Technical Development of Cardiovascular Magnetic Resonance Imaging
Condition: Cardiomyopathy; Congenital Heart Disease; Cardiovascular Disease; Cardiac Magnetic Resonance Imaging; Acute Myocardial Infarction
MeSH terms: Cardiovascular Diseases; Heart Diseases; Myocardial Infarction; Cardiomyopathies; Heart Defects, Congenital; Infarction
Study type: Observational

Summary: 
      This study will explore new ways of using magnetic resonance imaging (MRI) to evaluate the
      heart and blood vessels of patients with cardiovascular disease, including better detection
      of myocardial infarction (heart attack) and blockage of heart and leg arteries.

      Patients 18 years of age and older with cardiovascular disease may be eligible for this
      study.

      All participants will have magnetic resonance imaging of the heart. MRI uses a magnetic field
      and radio waves to show structural and chemical changes in tissues. For the procedure, the
      patient lies on a table surrounded by a metal cylinder (the scanner). A 'gadolinium contrast'
      material may be injected into the patient s vein during part of the study to brighten the
      images. Patients wear earplugs during the scan to muffle loud knocking sounds caused by the
      electrical switching of the magnetic fields. They will be asked to hold their breath
      intermittently for 5 to 20 seconds during the scan. They will be monitored with an
      electrocardiogram (EKG) during the procedure and will be in contact by intercom at all times
      with the person performing the scan. Patients can request to stop the study and come out of
      the scanner at any time. The procedure may last from 30 to 90 minutes. An echocardiogram a
      test that uses sound waves to produce pictures of the heart and blood vessels-may be done to
      confirm the MRI findings. In addition, patients may undergo one or more of the following
      optional studies:

        -  Dobutamine stress MRI - This test uses dobutamine-a medicine that simulates exercise by
           increasing heart rate and heart function-to detect blockages in the coronary arteries
           (vessels that supply oxygen and nutrients to the heart) and locate areas of the heart
           that are permanently damaged, perhaps by a previous heart attack. For this test, MRI
           pictures of the heart are taken before, during and after administration of dobutamine.
           Gadolinium may be injected during part of the study to brighten the images. An EKG will
           be used to monitor the heart during the procedure.

        -  Vasodilator MRI - The procedure and objectives of this test are the same as those
           described for dobutamine stress MRI, except that this study uses dipyridamole or
           adenosine. These drugs dilate blood vessels, causing increased blood flow to the heart.

        -  Plethysmography MRI - This test determines the presence and severity of narrowing in
           arteries that supply blood to the leg. Blockage of these vessels often causes pain while
           walking. This study will compare plethysmography MRI with venous occlusion
           plethysmography, an older method of measuring blood flow in the legs. For venous
           occlusion plethysmography, a large blood pressure cuff is placed around the upper leg
           and a strain gauge (thin elastic band) is placed around the calf. The pressure cuff is
           inflated very tightly for 5 minutes to block blood flow to the leg, and another pressure
           cuff over the ankle is also inflated. When the large cuff is deflated, blood rushes to
           the leg, a smaller cuff is inflated to a low pressure, and the strain gauge measures the
           maximum blood flow to the leg for 1 or 2 more minutes. This procedure is done once or
           twice outside the MRI scanner and once or twice inside the scanner. The scans are
           performed as described above for the dobutamine and vasodilator studies. The strain
           gauge is not used for plethysmography MRI the MRI pictures are used to measure flow.
    

Detailed description: 
      The purpose of this protocol is to allow development and testing of new MRI techniques
      suitable for evaluating patients with cardiovascular disease. Since such technical
      development work often depends on preliminary studies in healthy volunteers, the protocol
      also recruits healthy subjects. This protocol will provide the framework for technical
      development scans in patients with cardiovascular disease.
    

Intervention name(s): Siemens MRI scanner
Intervention type(s): Device
Intervention description(s): Investigational or research MRI coils may be used in the protocol. The coils are noninvasive devices external to the body. The coils act as antennae to receive small radiofrequency signals out of the body. Coils of the type we use are used daily in clinical MRI practice.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients with cardiovascular diseases and healthy subjects 18 years of age or older were
        recruited within this protocol. The exclusion criteria were developed from standard
        clinical practice but were more restrictive to err on the side of safety. Recruitment was
        via referral from local physicians. In addition, advertisements were placed in the
        "Washington Post". Finally, the protocol was listed on the NIH websites.

        A patient could participate in any combination of these tests/procedures. Clinical judgment
        was used to determine the number of tests/procedures suitable for a given patient.
        Specifically, the responsible physician avoided prolonging tests/procedures in patients in
        accordance with the patient's clinical status.
      
Keywords: Myocardial Infarction; Myocardial Viability; Myocardial Perfusion; Myocardial Ischemia; Atherosclerosis