Contrast ICE for Myocardial Scar in VT Ablations
Condition: Ventricular Tachycardia; Ischemic Cardiomyopathy
MeSH terms: Cardiomyopathies; Tachycardia; Tachycardia, Ventricular
Study type: Interventional

Summary: 
      There is a high correlation between scar areas identified by contrast-enhanced ICE and scar
      areas identified by conventional electroanatomic mapping. Therefore, the investigators will
      assess the utility of contrast-enhanced ICE to identify and localize myocardial scar
      real-time during VT ablation procedures.
    

Detailed description: 
      Ventricular tachycardia (VT) is a life-threatening arrhythmia which occurs frequently in the
      setting of structural heart disease, most often as result of myocardial fibrosis or scar.
      Catheter ablation is often performed to treat recurrent VT, but is predicated on precise
      localization of myocardial scar, as scar is often the source of VT. Currently during VT
      ablation procedures the identification of scar is based on electroanatomic mapping where
      bipolar voltage criteria have been established (i.e., bipolar electrogram voltage < 1.5 mV is
      considered scar). However this definition is purely based on electrical signal information
      and so has significant limitations: 1) there has not been definitive establishment of the
      sensitivity and specificity of this threshold for defining scar in comparison with tissue; 2)
      a detailed 3-D map created by time-consuming movement of the mapping catheter must be
      obtained in order to assess the existence and location of the scar; 3) only scar on the
      surface in contact with the mapping catheter (most often endocardial) may be definitively
      identified, whereas there may be intramyocardial or epicardial scar that would not be
      identified unless the mapping catheter makes direct contact with those areas which may
      involve additional risky access (epicardial) or even impossible (intramyocardial). For these
      reasons it would be very helpful to have another method to identify and localize myocardial
      scar during a VT ablation procedure. Cardiac MRI has been validated for identifying and
      localizing scar, but would not be recommended for many patients due to presence of ICD
      (implantable cardioverter-defibrillator) devices in these patients. Contrast-enhanced
      echocardiography has been validated to identify myocardial scar (Montant 2010), and
      intracardiac echocardiography (ICE) is standardly used in VT ablation procedures. Therefore,
      the investigators will assess the utility of contrast enhanced ICE by identifying and
      localizing myocardial scar real-time during VT ablation procedures.
    

Intervention name(s): Perflutren Lipid Microsphere Intravenous Suspension [DEFINITY]
Intervention type(s): Drug
Intervention description(s): Perflutren 1.3mL diluted in 50 mL is infused intravenously, and intracardiac echo imaging is recorded to analyze for areas of possible myocardial scar, which is then compared with areas of abnormal electrical signal via direct catheter mapping which is performed during ablation of ventricular tachycardia.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic