Gustavo Maid

Written Consent to Use the Drug in Children: The Problem of Off-Label Drugs

Cardiac arrhythmias in pediatric patients have different mechanisms and frequencies compared to adult patients. There are many physiological differences between children and adults that may affect the pharmacodynamic and pharmacokinetic of the antiarrhythmic drugs in pediatric population. Children, and specially breast feeding children, cannot be considered low weighted adults to select antiarrhythmic drug doses. Although radiofrequency ablation has experienced great technological advances, it is performed in selected pediatric patients. Therefore, the main therapeutic strategy is the use of antiarrhythmic drugs in children. The medical management of arrhythmias in pediatric patients is challenging and complex. There are few clinical guidelines. There is scarce and incomplete information about the efficacy and safety of antiarrhythmic drugs in pediatric population. Most of the doses and drug administration intervals are extrapolated from adult population and applied to children. Antiarrhythmic drug doses have been extensively studied in adult population. However, in pediatric population, there are very few clinical trials and the safety of these drugs is not well known. In general, dose regimens are based on small uncontrolled studies, extrapolation of drug doses from studies performed in the adult population or physician experience. As a consequence, there is a need for further studies to assess the most effective antiarrhythmic drug regimens in children reducing the risk of side effects. Evidence suggests that medical research in pediatric population is necessary and morally valuable. But investigators involved must take care of moral and ethical values, including the respect for the child-subject and his parents or legal representatives, and this respect compels them to consider the patient and family in the decision making process. The participation request and the informed consent must be obtained according to the competitions the patient exhibits, trying to anticipate information about benefits and possible damages derived from the investigation in an understandable language for him. In our opinion the pharmacologic clinical investigation of antiarrhythmic treatments in pediatrics is necessary. More clinical studies must be carried out under rigorous scientific rules that contemplate the particular ethical dilemmas this population faces.

Valor diagnóstico de la resonancia magnética cardíaca en pacientes con arritmia ventricular frecuente y ecocardiograma Doppler normal

Introduccion La arritmia ventricular frecuente puede ser una alteracion electrica primaria o estar asociada con una cardiopatia. El impacto pronostico y terapeutico depende de la presencia de cardiopatia estructural. El ecocardiograma Doppler transtoracico ha sido el estudio complementario mas importante para evaluar la presencia de alteraciones estructurales cardiacas. Objetivos Determinar la capacidad de la resonancia magnetica cardiaca para detectar alteraciones estructurales a nivel cardiaco en pacientes con ecocardiograma Doppler normal y conocer la incidencia de eventos cardiovasculares adversos en el seguimiento. Material y metodos Se incluyeron 66 pacientes consecutivos con arritmia ventricular frecuente definida como > 5.000 extrasistoles ventriculares en un registro Holter de 24 horas, taquicardia ventricular o muerte subita resucitada con ecocardiograma Doppler normal. A todos los pacientes se les realizo una resonancia magnetica cardiaca con protocolo para evaluar miocardiopatias. Resultados El 57% de los pacientes presentaron alguna alteracion estructural; las patologias diagnosticadas mas prevalentes fueron la secuela de miocarditis, el miocardio no compactado y la secuela de infarto subendocardico. En el seguimiento medio de 24 ± 22 meses, la incidencia de eventos cardiovasculares adversos fue del 6,06%. El numero de extrasistoles ventriculares fue mayor en los pacientes con resonancia anormal. Conclusiones Este trabajo demuestra que en pacientes con arritmia ventricular frecuente con ecocardiograma Doppler normal la realizacion de una resonancia magnetica cardiaca con gadolinio permite detectar en mas de la mitad de los casos alguna alteracion estructural. Los pacientes con arritmia ventricular frecuente en el Holter, Doppler normal y alteraciones leves en la resonancia presentan riesgo bajo de eventos cardiovasculares.(AU) Introduction Frequent ventricular arrhythmia can be a primary electrical disturbance or may be associated to cardiomyopathy. The prognostic and therapeutic impact depends on the presence of structural heart disease. Transthoracic Doppler echocardiography has been the most important complementary study to evaluate the presence of cardiac structural abnormalities. Objectives The aims of this study were to determine the ability of cardiac magnetic resonance imaging to detect structural heart disease in patients with normal Doppler echocardiography and to assess the incidence of adverse cardiovascular events during follow-up. Methods The study included 66 consecutive patients with frequent ventricular arrhythmia defined as > 5000 ventricular extrasystoles in a 24-hour Holter monitoring, ventricular tachycardia or resuscitated cardiac respiratory arrest with normal Doppler echocardiogram. All patients underwent cardiac magnetic resonance imaging to assess cardiomyopathies. Results Fifty-seven percent of patients had structural heart disease. The most prevalent diagnosed pathologies were myocarditis sequelae, non-compacted myocardium and subendocardial infarction scar. At mean follow-up of 24 ± 22 months, the incidence of adverse cardiovascular events was 6.06%. The number of ventricular extrasystoles was higher in patients with abnormal cardiac magnetic resonance. Conclusions This work demonstrates that in patients with frequent ventricular arrhythmia and normal Doppler echocardiogram, gadolinium cardiac magnetic resonance imaging can detect structural heart disease in more than half of the cases. Patients with frequent ventricular arrhythmia during Holter monitoring, normal Doppler and mild alterations in the magnetic resonance present low risk of cardiovascular events.(AU)