Variability in Agitated Saline Echocardiography Protocols: A Cross-Sectional Analysis of Bubble Study Techniques in Echo Labs Across Alberta, Canada

Intrapulmonary right-to-left shunts (RLS) are a clinical concern in Hereditary Hemorrhagic Telangiectasia (HHT), contributing to dyspnea, brain abscess, and ischemic stroke. HHT is a genetic disorder characterized by arteriovenous malformations (AVMs), with pulmonary AVMs (PAVMs) being a major source of intrapulmonary shunting. Screening for PAVMs is essential to prevent paradoxical embolization, guide management, and mitigate mortality risk. Agitated saline contrast echocardiography ("bubble echo") is the recommended method for detecting and grading RLS, as outlined in International HHT Guidelines. Given Western Canada's large rural population, satellite HHT clinics and affiliated echo labs have been established to improve access to care. This observational cross-sectional study evaluated the written policies governing bubble-echo protocols across Alberta's accredited echocardiography laboratories. With the help of the College of Physicians and Surgeons of Alberta (CPSA), all CPSA-accredited adult echocardiography laboratories were contacted (as of July 15, 2024) to determine whether they perform RLS assessments and to obtain available written bubble-echo protocols. Of the 62 accredited facilities identified, 12 performed bubble-echo studies. Policy review of participating labs revealed notable variations in injection techniques and shunt grading criteria. These findings suggest that considering a standardized protocol could reduce variability and allow for more reliable comparisons over time.