Instead of defibrillator's painful jolt, there may be a gentler way to prevent sudden death

Each year in the United States, more than 200,000 people have a cardiac defibrillator implanted in their chest to deliver a high-voltage shock to prevent sudden cardiac death from a life-threatening arrhythmia. While it's a necessary and effective preventive therapy, those who've experienced a defibrillator shock say it's painful, and some studies suggest that the shock can damage heart muscle. Scientists at Johns Hopkins believe they have found a kinder and gentler way to halt the rapid and potentially fatal irregular heart beat known as ventricular fibrillation. In a study published in the September 28 issue of Science Translational Medicine, they report success using lower amplitude, high-frequency alternating current at 100-200 Hz to stop the arrhythmia in the laboratory. They say this approach also may prove to be less painful for patients because of the lower amplitude and different frequency range than what is used for standard defibrillator shocks.
"We believe we have found a way to stop a life-threatening arrhythmia by applying a high-frequency alternating current for about one-third of a second," says Ronald Berger, M.D., Ph.D., a cardiac electrophysiologist at the Johns Hopkins Heart and Vascular Institute and a professor of medicine and biomedical engineering at the Johns Hopkins University School of Medicine. "The alternating current puts the disorganized, rapidly moving heart cells in a refractory state, like suspended animation. When we turn off the current, the cells immediately return to a normal state. If further research confirms what we have learned so far, this could be less painful for a patient while achieving the same result," says Berger, who is the senior author of the study.
Graduate student Seth Weinberg, a co-lead author of the study, says the way heart cells behave during ventricular fibrillation is like having a football stadium full of fans, all of whom are doing "the wave" in an uncoordinated, disorganized fashion. "Applying the alternating current," he says, "is like freezing all of the fans in a position halfway between sitting and standing. When the current is turned off, the fans sit down in an orderly way, ready to be instructed to do the wave in a coordinated way."
Berger says he and his colleagues, a team of Johns Hopkins cardiologists and biomedical engineers, have shown a proof of principle and a novel scientific finding: It's the first time heart cells have been put in a suspended state to interrupt ventricular fibrillation.
"The idea to put heart cells in a brief state of suspended animation came from studies showing that alternating current could be used to put nerve cells in a similar state to block the signals that cause pain," says Harikrishna Tandri, M.D., assistant professor of medicine and the other co-lead author of the study.
To ensure that they were correctly assessing the response of the heart cells to the high frequency current, and, at the same time, distinguishing the response from the cells' native electrical activity, the researchers used a technique called optical mapping. Unlike other electrical recording techniques, optical mapping measurements are not affected by applied electrical stimuli, according to co-author Leslie Tung, Ph.D., professor of biomedical engineering, who led the optical mapping aspect of the research.
In order to allow the team to explore the response of individual heart cells to the high-frequency electrical current, co-author Natalia Trayanova, Ph.D., professor of biomedical engineering, produced a multi-scale computational model of the heart.
While more testing is needed in animal models, the researchers are optimistic that their work may lead to a new approach to shock the human heart back to a normal rhythm. "We are ultimately hoping to develop a device that, instead of delivering a painful, high-voltage shock when it detects a life-threating arrhythmia, applies a more gentle alternating current for the right amount of time to stop the dangerous rhythm. We think that would be a great benefit to the millions of people worldwide who have a defibrillator to prevent sudden death," Berger says.
Ventricular fibrillation is an uncontrolled twitching or quivering of muscle fibers in the lower chambers of the heart. It is the most dangerous type of arrhythmia and is often caused by a heart attack. During ventricular fibrillation, the heart cannot pump blood to the rest of the body, which leads to sudden death unless the person is revived through CPR or a shock from an external defibrillator. People who are fortunate to have survived ventricular fibrillation and those who have other risk factors, are advised to have an implanted defibrillator to detect ventricular fibrillation and shock the heart back to a normal rhythm.

**Source: Johns Hopkins Medical Institutions

Un freno al dolor de espalda en Atención Primaria

'Doctor, me duele mucho la espalda'. Un altísimo porcentaje de la población ha pedido ayuda alguna vez a su médico por este problema que, en algunos casos, se prolonga en el tiempo y trae aparejadas consecuencias graves.
Conseguir una atención adecuada en Atención Primaria de los pacientes aquejados de estas molestias podría evitar muchas de esas complicaciones y ahorraría tiempo y dinero a las arcas públicas. Sin embargo, hasta la fecha este reto sigue siendo un desafío para los profesionales sanitarios.
La selección adecuada de los pacientes con más riesgo de empeorar es el muro con el que se encuentran muchos médicos, que no tienen una guía clara sobre cómo estratificar a los individuos que más pueden beneficiarse de intervenciones como la fisioterapia.
Un nuevo modelo propuesto esta semana en la revista 'The Lancet' podría ayudar en esta tarea. A través de un cuestionario que mide las posibilidades de desarrollar una discapacidad presente o futura, este método divide a los pacientes en riesgo bajo, medio y alto y establece unas guías de tratamiento para cada grupo.
Utilizarlo mejora el pronóstico y la calidad de vida del paciente y reduce los costes sanitarios, según una investigación realizada por un grupo de investigadores de la Universidad de Keele (Reino Unido).
Los autores de este trabajo realizaron un seguimiento a 851 adultos que entre junio de 2007 y noviembre de 2008 había acudido al médico a causa de sus dolores de espalda. Aproximadamente la mitad de ellos se dirigió a un especialista que evaluó su riesgo a través del modelo de estratificación, mientras que el resto siguió la atención habitual en la consulta de su médico de familia (grupo de control).
Después de cuatro y 12 meses de seguimiento, los investigadores comprobaron que los pacientes en el grupo de intervención presentaban una mejoría significativa y, en general, señalaban una mayor calidad de vida. Esta mejoría se veía también reflejada en un menor coste sanitario por paciente a medio plazo.

-Beneficios
"Este manejo estratificado en el que la selección del paciente y el establecimiento del tratamiento se combinaron produjo una mayor eficiencia en Atención Primaria, generando un mayor beneficio para los pacientes con dolor de espalda", señalan en la revista médica los investigadores, quienes también subrayan los beneficios económicos que proporciona el método.
"Sin una selección sistemática, muchos pacientes de medio y alto riesgo podrían quedarse potencialmente sin el acceso a un tratamiento más sofisticado que mejore su estado", añaden.
En un comentario que acompaña al trabajo en la revista médica, Bart Koes, de la Universidad Erasmus de Rotterdam (Holanda) señala que el modelo es "muy prometedor", aunque reclama nuevos estudios sobre el tema.
Para Alejandro Tejedor, miembro del Grupo de Enfermedades Reumatológicas de la Sociedad Española de Medicina de Familia y Comunitaria (semFYC) el modelo propuesto es "bastante sensato e interesante" ya que aporta una medición objetiva para distinguir a los pacientes con mayor riesgo.
"Es necesario implantar de forma progresiva este tipo de escalas de valoración objetivas en las enfermedades osteoarticulares", señala este especialista, quien subraya que "después del catarro, los dolores lumbares son el motivo más frecuente en la consulta del médico".
"Tablas de medición objetiva del riesgo ya se utilizan con enfermedades como las cardiovasculares o la diabetes y, del mismo modo, es necesario establecer un protocolo consensuado para diferenciar los distintos grados de dolor y de discapacidad".
Según su punto de vista, esta estrategia permitiría obtener mejores resultados clínicos y un menor gasto sanitario.

**Publicado en "EL MUNDO"

Study finds consumers may have more control over health costs than previously thought

The historic RAND Health Insurance Experiment found that patients had little or no control over their health care spending once they began to receive a physician's care, but a new study shows that this has changed for those enrolled in consumer-directed health plans. Patients with health coverage that includes a high deductible and either a health savings account or a health reimbursement arrangement reduced their costs even after they initiated care.
Overall, the study found about two thirds of the reduction in total health care costs was from patients initiating care less often and the remaining third was from a reduction in costs after care is initiated. The findings were published online by the journal Forum for Health Economics and Policy.
"Unlike earlier time periods, it seems that today's consumers can have greater influence on the level and mix of medical services provided once they begin to receive medical care," said Amelia Haviland, the study's lead author and a senior statistician at the RAND Corporation, a nonprofit research organization. "We found that at least part of the savings in cost per episode reflects choices for less-costly treatments and products, not just a reduction in the number of services."
Researchers from RAND, Towers Watson and the University of Southern California examined the claims experience of many large employers in the United States to determine how consumer-directed health plans and other high-deductible plans can reduce health care costs. The study was funded by the California HealthCare Foundation and the Robert Wood Johnson Foundation.
According to Haviland, at least three factors influenced the cost of care once the patient had initiated care: lower use of name-brand medications, less in-patient care and lower use of specialists. Researchers speculate that patients may talk to their doctors about their higher deductibles and ask them to help keep costs low.
"It is not surprising that deductibles of $1,000 or more reduced health care consumption, but we found that savings occurred even when employers helped employees offset these out-of-pocket costs by making contributions to their accounts," said Roland McDevitt, a study co-author and director of health research at Towers Watson, a human resource and employee benefits consultancy. "This was true for both health savings accounts and health reimbursement arrangements."
Health reimbursement arrangements and health savings accounts create different incentives for employees. Health reimbursement arrangements allow employers to pay for qualified medical expenses, including those that fall under the deductible. These payments or reimbursements are excluded from the taxable income of the employee. Unused portions may roll over at the end of the year, but any account balance is owned by the employer and employees generally forfeit the account balance if they leave the employer before retirement.
Health savings accounts create a stronger incentive for employees to manage their health care costs, because the employee owns the account. This type of account was shown to have the largest impact on cost reductions. It can earn interest and it follows employees when they change jobs.
Health savings account contributions are only allowed for those enrolled in high-deductible health plans as defined by law, but account balances may be used for qualified medical expenses at any time. The minimum health savings account deductibles for 2011 are $1,200 for single coverage and $2,400 for family coverage.
The study found that both the level of the deductible and the level of the employer account contributions influence the extent of savings. Higher deductibles of $1,000 or more together with employer account contributions of less than half the deductible produced the greatest cost reductions.
"It is clear that high-deductible health plans with personal medical accounts produce overall health care cost savings and not simply a cost shift," said co-author Neeraj Sood, associate professor at the Schaeffer Center for Health Economics and Policy at USC and a RAND economist. "This is mostly due to patients initiating less care, but a full third of the reduction is due to shifts in the mix of care they are receiving."
The authors cautioned that there was some reduction in the rate of cancer screenings and childhood immunizations during the first year of enrollment in a high-deductible plan. They found this first-year effect was relatively small, but expressed concern about the early trend. They say more research is needed to determine the extent to which these cost reductions come at a price of forgoing necessary medical care.

**Source: RAND Corporation

Una nueva técnica en España elimina metástasis hepáticas que antes eran inoperables

Una paciente acudió a un hospital madrileño con el hígado repleto de metástasis y salió de él con un órgano 'nuevo' sin haber recibido un trasplante. ¿Cómo? Con una técnica realizada por primera vez en España que permite aumentar el volumen de tejido sano antes de retirar el que contiene las lesiones cancerígenas.
La nueva intervención se realizó en dos etapas. En la primera se preparó el terreno y en la segunda se remató la faena. La paciente es una mujer con cáncer colorrectal y metástasis hepáticas; los artífices, un equipo multidisciplinar de médicos del Hospital Madrid Norte Sanchinarro.
El tratamiento idóneo de las metástasis hepáticas consiste en la administración de quimioterapia y cirugía. Esta combinación terapéutica "aporta resultados tremendamente satisfactorios", según Emilio Vicente, director del Servicio de Cirugía General y Digestiva del citado centro sanitario y principal responsable de la intervención.
Pero en muchos casos, como el de la paciente que nos ocupa, no se puede echar mano del bisturí porque las lesiones están extendidas por todo el hígado y para quitarlas hay que suprimir tanto tejido que el órgano se quedaría de un tamaño insuficiente para realizar sus funciones de depuración de tóxicos del organismo.
Los doctores lograron superar esta limitación manipulando el hígado de una forma muy ingeniosa. Dado que la mujer tenía mucho más afectado el lado (lóbulo) derecho del hígado, lo primero que hicieron fue separarlo del izquierdo y extirpar la única metástasis que tenía este último. A continuación, hicieron un 'truco' para que todo el flujo sanguíneo fuese hacia el lado sano, el izquierdo: cerrar la vena porta derecha. El objetivo era dar a este lóbulo el 'alimento' necesario para que incrementase considerablemente su tamaño. Y así dieron por finalizada la intervención y dejaron a la paciente con un hígado partido en dos.
Tuvieron que esperar tres semanas hasta que la parte izquierda alcanzó el tamaño suficiente para asumir todo el trabajo del hígado. Durante ese tiempo, el otro lóbulo, a pesar de que presentaba varias lesiones, seguía siendo indispensable. Cuando las técnicas de imagen confirmaron que el lado sano ya podía ser autosuficiente, los médicos volvieron a abrir a la paciente y retiraron el otro lóbulo.
La operación había sido un éxito, pero el equipo sanitario aún tuvo que afrontar otro contratiempo: el órgano no funcionaba correctamente. Tuvieron que utilizar en el posoperatorio inmediato un sistema de hígado artificial para mantener su funcionalidad. Se trata del sistema conocido como MARS, que funciona de forma similar a la diálisis renal y hasta ahora no se había utilizado en un caso como este.
Finalmente, la insuficiencia hepática se resolvió y la paciente pudo volver a su casa. Ya han transcurrido cuatro meses desde la primera intervención y, en palabras del doctor Vicente, esta persona "se encuentra libre de enfermedad tumoral y ha conseguido preservar su función hepática, lo que le permite llevar una vida normal". "Si no la hubiésemos tratado con la nueva técnica, probablemente no habría superado el año de vida", agrega el cirujano.
En cuanto a su pronóstico, el doctor Antonio Cubillo, coordinador de la Unidad de Tumores Digestivos del Centro Integral Oncológico Clara Campal, integrado en el Hospital Madrid Norte Sanchinarro, señala que los análisis de anatomía patológica del tejido extirpado mostraron "una respuesta completa al tratamiento previo con quimioterapia". Estos resultados reducen considerablemente el riesgo de recaída de su proceso cancerígeno. "Es raro que una enferma con tanta carga tumoral responda totalmente", apunta.
Los responsables de la intervención están seguros de que otros enfermos oncológicos podrán beneficiarse de este procedimiento pionero, pero señalan que siempre serán una minoría de casos muy complejos.

**Publicado en "EL MUNDO"

Computational modeling can help plan vaccine introduction, Pitt study finds

Proper planning before the introduction of new vaccines into a developing country's active immunization program could prevent storage problems and transportation bottlenecks that decrease the availability of existing vaccines by as much as two-thirds, according to a University of Pittsburgh study. Computational models can assess the evolving needs of the vaccine supply chain -- or the series of steps required to get a vaccine from the manufacturer to the target population. The modeling can forecast the impact of new vaccine introduction and identify potential disruptions, concluded the study, which will appear in the November issue of the American Journal of Public Health.
"Our study highlights the importance of prior planning when introducing new vaccines to avoid last-minute temporary fixes," said the study's lead author, Bruce Y. Lee, M.D., M.B.A., assistant professor of medicine, epidemiology and biomedical informatics at the University of Pittsburgh. "New vaccines may not fit smoothly into supply chains and therefore fail to reach their target populations easily. These problems may prevent other vaccines from reaching clinics as well. Manufacturers and policymakers should consider vaccine quantity and packaging before designing vaccines and introducing them in unfamiliar areas with limited resources."
The Pitt scientists, who are part of the Bill and Melinda Gate Foundation-funded Vaccine Modeling Initiative, developed a computational model to determine the impact of introducing rotavirus vaccine and the 7-valent pneumococcal conjugate vaccine to Niger's Expanded Programs on Immunization vaccine supply chain.
Thousands of West African children die every year from rotavirus and pneumococcal disease, such as pneumonia. The Expanded Program on Immunization (EPI) is a World Health Organization initiative that aims to make vaccines that can prevent these deaths available to all children around the world.
Introducing the rotavirus vaccine and the pneumococcal conjugate vaccine to Niger's EPI vaccine supply chain could displace other EPI vaccines from already limited storage and transport space and could prevent EPI vaccines from reaching patients, the study found. The scientists estimated introducing these vaccine inventories to the supply chain could decrease vaccine availability by 24 percent to 69 percent.
The study's predictions are similar to what happened when officials introduced rotavirus vaccine to a Latin American program in 2006 and 2007, the researchers noted. In that case, bulky vaccines displaced existing EPI vaccines in already limited refrigerator space and forced overburdened health care workers to carry additional thermoses to transport the new vaccines. As a result of these unforeseen problems, large stocks of vaccine expired.
Computational models can help decision makers plan and understand complex systems, Lee said.
"Although computational models have been widely used in similar logistics planning in many other industries, such as transportation, manufacturing, the military and aerospace, their use in public health has been comparatively limited," he said. "These models could be a very helpful tool for health workers to plan vaccine supply chains."

**Source: University of Pittsburgh Schools of the Health Sciences

Un estudio afirma que la luz y el sueño influyen en las emociones en todo el mundo

La red social Twitter no sólo es un nuevo medio de comunicarse las últimas noticias, conocer el día a día de los famosos o colaborar en revoluciones sociales (como la 'primavera árabe' o el 15-M). También ha servido para que un grupo de investigadores tomen el pulso al estado anímico de la Humanidad en función de la hora del día y la época del año. Y han descubierto que al margen de culturas, geografías o desarrollo tecnológico, los seres humanos sienten emociones muy parecidas en cada momento.
El exhaustivo trabajo, que se publica en la revista 'Science' esta semana, se ha basado en el análisis de 509 millones de mensajes enviados en Twitter (tweets) por parte de 2.4 millones de personas que viven en 84 países distintos durante un periodo de dos años.
Scott Golder y Michael Macy, de la Universidad Cornell de Ithaca (Estados Unidos), concluyen algo que ya dicta la intuición, y es que los seres humanos son más felices los fines de semana y también cuando se despiertan por la mañana que cuando se acuestan por la noche. Es decir, a medida que la jornada avanza, el buen humor se va deteriorando, hasta que se torna en malo (o casi). Sólo cuando piensan en la cama, vuelve el bienestar.
Los sábados, domingos y fiestas de guardar, sin embargo, los estados de ánimo positivo duran dos horas más por las mañanas, dado que esos días se duerme más. Y pasa lo mismo en países como los Emiratos Árabes Unidos, donde la semana laboral es de domingo a jueves, donde los días de buen humor coinciden con los festivos, como en el resto del planeta, algo que achacan a los ritmos de sueño y circadianos.

-Mensajes en tiempo real
Los investigadores utilizaron un popular programa de análisis de texto, llamado Indagación Lingüística y Conteo de Palabras (LIWC, en sus siglas en inglés), para analizar los cientos de millones de 'tweets' y calcular en cuantos se expresaban emociones positivas (como entusiasmo, placer, actividad, alerta, etcétera) o negativos (angustia, miedo, enojo, repugnancia y otras similares). Por primera vez, se tomaron los comentarios en tiempo real durante dos años.
Todo parece indicar que el sueño y la cantidad de luz al día son determinantes para emociones cíclicas como el placer, la alerta, el miedo o la ira. Los dos 'picos' de 'buen rollo' diarios se tendrían por la mañana temprano y cerca de la medianoche, cuando el cerebro se prepara para la cama, mientras que las tensiones más desagradables coinciden con el tiempo destinado al trabajo.
Golder y Macy también determinaron el estado emocional según las estaciones para determinar si hay cambios entre invierno y verano. Aunque no pudieron revelar una relación total entre la cantidad de luz y el humor, si que la había entre las emociones y los momentos de disminución y aumento gradual de la luz en los solsticios de invierno y de verano, respectivamente. En otras palabras, cuando se va la luz, las personas se deprimen.
El psicoterapeuta Luis Muiño, experto en redes sociales, apunta que las personas mienten mucho cuando escriben respecto a sus sentimientos, por lo que considera que, metodológicamente, el estudio es algo flojo. "Es interesante utilizar Twitter, pero, en general, la gente miente mucho sobre sus emociones, suele ocultar las negativas y depresivas, y también la mentira", señala.
Otra dificultad que encuentra es el giro de las palabras en cadas idioma, que hacen muy complicado decidir qué emoción se está expresando. "En español, hay palabras que depende del contexto expresan una u otra emoción", recuerda Muiño.
Aún así, considera que las redes sociales son un instrumento novedoso y válido, pero sobr todo para la psicología social.

**Publicado en "EL MUNDO"

Hepatitis C patients likely to falter in adherence to treatment regimen over time, Penn study shows

Patients being treated for chronic hepatitis C become less likely to take their medications over time, according to a new study from the Perelman School of Medicine at the University of Pennsylvania. Since the study also showed better response to the drugs when they're taken correctly, the researchers say the findings should prompt clinicians to assess patients for barriers to medication adherence throughout their treatment, and develop strategies to help them stay on track. The study is published online this month in Annals of Internal Medicine. "Our findings are particularly timely since many chronic hepatitis C patients are now being prescribed direct-acting antiviral drugs, which have a complex dosing regimen that may be even harder for patients to maintain than the two-drug standard therapy," said lead author Vincent Lo Re, MD, MSCE, an assistant professor of Infectious Disease and Epidemiology. "These data show us that we need to develop and test interventions to help patients be more successful at taking their medicine and have the best chance at being cured."

Literacy issues, financial hurdles, and socioeconomic problems such as unstable living situations can all hamper patients' abilities to properly maintain their drug regimen. The authors suggest that refilling patients' pill boxes for them, creating easy-to-follow dosing and refill schedules, and helping them set alarms to remind them to take their medicine may all help improve adherence.

The Penn researchers studied 5,706 chronic hepatitis C patients who had been prescribed the standard treatment for the virus -- pegylated interferon (given as a single weekly shot) and ribavirin (a twice-daily oral medicine) -- using pharmacy refill data and test results for virologic response during treatment. They found that patients who refilled their prescriptions on time had a higher likelihood of being cured of the infection. However, over the course of patients' treatment, adherence waned, and more often for ribavarin. That pattern, Lo Re notes, is similar to that among patients taking drugs for other chronic conditions, during which patients often develop so-called "pill fatigue."

The newer, more powerful direct-acting antiviral drugs, which must be taken every 8 hours, will add to the complexity, and cost, of chronic hepatitis C treatment. In addition, if the newer direct-acting antiviral drugs aren't taken properly, the hepatitis C virus may become resistant to treatment, compromising the chance of cure. Hepatitis C is a communicable disease spread via blood, from needle-sharing during IV drug use, tattooing or piercing, or even from more casual contact like sharing razors and toothbrushes. Worldwide, approximately 180 million people have the disease, about 4 million of them in the United States.

Monitoring for and treating drug-related side effects may also be a key factor in boosting adherence, Lo Re says. The study results showed that patients who received medication for thyroid dysfunction, anemia, or low white blood cell counts -- common side effects associated with hepatitis C drugs -- were more likely to remain adherent to their antiviral therapy. Although those drugs added more steps into their self care, Lo Re said the resulting relief for symptoms, including depression, fatigue and irritability, and more frequent visits to health care providers typically required with administration of these drugs, may play a role in patients' ability to maintain the regimen overall.

"We know that a major barrier to adherence is side effects of these drugs. People don't feel good when they're on them," he said. "If we can identify those problems and treat them when they occur, patients may be more motivated and feel well enough to continue with their prescribed regimen."

The study was funded by the National Institutes of Health, the Agency for Healthcare Research and Quality, and the Department of Veterans Affairs.

**Source: University of Pennsylvania School of Medicine