RESUMO
Congenital or familial short QT syndrome is a genetically heterogeneous cardiac channelopathy without structural heart disease that has a dominant autosomal or sporadic pattern of transmission affecting the electric system of the heart. Patients present clinically with a spectrum of signs and symptoms including irregular palpitations due to episodes of paroxysmal atrialfibrillation, dizziness and fainting (syncope) and/or sudden cardiac death due to polymorphic ventricular tachycardia and ventricular fibrillation. Electrocardiographic (ECG) findings include extremely short QTc intervals (QTc interval ≤330 ms) not significantly modified with heart rate changes and T waves of great voltage witha narrow base. Electrophysiologic studies are characterized by significant shortening of atrial and ventricular refractory periods and arrhythmias induced by programmed stimulation. A few families have been identified with specific genotypes: 3 with mutations in potassium channels called SQT1 (Iks), SQT2 (Ikr) and SQT3 (Ik1). These 3 potassium channel variants are the "genetic mirror image" of long QT syndrome type 2, type 1 and Andersen-Tawil syndrome respectively because they exert opposite gain-of-function effects on the potassium channels in contrast to the loss-of-function of the potassium channels in the long QT syndromes. Three new variants with overlapping phenotypes affecting the slow inward calcium channels havealso been described. Finally, another variant with mixed phenotype affecting the sodium channel was reported. This review focuses the landmarks of this newest arrhythmogenic cardiac channelopathy on the main clinical, genetic, and proposed ECG mechanisms. In addition therapeutic options and the molecular autopsy of this fascinating primary electrical heart disease are discussed.
Assuntos
Canalopatias , Potenciais de Ação , Animais , Arritmias Cardíacas/congênito , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/mortalidade , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/terapia , Canais de Cálcio/genética , Canais de Cálcio/metabolismo , Canalopatias/congênito , Canalopatias/diagnóstico , Canalopatias/metabolismo , Canalopatias/mortalidade , Canalopatias/fisiopatologia , Canalopatias/terapia , Eletrocardiografia , Técnicas Eletrofisiológicas Cardíacas , Predisposição Genética para Doença , Sistema de Condução Cardíaco/metabolismo , Sistema de Condução Cardíaco/fisiopatologia , Humanos , Mutação , Fenótipo , Canais de Potássio/genética , Canais de Potássio/metabolismo , Valor Preditivo dos TestesAssuntos
Feminino , Gravidez , Recém-Nascido , Criança , Humanos , Anomalias dos Vasos Coronários/diagnóstico , Arritmias Cardíacas/congênito , Arritmias Cardíacas/diagnóstico , Coração Fetal/anormalidades , Ultrassom , Cardiopatias Congênitas/complicações , Cardiopatias Congênitas/diagnóstico , Fatores de RiscoRESUMO
This study describes the method and principles of fetal echocardiography, analyzing the technics and the utility of bidimensional mode, M mode and Doppler ultrasound on congenital fetal cardiopathies. The importance of early diagnosis in the structural alterations and fetal cardiac arrhythmias is emphasized.
Assuntos
Ecocardiografia Doppler/métodos , Ecocardiografia/métodos , Ultrassonografia Pré-Natal/métodos , Arritmias Cardíacas/congênito , Arritmias Cardíacas/diagnóstico por imagem , Ecocardiografia/instrumentação , Ecocardiografia Doppler/instrumentação , Feminino , Coração Fetal/anormalidades , Coração Fetal/diagnóstico por imagem , Cardiopatias Congênitas/diagnóstico por imagem , Humanos , Gravidez , Ultrassonografia Pré-Natal/instrumentaçãoRESUMO
We present 119 echocardiographies in 90 high-risk pregnancies, 20 to 40 weeks gestational age. There were found 18 fetuses with abnormal examinations (20%), six of them with structural alteration (6.6%), and 14 arrhythmias (15.5%). The diagnostic correlation in structural alterations with a sensibility of 83% and 100% specificity, and 100% of sensibility and specificity in arrhythmias. The importance of antenatal diagnosis in cardiac malformations and arrhythmias is described.
Assuntos
Arritmias Cardíacas/diagnóstico por imagem , Ecocardiografia/métodos , Cardiopatias Congênitas/diagnóstico por imagem , Ultrassonografia Pré-Natal/métodos , Adulto , Arritmias Cardíacas/congênito , Arritmias Cardíacas/epidemiologia , Chile/epidemiologia , Ecocardiografia/instrumentação , Ecocardiografia/estatística & dados numéricos , Feminino , Cardiopatias Congênitas/epidemiologia , Humanos , Gravidez , Fatores de Risco , Ultrassonografia Pré-Natal/instrumentação , Ultrassonografia Pré-Natal/estatística & dados numéricosRESUMO
A newborn with supraventricular arrhythmia diagnosed during fetal life was found at autopsy to have a small nodule with hypertrophic and multinucleated myocardial cells in the atrial septum, near the atrioventricular node. There were no stigmata of Beckwith-Wiedemann syndrome or tuberous sclerosis. This focal giant-cell cardiomyopathy has been described only once, in an infant with Beckwith-Wiedemann syndrome. It is suggested that these dysplastic myocardial cells may be responsible for the atrial arrhythmia and that this hamartomatous lesion has the potential for malignant transformation.