Cardiovascular Physiology Autonomic Function Laboratory

The global focus of the Cardiovascular Physiology Autonomic Function Laboratory is to examine the adaptive capacity of the circulation.

  • Dr. Levine studies the effects of exercise training, bed rest deconditioning, spaceflight, high altitude, aging, and the effects of cardiovascular diseases, such as heart failure.
  • By using sophisticated tools to assess cardiovascular structure and function, Dr. Levine and his research team bring "Olympic" and "space age" science to the solution of common clinical problems such as fainting, hypertension, or patients with shortness of breath. 
  • The Cardiovascular Physiology Autonomic Function Laboratory focuses on measuring how the cardio-respiratory system distributes oxygen from the environment to the muscles.
  • Our facility is one of the few labs in the world that can measure the limitations to exercise capacity at every step along the "oxygen cascade" - including the lungs, heart and muscles.
  • We use invasive and non-invasive tools to assess cardiovascular structure and function, as well as circulatory control mechanisms.

Interests

The Impact of atrial fibrillation on exercise performance in patients with HFpEF (Heart failure with preserved ejection fraction)

  • About half of all elderly patients with a diagnosis of congestive heart failure have seemingly normal systolic function, so called ‘Heart failure with a preserved ejection fraction” or HFpEF. 
  • A common condition that these patients also have is atrial fibrillation (AF), with approximately two-thirds developing AF over the course of their disease.
  • The contribution of Atrial fibrillation to shortness of breath with exertion is unclear.  However, we hypothesize that patients with HFpEF and atrial fibrillation have markedly impaired aerobic capacity and exercise hemodynamics when in atrial fibrillation, compared to sinus rhythm. 

Mechanisms of Exercise Intolerance in Heart Failure with Preserved Ejection Fraction (HFpEF)

  • This multi-factorial condition, also called “diastolic heart failure” is associated with several abnormalities in diastolic function including increased chamber stiffness, impaired relaxation and impaired ventriculo-arterial coupling.
  • To date, there is no consensus on the key physiologic pathways that cause this type of heart failure.
  • Dr. Levine’s lab seeks to find out what causes exercise intolerance and shortness of breath (dyspnea) on exertion in these patients, and if specific exercise programs (whole body vs. single leg) will result in improved exercise tolerance.

Synchronizing Cardiac Cycle Phase with Foot Strike to Optimize Left Ventricular performance in Patients with Advanced Heart Failure and Cardiac Resynchronization Therapy (CRT)

  • Cardiac resynchronization therapy involves the insertion of electrodes in the left and right ventricles of the heart, as well as on occasion the right atrium, to treat heart failure by coordinating the function of the left and right ventricles via a pacemaker.  The pacemaker controls the timing of the upper heart chambers (atria) to the lower heart chambers (ventricles)
  • The investigators are curious about the effects of gait and cardiac cycle phase synchronization on muscle oxygenation, cardiac function and exercise performance in patients who have advanced heart failure and who have a CRT pacemaker. 
  • Subjects will walk on a treadmill for several short sessions; some of the sessions will include walking/stepping to an auditory tone. The auditory tone will attempt to synchronize to the patient’s heartbeat.

Safe and Effective Countermeasures to Reduce Intracranial Pressure (ICP) and Ameliorate Visual Impairment in Astronauts;

  • Current estimates suggest that up to 60% of astronauts report degraded visual acuity during short and long duration space flights.
  • Findings suggest ocular remodeling, which are consistent with signs and some symptoms reported in patients with increased intracranial pressure
  • In previous studies performed by Dr. Levine and his research team, we have demonstrated that the use of lower body negative pressure (LBNP) at -20 mmHg for 8 hours/day while in deep down head tilt restored circadian variability in ICP and prevented the expansion or thickening of choroid.

Current Projects

  • Synchronizing cardiac cycle phase with Foot Strike to Optimize LV Performance in Patients with Advanced Heart Failure and Cardiac Resynchronization Therapy
  • Mechanisms of Exercise Intolerance in Heart Failure with Preserved Ejection Fraction: ‘Precision’ Therapy Based on Patient Specific Pathophysiology
  • Efficacy of High Intensity Exercise  (HIE) for Increasing Cardiorespiratory Fitness in Patients with Hypertrophic Cardiomyopathy (HCM)

Media

Dr. Levine explains how his research with astronauts, whose physiology is affected by the lack of gravity, led to research on the circulation of the bed-ridden and elite rowers. He describes how exercise can help aid recovery from disease and the effects of space-flight at the March 2012 meeting, "The Biomedical Basis of Elite Performance," hosted by the Physiological Society, in partnership with the British Pharmacological Society and Wiley-Blackwell, and sponsored by the Gatorade Sports Science Institute.

Researchers

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