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Background: Long QT syndromes (LQTS) are inherited cardiac disorders caused by mutations in the genes that encode sodium or potassium transmembrane ion channel proteins. More than 200 mutations, in at least six genes, have been found in these patients. The Jervell and Lange-Nielsen (JLN) syndrome is the recessive form of the disease and is associated with deafness. Few families with JLN syndrome and genetic studies are reported in the literature., Methods: The KCNQ1 (KvLQT1) gene in a Mexican family with Jervell-Lange-Nielsen long QT syndrome was analyzed using an automated sequence method., Results: A missense mutation was found in the three affected individuals. This mutation is associated with complete loss of channel function. Correlation with the phenotype showed a prolonged QTc interval and deafness in the two siblings homozygous to the mutation. The mother, who was heterozygous for the mutation, also had prolonged QTc interval without deafness. The father and younger brother had normal QTc intervals. The mutation was not found in 50 healthy controls studied., Conclusions: We describe for the first time a mutation in the KCNQ1 gene in a Mexican family with JLN long QT syndrome. This mutation produces an amino acid change (Gly-Arg) at protein level at the 168 residue. This mutation has been previously reported in Caucasian families with LQTS.

Here are described the topics that we think are essentials in the anti-arrhythmia drug selection. Those factors are the subtract, the threshold and the modulator factors. Are also included the place were anti-arrhythmia agents acts, their general actions, their failure and finally the basis of the combined therapy.

Atrial flutter and fibrillation are common in patients with Wolff-Parkinson-White syndrome. Pathophysiology of these arrhythmias is poorly understood. Treatment is empirical and oriented to symptomatology. Here we describe a patient with Wolff-Parkinson-White syndrome with paroxysmal reentrant orthodromic AV tachycardias and atrial flutter episodes that disappeared after His Bundle fulguration. This suggests that a complete AV reentry circuit favored the occurrence of atrial flutter in this patient.

Although several mechanisms have been proposed to explain bupivacaine cardiotoxicity, the predominant effect remains to be determined. In this study, we used an isolated rabbit right atrial model that reproduces the effects on inotropic and chronotropic functions induced by 0.5 micrograms/mL bupivacaine; then we tried to counteract these events by electrical stimulation or by addition of CaCl2 or adenosine triphosphate (ATP) to the bathing solution. Contractile force was dramatically depressed by bupivacaine alone (-68%), even when the preparation was paced (-59%). CaCl2 partially counteracted this decrease (-37%). Inotropic function was almost completely restored (-9%) when ATP was added before administration of bupivacaine. Inhibition of energy metabolism seems to be a major explanation for bupivacaine cardiotoxicity.