As NASA moves toward long-duration missions, it is imperative that the adverse health effects of the space environment be understood. The cardiac effects of radiation from medical, occupational, and environmental exposures are of critical concern. This experiment aims to understand cardiac events from exposure to radiation therapy to develop tools for early identification of cardiac injury.
Human radiotherapy cohorts have not been utilized to identify adverse outcome pathways, progression rates and latency periods, and early surrogate markers for radiation-induced cardiovascular disease. The experiment will acquire data on cardiovascular impairments and associated biomarkers observed in patients undergoing cardiac exposure to ionizing radiation with emphasis on non-invasive imaging modalities to quantify predictive changes linked to late impairment. Identifying damage early on may prevent cardiac dysfunction though the use of interventions. Understanding cardiac functional changes that occur during and soon after radiation therapy may lead to the development of therapeutic interventions.
The objective of the experiment is to identify early markers of cardiac injury after radiation exposure in a timely manner so that steps can be taken to prevent irreversible cardiac dysfunction. In a short period after cardiac radiation exposure inflammation occurs and biomarkers are released. Without treatment radiation exposure progresses to reversible cardiac dysfunction and then irreversible cardiac dysfunction. Irreversible cardiac dysfunction can lead to coronary artery disease, valvular disease, myocardial damage, conduction defects, and diastolic dysfunction. This experiment has the following specific aims:
Approximately 30 patients who are receiving standard radiation therapy with moderate cardiac exposure, which is an estimated mean heart dose 6-12 Gy, will be enrolled in the study. Investigators will gather preliminary data, provided initial estimates, and explore potential associations. Several tests will be utilized to assess for early cardiac effects of radiation exposure. For aim 1, patients will undergo an echocardiogram with global longitudinal strain measurements. The percentage of patients who experience a cardiac injury, which is a strain reduction of greater than 10 percent from pre-treatment/detection of serum ultrasensitive troponin, will be reported. Included in the report will be whether the cardiac injury was determined by strain, detectable troponin, or both. For aim 2, dosimetry and cardiac MRI photos will be used to visually identify possible relationships. Side-by-side comparisons of three-dimensional (3D) magnetic resonance imaging (MRI) scans and radiation treatment plans will be performed. For aim 3, the relationship between regions of early cardiac injury and biomarkers will measured repeatedly over time.
The experiment is in progress. Results will be available at a later date.
Enrolled patients will undergo:
Evaluation by echocardiography with strain measurements and by cardiac MRI:
Patient history and physical examination (including patient reported outcomes regarding functional capacity:
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