Histological examination of the potential arrhythmic substrates in the setting of Ebstein's malformation.

Cardiac arrhythmias, notably Wolff-Parkinson-White syndrome, are known to represent a major issue in patients with Ebstein's malformation of the tricuspid valve. Abnormal conducting circuits, however, can also be produced by pathways extending either from the atrioventricular node or the ventricular components of the atrioventricular conduction axis, direct to the crest of the muscular ventricular septum. We hoped to provide further information on the potential presence of such pathways by investigations of six autopsied examples of Ebstein's malformation. All were studied by histological sectioning on the full extent of the atrioventricular conduction axis, with limited sectioning of the right atrioventricular junction supporting the inferior and antero-superior leaflets of the deformed tricuspid valve. We used the criteria established by Aschoff (Verhandlungen der Deutschen Gesellschaft für Pathologie, 14, 1910, 3) and Mönckeberg (Verhandlungen der Deutschen Gesellschaft für Pathologie, 14, 1910, 64) over a century ago to define abnormal connections across the atrioventricular junctions, as these definitions retain their validity for the identification of gross myocardial connections across the insulating tissues of the atrioventricular junctions. In one specimen, we found two discrete accessory myocardial connections across the parietal right atrioventricular junction. In all of the hearts, we found so-called nodoventricular connections, and in one heart we also observed a well-formed connection originating from the penetrating atrioventricular bundle. In addition to accessory myocardial connections across the parietal right atrioventricular junction, therefore, our histological findings demonstrate a potential role for direct connections between the atrioventricular conduction axis and the ventricular myocardium in the setting of Ebstein's malformation.

Anatomy of the normal fetal heart: The basis for understanding fetal echocardiography.

The rapid changes that have taken place in recent years in relation to techniques used to image the fetal heart have emphasized the need to have a detailed knowledge ofnormal cardiac anatomy. Without such knowledge, it is difficult, if not impossible, to recognize the multiple facets of congenital cardiac disease. From the inception of fetal echocardiographic screening, the importance of basic knowledge of cardiac anatomy has been well recognized. The current machines used for imaging, however, now make it possible potentially to recognize features not appreciated at the start of the specialty. So as to match the advances made in imaging, we have now revisited our understanding of normal cardiac anatomy in the mid-gestational fetus. This was made possible by our dissection of 10 fetal hearts, followed by production of addition histological sections that mimic the standard ultrasound views. The fetuses ranged in gestational age from between 20 and 28 weeks. We then correlated the obtained anatomic images with the corresponding ultrasonic images used in the standard fetal screening scan. We also interrogated the anatomic sections so as to clarify ongoing controversies regarding detailed features of the normal cardiac anatomy. We have been able to show that the views now obtained using current technology reveal many details of anatomy not always appreciated at earlier times. Knowledge of these features should now permit diagnosis of most congenital cardiac malformations. The anatomic-echocardiographic correlations additionally provide a valuable resource for both the understanding and teaching of fetal echocardiography.

Arritmias fetales: diagnóstico, tratamiento y resultado perinatal / Fetal arrhythmias: diagnosis, treatment and perinatal outcome

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Use of adenosine in the treatment of supraventricular tachycardia in a pediatric emergency department.

OBJECTIVE: Supraventricular tachycardia (SVT) is the most frequent arrhythmia requiring treatment in childhood, with an estimated incidence of 1/100 to 1/250 children. The treatment of choice of the acute event is intravenous adenosine. This study aimed to determine if doses of adenosine higher than previously described are needed to successfully revert SVT in children. METHODS: This is a retrospective study of SVT cases in a tertiary hospital from January 2007 to December 2011. RESULTS: A total of 44 episodes of SVT were recorded in 26 patients. Mean age was 3.1 years. In 39 patients (89%), adenosine was administered, reverting to stable sinus rhythm in 29 episodes, which represents an effectiveness of 75%. In relation to the number of doses administered, 12 patients (30%) received a single dose, with a mean (SD) response dose of 112 (35) µg/kg; 16 (41%) received 2 doses, with a mean (SD) response dose of 188 (55) µg/kg; and 9 (24%) received 3 doses, with a mean (SD) response dose of 249 (108) µg/kg. Finally, in 2 patients (4%), 4 doses of adenosine were administered, with only 1 of them responding to a dose of 300 µg/kg. The mean (SD) dose that reverted the SVT to normal sinus rhythm was 173 (84) µg/kg, and the mean (SD) number of doses administered was 1.7 (0.8) (range, 1-4). Sixty-six percent were discharged home, without the need to be transferred to pediatric intensive care unit or pediatric ward. CONCLUSIONS: Most of the patients with SVT episodes require treatment with more than 1 dose of adenosine. Doses higher than the usually described in the guidelines are necessary to revert SVT. Most patients can be discharged home from the emergency department, without the need of hospital admission.

Koch's triangle and the atrioventricular node in Ebstein's anomaly: implications for catheter ablation.

INTRODUCTION AND OBJECTIVES: The development of ablation techniques for supraventricular arrhythmias in patients with Ebstein's anomaly have led to a need for better understanding of the morphology of the triangle of Koch and the position of the atrioventricular (AV) node in this structure. METHODS: The study involved 17 human hearts: 11 with Ebstein's anomaly (age range: 37 weeks' gestation to 1 week after birth) and 6 structurally normal hearts (age range: 35 weeks' gestation to 2 days after birth). The area of the triangle of Koch was calculated and the length of the AV node and the bundle of His were measured. RESULTS: The area of the triangle of Koch was significantly smaller in specimens with Ebstein's anomaly than in control specimens (17.5+/-4.5 mm2 vs. 25.5+/-6.5 mm2; P< .05). The length of the AV node and its extensions were similar in hearts with Ebstein's anomaly and normal hearts. The AV node was displaced towards the base of the triangle in 73% of specimens with Ebstein's anomaly, and the inferior extensions reached the level of the cavotricuspid isthmus. In 91% of specimens with Ebstein's anomaly, the entry of the His bundle occurred before the apex of the triangle was reached and its length was shorter. CONCLUSIONS: Morphologic findings in this study indicate that performing an ablation procedure close to the base of the triangle of Koch in patients with Ebstein's anomaly could result in AV nodal block.

El triángulo de Koch y el nodo AV en la anomalía de Ebstein: implicaciones en la ablación con catéter / Koch’s triangle and the atrioventricular node in Ebstein’s anomaly: implications for catheter ablation

Introducción y objetivos. Los avances realizados en los procedimientos de ablación de arritmias supraventriculares en la anomalía de Ebstein (AE) han creado la necesidad de un mejor entendimiento de la morfología del triángulo de Koch (TK) y disposición en dicha estructura del nodo auriculoventricular (AV). Métodos. Se han estudiado 17 corazones humanos, 11 con AE (intervalo de edades, 37 semanas a 1 semana después de nacer) y 6 estructuralmente normales (intervalo de edades, 35 semanas a 2 días después de nacer). Se calculó el área del TK y se midió la longitud del nodo AV y el haz de His. Resultados. El área del TK es significativamente más pequeña en los especímenes con AE que en los controles (17,5 ± 4,5 mm2 frente a 25,5 ± 6,5 mm2; p < 0,05). En los corazones con AE, el nodo AV y sus extensiones son similares en longitud a los corazones normales. El nodo AV en los especímenes con AE se desplaza hacia la base del triángulo en el 73% y las extensiones inferiores llegan al nivel del istmo cavotricuspídeo (ICT). En el 91% de los especímenes con AE, la entrada del haz de His se produce antes de llegar al ápex del triángulo, y su longitud es más corta. Conclusiones. Con base en los hallazgos morfológicos obtenidos en este estudio, se puede deducir su utilidad en los procedimientos de ablación en las proximidades de la base del TK por la posibilidad de producir un bloqueo del nodo AV en pacientes con AE (AU)

Introduction and objectives. The development of ablation techniques for supraventricular arrhythmias in patients with Ebstein’s anomaly have led to a need for better understanding of the morphology of the triangle of Koch and the position of the atrioventricular (AV) node in this structure. Methods. The study involved 17 human hearts: 11 with Ebstein’s anomaly (age range: 37 weeks’ gestation to 1 week after birth) and 6 structurally normal hearts (age range: 35 weeks’ gestation to 2 days after birth). The area of the triangle of Koch was calculated and the length of the AV node and the bundle of His were measured. Results. The area of the triangle of Koch was significantly smaller in specimens with Ebstein’s anomaly than in control specimens (17.5±4.5 mm2 vs. 25.5±6.5 mm2; P < .05). The length of the AV node and its extensions were similar in hearts with Ebstein’s anomaly and normal hearts. The AV node was displaced towards the base of the triangle in 73% of specimens with Ebstein’s anomaly, and the inferior extensions reached the level of the cavotricuspid isthmus. In 91% of specimens with Ebstein’s anomaly, the entry of the His bundle occurred before the apex of the triangle was reached and its length was shorter. Conclusions. Morphologic findings in this study indicate that performing an ablation procedure close to the base of the triangle of Koch in patients with Ebstein’s anomaly could result in AV nodal block (AU)

Renal failure and acquired hypothyroidism.

The effects of thyroid metabolism on renal function in children are barely referred to in the literature. Primary hypothyroidism is known to be associated with a consistent elevation in serum creatinine levels. This is essentially because of the hypodynamic state that occurs in hypothyroidism, leading to a reduced glomerular filtration rate and hypercreatinemia. A teenager who developed renal failure due to primary hypothyroidism is reported. He displayed diverse serum biochemistry anomalies with an unremarkable physical examination. Thyroxine replacement therapy completely restored the euthyroid state and renal function. We propose, in accordance with other authors, measurement of thyrotropin levels in patients with hypercreatinemia.