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Dallas Researchers Make Six Major Presentations at American Heart Association Scientific Sessions
11/15/2011

DALLAS — Researchers at the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas made six presentations at this year’s American Heart Association’s Scientific Sessions.

Research team at the Institute for Exercise and Environmental Medicine at Texas Health Dallas
Dr. Benjamin Levine (left), director of the Institute for Exercise and Environmental Medicine at Texas Health Dallas, has mentored some of the country’s top young researchers in recent years. Four of his research fellows made major presentations at this year’s American Heart Association’s Scientific Sessions: Yongsheng Zhu, M.D., Ph.D.; Naoki Fujimoto, M.D., Ph.D.; Graeme Carrick-Ranson, Ph.D.; and Keri Shafer, M.D.
Click photo to download hi-res image

The annual conference brings together the world’s leading experts in heart disease, cerebrovascular disease and other cardiovascular conditions to present and discuss the most cutting edge science in cardiovascular medicine. Scientific directors of the conference, known to be highly selective, accepted six IEEM research projects for presentation out of nine submissions, more than double the usual acceptance rate. For example, last year 9,444 abstracts were submitted from investigators around the world, and only 3,463 (36 percent) were accepted.

This year’s conference was held Nov. 12-16 in Orlando, Fla.

“These researchers are the next generation of great scientists,” said Dr. Benjamin Levine, director of the IEEM and a professor of medicine and cardiology and distinguished professor in exercise science at UT Southwestern Medical Center. “I’m personally very proud of what they’ve accomplished, but what’s most important is that their work is improving our understanding of how the heart and brain are affected by aging and exercise, and how people with congenital heart defects function during exercise.”

“One day, their findings may lead to better treatments for conditions that affect millions of Americans,” Levine added.

In recent years, researchers at the IEEM, which is a joint collaboration between Texas Health Dallas and UT Southwestern, have become foremost experts on how exercise impacts long-term heart and brain health, as well as overall quality of life. Their cardiac research has been published in the country’s top peer-reviewed scientific journals.

Recently, IEEM researchers found that consistent lifelong exercise can make heart muscle in the elderly as healthy, or even healthier, than the heart muscle of young sedentary people. IEEM researchers also were among the first scientists to pinpoint the specific parts of the brain that benefit from long-term aerobic exercise, finding how and where exercise benefits brain function.

“The amount of quality research published by researchers at the Institute for Exercise and Environmental Medicine under Dr. Levine’s nurturing leadership is truly remarkable,” said Dr. Mark Feldman, chairman of internal medicine and medical director of research at Texas Health Dallas. “Their work translates what scientists are learning in the laboratory to the real world. That’s how science and medicine impact people’s lives in a positive way.”

The projects presented at the AHA’s Scientific Sessions focused on four areas of cardiovascular research: the physiology of patients with congenital heart disease and how they increase their cardiac output during exercise; how long-term exercise can prevent age-related reductions in the heart’s ability to pump blood; how to possibly limit the “natural” decline of maximum exercise capacity, which is associated with negative health outcomes including a higher risk of morbidity and mortality; and why some people with certain types of heart failure may not improve their exercise capacity with traditional endurance training.

“The hope is that our findings will lead to more research that one day helps people live healthy, richer lives as they age,” said Graeme Carrick-Ranson, Ph.D., a research fellow at the IEEM who presented two research projects at the AHA conference. Carrick-Ransom is a scientist from New Zealand who is particularly interested in the combination of aging and diabetes as it effects heart function during exercise. He is a postdoctoral fellow working under the direction of Levine.

In addition to Carrick-Ranson, other IEEM researchers who made presentations were Naoki Fujimoto, M.D., Ph.D.; Keri Shafer, M.D.; and Yongsheng Zhu, M.D., Ph.D.

Fujimoto is a cardiologist from Japan whose work centers around how aging and exercise training affect the compliance (flexibility) and function of the heart. Fujimoto’s projects looked into how the left ventricle, the “power plant” of the heart that pumps blood throughout the body to all organs and tissue, is affected by aging. “We know that the stroke volume of the left ventricle decreases as we age,” Fujimoto said, “but we need to know why.”

Shafer is the chief cardiology fellow at UT Southwestern and has a special interest in patients who were born with congenital heart disease, and who have survived into adulthood. Such patients are becoming increasingly common as cardiac surgery for congenital heart disease has improved, and few traditional cardiologists are trained to care for such patients. She is spending her research year at the IEEM under Levine’s direction.

Zhu is a cardiologist from China who is interested in the coupling between the heart and the brain. He is working in the research group of IEEM faculty member Rong Zhang, Ph.D., as a postdoctoral fellow.

Additional IEEM scientists who participated in the research projects include Levine; Tony Babb, Ph.D..; Shigeki Shibata, M.D., Ph.D.; Jeff Hastings, M.D.; Paul Bella, M.D.; Kara Boyd, research assistant; and Dean Palmer, research associate.

The presentations are:

  • The Importance of the Muscle and Ventilatory Blood Pumps During Exercise in Patients without a Sub-pulmonary Ventricle (Fontan Operation).
    Shafer, KM, Babb, TG, Fixler DE, Levine BD.
    The study focuses on the physiology of patients with congenital heart disease who have only three heart chambers. In this study they describe the mechanisms by which they increase their cardiac output during exercise.
  • Increased Cardiac Distensibility Is Not Associated with Lower Levels of Circulating Biomarkers of Extracellular Matrix Remodeling in Lifelong Exercisers.
    Carrick-Ranson G, Hastings JL, Fujimoto N, Shibata S, Spinale FG and Levine BD.
    Lifelong (>20 years) exercise training prevents the age-related reduction in left ventricular (LV) compliance. This study investigated whether the improved LV compliance in older (>62 years) adults who have performed lifelong exercise training results from remodeling of the extracellular matrix; the “scaffolding” that gives structural support to heart cells. The results of this study showed that while lifelong exercise training of four or more exercise sessions/week improved LV compliance, blood markers of extracellular matrix remodeling were not different between exercisers and non-exercisers. While our results suggest that the increased LV compliance with lifelong exercise is not associated with extracellular matrix remodeling, we cannot exclude the possibility that favorable remodeling that is not detectable with the current parameters may play a contributory role to the improved LV function in trained older adults.
  • Maximal Stroke Volume and Total Blood Volume Are Not Reduced with Healthy Aging Despite a Reduction in VO2max: The Critical Nature of Allometric Scaling.
    Carrick-Ranson G, Hastings JL, Fujimoto N, Shibata S, Palmer D, Boyd K, Bhella PS, Levine BD.
    Maximal exercise capacity as assessed by maximal oxygen uptake (VO2max) declines with advancing age. This reduction in VO2max is associated with negative health outcomes including a higher risk of morbidity and mortality. A reduction in maximal stroke volume (the maximal amount of blood the heart can pump per heart beat) and total circulating blood volume has been hypothesized to contribute to the reduction in VO2max in older adults; however this hypothesis has not previously investigated in a large cohort of healthy adults. Therefore, the purpose of this study was to investigate whether maximal stroke volume and total blood volume are reduced with advancing age, and whether scaling these variables in relation to age-related changes in body composition alters the findings. The results of this study showed that maximal stroke volume and total blood volume are well preserved in men and women with healthy aging. These results were strengthened when maximal stroke volume and total blood volume were scaled relative to metabolically active tissue (fat free mass). As a result, a reduction in maximal heart rate and oxygen uptake by metabolically active tissue seems to explain the decline in VO2max with aging in healthy individuals.
  • Tight Regulation of Left Ventricular Transmural Filling Pressure in Healthy Individuals.
    Fujimoto N, Hastings JL, Bhella PS, Carrick-Ranson G, Shibata S, Palmer D, Levine BD.
    Summary: Healthy aging impairs left ventricular (LV) compliance and relaxation, which results in a decreased stroke volume (SV) in elderly individuals. By contrast, lifelong exercise training can preserve LV compliance and increase SV in the elderly. In this study, we found that LV transmural pressure (TMP), which is the true preload for the LV, was tightly regulated in healthy subjects irrespective of age or lifelong exercise training. Therefore, changes in SV associated with aging or lifelong exercise training are not related to changes in TMP, but rather to changes in LV compliance.
  • Effects of One Year of Endurance Exercise Training on ‘Dynamic’ Starling Mechanisms in Heart Failure with Preserved Ejection Fraction.
    Fujimoto N, Shibata S, Hastings JL, Prasad A, Bhella PS, Carrick-Ranson GC, Palmer D, Levine BD.
    Summary: Endurance exercise training increases peak oxygen uptake (VO2max) in healthy controls, partly because of an improvement of beat-to-beat left ventricular (LV)-arterial coupling. In this study, we found that one year of exercise training failed to improve beat-to-beat LV-arterial coupling in patients with HFpEF, while it was improved in healthy controls. These results may partly explain why no improvement was observed in VO2max in HFpEF.
  • Exercise Training Decreases Arterial Stiffness and Improves Brain Perfusion in Sedentary Elderly Women. (oral presentation)
    Yong-Sheng Zhu, Benjamin Tseng, Rosemary Parker, Arjen Van Erkelens, Garrett Coles, Estee Brunk, Kyle Armstrong, Karen Rodrigue, Kristen Kennedy, Denise Park, Rong Zhang.
    Summary: 30 older women participated in this study. Researchers found that the regional and carotid arterial stiffness were decreased and the brain perfusion was improved significantly in sedentary women over 60 years old after three months of moderate aerobic exercise. It demonstrated that the cerebral hemodynamics of sedentary old women can get solid benefits from a short-term aerobic exercise training.

About the Institute for Exercise and Environmental Medicine
The Institute for Exercise and Environmental Medicine (IEEM) was founded as a joint program between Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center. Its mission is to promote basic and clinical research, education, and clinical practice in defining the limits to human functional capacity in health and disease, with the objective of improving the quality of life for human beings of all ages. The IEEM includes ten major laboratories tightly integrated and organized intellectually along the “oxygen cascade” — the path that oxygen must follow through the body from the external environment through the lungs, heart, skeletal muscles, and brain to perform cognitive function and physical activity. The IEEM is among the few research centers in the world that fosters the fusion of basic science and clinical medicine in a program designed specifically to study human physiology.

About Texas Health Presbyterian Hospital Dallas
Texas Health Presbyterian Hospital Dallas is an 898-bed acute care hospital and recognized clinical program leader, having provided compassionate care to the residents of Dallas and surrounding communities since 1966. U.S. News and World Report has ranked Texas Health Dallas among the nation’s best hospitals in digestive disorders, orthopedics, and neurology and neurosurgery. An affiliate of the faith-based, nonprofit Texas Health Resources system, Texas Health Dallas has approximately 4,000 employees and an active medical staff of more than 1,000 physicians. For more information, call 1-877-THR-WELL, or visit TexasHealth.org/Dallas.

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