root dimensions were calculated according to the nomograms of Pettersen et al, Gautier et al, Colan et al, and Lopez et al. Bland-Altman plots were used to estimate mean differences in Z-scores and to establish limits of agreement. RESULTS: The mean Z-score of the sinus of Valsalva for Lopez et al was significantly higher compared to Gautier et al (p < 0.01) and Pettersen et al (p = 0.03). The nomogram of Lopez et al resulted in substantially higher Z-scores in patients with a large sinus of Valsalva diameter. Thirty-five percentage of the studied patients would have a Z-score ≥ 2 using Lopez et al compared to 20% for Pettersen et al, 21% for Gautier et al, and 33% for Colan et al. CONCLUSION: The currently available nomograms for calculating Z-scores of aortic dilation in children with Marfan syndrome lead to clinically relevant differences in Z-scores, especially in children with a relative large aortic root diameter. This could have impact on both the diagnosis and treatment of patients with Marfan syndrome.

Implantable cardioverter defibrillator therapy for prevention of sudden cardiac death in children in the Netherlands.

INTRODUCTION: Implantable cardioverter defibrillator (ICD) therapy is increasingly used in children. The purpose of this multicenter study is to evaluate mid-term clinical outcome and to identify predictors for device discharge in pediatric ICD recipients. METHODS AND RESULTS: From 1995 to 2006, 45 patients in The Netherlands under the age of 18 years received an ICD. Mean age at implantation was 10.8 +/- 5.2 years. Primary prevention (N = 22) and secondary prevention (N = 23) were equally distributed. Underlying cardiac disorders were primary electrical disease (55%), cardiomyopathy (20%), and congenital heart disease (17%). The follow-up was 44 +/- 32.9 months. Three patients (7%) died and one patient (2%) underwent heart transplantation. ICD-related complications occurred in eight patients (17%), seven of whom had lead-related complications. Fourteen patients (31%) received appropriate ICD shocks; 12 patients (27%) received inappropriate ICD shocks. Fifty-five percent of 22 ICD recipients under the age of 12 years received appropriate shocks, which was higher as compared with 9% of 23 older ICD recipients (P = 0.003). Although the incidence of appropriate shocks in the present study was larger in secondary prevention (9/23; 39%) as compared with primary prevention (5/22; 23%), this difference did not reach significance. CONCLUSIONS: In our population of patients, children <12 years of age had more appropriate shocks than patients 13-18 years. The complication rate is low, and is mainly lead related.

Mechanism of right precordial ST-segment elevation in structural heart disease: excitation failure by current-to-load mismatch.

BACKGROUND: The Brugada sign has been associated with mutations in SCN5A and with right ventricular structural abnormalities. Their role in the Brugada sign and the associated ventricular arrhythmias is unknown. OBJECTIVE: The purpose of this study was to delineate the role of structural abnormalities and sodium channel dysfunction in the Brugada sign. METHODS: Activation and repolarization characteristics of the explanted heart of a patient with a loss-of-function mutation in SCN5A (G752R) and dilated cardiomyopathy were determined after induction of right-sided ST-segment elevation by ajmaline. In addition, right ventricular structural discontinuities and sodium channel dysfunction were simulated in a computer model encompassing the heart and thorax. RESULTS: In the explanted heart, disappearance of local activation in unipolar electrograms at the basal right ventricular epicardium was followed by monophasic ST-segment elevation. The local origin of this phenomenon was confirmed by coaxial electrograms. Neither early repolarization nor late activation correlated with ST-segment elevation. At sites of local ST-segment elevation, the subepicardium was interspersed with adipose tissue and contained more fibrous tissue than either the left ventricle or control hearts. In computer simulations entailing right ventricular structural discontinuities, reduction of sodium channel conductance or size of the gaps between introduced barriers resulted in subepicardial excitation failure or delayed activation by current-to-load mismatch and in the Brugada sign on the ECG. CONCLUSION: Right ventricular excitation failure and activation delay by current-to-load mismatch in the subepicardium can cause the Brugada sign. Therefore, current-to-load mismatch may underlie the ventricular arrhythmias in patients with the Brugada sign.

Implantable cardioverter defibrillator implantation in children in The Netherlands.

UNLABELLED: To evaluate the indications, underlying cardiac disorders, efficacy and complications involved with implantable cardioverter-defibrillators (ICDs) in paediatric patients in The Netherlands, the records of all patients aged 18 years or younger who underwent ICD placement were reviewed retrospectively. Between January 1995 and September 2002, 23 patients (11 males, 12 females; median age 12 years, range 6 months to 16 years) underwent ICD implantation. The ICD was implanted for aborted sudden cardiac death ( n = 14), syncope ( n = 5) or for primary prevention of sudden cardiac death ( n = 4). Underlying cardiac disorders were electrical diseases ( n = 16), hypertrophic or dilated cardiomyopathy ( n = 4) and congenital cardiac malformations ( n = 3). Five patients had an epicardially placed ICD, while 18 underwent a transvenous approach. The generator was placed in an abdominal position in eight patients, whereas it was placed in the subpectoral region in 15. There was no early mortality. Median hospital stay was 5 days (range 2-30 days). Median follow-up time was 29 months (range 1 month to 7 years). Seven patients experienced an inappropriate shock after a median period of 7 months; five patients an appropriate shock after a median period of 3 months. The reasons for inappropriate shock were supraventricular tachycardia ( n = 1), sinus tachycardia ( n = 4) or T-wave sensing (n = 2). One patient with malignant long QT syndrome died of intractable arrhythmias and irreversible cardiomyopathy. Generator replacement was necessary in four patients after 28, 44, 51 and 54 months respectively. CONCLUSION: Implantable cardioverter-defibrillator implantation in paediatric patients is a safe procedure with a good medium-term outcome. The most serious problem is the occurrence of a significant number of inappropriate shocks.