Nav: Home

PET/MR shows arterial CO2 as potent vasodilator for cardiac stress testing

June 05, 2017

RESTON, Va. -- More than 5 million cardiac stress tests performed annually in the U.S. employ injectable forms of pharmacological stress agents--such as adenosine or one of its analogues--to dilate blood vessels in the heart. However, these drugs can have severe side effects. Using PET/MR imaging, a new international study featured in the June issue of The Journal of Nuclear Medicine demonstrates that increases in partial pressure of arterial carbon dioxide (PaCO2) can safely and efficiently widen blood vessels of the heart during stress tests to help determine heart function.

Myocardial blood flow (MBF) is critical in determining heart function. While PaCO2's effect on MBF has been studied extensively in the past, previous findings have been inconclusive due to difficulty in quickly controlling PaCO2 to limit hypercapnia (too much carbon dioxide in the blood) and uncertain measures of the outcome variable. In this new study, these issues have been addressed.

"We have overcome these technical difficulties by incorporating new technology that can accurately, precisely and rapidly control arterial blood gas levels, and we have quantified the MBF response with 13N-ammonia PET, the gold standard approach for measuring MBF, in a clinically relevant animal model," explains Rohan Dharmakumar, PhD, of the Cedars-Sinai Medical Center and University of California, Los Angeles, California. "We report for the first time that a physiologically tolerable increase in PaCO2 (~25 mmHg) amplifies MBF more than two-fold, a key feature of clinically meaningful coronary vasodilators used for cardiac stress testing."

The study included three groups of canines: (1) without coronary stenosis, (2) with non-flow limiting stenosis and (3) pre-administered caffeine (which inhibits adenosine and can affect stress-test results). In all cases, PaCO2 proved just as effective at inducing MBF as the standard dose of adenosine and performs better than adenosine in animals pre-administered with caffeine.

"This key finding opens the door to a completely new protocol for cardiac stress testing--one that has the potential to benefit numerous patients who are contraindicated for commonly used pharmacological stress agents," says Dharmakumar. "Since hypercapnia is safe and effective when its magnitude is tightly controlled, it could also empower repeat stress testing in target populations with heart disease--overcoming a limitation of current stress tests that rely on injectable pharmacological agents."
The authors of "Arterial CO2 as a Potent Coronary Vasodilator: A Preclinical PET/MR Validation Study with Implications for Cardiac Stress Testing" include Hsin-Jung Yang, Damini Dey, Avinash Kali, Roya Yumul, Debiao Li, Piotr J. Slomka, Daniel S. Berman, and Rohan Dharmakumar, Cedars-Sinai Medical Center and University of California, Los Angeles, California; Jane Sykes, John Butler, Michael S. Kovacs, and Frank S. Prato, University of Western Ontario, London, Canada; Michael Klein, Olivia Sobczyk, and Joseph A. Fisher, University of Toronto, Toronto, Canada; Behzad Sharif, Ivan Cokic, Richard Tang, Antonio H. Conte, and Mourad Tighiouart, Cedars-Sinai Medical Center; Xiaoming Bi, Siemens Healthcare, Los Angeles, California; and Sotirios A. Tsaftaris, University of Edinburgh, Edinburg, UK.

This work was supported in part by a grant from the National Heart, Lung and Blood Institute at NIH (HL091989).

Please visit the SNMMI Media Center to view the PDF of the study, including images, and more information about molecular imaging and personalized medicine. To schedule an interview with the researchers, please contact Laurie Callahan at (703) 652-6773 or Current and past issues of The Journal of Nuclear Medicine can be found online at

About the Society of Nuclear Medicine and Molecular Imaging

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and medical organization dedicated to raising public awareness about nuclear medicine and molecular imaging, a vital element of today's medical practice that adds an additional dimension to diagnosis, changing the way common and devastating diseases are understood and treated and helping provide patients with the best health care possible.

SNMMI's more than 17,000 members set the standard for molecular imaging and nuclear medicine practice by creating guidelines, sharing information through journals and meetings and leading advocacy on key issues that affect molecular imaging and therapy research and practice. For more information, visit

Society of Nuclear Medicine

Related Adenosine Articles:

Structural framework for tumors also provides immune protection
Aggressive colorectal cancers set up an interactive network of checkpoints to keep the immune system at bay, scientists report.
Using caffeine as a tool to study information processing
Researchers are using caffeine to study how the brain processes information, and a new study shows the effectiveness of this approach.
Bone bandage soaks up pro-healing biochemical to accelerate repair
Researchers at Duke University have engineered a patch or bandage that captures a pro-healing molecule called adenosine that briefly surges at the site of a bone break or fracture to accelerate and improve the natural healing process.
Emerging role of adenosine in brain disorders and amyotrophic lateral sclerosis
The role of adenosine in neurodegeneration and neuroregeneration has led to growing attention on adenosine receptors as potential drug targets in a range of brain disorders, including neuroregenerative therapy and treatment for amyotrophyic lateral sclerosis (ALS).
Discovery of tanycytic TSPO inhibition as a potential therapeutic target for obesity treatment
Professor Eun-Kyoung Kim's team in the Department of Brain and Cognitive Sciences discovered the mechanism underlying the regulation of energy metabolism by hypothalamic tanycyte.
New pharmaceutical target reverses osteoporosis in mice
Biomedical engineers at Duke University have discovered that an adenosine receptor called A2B can be pharmaceutically activated to reverse bone degradation caused by osteoporosis in mouse models of the disease.
New target found for disease of the heart's smallest blood vessels
When we race walk, for example, part of our healthy heart muscle may want a little more blood and oxygen, so our tiniest blood vessels send a message upstream to the larger vessels to send more.
Impeding white blood cells in antiphospholipid syndrome reduced blood clots
A new study examined APS at the cellular level and found that two drugs reduced development of blood clots in mice affected with the condition.
Adenosine kinase deficiency makes liver more susceptible to carcinogen
A new study has shown that reduced adenosine kinase expression in the liver can make it more susceptible to carcinogenic damage and the development of liver cancer.
Is adenosine the missing link in restless leg syndrome?
Researchers have identified a common mechanism implicating adenosine in the cause of restless leg syndrome (RLS) symptoms -- the periodic limb movements characteristic of RLS and the state of enhanced arousal that both disrupt sleep.
More Adenosine News and Adenosine Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at