ABSTRACT
The purpose of this study was to evaluate the correlation between the vasovagal syncope (VVS) and the beta1 adrenergic receptor polymorphism at the 389 position. Seventy individuals with VVS were selected. DNA was extracted from peripheral blood by salting out and subjected to the amplification-restriction test. Genotype identification was made by polyacrylamide gel electrophoresis. A higher frequency in genotype and allele frequencies were found in individuals with positive tilted table test respect individuals with negative test, as well as a marked preference of the GlyGly phenotype in women. Genotype Arg389Gly was the most frequent between individuals with positive response in passive phase with respect to those in the induced phase. When the genotype was analyzed based on the hemodynamic response (VASIS) a gradient is observed in the frequency of Arg389Gly with the highest major frequency in the cardio-inhibitory response followed by the mixed response, and finally the vasodepressor response. These results suggest that the SVV has a genetic component associated with the Arg389Gly polymorphism of the adrenergic receptor. The Gly allele has a high risk association and it is maintained in the population through heterozygosis.
Subject(s)
Polymorphism, Genetic , Receptors, Adrenergic, beta-1/genetics , Syncope, Vasovagal/genetics , Adult , Female , Humans , MaleABSTRACT
The purpose of this study was to evaluate the correlation between the vasovagal syncope (VVS) and the beta1 adrenergic receptor polymorphism at the 389 position. Seventy individuals with VVS were selected. DNA was extracted from peripheral blood by salting out and subjected to the amplification-restriction test. Genotype identification was made by polyacrylamide gel electrophoresis. A higher frequency in genotype and allele frequencies were found in individuals with positive tilted table test respect individuals with negative test, as well as a marked preference of the GlyGly phenotype in women. Genotype Arg389Gly was the most frequent between individuals with positive response in passive phase with respect to those in the induced phase. When the genotype was analyzed based on the hemodynamic response (VASIS) a gradient is observed in the frequency of Arg389Gly with the highest major frequency in the cardio-inhibitory response followed by the mixed response, and finally the vasodepressor response. These results suggest that the SVV has a genetic component associated with the Arg389Gly polymorphism of the adrenergic receptor. The Gly allele has a high risk association and it is maintained in the population through heterozygosis.
Subject(s)
Adult , Female , Humans , Male , Polymorphism, Genetic , Receptors, Adrenergic, beta-1 , Syncope, VasovagalABSTRACT
Studies to assess the value of clinical symptoms to predict the head-up tilt test (HUT) outcome in patients with suspicion of vasovagal syncope have shown controversial results. We undertook this study to compare the frequency of symptoms between subjects with and without history of syncope, its association with syncopal spells in those with a history of syncope and positive or negative HUT, and to identify clinical predictors of HUT outcome. Sixty seven subjects with a history of unexplained syncope and 26 subjects without a history of syncope were interviewed using a structured questionnaire before undergoing HUT, which was performed first in a passive phase and, if negative, was repeated with pharmacological challenge using 5 mg of sublingual isosorbide. Questionnaire included the 16 symptoms most frequently reported in previous studies. Only five symptoms were reported more frequently by subjects with history of syncope in comparison with subjects without it: visual blurring, dysesthesia, sighing dyspnea, tremor in fingers, and diaphoresis. Comparison of symptom frequency between patients with history of syncope and positive or negative HUT revealed that only two were significantly different: nausea and hot flashes. However, a detailed analysis of the data indicates that only hot flashes occurring just before the syncope were more common in those with a positive HUT. Although some symptoms were found more frequently in patients with a history of syncope than in those without it, the use of a structured questionnaire in the group of patients failed to predict the outcome of the HUT.
