Predictors for Pulmonary Valve Replacement - Anatomic and Hemodynamic Using MRI
Condition: Congenital Disorders
MeSH terms: Tetralogy of Fallot
Study type: Observational

Summary: 
      Magnetic Resonance Imaging (MRI) is a non-invasive test that can look at the heart without
      using radiation. An MRI will allow the doctors to look at the heart in order to assess how
      well the ventricle is pumping, the amount of blood that it is pumping in addition to how much
      it is stretching. An engineer at Georgia Tech has developed a new way of looking at an MRI.
      It is believed that this new way of looking at an MRI may be better able to tell us when to
      replace the valve in these children. If this new process works, not only can we apply it now
      but we will be able to look at previously performed MRIs and gather more information about
      these children and their heart function in order to help these and other children in the
      future.

      We are planning on enrolling 30 subjects in this study. Some of the subjects will be enrolled
      and have their MRI strictly for the purpose of this study. Some of the subjects will be
      already scheduled for a routine MRI of their heart and we will ask them if we can do extra
      images for the study while they are already here.
    

Detailed description: 
      Cardiovascular disease remains a leading cause of morbidity and death in the Western World.
      Assessment of Myocardial function has proven to be a clinically relevant method for
      monitoring and evaluating outcomes of medical therapy and surgery for structural lesions or
      acquired disease.

      Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease with a
      prevalence of 0.26 to 0.8 per 1000 live births The current surgical approach favors primary
      repair in infancy. This decreases the necessity for palliative procedures and has a low
      operative mortality. Complete repair often results in pulmonary regurgitation (PR), which is
      generally well tolerated in infancy. Late complications may include ventricular dilatation,
      tricuspid regurgitation, diastolic and systolic dysfunction, arrhythmias and sudden cardiac
      death.

      Pulmonary valve replacement (PVR) is required in approximately 20% of patients with repaired
      TOF and has a 1-4% peri-operative mortality. Thus, early intervention may reduce irreversible
      right ventricle injury; however no definitive tools are presently available for determining
      patients at risk.

      Myocardial strain analysis has not been critically evaluated to determine its value for
      predicting RV failure. This study will investigate the practicality and accuracy of a novel
      mathematical method, developed by the investigators, for analysis of cardiac deformation
      recovery from dynamic Cardiovascular Magnetic Resonance Imaging (CMRI) sequences. The
      proposed method requires structural MRI data, offering several important advantages over
      existing methods. These include reduced requirements in imaging time and analysis effort, and
      the option to use a large database of prior structural MRI studies of TOF patients in
      retrospective research.

      This three-dimensional method is mathematically based on nearly incompressible tissue
      deformations. The project proposes validation of technique, comparing its results with
      current 'gold standard' methods that presently use CMRI myocardial tagging and phase velocity
      mapping, as a pilot study for clinical validation of strain imaging in TOF patients. The
      method tracks movement of myocardial tissue throughout the cardiac cycle to compute strain
      associated with normal and a clinical disease state.

      During the study we will customize the method and software for specific use with CMRI and
      TOF. We will test the method on normal controls and TOF patients pre and post pulmonary valve
      replacement.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Pediatrics and young adults aged 3-30 years following surgical repair of Tetralogy of
        Fallot. Also looking at normal control subjects.
      
Keywords: MRI; Ventricular Strain; Pulmonary Valve Replacement; Post Tetralogy of Fallot