Transthoracic contrast echocardiography for detection of pulmonary arteriovenous malformations in hereditary hemorrhagic telangiectasia: How can the process be improved for patient safety?

Abstract

Introduction: Patients with hereditary hemorrhagic telangiectasia (HHT) are at risk for pulmonary arteriovenous malformations (PAVMs). Extracardiac right-to-left shunts due to PAVMs can lead to systemic emboli; clinical sequelae including strokes and brain abscesses. Regular screening is required, with appropriate medical/interventional management to alleviate morbidity and mortality from PAVMs.  International HHT guidelines recommend standardized transthoracic contrast echocardiogram (TTCE) with agitated saline (in an HHT Foundation-accredited laboratory) as the initial screening test, and, when needed, non-contrast computerized tomography of the chest (CT Chest) to follow up on a positive TTCE.

Case presentation: A 40-year-old woman was seen for evaluation of HHT and referred for TTCE as part of her PAVM screen. Following administration of agitated saline, she developed a headache, visual changes in her right eye, and right arm weakness, followed by posturing and stiffness in her right arm. Her symptoms resolved after five minutes, consistent with a transient ischemic attack (TIA).

Clinical impact: Protocols at our institution were amended following this index case and echocardiography laboratory protocols were adjusted to use a maximum of 0.1 cc air to 9.9 cc saline for TTCE studies in the HHT population. Only the attending echocardiologist who is familiar with possible systemic air embolism during bubble contrast echocardiography in patients with HHT should perform agitation and infusion of contrast and should directly review the images for appropriate visualization during the exam for this test to be appropriately interpreted. Paradoxical emboli due to right-to-left shunt are important to recognize. Best practice for PAVM screening in HHT patients includes use of standardized protocols for the performance and reporting of TTCE in the evaluation of pulmonary shunts.