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.

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.

Inclusion Criteria:

• Age range 18-89 years old
• Diagnosis of Hereditary Hemorrhagic Telangiectasia by the Curacao criteria
• Prior diagnosis of one or more PAVMs treated by embolotherapy
• Chest CT performed within the Penn system for surveillance of PAVMs after \ embolotherapy

Exclusion Criteria:

• Known PAVM recurrence on most recent chest CT with feeding artery size amenable to repeat embolotherapy
• Known history of intracardiac shunt
• Discovery of intracardiac shunt during transthoracic contrast echocardiography

Individuals with a diagnosis of Hereditary Hemorrhagic Telangiectasia and a follow-up chest CT scan for PAVM surveillance after embolotherapy.