X-ray Fluoroscopy Fused With Computed Tomography (XFC) Technical Development

Background: * Computed tomography (CT) creates three-dimensional images based on X-ray imaging. CT is useful for determining treatment approaches for certain diseases, such as calcific aortic stenosis (narrowing of the aorta because of calcium deposits). * Comparing the data received from CT scans with the data received from heart catheterization (which assesses the heart's condition and function) can be used to improve treatment in patients with certain heart conditions. Researchers are interested in looking at the effectiveness of both procedures in assessing possible surgical treatments for patients with calcific aortic stenosis. Objectives: \- To analyze cardiac CT scans in conjunction with existing heart scan results to improve treatments for future minimally invasive aortic valve replacement. Eligibility: \- Patients 18 years of age and older who have been diagnosed with aortic valve stenosis that may be treated surgically, and who will undergo or have recently undergone heart catheterization. Design: * Participants will have a CT scan within 90 days of the medically necessary heart catheterization, but before any other surgical or catheter treatment. * During the CT scan, patients will be asked to hold their breath intermittently for about 5 to 20 seconds. Patients will be inside the scanner for less than 30 minutes. * Patients will be asked to return in 3 to 7 days for a blood test to check kidney function. * Researchers will analyze the results of the CT scan in conjunction with the previous results from the catheterization to determine possible improved treatment options.