The National Space Biomedical Research Institute is interested in learning more about heart
function in space. One potential problem with long duration, manned space flight is muscle
loss- including loss of heart muscle. One goal of our research is to help identify why this
muscle loss occurs. We are interested in patients undergoing aortic valve surgery because
this procedure is performed to correct a problem with the valve that may also change heart
function. This change in heart function may provide information that is useful in
understanding and potentially preventing the loss of cardiac muscle in space.
Three patient groups will be studied, patients having surgery for aortic regurgitation,
aortic stenosis, and coronary bypass. We are planing to perform this study on 30 patients,
10 in each group.
The aim of this study is to continue our ongoing study of the magnitude and predictors of
the changes in size of the left ventricle following acute volume and pressure unloading as a
ground-based analog for manned space flight.
Among the most serious of the risks identified by NASA in the area of cardiovascular
alterations are serious dysrhythmias and the development of orthostatic intolerance.
Prolonged exposure to microgravity may lead to a reduction in cardiac performance,
particularly during times of stress and that undiagnosed cardiovascular disease may manifest
during long missions. The PI and colleagues have worked closely with NASA and NSBRI over the
last six years to optimize use of ultrasound in the space program as an investigative
modality, addressing fundamental cardiovascular problems in need of countermeasures
development. We propose the following specific aim:
To continue our ongoing study of the magnitude and predictors of LV mass regression
following acute volume and pressure unloading as a ground-based analog for manned
spaceflight. This work will continue to focus on patients undergoing aortic valve surgery,
but exploit recent knowledge of the roles of cytokines and integrins involved in cardiac
hypertrophy and regression as well as emerging technologies such as gene chip analysis.
This work will be closely focused on risks and critical questions identified by the
Cardiovascular Alterations Team as described in the Bioastronautics Critical Path Road Map
Baseline Document. If successful, this project will enhance assessment of cardiac function
during long duration missions and potentially suggest cytokine promoters or signal
transduction pathways that could be targeted for cardiac atrophy countermeasures. In
addition, we will continue to provide the facilities of our Core laboratory for access by
investigators throughout the NASA and NSBRI programs in need of assistance in acquiring or
analyzing ultrasonic data.
- > 18 years of age
- Isolated severe aortic stenosis
- Preserved left ventricular function
- CABG patients will have normal LV function and mass