Polymorphisms in ß-adrenergic receptors are associated with increased risk to have a positive head-up tilt table test in patients with vasovagal syncope

Abstract Background Vasovagal syncope (VVS) is a frequent clinical condition in which a genetic background seems to be implicated. Considering that the adrenergic receptors (ARs) may play a role in VVS, the present study has as principal aim to determine if the α- and β-AR (ADRA and ADRB) gene polymorphisms are associated with an increased risk to have a positive head-up tilt table (HUTT) test in patients with VVS. Methods: Nine polymorphisms in the ADRA1A (rs1048101, rs1383914, rs574584, and rs573542), ADRB1 (rs1801252 and rs1801253), ADRB2 (rs1042713 and rs1042714), and ADRB3 (rs4994) genes were analyzed using the 5’ exonuclease TaqMan genotyping assay in a group of 134 patients with VVS. Results Under different models, the rs1801252 (OR = 8.63, 95% CI: 0.95-78.72, Precessive = 0.02), rs1042713 (OR = 1.94, 95% CI: 1.02-3.66, Padditive = 0.04), and rs4994 (OR = 2.46, 95% CI: 1.01-6.01, Pdominant = 0.042 and OR = 2.62, 95% CI: 1.04-6.63, Pover-dominant = 0.03) polymorphisms were associated with increased risk for a positive HUTT. All models were adjusted for statistically significant covariates. Conclusion These results suggest that some polymorphisms of the β-AR genes could contribute to a positive tilt test in patients with VVS.

Utilidad de las derivaciones paraesternales altas en el diagnóstico del Síndrome de Brugada / Utility of high parasternal electrocardiographic leads in the diagnosis of Brugada Syndrome

The use of high right precordial (HPL) leads to "unmask" Brugada syndrome (BrS) has been described by some groups. We report a family with three cases of BrS. In two, HPL were obtained by placing V1 to V3 electrodes on the first, second, and third right parasternal spaces, and V4 to V6 on the first, second, and third left parasternal spaces. A control group of 45 subjects without BrS was also studied. Compared with standard V1 and V2 leads, the abnormal repolarization pattern of the BrS was accentuated only in the BrS cases using HPL. In none of the control subjects alterations of the J point or ST segment were observed in HPL. These observations exemplify the relevance of HPL for the diagnosis of the BrS.

Avances recientes en la fisiopatología de la fibrilación auricular / Recent advances in the pathophysicology of atrial fibrillation

This review is a summary of the pathophysiology of atrial fibrillation (AF) and the progress in the understanding of this arrhythmia. The following factors should be considered in the genesis and maintenance of AF. The genetic factor is involved in cases of familial AF. Predisposing structural factors: atrial dilation, structural feature that allows the development of AF. Predisposing structural factors: the role of the Bachmann's bundle and frequency gradients between the left and right atrium. Electrophysiological factors: heterogeneous refractory periods favor the fibrillatory conduction. Triggers: abnormal electrical activity (ectopic foci). Modulating factors: autonomic nervous system. Increased vagal tone shortens atrial refractory periods, creating a greater dispersion of the refractory periods and the generation of reentries in the context of triggered activity. Finally, there are three types of atrial remodeling secondary to AF: structural, contractile, electrical. They are interrelated and contribute to maintaining the AF ("AF begets AF").