Why athletes are more likely to need pacemakers in old age

A new study by The University of Manchester has shed light on why athletes are more likely to have abnormal heart rhythms.

18 may 2014--Elderly athletes with a lifelong history of training and competing in endurance events like marathons, triathlons and iron man challenges can have heart rhythm disturbances, known as arrhythmias.

The Manchester research in rodents, funded by the British Heart Foundation, shows molecular changes in the heart's pacemaker occur in response to exercise training.

The finding, reported in Nature Communications, overturns the commonly held belief that an increased activity of the autonomic nervous system causes this specific reaction to endurance training.

While normal adults have resting heart rates between 60-100 beats per minute, hearts of endurance athletes can beat only 30 times per minute or even lower at night time when there can be long pauses between heart beats.

Cyclists Sir Chris Hoy and Miguel Indurain reportedly had resting heart rates of 30 and 28 beats per minute.

Dr Alicia D'Souza, from The University of Manchester and first author on the paper, said: "The heart rate is set by the heart's pacemaker, but this is controlled by the nervous system. The 'vagal' nerves lower the heart rate and therefore it was assumed the low heart rate of athletes is the result of over activity of the vagal nerves.

"But our research shows this is not the case. Actually the heart's pacemaker changes in response to training and in particular there is a decrease in an important pacemaker protein, known as HCN4, and this is responsible for the low heart rate."

The researchers say these molecular changes in the sinus node - the cardiac structure responsible for generating heart rhythm - may help us to understand the more frequent occurrence of heart rhythm disturbances or even loss of consciousness in athletes.

Professor Mark Boyett, lead researcher on the study, added: "This is important because although normally a low resting heart rate of an athlete does not cause problems, elderly athletes with a lifelong training history are more likely to need an artificial electronic pacemaker fitted."

More than 500 marathons take place in Europe and America each year with around one million participants. The number of people taking part is set to increase by 5% each year.

But Professor Boyett said: "Although endurance exercise training can have harmful effects on the heart, it is more than outweighed by the beneficial effects."

Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, said: "This study shows the heart's electrical wiring changes in mice that exercise for long periods, and these changes in heart rhythm are sustained afterwards.

"If the findings are reproduced in humans they could have implications for heart health in older athletes. But much more research is needed before we could draw that conclusion."

More information: Paper: dx.doi.org/10.1038/ncomms4775

Provided by University of Manchester

World's smallest Medtronic Micra pacemaker: Cardiac pacing game change?

 

15 dec 2013--Device maker Medtronic has accomplished a feat in device miniaturization, this time in the form of an implantable cardiac device the size of a large vitamin. Earlier this month, Minneapolis-based Medtronic said the first in-human implant of the world's smallest pacemaker, without surgery, has taken place in Linz, Austria, as part of a global clinical trial.

The pacemaker's size and the fact that it can be implanted without surgery are the key features. The device is called the Micra Transcatheter Pacing System (Micra TPS). The implant does not require a surgical incision in the chest. Pat Mackin, senior vice president for Medtronic and president of the company's cardiac rhythm disease management business, compared it to a traditional pacemaker. "There's no more generator. There's no more lead," he said. Rather, it can be directly introduced into the heart in a minimally invasive procedure, to eliminate a potential source of device-related complications. The device is 24 millimeters long and 0.75 cubic centimeters in volume, far smaller than the traditional size of a conventional pacemaker.

The device is delivered directly into the heart through a catheter inserted in the femoral vein, sent up through the femoral vein with a catheter, and placed right inside the heart. The little device will perform the same function as the traditional system.

"It's just a phenomenal development" said Dr. Bill Katsiyiannis with the Minneapolis Heart Institute Foundation. He said that eliminating the lead and pocket for the device.represents a huge advance. In Austria, the head of cardiology at Linz General Hospital also spoke about the advantages in Micra TPS. " Because of its small size and unique design, the Micra TPS can be introduced directly into the heart via a minimally invasive procedure, without the need for leads," said Clemens Steinwender, M.D., head of cardiology at the Linz General Hospital in Linz. "The combination of this novel technology with a transcatheter procedure can benefit patients by potentially reducing pocket or lead complications and recovery times observed with traditional surgical pacemaker implants."

The pacemaker delivers electrical impulses that pace the heart through an electrode at the end of the device. Once positioned, the pacemaker is securely attached to the heart wall and can be repositioned if needed.

The Micra TPS is an investigational device worldwide. A clinical trial will enroll up to 780 patients at approximately 50 centers. Initial results from the first 60 patients, followed up to three months, are anticipated in the second half of 2014.

Scientists test brain pacemakers for depression

By LAURAN NEERGAARD
27 may 2008--It's a new frontier for psychiatric illness: Brain pacemakers that promise to act as antidepressants by changing how patients' nerve circuitry fires.
Scientists already know the power of these devices to block the tremors of Parkinson's disease and related illnesses; more than 40,000 such patients worldwide have the implants.
But psychiatric illnesses are much more complex and the new experiments with so-called deep brain stimulation, or DBS, are in their infancy. Only a few dozen patients with severe depression or obsessive-compulsive disorder so far have been treated in closely monitored studies.
Still, the early results are promising. Dramatic video shows one patient visibly brightening as doctors turn on her brain pacemaker and she says in surprise: "I'm starting to smile." And new reports this month show that some worst-case patients — whose depression wasn't relieved by medication, psychotherapy, even controversial shock treatment — are finding lasting relief.
Six of 17 severely depressed patients were in remission a year after undergoing DBS and four more markedly improved, and more than half of 26 obsessive-compulsive patients showed substantial improvement over three years, say studies from a team at the Cleveland Clinic, Brown University, and Belgium's University of Leuven.
"Not all patients get better, but when patients respond, it's significant," says Dr. Helen Mayberg of Emory University, who has implanted about 50 depression patients. Her first remains in remission after five years; she estimates that four of every six show enough improvement to be classified "responders."
"We're rewiring the brain in many ways," says Dr. Ali Rezai, chief of the Cleveland Clinic's Center for Neurologic Restoration.
There's a need for innovative therapies. Up to 20 percent of depression patients and 10 percent of those with obsessive-compulsive disorder are treatment-resistent — several million people in the U.S. alone.
The rationale behind DBS is credible, says Dr. Wayne Goodman of the National Institute for Mental Health: Surgery sometimes helps worst-case patients by destroying misfiring patches of brain tissue. The electrodes are placed into similar spots, but don't destroy tissue — the electrical signals can be adjusted and turned off.
But it's not yet ready for prime-time, Goodman cautions. He worries that because the electrodes already are widely available, centers without proper training will start offering the $40,000 implant surgeries to psychiatric patients before science proves if they're really valuable.
"It is an invasive, experimental procedure," he warns, with risks including bleeding in the brain and infections. He calls DBS "the last resort for stringently selected patients."
Earlier this month, federal health officials and the Cleveland Clinic brought together the field's leading researchers to highlight progress so far and debate if it's time for much larger studies — even whether DBS might be tweaked to help people with traumatic brain injuries, such as Iraq war veterans.
"There's not enough awareness of what the potential is of this kind of stimulation," says meeting co-chair Dr. Margaret Giannini, who heads the government's Office on Disability.
In deep brain stimulation for Parkinson's, a wire is implanted within a walnut-sized area known as the thalamus, a hub of sensory information. That electrode is connected by a cable running through the neck to a pulse generated under the collarbone. Tiny electrical zaps disable overactive nerve cells, blocking tremors.
Scientists don't have nearly as much understanding of what goes awry to cause depression or other psychiatric illnesses — but they do know the thalamus isn't the right spot for those patients. They're focusing instead on two regions with names only a neurologist could love — the ventral capsule/ventral striatum and so-called Brodmann Area 25. Ignore the names; the point is that these are regions where brain circuitry involved in mood and anxiety intersect.
It's not yet clear who should have DBS in which spot, or if there are still other target areas. Much of the research to date has been funded by electrode manufacturers, with some paid for by the government — and consists of measuring patients' disability before and after DBS, not more rigorous studies that randomly assign patients to treatment.
Still, Diane Hire of Cleveland, the patient whose first smile was recorded, illustrates the hope.
The 12-year Navy veteran was medically discharged for depression and spent a decade on disability, unable to function. "I basically felt like a dead person walking. I had no feelings, no emotions," she told the scientists' meeting.
Her DBS was switched on in January 2007, and "my whole world changed," says Hire, 54. She's not back to work yet: "It is a real challenge to learn how to live as a healthy person again," she adds, saying she doesn't handle stress or multitasking well. But, "I wake up every day looking forward to what's ahead."