Featured Research

from universities, journals, and other organizations

Innovative imaging system may boost speed and accuracy in treatment of heart rhythm disorder

Date:
August 20, 2010
Source:
University of Maryland Medical Center
Summary:
Researchers have developed a novel 3-D imaging approach that may improve the accuracy of treatment for ventricular tachycardia, a potentially life-threatening heart rhythm disorder that causes the heart to beat too fast. The new approach couples CT (computed tomography) images with conventional ablation techniques to eliminate erratic electrical circuits in the heart that produce arrhythmias.

Researchers at the University of Maryland School of Medicine in Baltimore have developed a novel 3-D imaging approach that may improve the accuracy of treatment for ventricular tachycardia, a potentially life-threatening heart rhythm disorder that causes the heart to beat too fast. The new approach couples CT (computed tomography) images with conventional ablation techniques to eliminate erratic electrical circuits in the heart that produce arrhythmias.

Related Articles


The results of a feasibility study have been published online in Circulation: Arrhythmia and Electrophysiology, a journal of the American Heart Association.

Electrical signals control how frequently the heart beats and how the heart muscle contracts to move blood through the body. Following a heart attack, irregularly shaped sections of dead scar tissue may form in the heart and block the electrical flow or cause a short circuit. The researchers say a growing number of people who have survived severe heart attacks go on to face a weak, erratic heartbeat, and that has prompted the search for more effective ways to treat these electrical disturbances.

Current ablation procedures, which use high-energy radio waves to treat certain types of serious arrhythmias, have only 50-60 percent long-term success. The research team theorized that with the aid of sophisticated 3-D CT imaging, treatment may be more precise and take less time.

According to the study's senior author, Timm-Michael L. Dickfeld, M.D., Ph.D., associate professor of medicine at the University of Maryland School of Medicine, "We can use 3-D CT imaging to guide us more rapidly to areas of the heart that may cause the electrical abnormalities responsible for ventricular tachycardia, and move away from parts of the heart that do not contribute to the abnormalities." Dr. Dickfeld is a cardiologist at the University of Maryland Medical Center and chief of electrophysiology at the Baltimore VA Medical Center.

A CT scanner, which takes multiple X-ray images in a matter of seconds as it rapidly spirals around the body, yields three significant types of information about the heart; abnormal cardiac anatomy, blood flow and heart muscle contraction. After two years of testing and customizing software, the research team has succeeded in combining all of these factors into a three-dimensional imaging format that can work accurately with existing equipment in an electrophysiology laboratory, where ablation procedures are performed.

This project builds on the team's earlier work that studied how well a combination of PET (positron emission tomography) and CT technology would provide advanced imaging. Study co-author Jean Jeudy, M.D., a radiologist at the University of Maryland Medical Center and assistant professor of diagnostic radiology and nuclear medicine at the University of Maryland School of Medicine, says information from imaging technologies such as CT and PET has been used independently, up till now. "Each modality has advantages in imaging, but our idea is to pool their strengths to create a synergism that results in the best and safest therapies for patients."

Study design and results

Eleven men with ventricular tachycardia were evaluated in the study. Each had had a heart attack and required an implantable cardioverter-defibrillator to correct problems with their heartbeat. The participants were scanned for a total of 10-15 seconds with a 64-slice CT system. The scan data was reconstructed into 3-D images and compared to the clinical electrical mapping system routinely used to determine where to apply ablations.

The study's principal investigator, Jing Tian, B.M., Ph.D., says CT imaging was used only as a supplement to find the location of scars. To assess the potential value of this novel technology, the research team compared data from the 3-D imaging with the clinical data after ablations were performed on the patients in the study. "We found that the 3-D scar reconstruction from CT imaging predicted areas of abnormal electrical activity in 81.7 percent of heart segments analyzed. The imaging also correctly displayed the location and extent of cardiac scar tissue, determined by voltage mapping -- the gold standard for scar definition in current clinical practice," says Dr. Tian, a research associate at the University of Maryland School of Medicine. "Curative ablations were located within tissue that CT had identified as abnormal in 82 percent of the cases."

In order to clarify the utility of the 3-D imaging technology, Dr. Tian says there would have to be a randomized, controlled trial to quantify how much time can be saved, how much less radiation it requires, and the impact on patient care. "Such a trial would be the next step," she adds.

Ventricular tachycardia

A healthy heart beats about 60 to 100 beats per minute, and may beat faster with exercise or during stress or fever. In ventricular tachycardia, the heart routinely beats more than 100 times a minute. This rapid heartbeat can lead to dizziness or lightheadedness, fainting and shortness of breath, and may set the stage for sudden cardiac arrest.

Some patients respond well to medications that restore normal heartbeat, while others require a shock from an implantable cardioverter-defibrillator (ICD) to restore normal rhythm. The medications have side effects and the electrical disturbances in some people are so frequent that the ICD must fire multiple corrective shocks each day to prevent sudden cardiac arrest. The shocks are painful, causing many patients to fear their next shock. The goal of ablation is to burn a barrier around the scars to end the electrical disturbance and restore normal heart rhythm. For some patients, the procedure reduces the number of corrective shocks and eliminates the need for medication.

"Advances in cardiac care and the availability of defibrillators have helped many people with weakened hearts live longer," says E. Albert Reece, M.D., Ph.D., M.B.A., vice president for medical affairs at the University of Maryland and dean of the University of Maryland School of Medicine. "Nevertheless, the devices create their own set of problems, especially for people who have received multiple shocks. If this CT research yields quicker, more accurate ablations that are more widely available, it will go a long way toward improving the quality of life for these patients."

Electrical mapping

During electrical or voltage mapping, an electrophysiologist inserts a catheter with an electrode into an artery through the groin and guides it to the beating heart. Fluoroscopic imaging shows the placement of the electrode. The probe detects variations in electrical signals as it is moved a small distance at a time. High voltage indicates normal cardiac tissue. Low or no voltage is associated with dead scar tissue. A computer compiles the data into a map which shows where to apply ablation to eliminate cardiac tissue in and near the scars.

Electrical mapping is laborious and not error-free. Since the probe is moved only small distances, such as five to 15 millimeters at a time for each reading while the heart continues to beat, it may take up to several hours to complete the mapping process and extend the time that the patient is exposed to fluoroscopic X-rays. A scar section that is missed by just a few millimeters during ablation could be the source of additional electrical disturbances. Also, it is possible to get a false electrical reading if the probe does not actually make contact with the heart muscle.


Story Source:

The above story is based on materials provided by University of Maryland Medical Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. Tian et al. Three Dimensional Contrast Enhanced Multi-Detector CT for Anatomic, Dynamic and Perfusion Characterization of Abnormal Myocardium to Guide VT Ablations. Circulation Arrhythmia and Electrophysiology, 2010; DOI: 10.1161/CIRCEP.109.889311

Cite This Page:

University of Maryland Medical Center. "Innovative imaging system may boost speed and accuracy in treatment of heart rhythm disorder." ScienceDaily. ScienceDaily, 20 August 2010. <www.sciencedaily.com/releases/2010/08/100818121335.htm>.
University of Maryland Medical Center. (2010, August 20). Innovative imaging system may boost speed and accuracy in treatment of heart rhythm disorder. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2010/08/100818121335.htm
University of Maryland Medical Center. "Innovative imaging system may boost speed and accuracy in treatment of heart rhythm disorder." ScienceDaily. www.sciencedaily.com/releases/2010/08/100818121335.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Best Tips to Curb Holiday Carbs

The Best Tips to Curb Holiday Carbs

Buzz60 (Dec. 19, 2014) It's hard to resist those delicious but fattening carbs we all crave during the winter months, but there are some ways to stay satisfied without consuming the extra calories. Vanessa Freeman (@VanessaFreeTV) has the details. Video provided by Buzz60
Powered by NewsLook.com
Sierra Leone Bikers Spread the Message to Fight Ebola

Sierra Leone Bikers Spread the Message to Fight Ebola

AFP (Dec. 19, 2014) More than 100 motorcyclists hit the road to spread awareness messages about Ebola. Nearly 7,000 people have now died from the virus, almost all of them in west Africa, according to the World Health Organization. Video provided by AFP
Powered by NewsLook.com
Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins