Incremento en la dispersión de la onda P al disminuir el tiempo de eyección auricular en hipertensos y prehipertensos / Increment in P wave dispersion by decreasing atrial ejection time in hypertensive and prehypertensive patients

Introducción: hace algunos años se viene estudiando la relación entre disfunción diastólica y dispersión de la onda P del electrocardiograma, y en este sentido, la ecocardiografía emerge como herramienta para mejorar la estratificación de riesgo en hipertensos leves. Objetivo: determinar la dependencia de la dispersión de la onda P del electrocardiograma de variables ecocardiográficas en una población pediátrica. Métodos: se estudiaron 400 niños, de un total de 450, pertenecientes a tres escuelas primarias, y se excluyeron aquellos cuyos padres no desearon que participaran en el estudio y a quienes tuvieran patologías congénitas conocidas. Se realizó electrocardiograma de superficie de doce derivaciones y se practicaron cuatro tomas de presión arterial. Se midieron los valores de P máxima y P mínima, y se calculó la dispersión de la onda P del electrocardiograma; además se hizo, ecocardiografía para mediciones estructurales y Doppler pulsado del flujo mitral. Resultados: los valores de media para la duración de la onda A del flujo mitral no muestran diferencias significativas; sin embargo, existe un coeficiente de correlación (r) y p significativos entre la dispersión de la onda P y la duración de la onda A del flujo mitral para normotensos (r= - 0,117 p=0,05), prehipertensos (r= - 0,309 p=0,001) e hipertensos (r= - 0,586 p=0,001). Existen diferencias significativas entre las medias de dispersión de la onda P entre los grupos de diagnóstico. Conclusiones: se evidencia dependencia de la dispersión de la onda P, del electrocardiograma y de la duración de la onda A del flujo de entrada mitral, hechos que se relacionan con riesgo de fibrilación auricular en el adulto, por lo que quizás este resultado dé un acercamiento a predicciones de riesgo más tempranas en edades pediátricas.

Introduction: the relationship between diastolic dysfunction and P wave dispersion in the electrocardiogram is being studied since some years ago, and in this regard echocardiography is emerging as a tool to improve risk stratification in mild hypertension. Objective: to determine the dependence of the dispersion of the P wave of electrocardiogram with echocardiographic variables in a pediatric population. Methods: we studied 400 children from a total of 450 belonging to three elementary schools, and excluded those whose parents did not want them to participate in the study and those who had known congenital diseases. We performed 12-lead surface ECG and 4 blood pressure takings. We measured maximum and minimum P values and calculated P wave dispersion in the electrocardiogram. Echocardiography for structural measurements and pulsed Doppler of mitral flow were also performed. Results: mean values for duration of A wave of mitral flow showed no significant differences; however, there is a correlation coefficient (r) and significant p between P wave dispersion and duration of mitral flow A wave for normotensive (r = - 0.117 p = 0.05), NT (r = - 0.309 p = 0.001) and hypertensive (r = - 0.586 p = 0.001). There are significant differences between the mean P wave dispersion between diagnostic groups. Conclusions: we highlight the dependence of P wave dispersion, the electrocardiogram and the duration of the mitral inflow A wave, events that are related to risk of atrial fibrillation in adults, so perhaps this result gives an approach to earlier risk predictions in pediatric patients.

Hipertensión arterial en población pediátrica, sus efectos en la dispersión de la onda P y el área auricular izquierda / Hipertension in pediatric patients: effects upon P wave dispersion and left atrial area

Antecedentes: Entre los factores descritos para desarrollar fibrilación auricular se encuentra el mayor tamaño de la aurícula izquierda; esto lleva a cambios en sus propiedades eléctricas y a mayores valores de dispersión de la onda P del electrocardiograma. Objetivo: Determinar la dispersión de la onda P con relación al área de la aurícula izquierda en niños entre 8 a 11 años. Métodos: Se estudiaron 400 niños aparentemente sanos de ese rango de edad. Se les realizó electrocardiograma de superficie de 12 derivaciones para medir los valores de P máxima, P mínima y se calculó la dispersión de la onda P; se les midió 4 veces la presión arterial. Se realizó además, ecocardiograma para medición del área auricular izquierda. Resultados: Los valores de media de dispersión de la onda P aumentan desde normotensos a hipertensos (32.5 a 38.5 ms, respectivamente), existiendo diferencias significativas intergrupos, encontrando la mayor significación al comparar los normotensos con el grupo de prehipertensos (p=0.001). Un estudio de regresión demostró la dependencia de la dispersión de la onda P del electrocardiograma en el grupo de normotensos y prehipertensos con r=0,22 y p<0.05. Una regresión lineal para la muestra de niños hipertensos muestra una correlación positiva para la dependencia de la onda P con el área auricular izquierda. Conclusiones: Existe dependencia de la dispersión de la onda P del electrocardiograma con el área auricular izquierda, así como diferencias significativas entre valores medios de dispersión de la onda P en los subgrupos de niños normotensos, prehipertensos e hipertensos.

Background: left atrial size is a recognized factor in-creasing the risk of atrial fibrillation. Left atrial electrical properties are modified, with a greater dispersion of the P wave on the electrocardiogram. Aim: to determine the relation between left atrial area and P wave dispersion in children. Methods: 400 healthy children from 8 to 11 years of age had a 12 lead ECG. Maximum and minimum voltages of the P wave and P wave dispersion were measured. Blood pressure was recorded in 4 separate measurements. Echocardiography was used to determine left atrial area. Results: Compared to normotensive children, mean dispersion of the P wave was higher in hypertensives (38.5 vs 32.5 ms, respectively). The most significant difference was observed between normotensives and pre-hypertensive children (regression analysis, p=0.001). Linear regression analysis showed a positive correlation of P wave dispersion and left atrial area Conclusion: P wave dispersion and left atrial area are positively correlated in groups of normal, pre-hypertensive and hypertensive children. The corresponding mean values of dispersion follow the same tendency.

Brain-derived neurotrophic factor does not improve recovery after cardiac arrest in rats.

Increased brain-derived neurotrophic factor (BDNF) levels and extracellular-signal regulated kinase (ERK) signaling are associated with reduced brain injury after cerebral ischemia. In particular, mild hypothermia after cardiac arrest increases BDNF and ERK signaling. This study tested whether intracerebroventricular infusions (0.025 microg/h x 3 days) of BDNF also improved recovery of rats resuscitated from cardiac arrest and maintained at 37 degrees C. BDNF infusions initiated at the time of cardiac arrest did not alter survival, neurological recovery, or histological injury. Separate experiments confirmed that BDNF infusions increased tissue levels of BDNF. However, these infusions did not increase ERK activation in hippocampus. These data suggest that increased BDNF levels are not sufficient to explain the beneficial effects of mild hypothermia after cardiac arrest, and that exogenous BDNF administration does not increase extracellular ERK signaling.

Post-resuscitation hemodynamics and relationship to the duration of ventricular fibrillation.

OBJECTIVE: We have observed consistent hemodynamic patterns after restoration of spontaneous circulation (ROSC) after ventricular fibrillation (VF) cardiac arrest. We sought to characterize the time-course of these patterns, and to determine whether these differed based on duration of the VF insult. METHODS: We performed a retrospective review of data from a randomized animal experiment that was conducted in an AAALAC-approved animal laboratory. We used mixed-breed domestic swine of either sex. Animals were anesthetized and instrumented for continuous recording of ECG and blood pressures. VF was induced electrically and allowed to progress for various times ranging from brief (22s) to moderate (less than 3 min) to prolonged (3-10 min). All animals were initially shocked (150J) up to three times. If ROSC was not achieved on the three initial shocks, a standardized treatment protocol was followed. We defined cardiovascular collapse as a SBP<90 mmHg sustained for 1 min. For statistical purposes, we classified animals as having VF of <3 min, or >3 min duration. Data were analyzed with Fisher's exact test and survival analysis. RESULTS: A hyperdynamic phase, consisting of very high-blood pressures and tachycardia, was seen in all animals immediately after ROSC. This lasts from 1 to 4 min. Post-resuscitation cardiovascular collapse occurred in 2/7 (29%) animals in the <3 min group and 13/14 in the >3 min group (93%) p=0.006. Onset of cardiovascular collapse was highly related to duration of VF (log-rank p=0.004). CONCLUSIONS: There are two distinct phases of hemodynamic change after resuscitation of VF. The first phase is a brief hyperdynamic phase. The second phase is either stabilization or cardiovascular collapse. When VF is brief, blood pressures often return to normal without exogenous support. When VF was prolonged animals were rescued with exogenous pressor. Healthcare providers should be prepared to provide pressor support for patients having ROSC after prolonged VF.