Heart Catheterization Using Magnetic Resonance Imaging (MRI) Fluoroscopy and Passive Guidewires

Overview

Background: A heart catheterization is a diagnostic heart procedure used to measure pressures and take pictures of the blood flow through the heart chambers. Magnetic resonance imaging (MRI) fluoroscopy shows continuous pictures of the heart chambers that doctors can watch while they work. Researchers want to test this procedure with catheterization tools routinely used in x-ray catheterization called guidewires. Guidewires will help move the heart catheter through the different heart chambers. Guidewires are usually considered unsafe during MRI because MRI can cause a guidewire to heat while inside the blood vessels and heart. Researchers are testing special low energy MRI settings that allow certain guidewires to be used during MRI catheterization without heating. Using these guidewires during MRI may help to decrease the amount of time you are in the MRI scanner, and the overall time the MRI catheterization procedure takes. Objectives: To test if certain MRI settings make it safe to use a guidewire during MRI fluoroscopy. Eligibility: Adults 18 and older whose doctors have recommended right heart catheterization. Design: Researchers will screen participants by reviewing their lab results and questionnaire answers. Participants may give 4 blood samples. Participants will be sedated. They will have a tube (catheter) placed in the groin, arm, or neck if they don t already have one. Patches on the skin will monitor heart rhythm. Special antennas, covered in pads, will be placed against the body. Participants will lie flat on a table that slides in and out of the MRI scanner as it makes pictures. Participants will get earplugs for the loud knocking noise. They can talk on an intercom. They will be inside the scanner for up to 2 hours. They can ask to stop at any time. During a heart catheterization, catheters will be inserted through the tubes already in place. The catheters are guided by MRI fluoroscopy into the chambers of the heart and vessels. The guidewire will help position the catheter.

Heart catheterization is a minimally invasive procedure to measure pressure into specific heart cavities. Heart catheterization usually uses X-ray guidance, which involves radiation exposure, and which fails to visualize soft tissue. For several years, real-time magnetic resonance imaging (MRI) fluoroscopy has been the standard technique to guide right heart catheterization at the NIH clinical center. Guidewires are standard tools used to steer catheters through the body and heart. Guidewires have not been used during MRI fluoroscopy catheterization because of the risk of heating. We have developed MRI techniques that do not risk heating using specific commercial guidewires. In this protocol we will use this new low-energy real-time MRI fluoroscopy technique to enable use of guidewires during otherwise standard MRI catheterization of the right side of the heart through veins, and of the left side of the heart through the aorta. In the second phase of the protocol, we will begin performing systematic MRI guidewire heart catheterization without X-ray whenever possible. We will assess the heart s response to hemodynamic provocation during MRI catheterization tailored to the patient s problem. We will use this protocol to further refine the technique. This will enable future testing of devices for adult and pediatric MRI-fluoroscopy catheterization, which may lead to new non-surgical treatments of cardiovascular disease.