Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Procedure cures atrial fibrillation

13.11.2003


Radio waves ’zap’ tiny areas of heart muscle



An innovative procedure completely cures the overwhelming majority of patients with the most common form of irregular heartbeat, by stopping haywire electrical signals in areas of heart muscle and some of the veins that connect to it.

In several presentations at the American Heart Association’s Scientific Sessions 2003, and in a new paper in the Nov. 12 issue of the AHA journal Circulation, heart rhythm specialists from the University of Michigan Cardiovascular Center report their dramatic success in treating atrial fibrillation patients using a technique called radiofrequency catheter ablation.


The reports show that more than 85 percent of patients with intermittent AF were cured after a single session of catheter ablation, and no longer required medications to stabilize their heartbeat and cut their risk of clotting and strokes. Complication rates were extremely low.

"In all, we have treated more than 500 patients in the last three years and have achieved very favorable results in these patients," says cardiologist Hakan Oral, M.D., lead author of the Circulation paper and the U-M presentations at AHA. "It’s still a technically challenging procedure, but we hope to continue to simplify and improve it, and train others to perform it."

Catheter ablation aims to counteract irregular electrical impulses in heart muscle by delivering tiny bursts of intense radiofrequency waves to the areas of disorganized electrical activity. The radio wave "zap" heats the target areas of tissue, a process called ablation, but spares nearby tissue.

The catheters that record electrical signals in the tissue and deliver the radiofrequency energy are carefully inserted through the groin of a sedated patient, and wind through the major blood vessels and into the heart. Then, the catheter head pokes through the septum that divides the heart vertically, and enters the left atrium.

Depending on which areas will be targeted for ablation, doctors guide the tiny devices into position and deliver the radiofrequency pulses with painstaking precision in patterns that resemble dotted lines and circles. Then, they remove the catheter from the body, and monitor the patient overnight.

Recently, Oral says, the technique has been greatly enhanced by the development of new ablation strategies, and the ability to make three-dimensional digital maps of the heart and its electrical signals.

Of the few centers in the world performing catheter ablation, the U-M may be one of the most experienced and the most successful. But Oral hopes the technique can spread to other centers to help as many patients as possible. Oral will conduct a "how-to" session for other heart rhythm specialists at the AHA meeting, and the U-M team has welcomed many doctors to watch them performing the technique in Michigan.

Oral and Fred Morady, M.D., the U-M cardiologist who is senior author on the paper, hope the new results their team is publishing and presenting will help convince others in their field of the technique’s worth in tackling an otherwise difficult-to-treat condition. They especially point to the increased success they’ve had by ablating areas of the left atrium wall, rather than just the juncture between the pulmonary veins and the left atrium.

More than 2.2 million Americans have AF, and 160,000 more are diagnosed each year. In addition to causing heart palpitations, fatigue and pain that can be debilitating, the condition can quintuple a person’s risk of stroke, because of blood clots that form in the irregularly beating chambers of the heart. AF can also cause heart enlargement.

The Circulation paper is a prospective randomized trial involving 80 patients with the paroxysmal, or intermittent, form of AF, all of whom had experienced symptoms for years.

Ever since Michel Hassaguerre, M.D. and his colleagues in Bordeaux, France, first described how AF is initiated by electrical impulses that originate in the pulmonary veins, ablation attempts have primarily focused on electrical disconnection of the pulmonary veins from the left atrium. However, another approach proposed by Carlo Pappone, M.D., in Milan, Italy, suggested that higher efficacy might be possible via ablation within the left atrium, to encircle the pulmonary veins.

It was not clear which approach would be best. So, Oral and his colleagues randomized patients to undergo ablation in one of two ways. Some had it at the junction (ostia) between the pulmonary veins and the left atrium (a procedure called segmental ostial ablation or SOA). Others had a left atrial ablation procedure that was modified by Oral and his colleagues to include lines of ablation in the left atrium in addition to encircling the ostia (a procedure called left atrial catheter ablation or LACA).

Six months after treatment, 67 percent of the SOA patients were symptom-free without medication, compared with 88 percent of the LACA patients. Only one patient had a complication.

The results will help settle the controversy over which form of the technique is more reliable, Oral says, because it’s the first time SOA and LACA have been compared directly.

Catheter ablation for AF has been done for several years at a handful of centers. In addition to treating patients with paroxysmal AF, the U-M team treats patients with the much more debilitating and harder-to-treat form of the disorder called persistent AF.

At AHA, the U-M team will report the results of their efforts based on data gathered from more than 100 persistent AF patients. They treated 24 with the SOA technique, and the remaining patients underwent different forms of left atrial ablation. After six months, 25 percent of the SOA group, and more than 75 percent of the left atrial ablation group, were symptom-free without medication.

Also at AHA, the U-M team will report the results of their efforts to determine which patients undergoing catheter ablation for AF are more likely to develop atrial flutter, a related but different arrhythmia. They found that patients who had a history of atrial flutter, or who had inducible atrial flutter during the ablation procedure, were at risk of developing atrial flutter later on. Therefore, the authors suggest that in these patients, ablation with a certain region of the right atrium should be performed at the same time as the AF ablation, to minimize the risk of atrial flutter recurrence.

In all, Oral believes the new paper and presentations will help spread the word about the procedure. "I hope that patients and their treating physicians will become aware of the promise that catheter ablation holds, and that more centers will adopt the techniques," he says. "The more patients we can help, the better."



The U-M team’s research is funded by the Ellen and Robert Thompson Atrial Fibrillation Research Fund. Oral and Morady have served as consultants and speakers for Biosense-Webster, the company that makes the catheter that detects the electrical impulses in heart and vein tissue.

The other authors on the Circulation paper and AHA presentations are Christoph Scharf, M.D.; Aman Chugh, M.D., Burr Hall, M.D., Peter Cheung, M.D., Eric Good, D.O., Mehmet Ozaydin, M.D., Srikar Veerareddy, M.D., and Frank Pelosi, Jr., M.D.

References:
"Catheter Ablation for Paroxysmal Atrial Fibrillation: Segmental Pulmonary Vein Ostial Ablation Versus Left Atrial Ablation", Circulation, Vol. 108, Nov. 11, 2003, (published online in October)

Contact: Kara Gavin
At AHA meeting: cell 734-358-4910, or
Sally Pobojewski, pobo@umich.edu
At U-M: 734-764-2220

Kara Gavin | EurekAlert!
Further information:
http://www2.med.umich.edu/prmc/media/relarch.cfm

More articles from Health and Medicine:

nachricht Investigators may unlock mystery of how staph cells dodge the body's immune system
22.09.2017 | Cedars-Sinai Medical Center

nachricht Monitoring the heart's mitochondria to predict cardiac arrest?
21.09.2017 | Boston Children's Hospital

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>