Graded TTCE for Post-Embolization PAVM Monitoring
Condition: Hereditary Hemorrhagic Telangiectasia (HHT)
MeSH terms: Telangiectasis; Arteriovenous Malformations; Telangiectasia, Hereditary Hemorrhagic
Study type: Observational

Summary: 
      Current HHT guidelines recommend CT scan to detect new or recurrent PAVMs after
      embolotherapy. Recent studies using transthoracic contrast echocardiography (TTCE) shunt
      grade for PAVM screening suggest that graded TTCE can accurately predict the size of PAVMs on
      chest CT and their amenability to embolization. This study's purpose is to evaluate whether
      TTCE shunt grade can also accurately predict PAVM size and amenability to treatment in
      patients who are post-embolization.
    

Detailed description: 
      Embolization is the standard of care for pulmonary arteriovenous malformations (PAVMs) in the
      Hereditary Hemorrhagic Telangiectasia (HHT) population. PAVMs are abnormal connections
      between the veins and arteries and result in right-to-left shunting of blood within the
      lungs. Successful embolization results in PAVM resolution and decreases the complications
      associated with right-to-left shunting. Current guidelines recommend follow-up with interval
      chest CT scan to determine treatment success and detect new or recurrent PAVMs after
      embolization. This results in significant radiation exposure to the relatively young HHT
      population. An alternative to chest CT is graded transthoracic contrast echocardiography
      (TTCE), which measures the amount of right-to-left shunting within the lung and assigns a
      grade based on this amount. TTCE has the advantage of being radiation free compared to chest
      CT. To date, graded TTCE has only been studied as a screening tool for PAVMs. These studies
      have shown that graded TTCE is highly sensitive in detecting PAVMs and is comparable to chest
      CT when screening for PAVMs. Results indicate that TTCE grade can accurately predict PAVM
      size on chest CT and predict whether PAVMs are amenable to embolization. However, no studies
      have compared graded TTCE and chest CT in patients who are post-embolization and it is
      therefore unknown whether graded TTCE can be used in patients who have undergone PAVM
      embolization. The current study seeks to correlate post-embolization TTCE grade with chest CT
      findings to determine whether TTCE can accurately predict PAVM size and amenability to
      treatment in the post-embolization population.
    

Intervention name(s): Transthoracic Contrast Echocardiogram
Intervention type(s): Other
Intervention description(s): A transthoracic contrast echocardiogram (TTCE) is a still or moving image of the internal parts of the heart using ultrasound following the injection of microbubble contrast (agitated saline) into a vein in the arm, which then travels to the heart.
Observational model: Other
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Individuals with a diagnosis of Hereditary Hemorrhagic Telangiectasia and a follow-up chest
        CT scan for PAVM surveillance after embolotherapy.
      
Keywords: Hereditary Hemorrhagic Telangiectasia (HHT); Pulmonary Arteriovenous Malformation (PAVM); Transthoracic Contrast Echocardiogram (TTCE)