Cardiac Autonomic Response to Active Standing in Adults With Vasovagal Syncope.

PURPOSE: Little is known about the autonomic response to active standing in vasovagal syncope, and most works have focused on children or adolescents. The aim of this work was to study the changes in cardiac autonomic modulation in adult patients with vasovagal syncope through heart rate variability analysis with linear and short-term complexity (alpha-1) indexes during supine position and active standing, in patients with positive or negative head-up tilt test (HUTT). METHODS: Twenty-five patients with vasovagal syncope were included. Heart rate variability linear and short-term complexity (alpha-1) indexes were recorded during an active standing test (15 minutes in each position) and compared among patients grouped by HUTT outcome and between positions. RESULTS: During supine position, positive HUTT (+HUTT) patients had longer mean RR (1016 [850-1051] milliseconds), higher pNN50 (17.7 [9.2-26.2]), lower sympathovagal balance (1.3 [0.5-1.7]), and alpha-1 (0.9 [0.8-1.0]) than negative HUTT (-HUTT) patients (871 [776-969] milliseconds, 8.8 [2.1-14.5], 2.9 [1.3-3.9], and 1.2 [1.0-1.1], respectively). During active standing, heart rate and alpha-1 increased in both groups; in +HUTT patients, pNN50 decreased, whereas sympathovagal balance increased. The magnitude of change between positions of sympathovagal balance and alpha-1 was 6.1 and 4.8 times larger in +HUTT than -HUTT patients, respectively. CONCLUSIONS: The underlying cardiac autonomic mechanism in vasovagal syncope may involve different autonomic patterns in subjects with a history of recurrent syncope and +HUTT or -HUTT.

Simplified progressive approach for the ablation of scar related atrial macroreentrant tachycardias / Ablación de arritmias por macroreentrada auricular relacionadas con cicatriz posquirúrgica, mediante un abordaje escalonado

Introduction: Radiofrequency ablation of scar related right atrial flutter is challenging. Long procedures, prolonged fluoroscopic times and high percentages of recurrences are of concern. We present a simple and progressive approach based on a single electroanatomic map of the right atrium. Methods: Twenty-two consecutive patients with atrial flutter and history of cardiac surgery were included. An electrophysiologic study was performed to define localization (left or right) and cavo-tricuspid isthmus participation using entrainment mapping. After a critical isthmus was localized, ablation was performed with an external irrigated tip catheter with a power limit of 30 W. Potential ablation sites were confirmed by entrainment. Results: The predominant cardiopathy was atrial septal defect. All arrhythmias were localized in the right atrium; mean cycle length of the clinical flutter was 274 ± 31 ms. Only 40% had cavo-tricuspid isthmus participation. None of the patients with successful ablation had recurrences after 13 ± 9.4 months of follow-up. Conclusions: A progressive approach with only one activation/voltage CARTO® map of the atrium and ablation of all potential circuits is a highly effective method for ablating scar related macroreentrant atrial arrhythmias.

Introducción: La ablación con radiofrecuencia de flutter auricular relacionado con cicatrices posquirúrgicas es compleja. Procedimientos prolongados, con tiempos de fluoroscopia altos y una tasa de recurrencia elevada son problemas habituales. Mostramos un abordaje simple y progresivo basado en un solo mapa de cartografía electroanatómica de la aurícula derecha. Métodos: Se incluyeron 22 pacientes consecutivos con flutter auricular e historia de cirugía cardiaca. Se realizó estudio electrofisiológico para definir la localización del circuito de flutter (derecho o izquierdo) y la participación o no del istmo cavotricuspideo mediante encarrilamiento. Una vez localizado la zona de conducción lenta o critica del circuito, se realizó ablación con radiofrecuencia con catéter de irrigación externa a 30W. Posteriormente se llevó a cabo ablación de todos los circuitos potenciales. Resultados: La cardiopatía más dominante fue la comunicación interauricular. Todas las arritmias se localizaron en la aurícula derecha. El ciclo de flutter fue de 274 ± 31 ms. En solo 40% de los casos se demostró participación del istmo cavotricuspideo. No se observaron recurrencias de la arritmia durante un seguimiento de 13 ± 9.4 meses. Conclusiones: Este abordaje escalonado con un solo mapa CARTO® de activación/voltaje de la aurícula y la ablación de todos los circuitos potenciales es altamente efectivo para el tratamiento de arritmias por macrorreentrada relacionadas con cicatriz posquirúrgica.

Simplified progressive approach for the ablation of scar related atrial macroreentrant tachycardias.

INTRODUCTION: Radiofrequency ablation of scar related right atrial flutter is challenging. Long procedures, prolonged fluoroscopic times and high percentages of recurrences are of concern. We present a simple and progressive approach based on a single electroanatomic map of the right atrium. METHODS: Twenty-two consecutive patients with atrial flutter and history of cardiac surgery were included. An electrophysiologic study was performed to define localization (left or right) and cavo-tricuspid isthmus participation using entrainment mapping. After a critical isthmus was localized, ablation was performed with an external irrigated tip catheter with a power limit of 30 W. Potential ablation sites were confirmed by entrainment. RESULTS: The predominant cardiopathy was atrial septal defect. All arrhythmias were localized in the right atrium; mean cycle length of the clinical flutter was 274 ± 31 ms. Only 40% had cavo-tricuspid isthmus participation. None of the patients with successful ablation had recurrences after 13 ± 9.4 months of follow-up. CONCLUSIONS: A progressive approach with only one activation/voltage CARTO(®) map of the atrium and ablation of all potential circuits is a highly effective method for ablating scar related macroreentrant atrial arrhythmias.

Prevalence of fibromyalgia in vasovagal syncope.

BACKGROUND: Vasovagal syncope is an acute manifestation of autonomic nervous system dysfunction. This type of syncope is often associated with other dysautonomic expressions such as migraine, gastroparesis, or postural tachycardia syndrome. Autonomic nervous system dysfunction has been proposed as a key element in the pathogenesis of fibromyalgia. OBJECTIVES: The objectives of this study were to estimate the frequency of fibromyalgia in a sample of patients with vasovagal syncope and also to correlate the presence of syncope and fibromyalgia with different dysautonomic manifestations. METHODS: We studied 50 consecutive patients with vasovagal syncope seen at the Syncope Unit of the National Cardiology Institute of Mexico between June 2009 and June 2012. All individuals filled out the Composite Autonomic Symptoms and Signs questionnaire and the Fibromyalgia Impact Questionnaire. All cases underwent a head-up tilt test. A rheumatologist examined all participants to assess the presence of fibromyalgia. RESULTS: The median age of the studied population was 21 years. Sixty-eight percent of participants were women. Eight cases (16%) had concomitant fibromyalgia. Significantly, all fibromyalgia cases were female. This subgroup of fibromyalgia subjects had more secretomotor complaints (mainly dry eyes and dry mouth) and more bowel constipation than the remainder of the group. Also in this subgroup of fibromyalgia subjects, several significant associations were found between age, blood pressure, number of syncopal episodes, constipation, insomnia, pupillomotor impairment, and disability. In contrast, no correlations were found in the subgroup of fainters without fibromyalgia. CONCLUSIONS: Fibromyalgia was relatively frequent in these women with vasovagal syncope and could be associated with dysautonomic symptoms. Therefore, it seems important to search for dysautonomic comorbidities in patients with vasovagal syncope and/or fibromyalgia, to provide a patient-centered holistic approach, instead of the often currently used therapeutic partition.

Mecanismo da síncope em nadadoras de elite / Mechanisms of syncope in female elite swimmers

Os atletas podem ter baixa tolerância ao ortostatismo. O mecanismo envolvido ainda não é bem conhecido. Nossa hipótese se baseia em que as mulheres nadadoras de alta performance desmaiam facilmente durante o teste de inclinação, tilt test (TT), provavelmente devido a um pobre controle barorreflexo. A frequencia cardíaca e as variabilidades da pressão arterial diastólica, a sensibilidade barorreflexa, a hemdinâmica cardíaca e a velocidade do fluxo cerebral foram analisadas durante o TT em um grupo de 8 mulheres...

[Genetic study of the vasovagal syncope associated to the Arg389Gly polymorphism of the beta1 adrenergic receptor]. / Estudio genético del síncope vasovagal asociado al polimorfismo Arg389Gly del receptor adrenérgico beta1.

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.

Estudio genético del síncope vasovagal asociado al polimorfismo Arg389Gly del receptor adrenérgico beta1 / Genetic study of the vasovagal syncope associated to the Arg389Gly polymorphism of the beta1 adrenergic receptor

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.

Value of symptoms to predict tilt testing outcome in patients with clinical suspicion of vasovagal syncope.

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.

Non-invasive assessment of endothelial function. Intra and inter-observer variability

BACKGROUND AND OBJECTIVES: Non-invasive evaluation of endothelial function with high resolution ultrasound has become a widely accepted tool in determination of high risk subjects for early atherosclerosis. Despite its simple appearance, ultrasonographic assessment of brachial artery changes, is technically challenging and has a significant learning curve. In the present study, we evaluate the intra and inter-observer variability in assessing peripheral endothelial function with high resolution ultrasound at a tertiary referral center. METHODS: Assessment of endothelial function was performed by 2 physicians in 20 volunteers without evidence of coronary artery disease. Endothelial function is evaluated with a high frequency bidimensional ultrasound with a 10.0-MHz linear-array transducer used for the study. Each volunteer was examined by both observers using an identical protocol, measuring brachial artery diameter on three occasions. RESULTS: Excellent correlation was observed for all brachial artery measures with a Spearman's correlation coefficient > 0.9 (p < 0.0001). Flow-mediated dilation (FMD) in the study population was of 10.45+/-6.9%. Flow independent dilation (FID) was of 24.35+/-7.63%. Intra-observer variability was of 2.1% for observer A and 1.1 % for observer B. CONCLUSIONS: Non-invasive assessment of endothelial function using brachial artery ultrasound is reproducible and can be performed with low intra and inter-observer variability.

Diferencias en la modulación autónoma del corazón entre mujeres y hombres / Differences in cardiac autonomic modulation between women and men

Gender differences in cardiac autonomic modulation are a controversial topic in several studies. The aim of this study, was to describe and compare the heart rate variability in 30 women and 20 men, Mexicans, between 21 to 36 years of age. A 20 to 24 hours Holter monitoring was performed in all of them. Analysis of time (SDNNN and rMSSD), and frequency domains (HF, LF and LF/HF in absolute values and normalized units) were used. SDNN[IBM1] was significantly higher in men. When adjusted for age, there was a negative correlation in parasympathetic activity indexes (rMSSD and HF) in women. Physical training increased SDNN in men and HF in women. The increased parasympathetic activity found in women with physical training diminishes with age. These results demonstrate differences in cardiovascular autonomic modulation between women and men.

Cerebrovascular blood flow during the near syncopal phase of head-up tilt test: a comparative study in different types of neurally mediated syncope.

AIMS: This study analyses the changes in cerebral blood flow (CBF) velocity occurring in the near syncopal phase of head-up tilt test (HUT) to determine whether their appearance during the premonitory symptoms permits the differentiation of the different types of haemodynamic response. METHODS AND RESULTS: Six hundred and nineteen patients aged 35.9 +/- 16.4 with a prior history of syncope (55%) or presyncope (45%) were studied. Head-up tilt test was positive in 585 patients. The test was interrupted before syncope, once hypotension was evident and CBF changed. A vasovagal reaction (VVR) was observed in 245 patients. They had a 59% fall in diastolic CBF velocity, whereas systolic CBF velocity decreased by 12%. Postural orthostatic tachycardia syndrome (POTS) was observed in 82, systolic and diastolic CBF velocity decreased 44 and 60%, respectively. A similar response was observed in 258 patients with the orthostatic intolerance (OI) pattern. No significant changes were observed in the negative group. CONCLUSION: Patients with VVR had changes in CBF velocity, which are different from those presented by patients with POTS and OI pattern. Cerebral blood flow monitoring is useful to increase the yield of HUT and may allow early interruption before syncope occurs, reducing patient discomfort.

Neurocardiogenic syncope in chronic atrioventricular block.

We report a 37-year-old man with type I second-degree atrioventricular (AV) block (atypical Wenckebach's periodicity) referred to our department for pacemaker implantation because of an episode of syncope. After exhaustive evaluation, including electrophysiological test, in which Wenckebach's cycles with block within the AV node was demonstrated, syncope was considered to be neurally mediated. Head-up tilt testing with sublingual isosorbide dinitrate was positive. The decrease in atrial rate at the beginning of the vasovagal reaction was not immediately accompanied by a depressed AV node conduction. Only at the moment of syncope did incomplete AV block appear. This observation illustrates (1) a neurally mediated origin of syncope in a patient with chronic AV block, and (2) the different time-course responses of the sinus and AV nodes to autonomic tone.

Arrhythmic storm responsive to quinidine in a patient with Brugada syndrome and vasovagal syncope.

A 37-year-old man with Brugada syndrome (BrS) and arrhythmic storm is described. One month after implantation of a cardioverter-defibrillator he presented with recurrent appropriate shocks for spontaneous ventricular fibrillation (VF). Because of this arrhythmic storm, quinidine therapy was initiated with total suppression of all spontaneous arrhythmias. He had remained free of arrhythmias for 22 months since quinidine initiation. Two episodes of VF occurred after the patient stopped taking the medication. The patient resumed quinidine and has been free of VF for the last 3 months. This response to quinidine in a patient with symptomatic BrS supports its role in the prophylaxis of arrhythmic events in BrS.

Familial vasovagal syncope.

Vasovagal syncope (VVS) is a common clinical problem characterized by transient episodes of loss of consciousness due to abnormal autonomic activity. This paper describes two groups of monozygotic twins, from different families, affected by VVS and a family with several members with this condition. Their clinical characteristics, haemodynamic response to tilt, treatment, and outcome are described.

[Direct cryothermal ablation eliminates conduction of the slow pathway without inducing ectopic rhythms]. / La ablación criotérmica percutánea directa elimina la conducción a través de la vía lenta intranodal sin inducir ritmos ectópicos.

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia is based on the elimination of conduction of slow or fast intranodal pathway. To avoid potential atrioventricular (AV) block, a new technology has been developed, cryothermal ablation. We report a case of AV nodal reentrant tachycardia in whom direct cryoablation, without previous ice mapping, was successfully performed. Interestingly and as previously described, cryotherapy did not induce ectopic rhythms, the conventional surrogate during radiofrequency ablation.