The goal of this study is to develop advances in cardiovascular diagnostic and treatment methods using magnetic resonance imaging (MRI), a test that uses a strong magnetic field and radio waves to show anatomic detail. For the scan, the patient lies on a table in a cylinder containing a magnetic field. He or she can communicate with a staff member at all times during the procedure.

Patients 18 years of age or older who require 1) catheterization of the leg arteries for diagnosis or treatment of blocked arteries, or 2) heart catheterization for diagnosis or treatment of coronary artery disease or other heart problems may be eligible for this study. Participants will undergo one of the following procedures:

Blood Flow Measurement Using Standard Techniques and MRI

For patients with blockage in a leg artery, blood flow will be measured before and after successful catheter-based treatment (angioplasty or stenting) using standard venous occlusion plethysmography and a newer MRI technique. (Patients whose treatment is not successful will not undergo follow-up blood flow measurements in this study.) For venous occlusion plethysmography, a large pressure cuff is placed around the upper or lower legs. Thin elastic bands called a strain gauge are placed around the calves to measure blood blow to the legs. The pressure cuffs are inflated for 5 minutes, preventing blood from flowing to the legs, and are then deflated, allowing the blood to rush to the legs. A smaller cuff is inflated to a low pressure, and the strain gauge measures this maximum blood flow to the legs for 1 or 2 more minutes. For the new MRI technique, blood flow is measured while the patient is in the MRI scanner. Flow is first measured with the patient at rest. Then, the large pressure cuff is inflated for 5 minutes. The cuff is deflated and additional images are taken. Before the cuff is deflated, a dye called gadolinium contrast is injected into an arm vein to brighten the images. Patients may undergo six to eight cuff inflations on four to six different days.

Fusion of X-Ray and MRI Images of Peripheral Arteries

For patients with blockage in a leg artery - Participants will undergo catheterization and MRI of the legs. Special plastic beads are taped to the leg(s) to help compare the MRI and x-ray pictures. For the catheterization procedure, x-rays of the blood vessels are taken to guide placement of the catheters. Contrast dye is injected to brighten the images of the blood vessels. These injections work well in normal and partly blocked arteries, but not in arteries that are completely blocked. For this study, patients first have an MRI scan of their legs. During the scan, gadolinium contrast dye is injected into an arm vein. Then, during the catheterization procedure, a computer aligns the MRI pictures with the x-ray pictures to see if the combined images allow the doctor to better see where to place the catheters.

Fusion of X-ray and MRI Images of the Heart

For patients undergoing heart catheterization will undergo MRI and heart catheterization. Special plastic beads are taped to the chest to help compare the MRI and x-ray pictures. Patients first have an MRI scan of their heart. During the scan, gadolinium contrast dye is injected into an arm vein. Then, during the catheterization procedure, a computer aligns the MRI pictures with the x-ray pictures to see if the combined images allow the doctor to learn more about the pattern of heart disease.

Heart rhythm, blood pressure, heart function, and breathing will be monitored during all the MRIs.

Condition	Treatment or Intervention	Phase
03-H-0250	Procedure: MRI	Phase I

Further Study Details: 

Expected Total Enrollment:  56

Cardiovascular interventional procedures are minimally-invasive, catheter-based treatments such as coronary artery angioplasty and stenting. These procedures generally can be conducted on awake patients with few complications, and were developed as alternatives to conventional open surgery. Conventional cardiovascular interventional procedures are conducted by physicians manipulating medical devices inside patients under the guidance of fluoroscopic x-ray.

We are developing minimally-invasive cardiovascular interventional procedures using real-time magnetic resonance imaging, also known as MR Fluoroscopy. These procedures have the advantage of excellent imaging without surgery and without radiation exposure or toxic contrast agents (dyes). Moreover, because MR Fluoroscopy can produce excellent images of soft tissue, blood, and of three-dimensional structures, it may be possible to guide minimally-invasive procedures not possible even with invasive surgery.

The goal of this protocol is to develop and test incremental technical advances in patients.

Genders Eligible for Study:  Both

Criteria

Exclusion Criteria for All Arms of the Protocol
Patients with absolute contraindications to MRI scanning will be excluded. These contraindications include patients with the following devices:
Implanted cardiac pacemaker or defibrillator
Central nervous system aneurysm clips
Implanted neural stimulator
Cochlear implant
Ocular foreign body (e.g. metal shavings)
Insulin pump
Metal shrapnel or bullet.
When patients can provide evidence that their implanted device is labeled compatible with MRI, exceptions to the above exclusions can be made and recorded in the note. Furthermore, the following patient groups will be excluded because of the administration of MRI contrast agents:
Pregnant women (Patients who are uncertain as to whether they are pregnant will be required to have a screening urine or blood pregnancy test) or Lactating Women.
Patients with hemoglobinopathies
Patients with renal disease (CLcr less than 20 ml/min)
The creatinine clearance (CLcr) will be calculated in patients with known or suspected kidney disease using the Cockroft-Gault formula where (age) is in years, (kg) is weight in kilograms, and (Cr) is the serum creatinine within 12 months. If there is no history or suspicion of kidney disease from the patient or referring physician, this testing will not be performed. If a patient has a history of renal insufficiency, a recent blood Cr will be used unless the physician performing the test believes the Cr may have changed since the last test.
CLcr equals (140 minus Age) X (Weight (kg)) divided by Cr X 72 for men; for women, multiply by 0.85
Inclusion Criteria for All Arms of the Protocol
Patients with known or suspected cardiovascular disease will be eligible for participation in this protocol. The patient is eligible under the following conditions:
Patient's age is greater than 18 years of age.
Expected to undergo a clinically-indicated diagnostic or therapeutic catheterization procedure.
Additional Exclusion Criteria for Section #2: Lower Extremity Perfusion Measures
A patent autologous or prosthetic bypass graft that would require compression during arterial occlusion to induce reactive hyperemia. This exclusion is intended to avoid graft injury and possible thrombosis. If an old graft is known to be non-functional, from radiocontrast or MRI angiography, then this exclusion does not apply.
A patent intravascular stent that in a territory that would be compressed during arterial occlusion to induce reactive hyperemia. This exclusion is intended to avoid theoretical stent crush or fracture. If the stented vessel is known to be completely occluded, from radiocontrast or MRI angiography, then this exclusion does not apply. However, occlusive cuffs may be placed above or below stent devices to avoid this theoretical complication.
Active deep vein thrombosis of the lower extremity based on clinical findings.

Maryland
      National Heart, Lung and Blood Institute (NHLBI), 9000 Rockville Pike,  Bethesda,  Maryland,  20892,  United States; Recruiting

Study ID Numbers:  030250; 03-H-0250
Record last reviewed:  June 22, 2004
Last Updated:  November 23, 2004
Record first received:  July 14, 2003
ClinicalTrials.gov Identifier:  NCT00064896
Health Authority: United States: Federal Government
ClinicalTrials.gov processed this record on 2005-04-08