Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dartmouth researchers find new imaging method may lower risks for abdominal aortic aneurysms

03.04.2003


Results of a study by researchers at Dartmouth-Hitchcock Medical Center (DHMC) and Dartmouth Thayer School of Engineering could have implications for choosing which patients with abdominal aortic aneurysms should have surgery and which ones should simply have follow-up with noninvasive studies.



In an article published in the April issue of the Journal of Vascular Surgery, Dr. Mark Fillinger and colleagues describe a new noninvasive method for evaluating abdominal aortic aneurysms (AAA). They found that the new method – examining aneurysm wall stress – predicts AAA rupture risk better than aneurysm diameter, which has been used to predict rupture risk for over 40 years.

The multidisciplinary study was sponsored by the National Institutes of Health and the National Heart Lung and Blood Institute. In the study, conducted at Dartmouth-Hitchcock Medical Center, over 100 patients who had computed tomography scans (CT scans) during the course of routine care had AAA “wall stress analysis”. The CT scan is processed through a series of computer programs, including an engineering process called finite element analysis. Finite element analysis breaks the structure into thousands of tiny elements so a computer can calculate the wall stress using the three-dimensional shape of the AAA (from the CT scan), the patient’s blood pressure, and the tissue properties of typical AAAs. The result is a computer-generated “stress map” that displays the aneurysm wall stress (the force trying to pull the aneurysm apart and cause rupture).


The patients in the study were generally under observation for their aneurysm for one of three reasons: 1) because the aneurysm was felt to be too small to repair, 2) because the risks of repair were felt to be too high compared to the risk of aneurysm rupture, or 3) because the patient decided not to have aneurysm repair. The outcomes of observation were then compared based on the standard method of determining rupture risk (maximum AAA diameter) versus the maximum stress within the aneurysm wall. A prior study by this group had determined that wall stress was high at the time of rupture, but this was the first large study of AAA wall stress in patients under extended periods of observation.

Researchers found that the new technique (aneurysm wall stress analysis) predicted the risk of rupture better than maximum AAA diameter, with a 25 fold increase in rupture risk for patients with high AAA wall stress, and only 9 fold higher rupture risk for patients with large diameter (over 5.5 cm). The location of rupture (when known) was also consistent with the location of maximum stress predicted by the computerized stress map. Interestingly, some patients with small aneurysms had high wall stress (high risk of rupture) and some patients with large aneurysms had low wall stress (low risk of rupture).

“This study has several important aspects. Some patients with small aneurysms (based on diameter) have an unexpectedly high risk of rupture and should have surgery earlier than is typically recommended” says Dr Fillinger. “Other patients with larger aneurysms, but high risks for surgery, may delay surgery and have observation with noninvasive studies if we can reliably predict that they have a low rupture risk. Another impact of this study may be that blood pressure control in aneurysm patients will be examined with more scrutiny, since blood pressure plays a key role in AAA wall stress. We have made great strides with minimally invasive surgery for aortic aneurysms, but not everyone is a candidate for these techniques. AAA wall stress analysis may be able to prevent rupture in some patients and prevent unnecessary surgery in others."

The risk of rupture relative to AAA diameter and female gender (known risks for aneurysm rupture) were consistent with recent large clinical trials in the US and UK. In those studies, patients with AAAs under close observation with ultrasound every 6 months still had a small risk of rupture, with higher risks for women. “The consistency of our current study with the US and UK small aneurysm trials is encouraging. In future work, we hope to determine why females are at greater risk for rupture than males. We would like to improve the aneurysm tissue model, and hope to start a larger multicenter study within the next year.”

It is estimated that 2 million people in the US have abdominal aortic aneurysms, and AAA rupture is the thirteenth leading cause of death in men. Many people are unaware they have aortic aneurysms because they cause no symptoms prior to rupture. The increasing incidence of AAA nationwide has lead to more attention regarding screening for AAA, including a recent feature in the Wall Street Journal. Numerous famous people have died of AAA rupture, including Albert Einstein, Lucille Ball, and George C Scott. Senator Bob Dole and Rodney Dangerfield are among celebrities who have recently had AAA repair to prevent rupture.




Dartmouth-Hitchcock Medical Center (DHMC) is an integrated academic medical center located on a 225-acre campus in the heart of New Hampshire’s Upper Connecticut River Valley in Lebanon. DHMC comprises Mary Hitchcock Memorial Hospital, the Dartmouth-Hitchcock Clinic, Dartmouth Medical School and the Veterans Affairs Medical Center in White River Junction, VT.

For more information contact Tamsin Stubbs at (603) 653-1997.

Tamsin Stubbs | DHMC
Further information:
http://www.dhmc.org/webpage.cfm?site_id=2&org_id=2&morg_id=0&gsec_id=2&sec_id=2&item_id=16691

More articles from Health and Medicine:

nachricht Cholesterol-lowering drugs may fight infectious disease
22.08.2017 | Duke University

nachricht Once invincible superbug squashed by 'superteam' of antibiotics
22.08.2017 | University at Buffalo

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>