Treatment of hypertrophic cardiomyopathy in childhood

Early sensitization of myofilaments to Ca2+ prevents genetically linked dilated cardiomyopathy in mice

Background

Dilated cardiomoypathies (DCM) are a heterogeneous group of inherited and acquired diseases characterized by decreased contractility and enlargement of cardiac chambers and a major cause of morbidity and mortality. Mice with Glu54Lys mutation in α-tropomyosin (Tm54) demonstrate typical DCM phenotype with reduced myofilament Ca2+ sensitivity. We tested the hypothesis that early sensitization of the myofilaments to Ca2+ in DCM can prevent the DCM phenotype.

Methods and results

To sensitize Tm54 myofilaments, we used a genetic approach and crossbred Tm54 mice with mice expressing slow skeletal troponin I (ssTnI) that sensitizes myofilaments to Ca2+. Four groups of mice were used: non-transgenic (NTG), Tm54, ssTnI and Tm54/ssTnI (DTG). Systolic function was significantly reduced in the Tm54 mice compared to NTG, but restored in DTG mice. Tm54 mice also showed increased diastolic LV dimensions and HW/BW ratios, when compared to NTG, which were improved in the DTG group. β-myosin heavy chain expression was increased in the Tm54 animals compared to NTG and was partially restored in DTG group. Analysis by 2D-DIGE indicated a significant decrease in two phosphorylated spots of cardiac troponin I (cTnI) in the DTG animals compared to NTG and Tm54. Analysis by 2D-DIGE also indicated no significant changes in troponin T, regulatory light chain, myosin binding protein C and tropomyosin phosphorylation.

Conclusion

Our data indicate that decreased myofilament Ca2+ sensitivity is an essential element in the pathophysiology of thin filament linked DCM. Sensitization of myofilaments to Ca2+ in the early stage of DCM may be a useful therapeutic strategy in thin filament linked DCM.

Rehabilitación cardiaca en pediatría: ¿qué dice la evidencia?

Introducción. En las últimas cuatro décadas, las organizaciones de la salud han reconocido que la rehabilitación cardíaca es un elemento esencial para la recuperación de pacientes con enfermedades cardiovasculares.Objetivo. Realizar un análisis de la evidencia sobre la implementación de un programa de rehabilitación cardiaca, basado en ejercicio físico, en una población pediátrica con alteraciones congénitas cardiacas.Materiales y métodos. Se buscó y analizó la evidencia disponible de programas de rehabilitación cardiaca, basada en ejercicio físico, en pacientes pediátricos con alteraciones congénitas. Para la búsqueda se emplearon los términos MeSH: “Rehabilitation”, “Exercise”, “Resistance Training” y “Pediatrics” y se hizo revisión en las bases de datos Ebsco, Pedro, Hinari, Elsevier, Science Direct, Springer y Medline.Resultados. Se encontró que la implementación de un programa de rehabilitación cardiaca en población pediátrica tiene resultados significativos en la calidad de vida de estos pacientes, pero necesita de parámetros como evaluación, protocolo de rehabilitación, prescripción del ejercicio físico y evaluación de la calidad de vida.Conclusiones. Es necesario crear un protocolo estandarizado y validado de rehabilitación cardiaca, basada en ejercicio físico, para la población pediátrica con enfermedades cardiacas congénitas.

Lessons learned from the Pediatric Cardiomyopathy Registry (PCMR) Study Group

Cardiomyopathy is a rare disorder of the heart muscle, affecting 1.13 cases per 100,000 children, from birth to 18 years of age. Cardiomyopathy is the leading cause of heart transplantation in children over the age of 1. The Pediatric Cardiomyopathy Registry funded in 1994 by the National Heart, Lung, and Blood Institute was established to examine the epidemiology of the disease in children below 18 years of age. More than 3500 children across the United States and Canada have been enrolled in the Pediatric Cardiomyopathy Registry, which has followed-up these patients until death, heart transplantation, or loss to follow-up. The Pediatric Cardiomyopathy Registry has provided the most in-depth illustration of this disease regarding its aetiology, clinical course, associated risk factors, and patient outcomes. Data from the registry have helped in guiding the clinical management of cardiomyopathy in children under 18 years of age; however, questions still remain regarding the most clinically effective diagnostic and treatment approaches for these patients. Future directions of the registry include the use of next-generation whole-exome sequencing and cardiac biomarkers to identify aetiology-specific treatments and improve diagnostic strategies. This article provides a brief synopsis of the work carried out by the Pediatric Cardiomyopathy Registry since its inception, including the current knowledge on the aetiologies, outcomes, and treatments of cardiomyopathy in children.