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.

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...

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.

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.

Evidence of linkage between neurocardiogenic dysfunction and reactive hypoglycemia / Evidencia de una posible asociación entre disfunción neurocardiogénica e hipoglicemia reactiva

La hipoglucemia reactiva es un problema común en la práctica clínica cuya patofisiología es motivo de controversia. El objetivo del presente estudio fue investigar la prevalencia de anormalidades del sistema nervioso autónomo en pacientes con hipoglucemia reactiva comparada con controles sanos. Material y métodos. Se incluyeron para el estudio a seis mujeres con hipoglucemia reactiva con edad media de 31 ñ 5 años y 5 mujeres sanas con edad media de 24 ñ 4 años. Se investigó la variabilidad de la frecuencia cardiaca y los cambios en la presión arterial después de una prueba de inclinación con y sin isoproterenol. Se definió como prueba positiva a la presencia de síncope o presíncope asociados a bradicardia, hipotensión o ambas. Resultados. En respuesta a la prueba de inclinación con o sin isoproterenol 5 de 6 pacientes comparado con 1 de 5 controles sanos presentaron una prueba positiva. Las pacientes presentaron un tono hiperadrenérgico con una relación simpático/parasimpático de 2.3 ñ 0.8 en condiciones basales y 10.1 ñ 4.1 durante la infusión de isoproterenol, en comparación a 0.7 ñ 0.3 (p = 0.06) y 0.5 ñ 0.1 (p < 0.01) respectivamente en el grupo control. Conclusiones. Los pacientes con hipoglucemia reactiva pueden estar en un extremo de variabilidad biológica normal. Pueden cursar con un tono hiperadrenérgico y después de un estímulo provocativo la descarga simpática o la liberación sináptica de norepinefrina pueden ser insuficientes para mantener un tono vascular adecuado. Otra posibilidad es que la respuesta vascular a norepinefrina esté alterada. No se observó una respuesta vasovagal paradójica o excesiva.

Differences in heart rate variability between cardioinhibitory and vasodepressor responses to Head-Up tilt table testing

Background. Patients with syncope show different responses to head-up tilt (HUT) test, which may be due to different pathophysiological mechanisms. Methods. HUT (70º) was perfumed in 24 patients who experienced recurrent syncope. Nine patients had a cardioinhibitory (CI) response, 7 patients had a vasodepressor (VD) response, and 8 patients had a mixed (MX) response. Heart rate variability was analysed at 60-sec periods during HUT: Results. Total spectrum (TS) was greater at rest and 1 min after syncope in the CI and MX groups as compared to the VD group. Low frequency spectrum (LF) was significantly greater during rest and the first minute after syncope in the CI groups as compared with the VD group. After the rest period, the CI and MX groups showed more elevated high frequency spectrum (HF) values than the VD group (p <0.01). One minute after syncope, the HF increased in the CI and MX groups but not in the VD group (p < 0.01). The VD group showed higher LF/HF ratio from the beginning of rest (3.9 ñ 4.1) as compared to the CI and MX groups (p <0.01). This differnce was most significant 2 min before syncope occurred. The CI and MX groups showed greater pNN50 and rMSSD as compared to the VD group. Conclusions. Our results suggest that vagal tone is higher in subjects showing cardioinhibitory and mixed responses to HUT. In contrast, patients with a vasodepressor response showed predominanty sympathetic activity. These findings suggest that there are differ ent pathophysiological mechanisms underlyng syncope

Infarto del miocardio sin ondas Q patológicas / Myocardial infarction without pathological Q waves

La presencia o ausencia de ondas Q patológicas no guarda ninguna relación con el carácter transmural o subendocárdico de un infarto del miocardio. El pronóstico del infarto agudo del miocardio sin ondas Q patológicas, es motivo de controversia. Nosotros estudiamos 23 pacientes hospitalizados por angina prolongada, con elevación enzimática, alteraciones de la repolarización ventricular en el electrocardiograma y centellografía miocárdica con tecnecio-99m positiva. Estos pacientes, fueron clasificados en dos grupos de acuerdo a las características de captación del radiotrazador: grupo A con pratrón de capatación grado 2 + focal o mayor (N = 13) y grupo B con patrón 2 + difuso (N = 10). Los niveles enzimáticos fueron mayores sólamente para la transaminasa glutámico-oxalacética, en los pacientes del grupo A (P <0.05). La evolución hospitalaria fue similar en ambos grupos. Once pacientes fueron seguidos durante 31.7 meses: el 30.4% tuvo angina crónica, uno fué revascularizado, un paciente se reinfartó y ninguno ha fallecido. Se debe sospechar el diagnóstico de infarto agudo del miocardio en pacientes con angina prolongada, electrocardiograma con cambios en la repolarización ventricular, aumento de los niveles enzimáticos y centelleografía miocárdica con captación grado 2 + difuso, si la centelleografía muestra captación focal el diagnóstico puede establecerse aún si el electrocardiograma no tiene ondas Q patológicas